Exogenous Melatonin Promotes Cold Tolerance in Grape Seedlings: Physiological, Transcriptomic, and Functional...

Area of Science:

• Plant Physiology
• Molecular Biology
• Biochemistry

Background:

• Melatonin (MEL) is a known antioxidant that improves plant stress tolerance.
• The specific mechanisms of MEL in regulating cold signaling pathways in grapes are not fully understood.

Purpose of the Study:

• To investigate the physiological and transcriptomic changes in grape seedlings treated with exogenous MEL.
• To determine the protective role of MEL in grape cold tolerance.

Main Methods:

• Grape seedlings were treated with exogenous MEL (150 μM).
• Physiological assessments included reactive oxygen species (ROS) levels and chloroplast integrity.
• Transcriptomic profiling was performed to identify differentially expressed genes.
• Functional analysis of candidate genes (e.g., VvHSFA6b) was conducted.

Main Results:

• MEL treatment reduced cold-induced cell damage, ROS accumulation, and inhibited tannin degradation.
• Exogenous MEL altered endogenous hormone levels, increasing ABA, auxin, and cytokinin while decreasing gibberellin.
• Transcriptomic analysis identified 776 differentially expressed transcripts.
• Overexpression of VvHSFA6b enhanced cold tolerance in grape calli by activating jasmonic acid (JA) synthesis.

Conclusions:

• Exogenous MEL provides significant protection to grape seedlings against cold stress.
• MEL influences multiple physiological processes and hormone signaling pathways in grapes under cold conditions.
• VvHSFA6b plays a crucial role in mediating MEL's cold tolerance effects through the JA pathway.