Information

Is it possible to reduce maturity time of plants with biotechnology?


I've heard of speed breeding which makes use of optimal circumstances in glasshouses and growth chambers. Is it also possible to shorten a plant's maturity time (i.e. the time it needs from being planted until the time its yield can be harvested) using genetic modifications?


Perhaps investigate the families of YUC genes that synthesize the growth hormone auxin (ncbi.nlm.nih.gov/pmc/articles/PMC6941117) and ARF genes (ncbi.nlm.nih.gov/pmc/articles/PMC4737911) that respond to auxin. Auxin overproduction or changes to ARFs might speed growth. But some herbicides are synthetic auxins (e.g. 2,4-D) and work by exhausting and killing weeds (en.wikipedia.org/wiki/2,4-Dichlorophenoxyacetic_acid), so modifying these pathways may have unwanted side effects, depending on the crop.


Independent of the hormone manipulation suggested by Alex Reynolds, perturbation of transcription factor UPB1 has been found to have an effect on plant growth by Tsukagoshi and colleagues -- Transcriptional regulation of ROS controls transition from proliferation to differentiation in the root.

In short, disrupting UPB1 activity in model Arabidopsis roots alters the balance of free radicals, leading to delayed differentiation and continued cell growth. UPB1-deficient roots were faster growing and composed of larger cells. Artificially increasing UPB1 activity resulted in slower root growth.

Taking OP's definition of maturity time --

the time it needs from being planted until the time its yield can be harvested

-- the agricultural utility of this mutation depends on the crop. If the goal is to increase the amount of biomass as fast as possible, this is likely a beneficial mutation. If the goal is to decrease the time needed for a plant to bear mature fruit, this mutation would not be ideal, given that disruption of UPB1 activity leads to slowed cell differentiation.


11 Biotechnology Pros and Cons

Biotechnology is a field that merges concepts from biology with concepts of technology. It is broken down into four separate disciplines that are often represented by specific colors: red, white, blue, and green. These colors represent medical processes, industrial processes, marine processes, and agricultural processes respectively.

Advancement is the primary benefit that biotechnology is able to provide. Early pioneers in this field used information about various plant species to create cross-breeding opportunities to improve yield, flavor, size, and color of their harvests. Today’s biotechnology specialists are doing the same thing, but on a much larger scale thanks to technology improvements in the 20th and 21st centuries.

Abuse is the primary disadvantage that biotechnology can provide. When the concepts of this field of study are misused, it can have a devastating effect on people, society, the environment, and even our planet. For that reason, certain areas of study in biotechnology, such as human cloning, have been restricted or outlawed outright. In the wrong hands, biotechnology can even create weapons of mass destruction.

Here are additional biotechnology pros and cons to think about.

The Pros of Biotechnology

1. It can improve health and reduce hunger simultaneously.
Biotechnology has helped to improve the nutritional content of our food supply. Necessary vitamins and minerals can be produced in croplands and this reduces health issues that are related to a lack of nutrients. At the same time, biotechnology also improves cropland yields and nutritional density, so people can eat less and still receive the same nutritional values. That allows more people to have the food they need.

2. It creates flexibility within the food chain.
Biotechnology can also help croplands be able to produce foods that may not be possible under “regular” conditions. Using concepts from this field of study, it is possible to grow crops in the desert. It is possible to create crops that are naturally resistant to pests. Although the amount of land our planet can provide is finite, biotechnology allows us to be able to use more of it for what we need.

3. It offers medical advancement opportunities.
Biotechnology allows us to look within just as easily as we can look to the outside world for advancement. Studies that involve the human genome have allowed us to understand more about genetic diseases and some cancers, creating more effective treatments for them – and sometimes cures. It has allowed us to explore the reasons behind certain birth defects to understand the importance of folic acid. That makes it possible to extend average human lifespans.

4. It allows us to preserve resources.
Biotechnology gives us an opportunity to extend the lifespan of our food supplies. Practices that include salting foods to preserve them date back beyond Biblical times. Freezing and drying foods as methods of preservation have been known for centuries. Pasteur pioneered an approach of heating food products to remove harmful elements so they can be preserved for an extended period.

5. It helps us minimize or eliminate waste products.
According to National Geographic, the footprint that humanity leaves on our planet from waste is quite extensive. In 2006, the United States generated 251 million tons of trash. That equates to nearly 5 pounds of trash per person, per day. 65% of trash comes from homes and 55% of that trash will end up in a landfill. Biotechnology allows us to create waste products that have better biodegradable properties. It allows us to manage landfills more effectively. That way we can begin to minimize the footprint being left for future generations.

6. It can reduce infectious disease rates.
Biotechnology has helped us to create vaccines. It has helped us be able to create treatments that reduce difficult symptoms of disease. It has even helped us to learn how infectious diseases can be transmitted so their transmission can be reduced. That allows us to protect those who are most vulnerable to these diseases, giving them a chance to live a happy, fulfilling life.

The Cons of Biotechnology

1. It creates an all-or-nothing approach.
One of the biggest problems that biotechnology faces is a lack of genetic diversity. The processes included in this field can increase crop yields and improve medical science, but it comes at the price of a genetic bottleneck. Should something unforeseen happen, an entire crop or medical treatment opportunity could go to waste or even threaten the survival of certain species.

2. It is a field of research with many unknowns.
Although our database of biotechnology has greatly expanded in the last generation, there are still many long-term unknowns that we face. What happens if we tinker with the genetics of a person to treat a disorder? What happens to the environment if we dramatically alter crops to grow in locations that would normally not support crop growth? Should every action have an equal and opposite reaction, future generations could pay the price for our research that is happening today.

3. It could ruin croplands.
Biotechnology has allowed more vitamins and minerals to enter our food chain, but it could be coming at a cost. Many crops obtain their nutritional content from the soil in which they grow. If that soil is overloaded by the crop, it may lose its viability, even with crop rotation occurring. That may reduce the amount of growing time each land segment is able to provide while extending its recovery period at the same time. In some situations, the croplands could be permanently ruined.

