Selection Enabling Maize to Tolerate Moderate Heat May Limit Resistance to Severe Heat

Trait selection among maize has allow the crop to tolerate moderate increases in heat, but has limited its tolerance to severe heat, according to a new study appearing in PLOS Genetics. Severe heat stemming from climate change is expected to become more of an issue for crops, famers, and global food security. Researchers from Iowa State University and elsewhere sifted through 81 years of public yield trial records from four US states that includes 4,730 maize hybrids and related temperature data. After modeling the temperature responses of the different hybrids, the researchers found that they have become more resistant to moderate heat increases, but more sensitive to severe heat stress, suggesting a genetic tradeoff in heat tolerance. "Genetic analyses of heat and drought tolerance have identified numerous mechanisms by which plants can adaptively respond to heat and osmotic stress," the researchers note. "Targeting these mechanisms has been shown to improve drought tolerance in maize hybrids. This and continued research combined with emerging technologies are expected to contribute to further, more targeted adaptations in the future."