Temperature and photoperiod changes affect cucumber sex expression by different epigenetic regulations

Area of Science:

• Plant Biology
• Epigenetics
• Molecular Biology

Background:

• Cucumber (Cucumis sativus) exhibits plasticity in sex expression, influenced by environmental factors.
• DNA methylation regulates gene activity and is sensitive to environmental changes, suggesting a role in cucumber sex instability.
• The differential impact of temperature and photoperiod on cucumber sex expression via epigenetic mechanisms requires investigation.

Purpose of the Study:

• To investigate the effects of temperature and photoperiod on cucumber sex expression.
• To determine if temperature and photoperiod utilize similar epigenetic regulation mechanisms.
• To analyze methylome and transcriptome data from cucumber shoot apices under varying environmental conditions.

Main Methods:

• A two-factor experiment manipulating temperature and photoperiod.
• Generation of methylome and transcriptome data from cucumber shoot apices.
• Analysis of DNA methylation status, gene expression, and transposable element (TE) activity.

Main Results:

• A significant decrease in femaleness was observed in early autumn conditions (high temperature, long-day photoperiod).
• Both high temperature and long-day photoperiod treatments led to hypermethylation, with temperature being the predominant factor.
• Differentially expressed TEs and epiregulation sites were identified and clustered, showing reproducibility across treatments. Photoperiod primarily affected flower development genes, while temperature influenced phytohormone-related genes.

Conclusions:

• Seasonal sex expression changes are a widespread phenomenon in cucumbers.
• High temperature and long-day photoperiod may share a common gene-TE interaction mechanism for methylome changes.
• Distinct epicontrol sites mediate the different mechanisms underlying temperature- and photoperiod-dependent sex expression changes.