Untitled - 中国植物生理与分子生物学学会

Defect in Degradation of PSII Complex Causes a Stay-green
Phenotype during Dark-Induced Senescence in Arabidopsis thf1
Mutant
Fenhong Hu, Jirong Huang, Yungang Shen
Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences,
Chinese Academy of Sciences, 300 Feng Lin Road, Shanghai 200032
THF1 (Thylakoid Formation 1) is conserved in all oxygenic organisms. The null mutant thf1
exhibits yellow cotyledons, variegated leaves and slower growth rate. The previous studies have
shown that THF1 is involved in thylakoid membrane formation and photosynthetic complex II. In
this study, we observe that the thf1 mutant displays a nonfunctional stay-green phenotype during
dark-induced senescence.
Further analysis revealed that the stay-green phenotype of thf1 was caused by the retention of
the PSII core proteins (such as D1, D2 and CP47) and PSII light-harvesting proteins
(LHCB1-LHCB6). We also observed that after incubated in darkness for 6 days, the level of FTSH
family protease VAR1 and VAR2 which mainly responds to the D1 degradation was hardly detected
in thf1. So we suggest that the retention of PSII proteins which resulted in chlorophyll b
accumulation may due to the lower level of proteases in thf1 during darkness.
Keywords:Arabidopsis; THF1 (Thylakoid Formation 1); PSII complex; Stay-green phenotype
www.cspp.cn
55