A team of scientists at Clemson University has achieved a breakthrough in the genetics of crop aging that could dramatically impact the future of food security in the age of climate change.
Collaborative research investigating the genetic architecture of the poorly understood senescence process of corn and other cereal species has been published in The Plant Cell one of the top-rated studies in scientific journals of plant science. Rajan Sekhon, Plant Geneticist and Assistant Professor at the Department of Genetics and Biochemistry of the College of Science, is the lead author and corresponding author of the paper, entitled "Integrated Genome Scale Analysis Identifies Novel Genes and Networks That Underlie Corn Aging" [1
As a result, the leaves die after their play of colors. The energy gained from the leaves is stored in the stem or roots of the plant and used to quickly proliferate the leaves in the next spring. This makes perfect sense for trees. However, for some other edible crops, especially grains such as corn, rice and wheat, the story is quite different.
"These crops are cared for very carefully and supplied by the farmers with excess nutrients in the form of fertilizers," Sekhon said. "Instead of dying prematurely, the leaves can continue to produce food through photosynthesis, and scientists who understand the triggers of plant aging, such as corn, can change the plant in ways that benefit a hungry world."
Sekhon, whose research career The laboratory was established in 2014 as assistant professor and covers the areas of molecular genetics, genomics, epigenetics and plant breeding. He has played a key role in developing a "Genatlas" that is widely used in corn research. He has published several articles in peer-reviewed journals investigating the regulation of complex plant traits.
"If we can slow down aging, it can cause the plant to stay green longer – or not -" Sekhon said. "Plant breeders have selected plants that age late without fully understanding how senescence works on a molecular level."
These plants, known as "staying green" live up to their name. They stay green longer, produce higher yields, and are more resistant to environmental stresses that pollute plants, including drought and heat.
But even with the existence of green plants, there was little understanding of the molecular, physiological, and biochemical foundations of senescence. Senescence is a complex trait that is influenced by multiple internal and external factors and regulated by a set of genes that work together. Off-the-shelf genetic approaches are therefore not effective in fully deciphering this enigmatic process. The breakthrough of Sekhon and his colleagues was the result of a systemgenetic approach.
Sekhon and the other researchers investigated the natural genetic variation for the feature "Stay Green" in corn. The process involved growing 400 different corn types, each genetically distinct from each other on the basis of the DNA fingerprint (i.e., genotype), and then measuring their senescence (ie, the phenotype). The team then associated the "genotype" of each inbred line with its "phenotype" to identify 64 candidate genes that could control senescence.
"The other part of the experiment was to take a green plant and a non-green plant, stay green and look at the expression of about 40,000 genes during senescence," Sekhon said. "Our researchers looked at samples every few days and asked which genes gained expression during each period, identifying more than 600 genes that appear to determine whether or not a plant remains green.
" One of the big problems with everyone these approaches are the appearance of false positives, which means that some of the discovered genes are flukes, and cases of false negatives, meaning that we are skipping some of the causal genes. "
Therefore, Sekhon and his colleagues have had to carefully combine the results of the two major experiments using a" steam genetics "approach to identify some highly reliable target genes that can be further tested for their role in senescence to confirm genes and finally studied two genes in detail.
"One of the most notable discoveries was that sugar seems to dictate senescence," Sekhon said, "when the sugar is not moved away from t." Photosynthesis, these sugar molecules send signals to induce senescence. "
However, not all sugars found in plants can be signaled. One of the genes discovered by Sekhon and colleagues in the study appears to break down complex sugars in the leaf cells into smaller sugar molecules – six-carbon sugars such as glucose and fructose – that are able to relay the senescence signals.
"This is a double strike," Sekhon said. "Not only do we lose that extra sugar from plants that can feed hungry mouths, these unused sugars in the leaves begin to age and stop the sugar synthesis process altogether."
The impact on food safety is enormous. The sugars produced by these plants should be diverted to various plant organs that can be used for nutrition.
"We have found that the plant carefully monitors the seed filling, and this distribution of sugar is a key factor in senescence." What We've found is that there is a lot of genetic variation in US-grown corn varieties. "
Some plants fill seeds and can then fill other plant parts.
"At least part of the stay – green plants can do this by storing extra energy in the stems," Sekhon said. "When the seed is harvested, anything left on the field is called a stover."
Stover can be used as animal feed or as a source of biofuels. As food and energy demand increases, there is growing interest in the development of crops that deliver both grain and kiln. With the shortage of farmland, plants that age later gain in importance as they produce more total energy per plant.
The genes identified in this study are likely to have the same function in other crops such as rice, wheat, and sorghum. Sekhon said the next step is to study the function of these genes with the help of mutants and transgenes. For the population, food security is the biggest challenge humanity faces, "said Sekhon.
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Rajandeep S. Sekhon et al., Integrated Genome-Scale Analysis, identified novel genes and networks that underlie senescence in maize (19459014). The Plant Cell (19459015) (2019). DOI: 10.1105 / tpc.18.00930
The Genetic Breakthrough in Cereal Plants Can Help Improve Yield Worldwide (2019, July 10)
retrieved on 10th July 2019
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