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Gene variant preserves rice yields in warmer nighttime temperatures

A team of crop geneticists from Huazhong Agricultural University's National Key Laboratory of Crop Genetic Improvement and Hubei Hongshan Laboratory, both in China, has identified a gene variant that allows rice plants to continue producing grains at a high rate even during warmer-than-usual nighttime temperatures.

In their study in the journal Cell, the group tested multiple rice varieties against heat exposure to zero in on a variant that could prove useful as temperatures rise.

Over the past several years, rice farmers have produced shrinking yields during heat waves, which has been linked to global warming. Of particular concern are higher temperatures at night, which cause chalky grains and lower yields. Noting that heat waves have been occurring more often and that predictions suggest nighttime temperatures are likely to rise on average, researchers in China and elsewhere have been looking at ways to preserve rice yields despite rising temperatures.

The research team began looking for heat-resistant rice strains starting in 2012. Over the years, they have studied 533 varieties, hoping to find one or more that can withstand warmer temperatures while still producing high yields. Eventually, they found two varieties that seemed to fit the bill: OM1723 and Chenghui448. To identify which genes the two varieties might have that help them withstand heat, they crossbred them. In so doing, they found a gene variant on chromosome 12 they have named QT12 that was responsible for the heat tolerance.

The researchers next conducted experiments to learn how QT12 provided such tolerance. They found that, during normal temperatures, three specific transcription factors tend to bond, but as temperatures rise, one of them breaks away and binds to a promoter that turns on QT12, which in turn leads to interference in the process that results in starch molecules packing together during high temperatures, leading to chalky grains and lower yields.

The research team suggests future research will revolve around testing to see if engineering current rice varieties to give them the QT12 variant would produce better results than simply crossbreeding.