A new generation of salt tolerant rice developed by IRRI

Scientists at the International Rice Research Institute (IRRI), in Los Baños/Philippines, have crossed two different species of rice to produce a new rice variety that has double the salt tolerance of existing rice varieties.

In many coastal regions farmers lose their livelihood when seawater encroaches on their farms leaving the land too salty to grow rice. But there is new hope since scientists at the International Rice Research Institute (IRRI) succeeded in crossing two unlikely rice parents – the exotic wild rice species Oryza coarctata and the IRRI rice variety IR56 of the cultivated rice species O. sativa. 

Dr. Kshirod Jena, lead scientist at IRRI, is very optimistic, that within four to five years the new rice line will be available for rice farmers. He believes that much of the abandoned coastal farmland can be reclaimed with the new rice line. Unlike regular rice, the new variety can expel salt it takes from the soil into the air through salt glands it has on its leaves.

According to the IRRI scientist the wild rice species O. coarctata is extremely difficult to cross with cultivated rice varieties because the location of O. coarctata in the rice genome sequence is at the other end of the spectrum from that of rice varieties such as IR56.

The researchers have been trying to backcross these types of interspecific hybrids since the mid-1990s, without any success, until now. The reason scientists did not give up on crossing the two types of rice was because O. coarctata is a special type of rice that grows in brackish, salty water – making it highly resistant to saltiness in the soil. According to Dr. Jena, O. coarctata can tolerate a higher salinity concentration (similar to that of seawater), whereas current salinity-tolerant rice varieties can cope with only half that concentration. However, O. coarctata is unsuitable for the production of edible rice.

New hope came up when, out of 34,000 crosses made, three embryos were successfully “rescued.” Of these three, only one embryo germinated to produce one single plant, reports Dr. Jena. The surviving plant was then transferred into a liquid nutrient solution to ensure its survival. Once the plant was strong enough, it was grown in the field, where Dr. Jena and his team used it to backcross with IR56. Backcrossing ensures that the resulting progeny will contain all traits of IR56, and take only the desired O. coarctata trait, which is its salt tolerance.

According to Dr. Jena he and his team at IRRI will be perfecting the new doubly salt-tolerant rice and will test it widely to ensure it meets all the needs of farmers and consumers. They hope to have the new variety available for farmers to grow within four to five years.

Source: http://www.rural21.com (Apr. 26, 2013)