Transcriptomic Profiling of the Response to High-Nighttime-Temperature Stress in Tomato Leaves

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• High nighttime temperatures (HNT) significantly impede tomato (Solanum lycopersicum L.) growth and yield.
• Understanding tomato's molecular response to HNT is crucial for developing resilient crop varieties.

Purpose of the Study:

• To investigate the morphological and transcriptomic changes in tomato seedlings under prolonged HNT stress.
• To elucidate the molecular mechanisms underlying tomato adaptation to HNT.

Main Methods:

• Systematic examination of morphological traits and chlorophyll content under HNT.
• Transcriptome profiling (RNA sequencing) to identify differentially expressed genes (DEGs).
• Quantitative PCR (qPCR) to validate gene expression patterns.

Main Results:

• HNT suppressed growth and chlorophyll, induced H2O2 accumulation, and promoted thermomorphogenesis (reduced leaf angle, lower trichome density).
• 4,551 DEGs were identified, with down-regulated genes enriched in photosynthesis and metabolism, suggesting resource reallocation.
• The heat shock response (HSR) system (SlHSPs-SlHSFs) showed dynamic expression changes, indicating acclimation to HNT. Upregulated genes involved in stress resilience pathways like ROS homeostasis and DNA repair.

Conclusions:

• Tomato seedlings reprogram gene expression under HNT to conserve energy, maintain redox homeostasis, and enhance macromolecular stability for nocturnal heat acclimation.
• Findings provide insights into HNT adaptation and offer a foundation for breeding HNT-resilient tomato varieties.