SHIJIAZHUANG.- Maize is grown widely and the most productive staple cereal in the world, and is critical to global food security. Drought has become a severe abiotic stress that affects the global production of maize. Elucidation of the complex physiological mechanisms underlying drought tolerance will support the cultivation of new drought-tolerant maize varieties.

In collaboration with Prof. Chen Huabang from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, researchers led by Prof. Xie Qi from IGDB isolated one gene involved in drought response in maize by using comparative transcriptome and bin map subtraction.

They selected two drought-tolerant lines, RIL70 and RIL73, and two drought-sensitive lines, RIL44 and RIL93, from a drought-related recombinant line population for RNA-seq analysis. They found that gene expression differences not only existed between drought-tolerant and -sensitive lines, but also between the drought-tolerant lines through joint analysis.

A basic helix-loop-helix (bHLH) type transcription factor encoded by ZmbHLH124T-ORG originated from RIL73, was specifically up-regulated during drought stress. Overexpression of ZmbHLH124T-ORG in maize and rice enhanced plant drought tolerance and up-regulated the expression of drought-responsive genes. Moreover, ZmbHLH124T-ORG could directly bind the cis-acting elements in ZmDREB2A promoter to activate its expression.

This work identifies a valuable genetic locus and provides a new strategy for breeding drought-tolerant crops.

This study entitled "ZmbHLH124 identified in maize recombinant inbred lines contributes to drought tolerance in crops" was published online in Plant Biotechnology Journal on May 25.

This work was supported by the National Key R&D Program of China, and the Transgenic Research Projects.