Transcriptomic and physiological responses of Diplotaxis tenuifolia under heat stress

To determine strategies to increase plant tolerance to high temperature we must examine plant physiological and metabolic processes. High temperature leads to an alteration in photosynthesis, modification of plant metabolism, plant growth reduction, and overall reduction in the quality of horticultural products. Diplotaxis tenuifolia L., commonly known as wild rocket, is a member of the mustard family, Brassicaceae. This plant is cultivated as a baby-leaf salad. Our goal in this study was to understand the physiological and molecular responses in this plant when subjected to heat stress. This horticultural species is greatly appreciated for its sensorial characteristics and flavour. Because abiotic stresses can impact these organoleptic aspects, the aim of our study was to investigate plant changes induced by high temperature. This was done by growing the plants in a chamber under controlled conditions (24°C) and at fully expanded leaves stage, the temperature was increased to 37°C for 4 h day-1, for 4 days. For each condition (stress vs. control), in vivo analysis and sampling for both physiological parameter analysis and RNA-sequencing were conducted to identify changes induced by high temperature. Chlorophyll a fluorescence and physiological assay results confirmed the effects of heat stress, showing a reduction in chlorophyll content and leaf functionality as well as a decrease in sugars and nitrate content. Transcriptomic profile showed different regulation within the metabolic and physiological pathways under these conditions. These results provided a basis for further studies: the first plant response was to modify photosynthetic activity, which set off alterations in the primary metabolism and nutrient assimilation. The combination of physiological and molecular analysis helped us identify the pathways most affected by high temperature. We are also beginning to understand how to improve plant tolerance for extreme temperature events, which are increasingly common. As we go forward we are examining different strategies for plants to cope with high temperature by the application of biostimulants products to help plants recover from heat stress.

Alice Petrini won the ISHS Young Minds Award for the best poster presentation at the International Symposium on Adaptation of Horticultural Plants to Abiotic Stresses at IHC2022 in France in August 2022.

Alice Petrini, Department of Agricultural and Environmental Sciences, University of Milan, Via Celoria 2, 20133 Milan, e-mail: alice.petrini@unimi.it

The article is available in Chronica Horticulturae