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.
Emmenopterys henryi Oliv., a monotypic genus in family Rubiaceae with high scientific and application value, is currently endangered. Adaptability of E. henryi to environment is important for its cultivation, management, and application. In this paper, the effect of abscisic acid (ABA) on the photosynthesis of E. henryi under salt stress was discussed. Results showed that 0.3 % (m/v) NaCl led to reduction of net photosynthetic rate (PN), instantaneous carboxylation efficiency (ICE), and Rubisco activity but the increase of intercellular CO2 concentration (ci), which were remarkable relieved by ABA pretreatment. NaCl also induced reduction of the maximal efficiency of PS II photochemistry (Fv/ Fm), the photochemical quenching (qP), the non-photochemical quenching (NPQ), the actual PS II efficiency [Y(II)], the regulated-energy dissipation [Y(NPQ)], whereas the increase of the unregulated energy dissipation [Y(NO)]. ABA application remarkably mitigated the depression of F v/Fm, qP, Y(II) and the increase of Y(NO), but further promoted NPQ and Y(NPQ) in E. henryi due to high salinity. In addition, decrease of chlorophyll content, accumulation of MDA, and ion leakage in E. henryi due to high salinity were significantly alleviated by ABA pretreatment. Fluridone, an inhibitor of endogenous ABA synthesis, partially or completely reversed ABA mediated effects. These results suggested that ABA might improve the photosynthesis of E. henryi under salt stress via allocating more energy to photochemical reactions, or/and mitigating the decrease of Rubisco activity, or/and protecting photosynthetic apparatus by reinforcement of heat dissipation and alleviating oxidative damage.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.