Insights into sorghum’s alkaline tolerance could help improve crop yields in salty soils

As the world’s soils continue to be impacted by salt, threatening food production, researchers have identified a protein that plays a crucial role in helping plants like sorghum grow in alkaline, salty soils. The findings could inform the design of crops better suited to grow in underutilized sodic lands. Ensuring global food security in the future relies on continued agricultural production. However, due to climate change, declines in freshwater availability, and the widespread application of chemical fertilizers, agricultural soils worldwide are expected to become saltier, which could become a global problem affecting agricultural production. Alkaline sodic soils – those with higher pH levels and dominated by sodium carbonate and sodium bicarbonate salts – inhibit a plant’s ability to take in nutrients and manage salt stress. However, relatively little is known about plant alkaline tolerance, limiting the development of crops well suited for sodic soils. Huili Zhang and colleagues performed a genome-wide association study of plant growth in alkaline conditions using sorghum, a widely cultivated cereal crop known to be naturally tolerant to alkaline soils, and identified Alkaline Tolerance 1 (AT1) – a major locus specially related to the plant’s sensitivity to alkaline, sodic soils. AT1 encodes an atypical G protein γ subunit that regulates phosphorylation of aquaporins, which mediate the oxidative stress caused by alkaline conditions. Although overexpression of the protein resulted in higher sensitivity to alkaline stress, Zhang et al. found that gene knockout of AT1 in sorghum as well as its homologs in millet, rice, and maize increased the plant’s alkaline tolerance. These plants also produced higher yields when grown in alkaline soils in field trials. The findings suggest that designing knockouts of AT1 homologs in crops could improve their productivity in salty soils, opening up millions of hectares of sodic land to agriculture.