4. It turns human life into a commodity.
In the United States, the Supreme Court has ruled that DNA which is lab manipulated is eligible to be patented. The foundation of this ruling was that altered DNA sequences are not found in nature. At the moment, complementary DNA, or cDNA, has been specifically mentioned as an example of what could be patented. Obtaining DNA to create altered DNA sequences for profit minimizes human life (or plant and animal life) to profit potential. It also opens the door to ethical and moral questions, such as when human life begins, with the purpose of maximizing the dollars and cents that can be obtained.

5. It can be used for destruction.
All the benefits that biotechnology can provide could also be turned into a weapon that is used for mass destruction. Crops can be improved, but they can also be destroyed. Medicines can be made with biotechnology, but diseases can also be weaponized. If left unchecked, biotechnology could even create a societal class that is created specifically for research purposes only.

Biotechnology has done much to improve our way of life. It has helped the world to become a much smaller place. At the same time, we still face many challenges that must be overcome.


Pathogen Indexing Technologies

I.G. Dinesen , A. van Zaayen , in Advances in Botanical Research , 1996

A Clonal Selection

Selection of healthy plants is often the first step in obtaining disease-free plant material. The selection process in commercial nurseries should be done from their cleanest and healthiest plants produced the previous season. Early spring is often the optimal time for selection of basic plant material because plants are stressed and disease symptoms are most likely to be apparent under the low light and poor growing conditions that prevail during this time. Moreover, differences in growth rate are most apparent during the early spring which makes it easier to select vigorous plants for propagation.


What are the risks of biotechnology?

Along with excitement, the rapid progress of research has also raised questions about the consequences of biotechnology advances. Biotechnology may carry more risk than other scientific fields: microbes are tiny and difficult to detect, but the dangers are potentially vast. Further, engineered cells could divide on their own and spread in the wild, with the possibility of far-reaching consequences. Biotechnology could most likely prove harmful either through the unintended consequences of benevolent research or from the purposeful manipulation of biology to cause harm. One could also imagine messy controversies, in which one group engages in an application for biotechnology that others consider dangerous or unethical.

1. Unintended Consequences

Sugarcane farmers in Australia in the 1930’s had a problem: cane beetles were destroying their crop. So, they reasoned that importing a natural predator , the cane toad, could be a natural form of pest control. What could go wrong? Well, the toads became a major nuisance themselves, spreading across the continent and eating the local fauna (except for, ironically, the cane beetle).

While modern biotechnology solutions to society’s problems seem much more sophisticated than airdropping amphibians into Australia, this story should serve as a cautionary tale. To avoid blundering into disaster, the errors of the past should be acknowledged.

  • In 2014, the Center for Disease Control came under scrutiny after repeated errors led to scientists being exposed to Ebola, anthrax, and the flu. And a professor in the Netherlands came under fire in 2011 when his lab engineered a deadly, airborne version of the flu virus, mentioned above, and attempted to publish the details. These and other labs study viruses or toxins to better understand the threats they pose and to try to find cures, but their work could set off a public health emergency if a deadly material is released or mishandled as a result of human error.

  • Mosquitoes are carriers of disease – including harmful and even deadly pathogens like Zika, malaria, and dengue – and they seem to play no productive role in the ecosystem. But civilians and lawmakers are raising concerns about a mosquito control strategy that would genetically alter and destroy disease-carrying species of mosquitoes. Known as a ‘ gene drive ,’ the technology is designed to spread a gene quickly through a population by sexual reproduction. For example, to control mosquitoes, scientists could release males into the wild that have been modified to produce only sterile offspring . Scientists who work on gene drive have performed risk assessments and equipped them with safeguards to make the trials as safe as possible. But, since a man-made gene drive has never been tested in the wild, it’s impossible to know for certain the impact that a mosquito extinction could have on the environment. Additionally, there is a small possibility that the gene drive could mutate once released in the wild, spreading genes that researchers never planned for. Even armed with strategies to reverse a rogue gene drive, scientists may find gene drives difficult to control once they spread outside the lab.
  • When scientists went digging for clues in the DNA of people who are apparently immune to HIV, they found that the resistant individuals had mutated a protein that serves as the landing pad for HIV on the surface of blood cells. Because these patients were apparently healthy in the absence of the protein, researchers reasoned that deleting its gene in the cells of infected or at-risk patients could be a permanent cure for HIV and AIDS. With the arrival of the new tool, a set of ‘DNA scissors’ called CRISPR/Cas9 , that holds the promise of simple gene surgery for HIV, cancer, and many other genetic diseases, the scientific world started to imagine nearly infinite possibilities. But trials of CRISPR/Cas9 in human cells have produced troubling results, with mutations showing up in parts of the genome that shouldn’t have been targeted for DNA changes. While a bad haircut might be embarrassing, the wrong cut by CRISPR/Cas9 could be much more serious, making you sicker instead of healthier. And if those edits were made to embryos, instead of fully formed adult cells, then the mutations could permanently enter the gene pool, meaning they will be passed on to all future generations. So far, prominent scientists and prestigious journals are calling for a moratorium on gene editing in viable embryos until the risks, ethics, and social implications are better understood.

2. Weaponizing Biology

The world recently witnessed the devastating effects of disease outbreaks, in the form of Ebola and the Zika virus – but those were natural in origin. The malicious use of biotechnology could mean that future outbreaks are started on purpose. Whether the perpetrator is a state actor or a terrorist group, the development and release of a bioweapon, such as a poison or infectious disease, would be hard to detect and even harder to stop. Unlike a bullet or a bomb, deadly cells could continue to spread long after being deployed. The US government takes this threat very seriously , and the threat of bioweapons to the environment should not be taken lightly either.

