Microarray analysis of ripening-regulated gene expression and its modulation by 1-MCP and hexanal.

Area of Science:

• Plant Physiology
• Molecular Biology
• Biochemistry

Background:

• Hexanal is a phospholipase D (PLD) inhibitor used for pre- and post-harvest treatments.
• Ethylene plays a crucial role in fruit ripening and senescence.

Purpose of the Study:

• To analyze gene expression changes induced by hexanal and 1-methylcyclopropene (1-MCP) in tomato fruits.
• To investigate the potential of hexanal as an ethylene inhibitor.

Main Methods:

• Microarray analysis using TOM2 tomato oligo-array (approx. 12,000 unigenes).
• Treatment of mature green tomatoes with 1-MCP and hexanal.
• RNA isolation, cDNA synthesis, and gene expression profiling after 10 days of storage.
• Gas Chromatography-Mass Spectrometry (GC-MS) for volatile compound analysis.

Main Results:

• 1-MCP significantly down-regulated genes in ethylene biosynthesis, ethylene receptors, response factors, cell wall degradation, and carotenoid development.
• Hexanal significantly down-regulated ACC-synthase and, to a lesser extent, other ethylene signal transduction components.
• Hexanal-treated fruits ripened gradually with higher lycopene and β-carotene levels and increased volatile compounds compared to 1-MCP treated fruits.
• Gene expression patterns indicated hexanal may act as a weak ethylene inhibitor.

Conclusions:

• Hexanal's effect on gene expression shares similarities with ethylene inhibition by 1-MCP.
• Hexanal may function as a weak ethylene inhibitor, in addition to its role as a PLD inhibitor.
• Hexanal treatment promotes gradual ripening and enhances carotenoid accumulation in tomatoes.