Abstract
The signal molecules melatonin and ethylene play key roles in abiotic stress tolerance. The interplay between melatonin and ethylene in regulating salt tolerance and the underlying molecular mechanism of this interplay remain unclear. Here, we found that both melatonin and 1-aminocyclopropane-1-carboxylic acid (ACC, a precursor of ethylene) enhanced the tolerance of grapevine to NaCl; additionally, ethylene participated in melatonin-induced salt tolerance. Further experiments indicated that exogenous treatment and endogenous induction of melatonin increased the ACC content and ethylene production in grapevine and tobacco plants, respectively. The expression of MYB108A and ACS1, which function as a transcription factor and a key gene involved in ethylene production, respectively, was strongly induced by melatonin treatment. Additionally, MYB108A directly bound to the promoter of ACS1 and activated its transcription. MYB108A expression promoted ACC synthesis and ethylene production by activating ACS1 expression in response to melatonin treatment. The suppression of MYB108A expression partially limited the effect of melatonin on the induction of ethylene production and reduced melatonin-induced salt tolerance. Collectively, melatonin promotes ethylene biosynthesis and salt tolerance through the regulation of ACS1 by MYB108A.
Highlights
Soil salinization is an important environmental problem, and salt has become one of the most commonly encountered abiotic stresses that affects fruit crops, including grapevines, causing nutritional imbalance, ion toxicity, osmotic stress and oxidative damage and severely reducing crop growth, yield and fruit quality
ACC and melatonin treatment enhanced the tolerance of vines to NaCl
It is suggested that melatonin possibly upregulates VviMYB108A through abscisic acid (ABA). These results suggest that melatonin may regulate ethylene biosynthesis via complex crosstalk with other signal molecules and that the signaling molecules involved may at least partially determine the effect of melatonin on ethylene in a positive or negative manner
Summary
Soil salinization is an important environmental problem, and salt has become one of the most commonly encountered abiotic stresses that affects fruit crops, including grapevines, causing nutritional imbalance, ion toxicity, osmotic stress and oxidative damage and severely reducing crop growth, yield and fruit quality. ~830 million ha of land is affected by salinization, and this area is anticipated to increase in the near future[1]. Grapevines are widely cultivated worldwide and are ranked as sensitive or moderately sensitive to salt stress[2]. It is difficult to obtain highly salt-tolerant grapevine cultivars through traditional breeding methods; in contrast, Ethylene is an important signaling molecule mediating numerous important biological processes, including responses to abiotic stresses[7]. The action of ethylene depends on its concentration in cells and the sensitivity of plants to this hormone[8]. Ethylene biosynthesis is primarily regulated by 1-aminocyclopropane-1-carboxylate (ACC)
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