Combined drought and heat stress in Camellia oleifera cultivars: leaf characteristics, soluble sugar and protein contents, and Rubisco gene expression

Leaf relative water content, leaf area, leaf fresh weight, and SPAD chlorophyll meter readings along with Co - rbcL and Co - rbcS expression can be used for evaluating Camellia oleifera responses to combined drought and heat stress and subsequent recovery after rainfall events. Leaf characteristics, soluble protein and total soluble sugar contents as well as Rubisco-related gene expression in three cultivars of C. oleifera were measured during a combined drought and heat stress period and after subsequent rainfall events. Leaf relative water content (RWC) was significantly correlated with leaf area (LA), leaf fresh weight (FW), SPAD chlorophyll meter readings, and the levels of Co-rbcL and Co-rbcS expression. Results suggest that leaf RWC, LA, leaf FW, SPAD readings together with Co-rbcL and Co-rbcS expression can be used for evaluating responses of C. oleifera cultivars to combined drought and heat stress and subsequent recovery after rainfall events. Rubisco activase might be used for evaluating plant recovery after rainfall. This study identified cultivars differing in tolerance to the combined stress and recovery. Information derived from this study should be valuable for improving survivability and productivity of C. oleifera cultivars.