PsAOS3 Enhances High-Temperature Tolerance of Tree Peony by Promoting JA Accumulation

High-temperature stress severely restricts plant growth and development by inducing oxidative damage and photosynthetic inhibition. Allene oxide synthase (AOS) is a key enzyme in jasmonic acid (JA) biosynthesis, yet its role in the high-temperature stress response of woody ornamental plants remains largely uncharacterized. In this study, PsAOS3 was isolated and characterized from tree peony (Paeonia suffruticosa Andr.), an economically important ornamental species susceptible to high-temperature stress. PsAOS3 was localized to the plasma membrane and was strongly induced by high-temperature stress. Functional analyses using virus induced gene silencing in tree peony showed that silencing of PsAOS3 accelerated chlorophyll loss, increased reactive oxygen species (ROS) accumulation, impaired photosystem II efficiency and membrane integrity, and reduced antioxidant enzymes and endogenous JA contents under high-temperature stress. Conversely, overexpression of PsAOS3 in tobacco (Nicotiana tabacum L.) alleviated chlorophyll loss, decreased ROS accumulation, improved photosystem II efficiency and membrane integrity, and elevated antioxidant enzymes and endogenous JA contents under high-temperature stress. Collectively, this study reveals a potential role of PsAOS3 in regulating high-temperature responses in tree peony.