Protein dynamics in thylakoids of the desiccation-tolerant plant Boea hygroscopica during dehydration and rehydration.
Plants of Boea hygroscopica F. Muell were dehydrated to 9% relative water content (RWC) by withholding water for 26 d, and afterward the plants were rehydrated. Leaves were taken from control plants after 7, 12, and 26 d from the beginning of dehydration, and after 6 and 48 h from rehydration. The RWC decreased by 80% during dehydration, but the leaves regained RWC with rehydration. Dehydrated plants showed lesser amounts of proteins, lipids, and chlorophyll, all of which increased following rewatering. The lipid-to-protein ratio, which decreased during dehydration, returned to control level after 48 h of rehydration. Thylakoid lipids were more unsaturated when RWC reached the value of 9%. EPR measurements of spin-labeled proteins showed the presence of three different groups of proteins with different mobility in thylakoid membranes. The rotational correlation time of groups 1 and 2 increased with dehydration and decreased upon rehydration, whereas group 3 showed little changes. Desiccation did not cause thylakoid swelling or breakage, but the membrane system assemblage showed changes in thylakoid stacking. After 48 h of rehydration the membrane system recovered completely the organization of the fully hydrated state, showing several well-defined and regularly distributed grana.
Navari-Izzo
F
F
Dipartimento di Chimica e Biotecnologie Agrarie, Università di Pisa, Via del Borghetto, 80, I-56124 Pisa, Italy. fnavari@agr.unipi.it
Quartacci
M F
MF
Pinzino
C
C
Rascio
N
N
Vazzana
C
C
Sgherri
C L
CL
D000975:Antioxidants / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003890:Desiccation; D004578:Electron Spin Resonance Spectroscopy; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D008563:Membrane Lipids / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D010944:Plants / Q000378:metabolism* / Q000648:ultrastructure; D020524:Thylakoids / Q000378:metabolism* / Q000648:ultrastructure
D000975:Antioxidants; D008563:Membrane Lipids; D008565:Membrane Proteins; D002734:Chlorophyll