Advances in deciphering salt tolerance mechanism in maize

Maize (Zea mays L.) is a global cereal crop whose demand is projected to double by 2050. Along with worsening of farmland salinization, salt stress has become a major environmental threat to the sustainability of maize production worldwide. Accordingly, there is an urgent need to decipher salt-tolerant mechanisms and facilitate the breeding of salt-tolerant maize. As salt tolerance is a complex trait regulated by multiple genes, and maize germplasm varies widely in salt tolerance, efforts have been devoted to the identification and application of quantitative-trait loci (QTL) for salt tolerance. QTL associated with ion regulation, osmotic tolerance, and other aspects of salt tolerance have been discovered using genome-wide association studies (GWAS), linkage mapping, and omics-based approaches. This review highlights recent advances in the molecular-level understanding of salt stress response in maize, in particular in (a) the discovery of salt-tolerance QTL, (b) the mechanisms of salt tolerance, (c) the development of salt-tolerant maize cultivars, and (d) current challenges and future prospects.