Developed nations, and even impoverished ones, have the resources and know-how to produce bioweapons. For example, North Korea is rumored to have assembled an arsenal containing “ anthrax, botulism, hemorrhagic fever, plague, smallpox, typhoid, and yellow fever ,” ready in case of attack. It’s not unreasonable to assume that terrorists or other groups are trying to get their hands on bioweapons as well. Indeed, numerous instances of chemical or biological weapon use have been recorded, including the anthrax scare shortly after 9/11, which left 5 dead after the toxic cells were sent through the mail. And new gene editing technologies are increasing the odds that a hypothetical bioweapon targeted at a certain ethnicity , or even a single individual like a world leader, could one day become a reality.

While attacks using traditional weapons may require much less expertise, the dangers of bioweapons should not be ignored. It might seem impossible to make bioweapons without plenty of expensive materials and scientific knowledge, but recent advances in biotechnology may make it even easier for bioweapons to be produced outside of a specialized research lab. The cost to chemically manufacture strands of DNA is falling rapidly , meaning it may one day be affordable to ‘print’ deadly proteins or cells at home. And the openness of science publishing, which has been crucial to our rapid research advances, also means that anyone can freely Google the chemical details of deadly neurotoxins. In fact, the most controversial aspect of the supercharged influenza case was not that the experiments had been carried out, but that the researchers wanted to openly share the details.

On a more hopeful note, scientific advances may allow researchers to find solutions to biotechnology threats as quickly as they arise. Recombinant DNA and biotechnology tools have enabled the rapid invention of new vaccines which could protect against new outbreaks , natural or man-made. For example, less than 5 months after the World Health Organization declared Zika virus a public health emergency , researchers got approval to enroll patients in trials for a DNA vaccine .


Is it possible to reduce maturity time of plants with biotechnology? - Biology

Biotech improves crop insect resistance, enhances crop herbicide tolerance and facilitates the use of more environmentally sustainable farming practices. Biotech is helping to feed the world by:

  • Generating higher crop yields with fewer inputs
  • Lowering volumes of agricultural chemicals required by crops-limiting the run-off of these products into the environment
  • Using biotech crops that need fewer applications of pesticides and that allow farmers to reduce tilling farmland
  • Developing crops with enhanced nutrition profiles that solve vitamin and nutrient deficiencies
  • Producing foods free of allergens and toxins such as mycotoxin and
  • Improving food and crop oil content to help improve cardiovascular health.

Currently, there are more than 250 biotechnology health care products and vaccines available to patients, many for previously untreatable diseases. More than 13.3 million farmers around the world use agricultural biotechnology to increase yields, prevent damage from insects and pests and reduce farming's impact on the environment. And more than 50 biorefineries are being built across North America to test and refine technologies to produce biofuels and chemicals from renewable biomass, which can help reduce greenhouse gas emissions.

Recent advances in biotechnology are helping us prepare for and meet society’s most pressing challenges.

BIO is the world's largest trade association representing biotechnology companies, academic institutions, state biotechnology centers and related organizations across the United States and in more than 30 other nations.

We offer membership, events, industry analysis reports and more that serve the entire spectrum of the biotech industry.

BIO has put together several comprehensive reports and tools for detailed industry analysis on COVID-19 therapeutic developments, emerging company investment trends, chronic disease trends, clinical success rates and more.


Integration of Post-Harvest Disease Management Strategies

Integration of disease management strategies in fruits and vegetables emerged an answer to shortcomings of reliance on chemical control. It deals with integration of all available disease control methods to manage the diseases effectively and economically to satisfy human needs at the same time guarding the quality of harvested produce and environment.

Several studies have highlighted the advantages of Post-harvest application of biological control agents over field or soil application.

The major advantages are the convenience of bringing the antagonist in contact with the commodity as compared to its addition to the soil and the possibility of acting under controlled conditions, created and maintained during storage. Likewise, it is possible to introduce Bacillus subtilis into the wax applied to peaches in the packinghouse to protect them from the brown rot caused by Monilinia fructicola.

The antagonistic yeast Pichia guilliermondii can be introduced into the wax mixture applied to citrus fruit in packinghouse. Compatibility between a microbial antagonist and a synthetic fungicide offers the option of using the antagonist in combination with reduced levels of the fungicide.

Applying the yeast antagonist, Pichia guilliermondii to citrus fruit in combination with substantially reduced concentrations of thiabendazole reduced Penicillium digitatum decay to a level similar to that achieved by the currently recommended concentration of thiabendazole applied alone.

Thus, an integrated pest management system adaptation provides effective pest control and maintains very low levels of chemical residues.

The intensive studies on biocontrol of Post-harvest diseases have led to the registration of two biological products for commercial Post-harvest applications on citrus fruits i.e. Aspire, which is Candida oleophila, and Bio-Save 1000 from Pseudomonas syringae.

The biological agent must have low sensitivity to any of the supplemented chemical fungicides. Combining Aspire with each of the chemicals used improved the results sometimes combinations with a low rate of fungicide were sufficient to achieve effects similar to those obtained by the chemicals at standard rates.

Safe compounds or natural products of plant origin have been suggested as alternatives to synthetic and conventional fungicides could also be used in combination with biocontrol agents, complementing their activity. Pathogens treated with such antifungal substances might be weakened and become more vulnerable to the antagonist activity.

The integration of Post-harvest biocontrol into modern production, storage and handling systems must begin before harvest. Several preharvest factors that affect fruit quality may have profound effects on the efficacy of Post-harvest biological control agents.

Preharvest calcium sprays during the growing season of apples and pears can increase fruit firmness, decrease the incidence of certain disorders and enhance resistance to Post-harvest infection. Calcium amendments and Post-harvest application of some antagonistic yeasts can be additive in reducing fruit decay and significantly increase disease control compared with either treatment alone.

