Coregulation of light-harvesting complex II phosphorylation and lhcb mRNA accumulation in winter rye

Pursiheimo, S Mulo, P Rintamaki, E Aro, EM

S. Pursiheimo et al., Coregulation of light-harvesting complex II phosphorylation and lhcb mRNA accumulation in winter rye, PLANT J, 26(3), 2001, pp. 317-327

46

INGLESE

Article

Plant Sciences","Animal & Plant Sciences

PLANT JOURNAL

0960-7412 → ACNP

26

3

2001

317 - 327

ISI

0960-7412(200105)26:3<317:COLCIP>2.0.ZU;2-G

Winter rye plants grown under contrasting environmental conditions or just transiently shifted to varying light and temperature conditions, were studi ed to elucidate the chloroplast signal involved in regulation of photosynth esis genes in the nucleus. Photosystem II excitation pressure, reflecting t he plastoquinone redox state, and the phosphorylation level of thylakoid li ght-harvesting proteins (LHCII and CP29) were monitored together with chang es occurring in the accumulation of Ihcb, rbcS and psbA mRNAs. Short-term s hifts of plants to changed conditions, from 1 h to 2 d, were postulated to reveal signals crucial for the initiation of the acclimation process. Compa rison of these results with those obtained from plants acclimated during se veral weeks' growth at contrasting temperature and in different light regim es, allow us to make the following conclusions: (1) LHCII protein phosphoyl ation is a sensitive tool to monitor redox changes in chloroplasts; (2) LHC II protein phosphorylation and Ihcb mRNA accumulation occur under similar c onditions and are possibly coregulated via an activation state of the same kinase (the LHCII kinase); (3) Maximal accumulation of Ihcb mRNA during the diurnal light phase seems to require an active LHCII kinase whereas inacti vation of the kinase is accompanied by dampening of the circadian oscillati on in the amount of Ihcb mRNA; (4) Excitation pressure of photosystem II (r eduction state of the plastoquinone pool) is not directly involved in the r egulation of Ihcb mRNA accumulation. Instead (5) the redox status of the el ectron accepters of photosystem I in the stromal compartment seems to be hi ghly regulated and crucial for the regulation of Ihcb gene expression in th e nucleus.