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)
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