S11 - Session O1 - Keynote: Physiological and genetic study inspired insights into tomato responding to multiple abiotic stress

Authors: Rong Zhou *, Xiaqing Yu, Eva Rosenqvist, Carl-Otto Ottosen

Abiotic stresses caused by global climate change have negative impacts on crop development, growth and thereby reducing the food production. More importantly, plants were usually challenged by multiple stress since several stresses can happen simultaneously. However, the response of plants to multiple stress cannot be simply concluded from individual stress. Tomato, as a world widely grown vegetable, was sensitive to various abiotic stresses, such as heat, cold, drought. We aim to clarify tolerance mechanisms of tomato plants responding to multiple stress conditions using physiological and molecular approaches. Firstly, we found that tomatoes under drought stress showed similar physiological response when subjected to the combination of drought and heat, indicating the predominant effect of water deficit on tomato compared to heat stress. Apart from the physiological response, the miRNAs-mRNAs and circRNAs regulatory mechanism in tomatoes actively responded to combined drought and heat stress. Elevated CO 2 concentration (800 ppm) increased the sensitivity of tomato to combined drought and heat stress compared with controlled CO 2 concentration (400 ppm). Secondly, combined drought and cold stress decreased tomato photosynthesis, induced hormone accumulation and ROS metabolism disorder regulated by gene expression, where low temperature played the primary role. Thirdly, tomato plants being suffered repeated heat stress showed higher stomatal conductance and lower leaf temperature than those being subjected to heat stress once, even though there were no difference in the net photosynthetic rate. This suggested that heat priming did improve the heat tolerance by decreasing the leaf temperature. Overall, the multiple stresses are new state of stress conditions, where the plants exhibited both similar and unique responses as compared with the individual stress. The crosstalk between plant physiology and key gene expressions involved in ROS, phytohormones, photosynthesis and carbohydrate transport contributed to the performance of tomato plants to multiple stresses.