Functional identification of trehalose and a trehalose-6-phosphate synthase gene involved in heat stress tolerance of rose

Global warming-induced heat stress increasingly threatens the ornamental quality and productivity of roses. Previous studies have indicated that trehalose and the trehalose-6-phosphate synthase (TPS) gene family regulate plants' stress resistance, yet their roles in thermotolerance in rose remain uncharacterized. We previously identified RcTPS7b as a putative heat-responsive gene in Rosa chinensis 'Slater's Crimson China'. This study aimed to investigate whether exogenous trehalose enhances heat tolerance in rose, and elucidate the functional role of RcTPS7b in heat stress regulation. The results showed that exogenous application of 5 mmol/L trehalose significantly enhanced rose's heat tolerance by reducing the heat damage index, elevating superoxide dismutase (SOD) activity, and preserving the efficiency of Photosystem II (PSII). Overexpression of RcTPS7b in Arabidopsis thaliana enhanced the heat tolerance and antioxidant enzyme activities in transgenic plants, concomitant with upregulated expression of heat-resistant genes such as HEAT SHOCK FACTOR/PROTEIN (AtHSF/P). Furthermore, tobacco rattle virus-induced silencing of RcTPS7b in R. chinensis compromised thermotolerance and induced severe oxidative damage. Transient overexpression of RcTPS7b in rose petals reduced heat damage and maintained petal integrity through redox homeostasis under high temperature treatment. Collectively, this study demonstrates that exogenous trehalose potentiates RcTPS7b expression to enhance thermotolerance, revealing the trehalose metabolism pathway's pivotal role in heat stress regulation in R. chinensis, and will be helpful for the molecular breeding of heat tolerance in R. chinensis.