SMALL WONDER: The team has submitted the gene to the international gene bank and is awaiting US and European patents

If you think the pristine seaside is good only for growing coconuts, think again — you can grow paddy, or mustard or even vegetables. In what could be a precursor to growing paddy, mustard and more on the vast coastal stretch of the Indian subcontinent, plant geneticists at Calcutta’s Bose Institute have discovered a gene in a mangrove plant that’s capable of conferring salt tolerance to crop plants to produce wonder crop varieties that can survive hitherto unimaginable levels of soil salinity.

The discovery, which comes after decades of research at the institute's plant molecular and cellular genetics unit, means that the gene could hold the key to turning hundreds of thousands of kilometres of shore land into lush green crop fields in the not-so-distant future.

Prof. Arun Lahiri Majumder and his team at the institute are developing a greenhouse facility at Madhyamgram, the institute's experimental farm on the ourskirts of Calcutta, to further their path-breaking research. “When we cloned the gene from a wild rice variety that grows in the Sunderban mangrove delta in the Bay of Bengal, little did we know that something big was in the offing. Today, we are successfully raising salt-tolerant rice and mustard on a laboratory scale. This indeed makes a lot of sense for an agro-based economy like ours,” Prof. Majumder says.

The team has submitted the gene to the international gene bank at the National Centre for Biotechnological Information in Maryland and is awaiting US and European patents, which are in the final stages of being processed.

The plant geneticists ensured that a key enzyme — inositol synthase — gets into the paddy plant and triggers off the production of a chemical, inositol, which counters the adverse effect of salt. The scientists struck upon the all-important gene while trying to understand the biological process of mangroves, which can withstand high levels of salinity. They scoured the creeks and delta criss-crossed with rivers to study the chemicals in mangrove plants that are responsible for salt tolerance.

“These chemicals are named inositols and may be responsible for keeping the physiological process of the mangroves going despite the abundance of salt in their surroundings. And this is what caught our interest,” Prof. Majumder says.

In normal everyday plants, the enzyme stops functioning in saline environments and they wither owing to salt shock. The trick with the mangrove plant, from which the gene has been isolated, is that the enzyme does not stop functioning even in soil with high salt content and produces enough inositol for its survival in saline waters.

The scientists found this enzyme in Porteresia coarcata, a wild rice variety from the Sunderbans, obtained a full length cloned DNA for the inositol synthase gene from its leaf, and sequenced it. A series of experiments later, the team found that the recombinant gene was ideal for incorporating into rice varieties as it retained its salt tolerant character.

The plant biologists are breeding them for what they call ‘generation advancement’ under contained trial conditions. They will go till fourth generation plants and then hand the transgenics over to the Centre’s Department of Biotechnology, which is funding the project.

Writing in the international journal FEBS Letters, Prof. Majumder and his colleagues Aparajita Das-Chatterjee, Lily Goswami, Susmita Maitra, Krishnarup Ghosh Dastidar and Sudipta Ray discussed the multifold challenges posed by salinity to all organisms in terms of perturbed osmotic balance, ionic disequilibria and toxic metabolites that limit plant productivity worldwide. “Depending upon the genetic make-up of the organism and the environment, these responses vary greatly, although some reactions seem to be universal for steady survival in salt environment. Classical breeding for developing salt tolerance in crops had till now been attempted with limited success,” they contended.

Since Inositol or the intermediates of inositol biosynthesis are innocuous chemicals and neither toxic to cells nor their overaccumulation detrimental to cellular functions, the findings point towards the huge prospect of raising diverse salt tolerant plants by using the gene.

Meanwhile, their work has received peer acclaim in the Journal of Biological Chemistry by the American Society for Biochemistry and Molecular Biology and in Plant Physiology, brought out by the American Society of Plant Biologists.