The advantages in increased firmness, enhanced resistance to Post-harvest decay and enhanced biocontrol efficacy under some circumstances reflect the multiple benefits of integrating Post-harvest biological control with cultural and production practices.

Post-harvest factors may have a major impact on the effectiveness of biological control. Fruit maturity at harvest and the application of antagonists is affecting Post-harvest biological control. Delayed picked and over matured fruits are more susceptible to decay than are fruits picked at optimal storage maturity.

Roberts (1990, 1994) found that fruit maturity in apples and pears markedly affected biocontrol efficacy of antagonistic yeast Cryptococcus, while excellent control was achieved on freshly harvested fruit and treatments of ripened fruit gave much lower levels of control.

Temperature management is a critical factor in the maintenance of fruit quality and pathogen development, may enhance biological control of storage decay.

Janisiewicz (1991) demonstrated that as the storage temperature of apples and pears decreased, there was a reduction in the concentration of pyrrolnitrin (a metabolite of Pseudomonas cepacia and other Pseudomonas spp.) needed to protect the fruit from gray mould (Botrytis cinerea) and blue mould caused by Penicillium expansum.

An integrated strategy to control Post-harvest decay in pome and stone fruits has been advanced in recent years comprises several pre and Post-harvest components viz., alteration of fruit nutrient status, calcium applications as sprays during the growing season, lower fruit nitrogen content have been associated with reduced disease severity and influence the susceptibility of pome fruits to decay.

Controlled atmosphere storage with reduced O2 and elevated CO2 can reduce the severity of Post-harvest fungal decay in apples by inhibiting fruit senescence and maintaining host resistance to infection.

Integration of early harvest, low fruit nitrogen, high fruit calcium, yeast or yeast + one-tenth of the dose of thiabendazole along with a controlled atmosphere (2% O2, 0.6% CO2) were found to reduce blue mould severity in picked pears.

All the components of the integrated approach were found to be compatible with thiabendazole fungicides used for the management of Post- harvest decay and blue mould (P. expansum) in harvested pears.

Several yeast species such as Cryptococcus laurentii, are capable of colonizing wounds of pear fruit under conditions of low temperature, ambient or reduced O2 and CO2 therefore, can be integrate into Post-harvest strategies.

The two Post-harvest treatments, biological control and modified atmosphere packaging were combined with preharvest iprodione spray the incidence of the brown rot was reduced from 41.5 per cent in the control to only 0.4 per cent.

A combined strategic approach was elaborated by various worker to control wound infecting pathogens by a series of treatments including disinfection of the fruit surface and environment, eradication or suppression of fungal spore germination at wound sites by a combination of fungicides and reduction of wound susceptibility to infection by the addition of biocontrol antagonists which act as protecting agents.

It is being apparent that a multifaceted integrated approach has been advantageous over the use of solitary measures. Thus, the application of antagonists, induced resistance, physical treatments, chemicals, natural and safe fungicides etc. can be utilized in a unified way to provide greater consistency and efficacy to management of Post-harvest diseases.


FUTURE APPLICATIONS OF GENOME EDITING

Of the emerging genetic-engineering technologies reviewed above, genome editing is the closest to being used to modify commercially available crops. A key component of effective and efficient application of genome editing is understanding the biochemical, molecular, and physiological basis of agronomic traits such as plant architecture, photosynthesis, pathogen resistance, and stress tolerance. Given advances in knowledge, additional genome-editing targets will emerge, and they will probably involve the manipulation of multiple genes (see Chapter 8). The committee also expects advances in the ability to edit plant genes precisely—that is, to make precise changes in specific genes without disrupting other genes. Such advances often come from basic research, whose far-reaching applications are not anticipated. For example, TALENs resulted from a study of how some plant-pathogenic Xanthomonas species modify gene expression in host plant cells. The CRISPR/Cas9 system resulted from the surprising discovery that some bacteria have an adaptable “immune system” to resist infection by viruses. The TALEN and CRISPR/Cas9 systems ushered in rapid advances in not only the ease but the range of genome-editing possibilities. In this section, the committee provides an overview of some of the expected applications of this transformation technology.

Removal of Genome-Editing Reagents in Genetically Engineered Crops

It is envisioned that genome editing will be useful in most agricultural crops in generating modified alleles that are homozygous in the modified line for several reasons: to prevent segregation of the altered allele in derived progeny, to eliminate the production of the wild-type target mRNA and protein, and to increase the dosage of the modified allele as the level of transcript of a gene is correlated with numbers of alleles. As described earlier, DNA-free genome editing via CRISPR is possible (Woo et al., 2015). With TALEN and CRISPR/Cas9 reagents, both heterozygous and homozygous mutations can be generated in the first transformed generation. Simple molecular-biology screens can be performed to identify individuals homozygous for the modified allele. Alternatively, for sexually reproducing self-compatible species, individual heterozygous transformed plants can be crossed with their own pollen and homozygous progeny identified in the second transformed generation. An important consideration when generating some genome-edited plants is to ensure that the reagent (TALEN, Cas9) is not present in the selected progeny additional mutations can be generated if the reagents remain active. In some situations, the continued presence of the reagent is desirable. For example, the retained editing reagents can act as a constant mutagen and generate various modified alleles if sufficient gene family members that could be substrates for the reagents are present. However, that might not be desirable in an agronomic situation as stability of genetic material is essential for commercial production. Another example in which the continued presence of the reagent is necessary is gene-drive applications.

