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Chinese scientists have identified and cloned a rice gene that influences
rice grain weight and yield, which could help scientists develop higher
yielding varieties of the world's most important food crop by Hepeng Jia.

Little is known about the genetic mechanisms that determine yield and seed
weight in plants, despite tremendous efforts by agricultural scientists in
the past decade.

In a study published this week (8 April) in Nature Genetics, lead author Lin
Hongxuan and colleagues from the Shanghai Institutes for Biological
Sciences, studied two varieties of rice with highly significant differences
in grain size.

After mapping their genomes, they found a gene called GW2 in the large-grain
rice that was lacking in the small-grain rice.

They then created a variety of the naturally small-grained rice with the GW2
gene, and found that the gene increased the width and weight of rice grains
and increased grain yield per plant by nearly 20 per cent.

The high-yield variant had nearly the same cooking or eating quality as
conventional rice, although the grains had a darker appearance.

The team say the GW2 gene will facilitate breeding efforts to improve grain
yield in food crops. But they say further evidence is needed to support
their finding.

"The increased output of single plants might be influenced by environmental
factors, so our finding needs to be tested in the randomised blocks of
plants in paddies," Lin told SciDev.Net.

He said the GW2 gene might affect grain size by regulating the cell division
cycle.

Zhu Zhen, deputy director of the Bureau of Life Sciences and Biotechnology
of the Chinese Academy of Sciences, praised the study, saying it would give
breeders more alternatives to explore in the search for improved varieties
of rice.

"In the process of developing new crop varieties, the discovery of important
agronomical genes is very important," Zhu told SciDev.Net.

[www.scidev.net]