THERE is hope for wheat farmers whose crop yields are affected by soil salinity. A team of researchers at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Waite Research Institute in Australia have developed a salt-tolerant strain of durum wheat which yields 25 per cent more grains in saline soil conditions.
The new variety uses a gene from the ancestor of the durum wheat, Triticum monococcum. Durum wheat is high in gluten and has uniform golden colour, which makes it commercially important. Salinity in soil induces water from plant roots to flow out rather than flow in, causing root cells to die.
Researchers have earlier shown that putting a salt-tolerant Nax2 gene locus(specific place in a chromosome where a gene is located), isolated from Triticum monococcum, in durum wheat reduced sodium ion concentration in the leaves. This time, lead researcher Rana Munns identified the gene responsible for salinity tolerance—TmHKT; 5-A—in the locus . The gene produces a protein that helps plant roots to selectively control ion influx from soil near the root. The sodium ions are thus restrained from reaching the root’s conducting tissue, thereby lowering sodium concentration in the foliage. The process is called sodium exclusion.
The researchers introduced the gene in durum wheat and studied its impact. Four field blocks of varying salinity were selected in Australia. Sodium exclusion was evaluated by comparing ion concentration in the uppermost leaf. It was observed that plant varieties with TmHKT;5-A yielded more grains. Mathhew Gillium senior author of the study says the salt-resistant wheat might be commercially available in five years. The work was published in Nature Biotechnology in March 2012.
Further testing is required to “determine the robustness of the observations,” says Malcolm Hawkesford, plant scientist at Rothamsted Research, an agricultural research institute in the UK. Sushil Kumar, senior scientist with the National Institute of Plant Genomic Research in Delhi, says it is better to use such conventional methods for incorporating genes to increase the yields as it is difficult to get clearance for cultivating transgenic food crops.
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