Genes key to increasing heat tolerance of grains

Amid global climate change, Chinese scientists have recently made significant progress in understanding the heat tolerance mechanisms in rice, identifying its heat-tolerant genes, and developing new varieties suited to future climates.

Their study involved field trials simulating high-temperature conditions, where the scientists identified two key regulatory factors in rice that sense and respond to heat. Results showed that rice lines with single-gene modifications increased yield by 50 to 60 percent compared with control lines, while those with dual-gene modifications nearly doubled in yield.

Such results are expected to provide a promising new avenue for ensuring food security in the face of global warming. A paper about the study by researchers from the Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Jiao Tong University, and Guangzhou Laboratory was published in the journal Cell on Wednesday.

Prolonged high temperatures threaten global food security by damaging crop pollen viability, disrupting pollination and grain filling, and significantly reducing yield and quality, according to experts. Understanding the heat tolerance mechanisms in crops and breeding new varieties adapted to future climates have thereby become an urgent task in agricultural science.

The research teams successfully identified two critical regulatory factors in rice: DGK7, a type of kinase, and MdPDE1, a type of lipase. These factors function as a sophisticated alarm system, converting external heat signals into biological instructions that the cell can understand, completing a communication process from the cell membrane to the nucleus.

The scientists found that when high temperatures threaten the cell membrane, the "border wall" of plant cells, the sentinel DGK7 is activated first, decoding and releasing the initial signal response by generating lipid messengers. This process translates and amplifies the external physical heat into an internal chemical alert.

Subsequently, a messenger enters the cell, accurately transmitting the external heat signal and activating the "middle commander" MdPDE1, which assists in entering the nucleus, the core command center. MdPDE1 prompts the synthesis of heat-resistant weapons, resisting heat stress.

This mechanistic understanding provides precise targets for breeding. The research teams conducted genetic design based on DGK7 and MdPDE1, achieving promising results in field trials under simulated high temperatures.

"In our field trials, we set peak temperatures at 46 C for one to two hours during the day, and allowed the temperature to cool down in the evening, mimicking scorching days. The quality of the rice improved compared with controls, without affecting yield under normal conditions," said Lin Hongxuan, one of the corresponding authors of the paper and a researcher at the CAS center.

"This means that scientists cannot only enhance crop heat tolerance, but also precisely design 'gradient heat-tolerant' varieties."

This study provides a solid theoretical framework and valuable genetic resources for improving heat tolerance in staple crops, including rice, wheat and corn, potentially offering new solutions to address food production declines caused by global warming, said the researchers.

zhouwenting@chinadaily.com.cn