Contrasting effect of dark-chilling on chloroplast structure and arrangement of chlorophyll–protein complexes in pea and tomato: plants with a different susceptibility to non-freezing temperature

Abstract

The eVect of dark-chilling and subsequent photoactivation on chloroplast structure and arrangements of chlorophyll-protein complexes in thylakoid membranes was studied in chilling-tolerant (CT) pea and in chillingsensitive (CS) tomato. Dark-chilling did not inXuence chlorophyll content and Chl a/b ratio in thylakoids of both species. A decline of Chl a Xuorescence intensity and an increase of the ratio of Xuorescence intensities of PSI and PSII at 120 K was observed after dark-chilling in thylakoids isolated from tomato, but not from pea leaves. Chilling of pea leaves induced an increase of the relative contribution of LHCII and PSII Xuorescence. A substantial decrease of the LHCII/PSII Xuorescence accompanied by an increase of that from LHCI/PSI was observed in thylakoids from chilled tomato leaves; both were attenuated by photoactivation. Chlorophyll Xuorescence of bright grana discs in chloroplasts from dark-chilled leaves, detected by confocal laser scanning microscopy, was more condensed in pea but signiWcantly dispersed in tomato, compared with control samples. The chloroplast images from transmission-electron microscopy revealed that dark-chilling induced an increase of the degree of grana stacking only in pea chloroplasts. Analyses of O-J-D-I-P Xuorescence induction curves in leaves of CS tomato before and after recovery from chilling indicate changes in electron transport rates at acceptor-and donor side of PS II and an increase in antenna size. In CT pea leaves these eVects were absent, except for a small but irreversible eVect on PSII activity and antenna size. Thus, the diVerences in chloroplast structure between CS and CT plants, induced by dark-chilling are a consequence of diVerent thylakoid supercomplexes rearrangements.Keywords Chloroplast and thylakoid membrane structure · Chilling-sensitive · Chilling tolerant · Chlorophyll-protein complexes · Cation-induced thylakoid stacking · O-J-D-I-P chlorophyll Xuorescence · Confocal laser scanning microscopy · Dark-chilling stress · Pea · Tomato Dedicated to Prof. Zbigniew Kaniuga on the 25th anniversary of his initiation of studies on chilling-induced stress in plants.

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