Local maize responses to salinity stress through morphological and molecular alterations of r40C1-like and SOS1 gene

Salinity stress is one of the most critical abiotic constraints limiting maize (Zea mays L.) productivity. This study investigated the morphological and molecular responses of four local maize varieties exposed to NaCl induced salinity. Morphological observation, including plant height, root length, and biomass accumulation, were evaluated alongside the expression level of r40C1-like and SOS1 genes using quantitative PCR. All varieties exhibited growth suppression under saline conditions. However, the degree of reduction differed considerably among genotypes. Srikandi Putih showed relatively higher tolerance, with plant height declining by 31.7% at 10,000 ppm NaCl, whereas Bisma experienced a more pronounced reduction of 60.3% under the same treatment. Similarly, the dry weight of Srikandi Putih decreased by 22% at 5,000 ppm, while Srikandi Kuning displayed a greater decline of 28.2%. Gene expression analysis revealed substantial induction of defense-related genes under moderate salinity. At 5,000 ppm, Srikandi Putih exhibited upregulation of r40C1-like (10.03 fold) and SOS1 (5.27 fold), whereas Pulut Uri reached 7.29 fold and 10.30 fold for the respective genes. In contrast, expression levels dropped sharply at 10,000 ppm, with Srikandi Kuning showing the lowest expression of r40C1-like (0.33 fold) and SOS1 (0.03 fold). Overall, the results demonstrate that Srikandi Putih possesses a more effective adaptive response to saline conditions, emphasizing its potential for cultivation in salt affected agricultural systems.