A teosinte-derived allele of ZmSC improves salt tolerance in maize.

Maize, a salt-sensitive crop, frequently suffers severe yield losses due to soil salinization. Enhancing salt tolerance in maize is crucial for maintaining yield stability. To address this, we developed an introgression line (IL76) through introgressive hybridization between maize wild relatives , , and inbred Zheng58, utilizing the tri-species hybrid MTP as a genetic bridge. Previously, genetic variation analysis identified a polymorphic marker on (designated as ZmSC), which encodes a vesicle-sorting protein described as a salt-tolerant protein in the NCBI database. To characterize the identified polymorphic marker, we employed gene cloning and homologous cloning techniques. Gene cloning analysis revealed a non-synonymous mutation at the 1847th base of , where a guanine-to-cytosine substitution resulted in the mutation of serine to threonine at the 119th amino acid sequence (using as the reference sequence). Moreover, homologous cloning demonstrated that the variation site derived from . Functional analyses showed that transgenic lines overexpressing exhibited significant reductions in leaf number, root length, and pod number, alongside suppression of the expression of genes in the SOS and CDPK pathways associated with Ca signaling. Similarly, fission yeast strains expressing displayed inhibited growth. In contrast, the allele from alleviated these negative effects in both and yeast, with the lines overexpressing exhibiting significantly higher abscisic acid (ABA) content compared to those overexpressing . Our findings suggest that ZmSC negatively regulates salt tolerance in maize by suppressing downstream gene expression associated with Ca2+ signaling in the CDPK and SOS pathways. The allele from , however, can mitigate this negative regulatory effect. These results provide valuable insights and genetic resources for future maize salt tolerance breeding programs.