IRRI develops salt-resistant rice

A NEW generation of rice will make coastal land ravaged by seawater useful again. Abandoned by farmers because the soil is too salty for crop planting, such areas could once again be a source of profit when the salt-resistant rice being developed at the International Rice Research Institute (IRRI) is perfected for propagation.

Unlike regular rice, the new variety can expel salt into the air through its salt glands in the leaves, said lead scientist Dr Kshirod Jena. It was created by crossing the wild rice species Oryza coarctata with rice variety IR56 of the cultivated rice species O. sativa. Dr Jena’s team is improving their new doubly salt-tolerant rice and will test it widely to ensure it meets the needs of farmers and consumers. The new variety will be available for farmers to grow within 4 to 5 years.

Breakthrough experiment

The mating of the two rice parent is said to be extra special because O. coarctata is extremely difficult to cross with cultivated rice varieties. Its location in the rice genome sequence is at the other end of the spectrum from that of rice varieties such as IR56.

“When we cross two types of rice with genomes so far off from each other in the genome sequence, the resulting embryo tends to abort itself," Dr. Jena said. "We've been trying to backcross these types of interspecific hybrids since the mid-1990s, but we have never been successful, until now,” Dr Jena said.

However, this variety has important characteristics, including the ability to grow in brackish water and its resistance to saltiness in soil, and so the team continued with the experiment, yielding three embryos out of 34,000 crosses.

Only one embryo survived and this 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 the team used it to backcross with IR56. Backcrossing ensures that the resulting progeny will containSneakers