The effects of chilling-light stress on photosystems I and II in three Paphiopedilum species

Ying-Jie Yang,Shi-Bao Zhang,Wei Chang,Hong Hu,Wei Huang

doi:10.1186/s40529-017-0208-4

Abstract

BackgroundLow temperatures pose a critical limitation to the physiology and survival of chilling-sensitive plants. One example is the genus Paphiopedilum (Orchidaceae), which is mainly native to tropical and subtropical areas from Asia to the Pacific islands. However, little is known about the physiological mechanism(s) underlying its sensitivity to chilling temperature. We examined how chilling-light stress influences the activities of photosystem I (PSI) and photosystem II (PSII) in three species: P. armeniacum, P. micranthum, and P. purpuratum. All originate from different distribution zones that cover a range of temperatures.ResultsPhotosystem II of three Paphiopedilum species was remarkable sensitivity to chilling stress. After 8 h chilling stress, the maximum quantum yield of PSII of three species of Paphiopedilum was significantly decreased, especially in P. purpuratum. The quantity of efficient PSI complex (Pm) value did not significantly differ after 8 h chilling treatment compared to the original value in three species. The stronger PSII photoinhibition and significantly less capacity for cyclic electron flow (CEF) were observed in P. purpuratum.ConclusionsIn conclusion, the three species of Paphiopedilum showed significant PSII photoinhibition when exposed to 4 °C chilling treatment. However, their PSI activities were not susceptible to chilling-light stress during 8 h. The CEF was important for the photoprotection of PSI and PSII in P. armeniacum and P. micranthum under chilling conditions. Our findings suggested that the photosynthetic characteristics of Paphiopedilum were well adapted to their habitat.

Highlights

Low temperatures pose a critical limitation to the physiology and survival of chilling-sensitive plants
At a relatively low level of 200 μmol photons m−2 s−1, photoinhibition of photo‐ system II (PSII) was stronger in P. purpuratum than in P. armeniacum and P. micranthum
In order to determine whether the rate of PSII photodamage at chilling-light stress differs between the three species, detached leaves were pre-incubated with lincomycin and exposed to 500 μmol photons m −2 s−1

Summary

Introduction

Low temperatures pose a critical limitation to the physiology and survival of chilling-sensitive plants. The activities associated with energy capture and electron transfer are essential for photosynthesis. These reactions perform high-potential redox chemistry and lead to photodamage of the photosynthetic machinery. Over-collection of the genus has become so extensive that many species are sub-viable in their natural habitats These plants usually occur in limestone or mountainous forests within tropical and subtropical zones ranging from Asia to the Pacific islands (Cribb 1998). Due to their tropical or subtropical origins, it is believed that these orchids cannot survive in regions with long-term natural chilling temperatures. The mechanism underlying their potential adaption to such conditions is unknown

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