Abstract: Saline-alkali stress is one of the main adverse environmental factors limiting agricultural production and crop yield. In recent years, great progress has been made in the dissection of the molecular mechanisms of plant’s responses to salt stress, but little is known concerning those for alkaline stress. Lack of the knowledge on alkaline tolerance has severely impeded the effort to improve saline and alkaline stress tolerance of crops through molecular designing and breeding. Recently, Professor Qi Xie at the Institute of Genetics and Developmental Biology of Chinese Academy of Sciences, teamed with Dr. Feifei Yu at China Agricultural University and Dr. Yidan Ouyang at Huazhong Agricultural University, made a breakthrough discovery towards the understanding of the molecular regulation of alkaline tolerance. They detected a major gene AT1, which negatively regulates alkaline tolerance, through sorghum genome-wide association study. The knockout of AT1 and its homologous genes increased the tolerance of sorghum, rice, millet and maize to alkali and increased the yield. AT1 encodes an atypical G protein γ subunit, which alters the cellular distribution of H₂O₂ via regulating the phosphorylation level of the aquaporins PIP2;1 to alleviate the alkali-induced oxidative stress in cells. This work reveals a new mechanism in the adaptation of crops to alkaline stress, which is of great significance to crop breeding for alkaline resistance.

Key words: alkaline stress, sorghum, AT1, Gγ protein, oxidative stress