Oct. 23, 2011 Not long ago, thousands of families lost their homes and crops as flood waters swept across Central America. In Thailand huge tracts of farmland were submerged as the country faced its worst flooding in 50 years. Across the globe agricultural production is at risk as catastrophic flooding becomes a world-wide problem.
Prolonged flooding drastically reduces yields by cutting off the supply of oxygen crops need to survive. Now experts at The University of Nottingham, working in collaboration with the University of California, Riverside, have identified the molecular mechanism plants use to sense low oxygen levels. The discovery could lead, eventually, to the production of high-yielding, flood-tolerant crops, benefiting farmers, markets and consumers across the globe.
The mechanism controls key proteins in plants causing them to be unstable when oxygen levels are normal. When roots or shoots are flooded and oxygen levels drop these proteins become stable. The research is published on October 23 in the journal Nature.
Michael Holdsworth, Professor of Crop Science in the School of Biosciences at Nottingham said: "We have identified the mechanism through which reduced oxygen levels are sensed. The mechanism controls key regulatory proteins called transcription factors that can turn other genes on and off. It is the unusual structure of these proteins that destines them for destruction under normal oxygen levels, but when oxygen levels decline, they become stable. Their stability results in changes in gene expression and metabolism that enhance survival in the low oxygen conditions brought on by flooding. When the plants return to normal oxygen levels, the proteins are again degraded, providing a feedback control mechanism."
As Pakistan, Bangladesh, Vietnam, Australia, the UK and America have all fallen victim to catastrophic flooding in recent years tolerance of crops to partial or complete submergence is a key target for global food security. Starved of oxygen, crops cannot survive a flood for long periods of time, leading to drastic reductions in yields for farmers.
Professor Holdsworth's work, in collaboration with Professor Julia Bailey-Serres, a geneticist and expert in plant responses to flooding at the University of California, Riverside, is just the beginning.
The team expects that over the next decade scientists will be able to manipulate the protein turnover mechanism in a wide range of crops prone to damage by flooding.
Professor Bailey-Serres said: "At this time, we do not know for sure the level of conservation across plants of the turnover mechanism in response to flooding. We have quite a bit of assurance from our preliminary studies, however, that there is cross-species conservation. Our experiments on Arabidopsis show that manipulation of the pathway affects low oxygen stress tolerance. There is no reason why these results cannot be extrapolated to other plants and crops. Still, we have many research questions to answer on the turnover mechanism. What we plan to do next is to nail down this mechanism more clearly."
Professor Holdsworth, an international expert in seed biology had the first hint of the discovery while investigating the regulation of gene expression during seed germination. He connected the mechanism of degradation of key regulatory proteins with changes in the expression of genes associated with low oxygen stress that Bailey-Serres has studied extensively.
Professor Holdsworth said: "The puzzle pieces fell quickly into place when the expertise of the two teams was combined."
The work was carried out by Professor Holdsworth and his team in the School of Biosciences in collaboration with researchers at the University of California, Riverside in the United States, Rothamsted Research in the United Kingdom and University Pierre and Marie Curie, France.
The work was funded by the UK Biotechnology and Biological Sciences Research Council (BBSRC), Malaysian government through MARA, the US Department of Agriculture National Institute of Food and Agriculture (USDA-NIFA), and the US National Science Foundation.
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