Analysis of volatile emission of tea (Camellia sinensis) shoots in response to temperature-dependent postharvest treatments

Volatile blends contain numerous information about the emitters. Volatile organic compounds (VOCs) have been used as biomarkers to monitor agri-products' state during postharvest management. We placed tea shoots at 15 degrees C or 25 degrees C after plucking and wondered if the emitted VOCs may reflect the freshness of these plucked tea shoots or differentiate tea shoots experiencing different postharvest treatments. Headspace solid-phase micro-extraction combined with gas chromatography-mass spectrometry was applied in this research to profile volatiles that were released from plucked tea shoots. Twenty-nine VOCs were found from all tea shoots samples, and the composition of released VOCs varied under different temperatures. Assessed by PLS-DA and two-way ANOVA, fourteen volatiles were selected as putative markers. All the markers were detected under the low-temperature condition, but not under the room-temperature condition. Transcriptome analysis showed that low temperature caused less variation in gene expression compared to room temperature. Many genes in volatile biosynthetic pathways had similar expression trends in either condition, while some changes occurred with a delay in the low-temperature environment. The study advances the understanding of the physiological changes of tea shoots subjected to temperature-dependent postharvest treatments.