Characterization of energy transfer processes and flash oxygen yields of thylakoid membranes isolated from resurrection plant haberlea rhodopensis subjected to different extent of desiccation

Abstract

The resurrection plants are unique with their extra desiccation tolerance. The physico-chemical properties of photosynthetic apparatus are of crucial importance for survival of plants upon water stress. In present work the effect of different extent of desiccation on the energy transfer properties and oxygen evolving capacity of isolated thylakoid membranes from resurrection plant Haberlea Rhodopensis are investigated. The plants from different habitats in Bulgaria are compared. Energy distribution and spillover between both photosystems are studied by means of 77 K chlorophyll fluorescence. The dependence of fluorescence ratio F735/F685 on the degree of desiccation of plants is also followed. Functionality of PSII and especially of oxygen-evolving apparatus under water deficit is estimated by flash oxygen yields and initial oxygen burst of thylakoid membranes isolated from plants desiccated up to 50% and 8% relative water content (RWC). Population of Si states as well as the misses and the double hits are calculated according non-cooperative Kok’s model and compared for plants from different habitats and different RWC. The results are discussed in terms of involvement of “fast” and “slow” centers from grana and stroma regions in oxygen evolution and alteration of their contribution as a result of desiccation.