Physiological genetic variation in tomato fruit chilling tolerance during postharvest storage

Area of Science:

• Plant Physiology
• Horticultural Science
• Molecular Biology

Background:

• Low-temperature storage extends postharvest life of fruits and vegetables.
• Chilling injury at non-freezing temperatures causes physiological disorders and economic losses in susceptible produce.
• Tomato (Solanum lycopersicum L.) is susceptible to chilling injury, impacting its postharvest quality.

Purpose of the Study:

• To investigate the genetic variation in postharvest chilling tolerance in a tomato recombinant inbred line (RIL) population.
• To identify physiological and molecular markers for assessing chilling tolerance in tomato fruit.
• To explore the role of antioxidant activity and CBF gene expression in chilling response.

Main Methods:

• Generated and screened 148 RILs from a cross between chilling-sensitive *S. lycopersicum* and chilling-tolerant *S. pimpinellifolium* under cold storage (1.5°C).
• Assessed physiological parameters including weight loss, chlorophyll fluorescence (Fv/Fm, PI), antioxidant activity, and ascorbic acid content.
• Quantified the expression of C-repeat/DREB binding factors (CBFs), specifically *SlCBF1*, using quantitative PCR.

Main Results:

• Significant variation in chilling tolerance was observed among RILs, with distinct tolerant and sensitive groups identified.
• Chlorophyll fluorescence parameters *Fv/Fm* and *PI* effectively indicated physiological damage and early photosystem II dysfunction, respectively.
• Chilling-tolerant lines exhibited higher antioxidant activity and ascorbic acid content, alongside generally higher *SlCBF1* transcript levels post-chilling.

Conclusions:

• The tomato RIL population possesses substantial genetic variation for postharvest fruit chilling tolerance.
• Physiological markers (*Fv/Fm*, *PI*) and molecular markers (*SlCBF1* expression) can efficiently differentiate chilling response.
• Further research into these mechanisms can guide breeding efforts for enhanced tomato postharvest cold storage.