Gene Drive

In natural populations, genome-editing reagents can be used to create a gene-drive system, in which the frequency of a specific allele in the population is altered, affecting the likelihood that the desired allele will be inherited. A gene-drive system can be created by retaining the genome-editing reagents in the transgenic organism to enable continued editing of the target alleles throughout the population when the reagents are incorporated into the germline and passed to other members of the population through sexual reproduction the use of CRISPR/Cas9 to create such a genome-editing system has been referred to as mutagenic chain reaction (Gantz and Bier, 2015). Gene drive has applications in the control of insect pests, such as mosquitoes, and various pests in crops (Esvelt et al, 2014). Inadvertent creation of a CRISPR/Cas9 gene-drive system can be avoided by ensuring that the gene constructs that encode the two cassettes 5 for Cas9 and the guide RNAs are not present in the GE plant that is developed. There are many ways to ensure this (Akbari et al., 2015). One way is to genetically segregate away the constructs after editing occurs. Another way is to employ DNA-free or transgene-free genome editing (Woo et al., 2015) in which only proteins and RNAs are introduced into the plant to accomplish gene editing.

Traits Involving Gain versus Loss of Function

Most commercialized GE crops have gain-of-function traits, such as herbicide resistance or insect resistance. Only recently have loss-of-function traits been readied for commercial sale in GE crops. An example is the nonbrowning apple (see Chapters 3 and 8). Chapter 8 describes a number of complex traits that were in the research stage when the committee was writing its report many of them (such as water-use efficiency, nitrogen fixation, and enhanced carbon-fixation efficiency) exhibit gain of function, or perhaps a combination of gain of function with loss of function, and will probably involve the introduction of multiple genes (Box 7-2).

BOX 7-2

Disease-Resistant Wheat by Genome Editing.

Given the time and expense associated with the regulatory process, intellectual-property constraints, and consumer wariness (see Chapter 6), some firms and organizations seek to develop desired traits without genetic-engineering approaches. Loss-of-function traits, particularly if only a single gene has to be disabled, can be readily obtained with the non-GE approach of mutagenesis because random changes in DNA sequence are more likely to disrupt than to improve protein function. At the other end of the spectrum, traits that require introduction of novel genes, or perhaps complex redirecting of gene expression to different tissue or cell types, may be achievable only with genetic-engineering approaches.

Consider the following theoretical example that aims to reduce the concentration of a toxic compound in the leaves of a potentially new crop plant. All available germplasm of the plant contains the toxic compound at unacceptable concentrations. Proof-of-concept studies might first explore the efficacy of downregulating the target gene responsible for synthesis of the toxic compound by using RNAi or knocking it out via CRISPR/Cas 9 or TALENs. Once the target is identified, an approach that does not involve genetic engineering, such as targeting induced local lesions in genomes (TILLING), could be applied. TILLING relies on initial chemical mutagenesis of a plant population followed by molecular identification of the required mutant allele and then crossing to obtain plants homozygous in that allele (Henikoff et al., 2004). It does not require the target plant to be genetically transformable. Although setting up the initial mutant TILLING population is expensive and fixing the required allele can be complex in polyploid outcrossing species, the approach can be cost-effective if multiple traits are being sought in the same species. TILLING populations have been available for several years for many crop and model species (Perry et al., 2003 Comis, 2005 Weil, 2009) and are being used in agricultural biotechnology (Comis, 2005 Slade and Knauf, 2005). However, it is not clear that traits produced by TILLING would pose less risk of unintended effects to the environment or food safety than those introduced by genetic-engineering approaches, such as RNAi and genome editing. The chemical mutagenesis used in TILLING introduces random mutations into the plant genome although most of the mutations can be removed by backcrossing in most crop species, the resulting modified crop plant might have more unknown changes than the same change in the target gene of interest brought about by use of CRISPR/Cas 9 (although somaclonal variation will not be an issue because TILLING does not require a tissue-culture step).

There are both conventional-breeding and genetic-engineering approaches for the selection of gain-of-function traits such as increasing the amount of a beneficial component (for example, a nutrient or useful pharmaceutical compound). If sufficient natural variation is present in the species, breeding for increased production can be advanced by using marker-based or genomics-based approaches and development of an improved variety through marker-assisted introgression. A good example of this approach is the increase in production of the antimalarial compound artemisinin in wormwood (Graham et al., 2010). If natural variation is not present, as is the case in trying to introduce condensed tannins in foliage to improve forage quality in alfalfa (Lees, 1992), a genetic-engineering approach may be the only option available. Theoretically, it may be possible to introduce a gain-of-function trait through TILLING if not, the trait can be introduced by overexpression of a key, rate-limiting biosynthetic enzyme or one or more positively regulating transcription factors. Examples of these approaches are presented in Chapter 8.

Editing Quantitative Trait Loci

Not every trait is governed by a single gene. Many agronomic traits are complex traits and are governed by multiple genetic loci that contribute to overall variation in the phenotype the multiple genes involved in complex traits are known as quantitative trait loci (QTL). Scientists have identified a number of QTL for diverse agronomic and quality traits of a wide array of crop species. On the basis of high rates of coinheritance (linkage) with specific DNA sequences, specific progeny can be selected from conventional breeding to create combinations of QTL that are expected to perform well. They can be tested by field experimentation.

The use of QTL selection has limitations and impediments. First, for a number of crop species, backcrossing is difficult or impossible because of low sexual fertility, long reproduction cycles, inbreeding depression, or some combination thereof. Second, desirable QTL may be closely linked (coinherited) with genes that adversely affect other important traits, that is, “linkage drag” this is common among genes in low-recombination regions of chromosomes and when desirable QTL are found in wild crop relatives whose genomes are less prone to recombination with the crop genome. Third, considerable effort is required to introgress a specific QTL into all plants of interest. Multiple backcrosses must be made to remove unlinked introgression events, which is expensive in terms of growing populations in the greenhouse or field for multiple generations. Thus, genome editing of QTL provides an alternative approach for developing elite varieties in species whose breeding cycles pose logistical challenges.

In the event that the specific nucleotides that govern a QTL are known, genome editing could be used to modify nucleotides in the QTL to the favorable alleles. Not all QTL have been defined at the gene or allele level for most QTL, only a localized region of the genome has been defined as the QTL. Therefore, a region of the genome might be replaced by using genome-editing technologies, although current methods are inefficient and the restrictions on the length of DNA that can be edited are not yet known.

