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2-Plants: Non-GE approach to breed salt resistant rice

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TITLE:  Salt of the Earth
SOURCE: The Far Eastern Economic Review, by Anne Marie Ruff, posted by
DATE:   November 22, 2001(issue cover-dated)

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Salt of the Earth

In a Bangkok lab, rice seedlings are growing in salty water.
Next step: making it work in the field.

IN PARTS OF northeast Thailand the soil is so severely encrusted with 
sodium and other mineral salts, it mostly yields poverty. Rice harvests are 
one-tenth of those in other parts of the country. It is no coincidence that 
many of Bangkok's migrant workers are from this region. But in the centre 
of Bangkok, a few blades of grass that are growing in glass jars could 
dramatically change the situation in the northeast. These are rice 
seedlings, selected because they can withstand water that contains 2%-3% 
sodium chloride, or salt. That's nearly as salty as seawater.

Chalermpol Kirdmanee, manager of the Plant Cell Technology Laboratory at 
the government-funded National Centre for Genetic Engineering in Bangkok, 
discovered these unusual rice strains after searching through the country's 
rice "gene bank," which is a collection of 7,000 indigenous varieties of 
rice. Out of 230 varieties that he grew in his lab and watered with salt 
water, four varieties survived. His next step is to see if they will yield 
useful levels of rice or will even survive at all in the field. "All I know 
now," he says, "is they are not dead in the lab in a 3% sodium chloride 

But even that bit of knowledge is a significant discovery. Salt-tolerant 
varieties of crop plants are something of a Holy Grail for researchers from 
China to Australia to California. Yan Guo, a post-doctorate researcher at a 
University of Arizona lab, says he finds the idea exciting, "I have worked 
on salt-tolerant rice for seven years and have not seen anything that could 
withstand such high levels of salt."

The search for salt-tolerant plants is intense because the problem of salty 
soil is immense, and growing. In Asia, saline soils are a major problem in 
China, India, Thailand, Indonesia, Australia and a wide stretch of land 
from western China through Central Asia to the Middle East. Saline soils 
are sometimes naturally occurring--in coastal areas for example--but they 
are also created in irrigated areas where water evaporates and leaves salt. 
The United Nations Food and Agriculture Organization estimates that 20% of 
irrigated land worldwide has already become saline.


In the last year there have been a number of encouraging salt-tolerance 
research results from around the world. A tomato plant that sequesters salt 
in its leaves has come out of the University of California, Davis. 
Researchers at the Chinese Academy of Sciences Institute of Genetics have 
isolated genes from a desert plant known as a salt bush that are being used 
to develop salt-tolerant rice. In India, at the M.S. Swamination Research 
Foundation, genes from a mangrove tree species have been inserted into a 
number of crops, such as eggplant and papaya to boost salt tolerance.

So far, all of these developments have relied on molecular biology to find 
salt-tolerant genes and move them into other plant species.

Chalermpol's work in Thailand differs from other breakthroughs, in that it 
isn't based on transgenic plants (plant containing genes from another 
species). Chalermpol says, "We can't grow genetically modified organisms in 
Thailand, so I wanted to find something that farmers could use." He credits 
the country's rich bio-diversity with his progress, saying: "These results 
wouldn't have been possible in countries that don't have the same kind of 
genetic range that we do."

The newly selected rice strains are part of a larger project to find salt-
tolerant plants for the northeast. These salt-tolerant plants not only 
survive in the northeast, they actually reduce the salinity of the soil. In 
a four-year field experiment conducted by Chalermpol's lab, salt-tolerant 
grasses and trees reduced the level of salt in the soil from 10% to less 
than half a percent. The Thai Land Development and Forestry Departments are 
currently trying to scale up Chalermpol's process.

If they are successful, Chalermpol predicts the results could be felt 
beyond the region "because [rice farmers] won't have to send their children 
to Bangkok."


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