Figure Genetic modification of AT1 enhances alkaline stress tolerance.

Over one billion hectares of land are affected by salts worldwide, of which 60% are sodic land with a high pH. Soil alkalinity affects crop growth and yield, and threat the food security. In China, there is about 100 million hectares of lands affected by salt and alkali. Breeding crops with salt-alkaline resistance are well recognized to facilitate the utilization of sodic land resources and contribute to food security. However, relatively little is known about plant alkaline tolerance, limiting the development of crops well suited for sodic soils.

In a recent study published in Science, complemented by Prof. Qi Xie from the Institute of Genetics and Developmental Biology at the Chinese Academy of Sciences, Prof. Feifei Yu from Chinese Agricultural University, and Prof. Yidan Ouyang from Huazhong Agricultural University in collaboration with five other institutions identified a key gene Alkaline Tolerance 1 (AT1) that regulates alkaline tolerance across multiple cereal crops. This work was supported by National Natural Science Foundation of China grants U1906204 (to Q.X.). 

Sorghum was first cultivated as a food source in the Sahelian belt of Africa and has a good resistance to salt-alkaline stress condition. Huili Zhang and colleagues performed a genome-wide association study of plant growth in alkaline conditions using a panel of 352 sorghum accessions, and identified AT1 – a major locus specially related to the plant’s sensitivity to alkaline, sodic soils. AT1 encodes an atypical G protein γ subunit, and in rice, it was named GS3. AT1/GS3 inhibits the phosphorylation of aquaporins PIP2s, which mediates the oxidative stress caused by alkaline conditions. Although overexpression of the protein resulted in higher sensitivity to alkaline stress, Zhang et al. found that knockout of AT1 gene in sorghum as well as its homologs in millet, rice, and maize enahnced the plant’s alkaline tolerance, with higher yields, biomass and survival rate when grown in alkaline soils in field trials. The findings suggest that genetic modification of AT1 homologs in crops could improve their productivity in salty soils, opening up millions of hectares of sodic land to agriculture.