FINDING: Genome-editing methods can complement and extend contemporary methods of genetic improvement by modifying composition and expression of genes and by targeting insertion events.

FINDING: Current genome-editing methods and reagents are improving rapidly in precision and efficiency.


CLIMATE CHANGE: A 50-YEAR VIEW FROM THE PLANT PERSPECTIVE

In the last 250 years, atmospheric [CO2] has risen from 280 μmol mol −1 to 381 μmol mol −1 . This exceeds the [CO2] at any time in the last 650,000 years and probably the last 23 million years ( IPCC, 2007). Atmospheric [CO2] is projected to continue rising to at least 550 μmol mol −1 by 2050 ( IPCC, 2007). Rising concentrations of CO2 and other greenhouse gases have resulted in a 0.76°C increase in global surface temperature since the 1800s, and the mean global surface temperature is predicted to increase by an additional 1.3°C to 1.8°C by 2050 ( IPCC, 2007). Warming over land is expected to be greater than this average, and it is very likely that heat waves will be more intense, more frequent, and longer lasting. Daily minimum temperatures are predicted to rise more rapidly than daily maximum temperatures. The number of frost days will decrease, and in mid- to high latitudes, an extension of the growing season is likely ( IPCC, 2007).

Warming will generally increase evaporation, total precipitation, and the spatial variability of precipitation, leading to less rainfall in the tropics and more rainfall at higher latitudes. However, the spatial and temporal boundaries between areas of projected increasing and decreasing precipitation are uncertain. Globally, the intensity of precipitation events is projected to increase, even in areas with a mean reduction in precipitation, and the time between precipitation events is also projected to increase, thereby increasing both the risk of flooding and drought ( IPCC, 2007).

Unlike [CO2], tropospheric [O3] is spatially and temporally heterogeneous because O3 is short lived and its synthesis is tied to the abundance of its pollutant precursors, and water vapor and sunlight. In industrialized countries of the northern hemisphere, daily 8-h tropospheric [O3] is estimated to have increased from approximately 10 nmol mol −1 prior to the industrial revolution to a current level of approximately 60 nmol mol −1 during summer months, and is predicted to increase 20% more by 2050 ( IPCC, 2007). This is particularly relevant to agriculture because sensitive crops show a reduction in yield once the [O3] exceeds 40 nmol mol −1 for extended periods ( Heagle, 1989).

The changes in temperature, precipitation, and tropospheric [O3] projected for 2050 are spatially and temporally variable, poorly constrained, and occurring in parallel. This moving and poorly defined target presents a significant challenge to a biotechnology industry hoping to provide cultivars tailored to regional production environments. In contrast, the increase in [CO2] is uniform, global, and unfortunately, committed. Even in the unlikely event that we stabilize CO2 emissions at present-day levels, atmospheric [CO2] would still be >500 μmol mol −1 by 2050 ( IPCC, 2007). Therefore, attempts to engineer crops to perform better under the conditions of increasing environmental stress associated with increased O3 exposure, temperature, and changing precipitation patterns should be considered against the back drop of a guaranteed and ubiquitous increase in atmospheric [CO2].


Definition of Post Harvest Loss

Post-harvest loss can define as the loss from the stage of harvesting to the stage of consumption resulting from qualitative loss, quantitative loss and the food waste (by the consumers) altogether.

What is Food Waste?

Food waste is the subcategory included in the post-harvest losses that occur after marketing the food product to the consumers. Thus, it can be defined as the wastage of edible food that has been unutilized by the consumers. Food waste is strongly linked with the consumer’s behaviour, and it occurs by several ways like:

  • Consumer’s refusal to the retailer in purchasing the product.
  • Discarding of leftover food.

What is Food Loss?

Food loss in the post-harvesting chain results from the loss during the harvesting stage to food marketing at the consumers level. It occurs as a result of both qualitative and quantitative food loss.

  • Quantitative food loss occurs due to weight loss, spillage of crops, microbial attack and pest attack.
  • Qualitative food loss occurs as a result of nutrient loss, undesirable change (in taste and texture), presence of excreta (like birds and rodents) and contamination by mycotoxin.

The Objectives of Post Harvest Losses

Post-harvest technology targets the following attributes :

  1. Maintenanceof food quality: The quality of food is maintained without altering the appearance, texture, weight, flavour, nutritive value, and other food properties.
  2. Food safety: Post harvest technology maintains food safety by keeping the food items at proper storage conditions to avoid contamination.
  3. Reduction in food loss: The technique also targets to reduce the food loss between the period of harvesting and consumption by improving harvesting, storage, transportation facilities and marketing policies.
  4. Reductionof food waste: It also minimizes the food wastage at the consumer’s level by improving marketing skills and proper distribution of the product.
  5. Effectivemanagement of the post-harvest losses.
  6. Promotion: It includes the promotion of both small and large scale production of crops.

Factors Affecting

There are some primary and secondary factors, which affect the post-harvest loss of food products.

Primary Factors

  1. Mechanical loss is caused by poor handling from the stage of harvesting to storage.
  2. Microbial action is caused by microorganisms like bacteria, fungi, and yeasts etc., which readily affects the perishable food crops like fruits and vegetables.
  3. Environmental factors like temperature and humidity are the two important factors primarily responsible for the post-harvest losses.

Secondary Factors

  1. Inadequate harvesting methods
  2. Incomplete drying before threshing
  3. Inadequate storage facilities
  4. Longer shipment
  5. Longer distribution period
  6. Lack of market access and policies

Potato crop response to radiation and daylength

17.1.2 Measurement of radiation interception

Solar radiation intercepted by green leaves is used for dry matter production. As explained in the introduction, photosynthetically active radiation (PAR) is only about half of the incident solar energy. Several methods exist to assess the proportion of solar radiation that is intercepted by the crop.

