Exogenous treatment with melatonin enhances waterlogging tolerance of kiwifruit plants

Waterlogging stress has an enormous negative impact on the kiwifruit yield and quality. The protective role of exogenous melatonin on water stress has been widely studied, especially in drought stress. However, the research on melatonin-induced waterlogging tolerance is scarce. Here, we found that treatment with exogenous melatonin could effectively alleviate the damage on kiwifruit plants in response to waterlogging treatment. This was accompanied by higher antioxidant activity and lower ROS accumulation in kiwifruit roots during stress period. The detection of changes in amino acid levels of kiwifruit roots during waterlogging stress showed a possible interaction between melatonin and amino acid metabolism, which promoted the tolerance of kiwifruit plants to waterlogging. The higher levels of GABA and Pro in the roots of melatonin-treated kiwifruit plants partly contributed to their improved waterlogging tolerance. In addition, some plant hormones were also involved in the melatonin-mediated waterlogging tolerance, such as the enhancement of ACC accumulation. This study discussed the melatonin-mediated water stress tolerance of plants from the perspective of amino acid metabolism for the first time

Exogenous γ-aminobutyric acid enhances heat tolerance of kiwifruit plants by protecting photosynthetic system and promoting heat shock proteins expression

Kiwifruit plants are highly susceptible to increased atmospheric temperature, and the extreme high temperature often causes the loss of production and quality of the fruit. The γ-aminobutyric acid (GABA) has been widely proved to play important roles in plants in response to abiotic stresses, showing an important potential for application in agricultural industry to overcome environmental challenges. However, application of GABA in kiwifruit plants to resist external stresses has not been reported yet. This study found that pre-irrigation of kiwifruit plants with 0.5 mM GABA was effective in alleviating the heat damage on them. GABA treatment led to better antioxidant capacity and reduced ROS production in kiwifruit plants under high temperature. Moreover, exogenous GABA protected the photosynthetic system of kiwifruit plants when exposed to high temperature. Particularly, we found that endogenous ABA, Glu, Pro metabolisms were participated in the GABA-mediated heat resistance of kiwifruit plants. Furthermore, GABA treatment induced higher expression of AdHsps in kiwifruit plants, being partly responsible for their better performance under heat stress. In summary, this research first demonstrated that exogenous GABA treatment plays a positive role in kiwifruit plants to response to extreme heat stress