Abscisic acid synthesis and root water uptake contribute to exogenous methyl jasmonate-induced improved tomato drought resistance
2022
Yan, Jiakun | Li, Haipeng | Li, Yu | Zhang, Nan | Zhang, Suiqi
In rain-fed semi-arid agricultural areas, unevenly distributed seasonal rainfall influences tomato production. Meanwhile, jasmonic acid, an essential plant hormone, enhances plant resistance to biotic and abiotic stresses; however, its effect on tomato drought resistance remains unclear. In this study, a series of pot experiments were conducted to investigate the effects elicited via addition of exogenous methyl jasmonate (MeJA), an active ingredient of jasmonic acid, on tomato physiology, biochemistry, and transcription under two water conditions. The results indicate that 100 μM MeJA application significantly improved drought resistance in tomato and increased the biomass. Moreover, water deficiency significantly decreased the tomato plant photosynthetic rate, stomatal conductance, and root exudation and increased the leaf abscisic acid (ABA) content. Meanwhile, MeJA application increased root exudation and whole plant transpiration rate to maintain relatively high leaf water content. In leaves, specifically, MeJA increased the expression of carotenoid cleavage dioxygenases and reduced ABA content, which might contribute to the maintenance of a high stomatal conductance. In addition, many genes involved in photosynthetic carbon metabolism and sugar transport were upregulated by MeJA, resulting in a low soluble sugar-to-starch ratio, to maintain plant growth. Collectively, these findings indicate that exogenous MeJA decreases ABA content to maintain high stomatal conductance and enhance root water uptake capacity to maintain improved leaf relative water status, consequently improving tomato drought resistance.
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