In a world where greenhouse gas emissions, mainly carbon dioxide, are on the rise, can the crops that ensure food and nutrition security remain unaffected? A group of researchers at a Hyderabad-based premier crop research institute have made findings that suggest not. Underscoring the problem, their findings also shed light on the solution.
Two research groups at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) studying the physical and molecular manifestations of increasing carbon dioxide (CO 2) on certain crops have found that the gas significantly and negatively alters chickpea under stressed conditions. Chickpea or channa, is an important legume crop and a staple protein source in India and many other parts of the world.
For their study, researchers at ICRISAT’s Center of Excellence in Climate Change Research for Plant Protection, led by Dr Mamta Sharma, cultivated two popular varieties of chickpea (desi chickpea JG 11 and kabuli chickpea KAK 2) in ambient conditions (380 ppm, the current ambient CO 2 level) and under two higher levels of 550 ppm and 700 ppm to stress the plants and mimic rising levels in the world.
Following the early impressive growth, the scientists observed that the plants started to demonstrate negative effects as they aged. The changes in the stressed plants made for a stark contrast with those of the same age that were grown in ambient conditions, they observed. The leaves, roots and shoots of plants grew faster under stressed conditions but quickly lost green-ness and shed leaves. This also meant that the crop lost its chlorophyll content sooner, implying lesser yield and lesser food.
To understand and correlate the changes at a chemical and molecular level, a second team of researchers from ICRISAT’s Center of Excellence in Genomics and Systems Biology, led by Dr Rajeev Varshney, performed gene expression studies on samples of the stressed crops. They found that the expression of as many as 18,644 genes in the stressed plants was different compared to the normal expression of these genes in plants grown under ambient conditions.
These different expressions, referred to scientifically as Differentially Expressed Genes (DEGs), suggested that several important metabolic pathways related to sugar metabolism, chlorophyll metabolism and the plant’s defence mechanism were adversely affected in ways that accelerated senescence or aging.
The findings of the study were recently published in the paper ‘Molecular and Physiological Alterations in Chickpea under Elevated CO 2 Concentrations’, in the journal Plant & Cell Physiology. The study’s first author is Dr Paramita Palit, a former research scientist in Dr Varshney’s team at ICRISAT.
Armed with the findings, the researchers now believe they have taken a giant leap towards developing a climate-smart variant of chickpea.
Dr Varshney, a noted plant geneticist and a molecular breeding expert, says that 550 ppm and 700 ppm of CO 2 concentrations could be the scenario in a couple of decades or more and the question was if chickpea would survive those conditions. “We wanted to first understand the changes in chickpea at high levels of CO 2 and which genes are affected. Should we develop chickpea varieties for such stressed levels, it should still be able to give the same or better yield.”
“We found that different metabolic pathways are adversely affected at 700 ppm level in the reproductive phase leading to reduced yield. We have identified several underlying genes. We now know the different pathways where these genes are affected,” he said.
“The question is” he added, “can we develop new varieties of chickpea that, even at higher CO 2 levels, are not affected, produce more food and continue to give farmers good yield?”
“Yes,” he emphatically answered, “and it will be challenging.”
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