AsianScientist (Jul. 16, 2015) – Two independent research labs in China identified a gene, called GW7 or GL7, in hybrid rice grains that regulates grain quality that allows breeding rice of fine quality without a compromise in yield. Their work, published in Nature Genetics, provides a foundation for rice breeders to simultaneously improve quality and quantity of rice crops. Before this, an increase in yield almost always reduced grain quality, says the researchers.
Rice is a staple food for three billion people across Asia. With the continued increase in population and urbanization in Asia, rice growers need to find creative solutions to grow quality rice without a sacrifice in yield. Quality rice grain is transparent, with reduced opaque chalky spots. In certain regions, rice with long, slender shape is considered to be of fine quality.
The researchers took advantage of molecular genetics and outbred rice crops to obtain rice with long, slender grains and reduced chalkiness. They then analyzed the genome of the superior crop to identify the gene, GL7 or GW7, that is responsible the quality grain trait. The higher the expression of this gene, through an increase in number of copies of that allele, was correlated with a more slender rice grain.
Although very similar in their findings and conclusions, the authors from the two papers differ in their opinions about the mechanism underlying the increased grain length in the crop.
Professor Fu Xiangdong, from Chinese Academy of Sciences in Beijing, explained that “[this was] a result of increased cell division in the longitudinal and decreased cell division in the transverse direction [in the rice grain].”
On the other hand, Dr. Xiong Guosheng, from the Chinese Academy of Agricultural Sciences in Shenzhen, explained, “[GL7] regulates cell longitudinal elongation.”
No matter the slight difference, there is clearly an increase in grain length associated with increased expression levels of this gene.
Rice growers have already been taking advantage of genetics to breed rice of superior quality and yield. For instance, rice carrying the beneficial GL7 and gs3 genes (Yuefeng) is already available in the market in China, says Xiong.
But with their findings, “breeders could further combine the good appearance quality with other grain quality parameters, such as good taste and cooking qualities, fragrant and nutrition quality, to produce optimal rice varieties to meet the demand of diverse preferences of rice grain quality,” explained Xiong.
The articles can be found at:
Wang et al. (2015) Copy Number Variation at the GL7 Locus Contributes to Grain Size Diversity in Rice.
Wang et al. (2015) The OsSPL16-GW7 Regulatory Module Determines Grain Shape and Simultaneously Improves Rice Yield and Grain Quality.
Copyright: Asian Scientist Magazine; Photo: Fu Xiangdong.
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