Does jasmonic acid control the maize shoot growth during the first phase of salt stress?

Jasmonic acid (JA) is involved in plant adaptations to biotic and abiotic stresses and accumulates transiently in response to osmotic/salt stress. Effects of 100 mM NaCl (osmotic stress) on shoot growth and biosynthesis of JA in two maize genotypes (Zea mays L.), salt-sensitive Across 8023 and resistant hybrid SR 03 were investigated. Plants were grown in aerated nutrient solution under controlled conditions. The analysis of jasmonic acid in root and shoot tissues was carried out by means of gas chromatography-tandem mass spectrometry (GC-MS/MS). Salt stress-induced reduction in shoot growth was more pronounced in the salt-sensitive genotype (30%) than the salt-resistant one (17%). Endogenous concentration of JA was not affected in both roots and shoots of SR 03, but it was increased in the roots of Across 8023 during the first phase of salt stress. In the second experiment, 6 d old maize seedlings were grown with or without 30 µM JA in the root medium. Exogenous treatment of JA, significantly reduced the maize seedling growth in terms of shoot extension, root length and root and shoot fresh weights. The differences in JA biosynthesis in genotypes of contrasting salt resistance indicate that jasmonic acid may have a role in plant adaptation to osmotic stress and increased JA in roots of the salt-sensitive genotype may be responsible for shoot growth inhibition