Endogenous ascorbic acid delays ethylene-induced leaf senescence in Arabidopsis thaliana

Abstract

Leaf senescence is an important event in the plant life cycle. Ethylene and ascorbic acid (AsA) both regulate the leaf senescence process. The role of endogenous AsA in ethylene-induced leaf senescence was explored in two independent endogenous AsA changing Arabidopsis thaliana mutants. The line vtc2-1 with a single base change in VTC was AsAdeficient mutant; the GLDH-overexpressing line (GLDHOE) driven by the CaMV 35S promoter was AsA-overaccumulating mutant. After spraying 600 μM ethephon for 6 d, vtc2-1 showed the most serious leaf chlorosis, reactive oxygen species (ROS) accumulation, chlorophyll breakdown, Rubisco degradation, and had the highest expression level of senescenceassociated genes (SAGs), such as SAG12, SAG13, SAG20, and SAG21 among the three lines. In contrast, GLDHOE maintained the highest photosynthetic pigments contents, Rubisco content, antioxidant capacity, and the lowest expression of SAG2, SAG20, and SAG21 among the three lines. Taken together, we conclude that endogenous AsA can delay ethyleneinduced senescence by scavenging ROS and inhibiting SAGs expression.

Ethylene involvement in the regulation of heat stress tolerance in plants

“…Heat stress also greatly affects Rubisco levels and activity (Salvucci and Crafts-Brandner 2004;Demirevska-Kepova et al 2005;Sharkey 2005;Perdomo et al 2017) which can also be mediated by ET (Jespersen and Huang 2015). ET plays a crucial role in progressing senescence and a decrease of Rubisco content (Young et al 2004;Martínez et al 2008;Liu et al 2019;Zheng et al 2020). This was confirmed by the application of ET inhibitor AVG which elevated Rubisco and Rubisco activase protein levels under heat stress (35/30 °C) in bentgrass suggesting the role of ET in promoting heatinduced senescence (Jespersen and Huang 2015).…”