Figure 17.4 represents two courses in the development of ground cover and, hence, radiation interception. One where full ground cover is achieved and sustained and one where the crop does not achieve 100% ground cover. Proper measurement of radiation interception by the canopy is essential for interpretation of the influence of the environment on the crop, although measurement of ground cover by the canopy provides an approximation. Simulation of the effects of the environment on crop growth and development hinges on good estimates of both incident and intercepted solar radiation.

Fig. 17.4 . The development of the fraction of the ground covered with green leaves (Ft) with thermal time during the growing season where the crop reaches full ground cover (a) and where it does not (b). R0 indicates the relative rate of increase in light interception, M the maximum ground cover and t50 the thermal time when the ground cover is reduced to 50% of full ground cover ( Kooman, 1995 ).

An appropriate estimate of the proportion of PAR that is intercepted by the foliage can be made using tube solarimeters above and below the canopy with a length equal to the distance between the rows of the crop so as to sample all parts of the row equally. Tube solarimeters measure total solar radiation, and so, an assumption is made that any changes in the spectral composition above and below the canopy are non-significant. Other instruments (e.g. Ceptometer) are available that will measure PAR rather than total solar radiation, but these are more expensive and tend to be used as portable devices to make spot measurements across a crop. Using the cheaper tube solarimeters in permanent locations allows measurements to be integrated across the whole day.

The proportion of the ground covered by green leaves can provide an acceptable estimate of intercepted radiation. Proportional ground cover (PGC) can be estimated using a grid divided in 100 equal sections viewed directly from above ( Burstall and Harris, 1983 ). The dimensions of the frame should be a multiple of the planting pattern. When rows are 75 cm apart and plants are spaced at 30 cm within the row, a frame of 75 x 90 cm is appropriate. A measurement consists of counting the sections more than half filled with green leaves.

Measurements of the amount of incoming infrared radiation reflected by the canopy have been found to correlate well with the PGC ( Birnie et al., 1987 ), offering a third non-destructive estimate. A radiometer may be multispectral, but for estimating canopy cover, the radiometer is fitted with filters allowing wavelengths between 836 and 846 nm to pass. The hemispherical irradiance and the crop reflectance are measured nearly simultaneously. The downward angle of view of the system is such that the estimate is based on about 1 m 2 of the canopy.

Light entering at the top of the canopy is extinguished with different extinction coefficients of the several radiation components (e.g. Spitters et al., 1986 Monteith, 2000 ). The light profile within the canopy can be characterized experimentally by destructive means in which light is measured above and below the canopy, and the leaf area is determined by detaching leaves and determining their area with a commercially available leaf area meter. The proportion of PAR intercepted is calculated as PPAR = 1 – e −kL where L stands for LAI and k for the extinction coefficient that, typically, has a value of about 0.4 ( Khurana and McLaren, 1982 Burstall and Harris, 1983 Haverkort et al., 1991 ).

Haverkort et al. (1991) compared PGC measured with the grid, LAI and infrared reflectance. They found highly significant correlations between the various methods ( Fig. 17.5 ). The authors found that a disadvantage of the solarimeter is that it does not distinguish between green leaves and brown leaves and stems. The method tends to overestimate intercepted radiation in the second half of the growing season. The relationship between PGC measured with the grid and LAI was linear up to LAI = 3 after which full ground cover was reached.

Fig. 17.5 . Relationship between proportion ground cover with green leaves observed with the grid (Pgc) and the proportion of infrared reflected by the crop (Pir). Arrows indicate the course of time from emergence until crop senescence

(redrawn from Haverkort et al., 1991 ).


Do GMO crops “foster monocultures?”

by Guest Expert 8 August 2014

Corn harvest, from United Soybean Board
Do GMO crops “foster monoculture?” This is a frequent criticism of modern agriculture. I have three problems with it:

  1. “Monoculture” isn’t the right term to use to describe the relevant issues – its really about a limited crop rotation
  2. History and economics are the drivers behind this phenomenon, not crop biotechnology
  3. The solutions – to the extent that they are needed – are not what most critics seem to imagine

The Corn Belt of the Midwestern US, is a multi-million acre farming region almost entirely dominated by just two crops – corn and soybeans. This phenomenon is often termed “monoculture,” but monoculture is merely the practical approach of growing a single crop in a given field. The opposite of monoculture is “polyculture” and it is entirely impractical for even minimally mechanized farming.
The Corn Belt is more accurately described as an example of a “limited crop rotation.” The typical pattern is an alternation between corn and soybeans in each field. There are also some fields where the growers plant continuous corn or continuous soybeans. There are many reasons that a more “diverse crop rotation” could be a good idea. Mixing up crop types over time can help build soil quality because of different rooting patterns or residue characteristics. Some plant pests can be more easily managed if their life cycles are disrupted by cropping changes. All of this is well known, but for a variety of reasons that I’ll discuss below, the less diverse rotation persists.
Corn and soybeans happen to be crops which involve widespread use of biotech crop options, but there are many other farming areas with a narrow crop rotation where “GMO” options have never been available. There are areas in Northern Europe where “continuous wheat” is the norm and many premium wine regions where essentially only grapes are grown. If farmers somewhere are not using a diverse crop rotation – there is a rational explanation involving history, economics, and risk management.

