Intermittent Changes in Temperature and Humidity Repress Gray Mold in Tomato

Area of Science:

• Plant Pathology
• Environmental Science
• Molecular Biology

Background:

• Environmental temperature and humidity significantly influence plant-pathogen interactions and crop disease development.
• The precise mechanisms by which fluctuating environmental conditions mitigate plant diseases are not fully understood.

Purpose of the Study:

• To determine the optimal intermittent temperature and humidity combination for controlling tomato gray mold (caused by *Botrytis cinerea*).
• To elucidate the molecular interactions between tomato plants and *B. cinerea* under controlled environmental changes.

Main Methods:

• Six different temperature and humidity combinations were tested.
• Disease severity and fungal biomass were quantified.
• Pathogen infection processes were observed using optical microscopy.
• Dual RNA-sequencing (RNA-seq) was employed to analyze plant and fungal gene expression.

Main Results:

• The treatment involving 12 hours of regulation at 24 hours postinoculation (hpi) during the day significantly reduced gray mold severity and *B. cinerea* biomass.
• This optimal treatment also inhibited fungal mycelial growth.
• Tomato plants showed upregulated genes related to light reactions, photorespiration, and the Calvin cycle.
• Conversely, *B. cinerea* exhibited downregulated genes involved in the biosynthesis of the toxins botrydial and botcinic acid.

Conclusions:

• A specific intermittent temperature and humidity strategy (24 hpi-12 h day) is effective in controlling tomato gray mold.
• This environmental manipulation impacts host plant photosynthesis-related pathways and pathogen virulence factor production.
• The findings provide a theoretical foundation for the ecological control of plant diseases.