Shifting flower timing to beat the heat of warming climate in crops

Climate-induced heat stress is intensifying across a spectrum of timescales, spanning from annual and seasonal cycles to monthly and even daily fluctuations. The development of heat-resistant crops is imperative to safeguard food security in the face of a warming climate. This study investigates the warming trend in global croplands, explores a heat escape strategy and its underlying mechanism, and evaluates its efficacy in mitigating heat stress. We analyzed the global-scale warming trend since 1850, compared the diurnal variation of temperature during the hottest months across global croplands over the past 20 years, collected diurnal floret opening time (DFOT) data from 102 plant species, and summarized the molecular mechanism underlying DFOT regulation in cereal crops. During the hottest season globally, the daily maximum temperature increased at an average rate of 0.062 °C per year, while the duration of mid-day heat episodes in global croplands extended by an average of 0.05 h per year. In the plant kingdom, species like sorghum and pearl millet escape midday heat during hot seasons by shifting their floret opening time to early morning, thereby effectively coping with prolonged heat episodes. Multiple pieces of evidence confirm that the early-morning flowering trait significantly enhances heat resistance in rice, wheat, and maize. The molecular mechanism of the early-morning flowering trait is relatively clear in rice, based on which, we identified homologous genes in more than 60 plant species, which provides insights into the potential for widely enhancing crop heat escape in a warming climate.