The Heart of the Corn Belt


Let’s start by looking at Iowa, which sits in the very heart of the “Corn Belt.” As you can see from the graph to the left, corn has been the dominant Iowa crop for a very long time, because Iowa is just about the ideal place to grow that crop. Most farmland in that part of the Midwest is “rain-fed” rather than irrigated. The amount of rain that typically falls in Iowa is sufficient to produce a good corn crop without limiting yield by the number of cloudy days.
The rainfall in Central Iowa is usually “just right” for corn
The growing season is long enough and warm enough, but usually does not involve the yield-limiting heat that is typical further south. Corn is heavily planted because it typically returns the highest net profit with the least risk. The income potential from corn is what drives the cost of land for purchase or rent. As the farming population shrank and farm size increased over the last century, the remaining growers have expanded somewhat through land purchases, and more commonly through rentals. For a farmer to keep up with a mortgage or lease typically requires growing a lot of corn.
Back in the 1930s, the main crop that was rotated with corn was oats – ironically much of that to be used as a “transportation biofuel” for horses. Starting in the 1940s, soybeans began to evolve into the favored rotational crop – mostly as an animal feed with a co-product of oil for human consumption. Soybeans have much lower yield than corn, but they are able to generate their own nitrogen fertilizer (with microbial help) and don’t require many other inputs. Thus, soy has also been a reliable way to generate enough profit to cover land and operating costs. All other crops have only ever had niche status in Iowa. When biotech crops arrived they were simply sold into that pre-existing market.

Illinois and Indiana have also been mostly two crop states ever since soybeans filled in for declining oat demand in the 50s and 60s. There has always been a small, but significant wheat sector in both of these states, part of a “double cropping” system in which corn is followed by winter wheat and then soy, producing three cash crop harvests in two years. Indiana now has a small alfalfa segment – a case of crop diversification “fostered by a GMO crop.”

The Northern Edge of the Corn Belt – Minnesota and North Dakota


Minnesota had a more diverse agriculture than its neighbors to the south, but like them, it replaced oats with soybeans long before the biotech era. The expansion of soybeans has continued in the biotech era, partially because of the attractiveness of Roundup Ready Soy, but also because cultivars better adapted to colder springs have also been introduced through conventional breeding. Barley, rye and flax have declined in the biotech era as has wheat to some degree.

The recent decline of wheat is even more pronounced in North Dakota as it went from approximately 50% of all plantings to about 30%. As in Minnesota, the rapid increase in soybeans came from a combination of more cold tolerant lines and the herbicide tolerance trait. Corn plantings have also increased in the biotech era. For both crops the expansion is mostly in the wetter Red River Valley portion of the state. The expansion of corn and soy at the expense of cereals like wheat, barley and rye may seem like a case where biotech is reducing rotational diversity, but the story is a bit more complex.
There is a disease of wheat and barley called Fusarium Head Blight, which has been an increasing issue in all five of these states since the 1980s (and again in 2014). Corn, and particularly the crop residue in no-till corn, serves as a source of spores which can then infect the wheat or barley during their bloom period. Head blight is difficult to control and it can lead to significant yield losses. Infection can also lead to contamination of the grain with a mycotoxin called DON– or more colorfully, “vomitoxin.” Throughout the Midwest, wheat does not tend to have as much profit potential as corn or soy even in good years, but the risk of severe yield or quality loss from Head Blight is really what makes wheat much less attractive. Biotech had the potential to help wheat keep a place in the Corn Belt rotation, but that solution was thwarted by anti-GMO campaigning.
Fusarium infected wheat (right), from Wikipedia
There was a “GMO wheat” in advanced development around 2002 which was much more resistant to Fusarium Head Scab. This product had the potential to reduce the risk of growing wheat, both in the historic wheat growing states like ND and MN, but also in the “I States.” Unfortunately, the trait was never commercialized. Major wheat importing companies in Europe and Japan put pressure on the US and Canadian wheat grower organizations, threatening to boycott all North American wheat if any biotech wheat was commercialized. This was not because of any safety concern, but rather the fact that food companies in those countries didn’t want to have to label wheat-based products as “GMO.” Reluctantly the growers asked Syngenta to stop the development of their disease resistant wheat. Ironically, this is a case where a GMO opposition “fostered monoculture,” when biotechnology could have enhanced rotational diversity. The wheat growers of the US, Canada and Australia have pledged to do a simultaneous release of biotech wheat in the future so that they can avoid this sort of extra-regulatory blockage.

How Could The Corn Belt Rotation Be Diversified?

First of all, the corn/soy rotation in the corn belt is a highly successful production system. It also includes enough genetic diversity within those species to continue to perform. That said, some additional diversity would be a good thing. Scab-resistant wheat would both reduce risk and increase private investment in that very important and highly traded crop while simultaneously diversifying the rotation. Another excellent way to get the soil quality benefits of rotation is to add a winter cover crop (see Midwest Cover Crops Council). It is actually best for the soil to have something growing as much of the year as possible, and cover crops can also include a legume to make nitrogen for the next season or a grass to scavenge any excess fertilizer when that is an issue.
Probably the best way to facilitate more rotational diversity would be through education of the absentee landlord community. Much of the land in the Midwest is held in trusts for the families who have long since migrated to the cities. Typically all they do is collect the rent checks through a farm management company. If those families could be educated about sustainable cropping practices, they might be willing to engage in re-designed leases designed around medium to long-term economics rather than the typical annual, cash lease. What is needed is a way to give the grower/renters the incentive to implement the practices that might not optimize income for each year, but which lead to improved soil quality over time which in turn leads to higher income potential and more protection from drought (e.g. no-till, cover cropping, controlled wheel traffic and more diverse rotations). The very real benefits of such a system would flow to the land-owner – increasing the value of the asset. It would be far more constructive to find creative ways to share that value between farmers and landowners rather than to worry about “monocultures.”
Planting graphs based on data from USDA-NASS Quick Stats
Rainfall distribution graph based on NOAA National Climatic Data Center information

Written by Guest Expert

Steve Savage has worked with various aspects of agricultural technology for more than 35 years. He has a PhD in plant pathology and his varied career included Colorado State University, DuPont, and the bio-control start-up, Mycogen. He is an independent consultant working with a wide variety of clients on topics including biological control, biotechnology, crop protection chemicals, and more. Steve writes and speaks on food and agriculture topics (Applied Mythology blog) and does a bi-weekly podcast called POPAgriculture for the CropLife Foundation.