Salinity and foliar application of methyl jasmonate change the expression of the heat shock protein 90 (Hsp90) gene and morphological traits during the reproductive stage of rice (Oryza sativa)

Salinity is one of the problems in rice growth and yield. Studies on the effect of exogenous plant growth regulators on salinity-stressed plants remain limited. Therefore, this study aimed to investigate the impact of salinity stress and methyl jasmonate (MeJA) foliar application on growth characteristics and OsHsp90 gene expression in three rice cultivars (MR219, MR219-4, and MR219-9). Suggesting that the combined application of MeJA and activation of the OsHsp90 gene may have synergistic effects in enhancing salt tolerance. The Real-Time PCR was used to quantify the expression level of the gene in the leaves from the rice plants at the early reproductive stage. The plant growth parameters were measured 100 days after planting. Results showed that the expression of the OsHsp90 gene in the leaves of rice plants to MeJA treatment and salinity conditions varied among the rice varieties. The finding indicates that the MR219-9 variety exhibits greater tolerance and better growth in saline conditions than the other two genotypes (MR219 and MR219-4). Notably, a significant up-regulation expression (p < 0.05) of the OsHsp90 gene levels in the MR219-9 genotypes under the MeJA + salinity treatment (21.41 ± 5.34-fold) suggests its potential role in responding to stress conditions. This study provides valuable insights into the role of exogenous plant regulators, particularly MeJA, in mitigating the effects of salinity stress on rice plants. Future research should investigate the impact of other plant growth regulators on the expression of various genes in rice plants grown under saline conditions to improve the growth and production.