A team of researchers, led by a University of California (UC), Davis, plant scientist, has identified a lettuce gene and related enzyme that put the brakes on germination during hot weather — a discovery that could lead to lettuces that can sprout year-round, even at high temperatures. The study also included researchers from Arcadia Biosciences in Davis, California, and Acharya N.G. Ranga Agricultural University in India. The finding is particularly important to the nearly $2 billion lettuce industries of California and Arizona, which together produce more than 90 percent of the nation’s lettuce. The study results were published online in March 2013 in the journal The Plant Cell. “Discovery of the genes will enable plant breeders to develop lettuce varieties that can better germinate and grow to maturity under high temperatures,” said the study’s lead author Dr. Kent Bradford, a professor of plant sciences and director of the UC Davis Seed Biotechnology Center. “And because this mechanism that inhibits hot-weather germination in lettuce seeds appears to be quite common in many plant species, we suspect that other crops also could be modified to improve their germination,” he said. “This could be increasingly important as global temperatures are predicted to rise.” Most lettuce varieties flower in spring or early summer and then drop their seeds — a trait that is likely linked to their origin in the Mediterranean region, which, like California, characteristically has dry summers. Scientists have observed for years that a built-in dormancy mechanism seems to prevent lettuce seeds from germinating under conditions that would be too hot and dry to sustain growth. While this naturally occurring inhibition works well in the wild, it is an obstacle to commercial lettuce production.
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