Influence of trehalose on photosynthesis in the rare and endangered Emmenopterys henryi Oliv. during heat stress and recovery process

Abstract

The effects of trehalose on photosynthesis of rare and endangered Emmenopterys henryi Oliv. in response to high temperature were investigated. Results showed that trehalose pretreatment not only alleviated heat-induced reductions of chlorophyll content, net photosynthetic rate (P N ), stomatal conductance (G s ), transpiration rate (T r ) and instantaneous carboxylation efficiency (ICE) but also advanced the recoveries of chlorophyll level, P N , water use efficiency (WUE), ICE, G s , and T r after removal of heat treatment. The decrease of the actual PSII efficiency (Ф PSII ), the maximal efficiency of PSII photochemistry (F v /F m ), photochemical quenching (q P ) and electron transport rate (rETR (II)) owing to high temperature were significantly mitigated under trehalose pretreatment. In addition, the recoveries of the initial fluorescence (F o ), F v /F m , Ф PSII , q P and rETR (II) were promoted by trehalose pretreatment after the cancellation of heat treatment. The results suggested that trehalose application relieved the damage of high temperature on photosynthesis in E. henryi and promoted its restoration, which might involve with mitigation of chlorophyll degradation, stomata regulation, improvement of ICE, renovation of PSII reaction center, allocation of more energy to photochemical reaction, and promotion of electron transport activity.

Trehalose alleviates salt tolerance by improving photosynthetic performance and maintaining mineral ion homeostasis in tomato plants

“…Notably, the addition of exogenous Tre not only promoted the significant increase in Tr and Pn in tomato plants under normal growth conditions but also increased Pn and Tr and decreased Ci under salt stress (Figure 1). This was consistent with Feng et al (2022). Under high temperature stress, Tre treatment increased Pn and Ci, but decreased gs and Tr, this differs from part of our results and may be that a Tre film was formed on the surface of leaves to reduce excessive evaporation of water and maintain water balance, thus inhibiting damage caused by high temperature (Zhao et al, 2019).…”

“…However, excessive excitation energy limited production of reactive oxygen species (ROS), which leads to oxidative damage of the photosynthetic mechanism. Several studies have shown that Tre can enhance the activity of antioxidant enzymes in plants under abiotic stress, and regulate the expression of osmoprotectant biosynthetic genes such as proline (de Novais Portugal et al, 2021;Kosar et al, 2021;Zulfiqar et al, 2021;Feng et al, 2022). Therefore, the enhancement of ROS scavenging system induced by Tre may be one of the important reasons for the increase of photosynthetic oxygenation capacity and electron transfer rate of tomato seedlings under NaCl stress.…”

“…In another study, application of Tre alleviated the negative effects of drought by partially restoring chlorophyll levels and photosynthetic activity in Sweet Basil (Zulfiqar et al, 2021). In addition, the application of Tre not only alleviated the heat-induced chlorophyll content and gas exchange parameters of Emmenopterys henryi Oliv., but also promoted the recovery of photosynthesis after heat treatment (Feng et al, 2022). Alternatively, Tre decreased the Na + /K + ratio of rice seedlings under salt stress (Nounjan et al, 2012).…”