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The chloroplast protein BPG2 functions in brassinosteroid‐mediated post‐transcriptional accumulation of chloroplast rRNA
Author(s) -
Komatsu Tomoyuki,
Kawaide Hiroshi,
Saito Chieko,
Yamagami Ayumi,
Shimada Setsuko,
Nakazawa Miki,
Matsui Minami,
Nakano Akihiko,
Tsujimoto Masafumi,
Natsume Masahiro,
Abe Hiroshi,
Asami Tadao,
Nakano Takeshi
Publication year - 2010
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2009.04077.x
Subject(s) - chloroplast , mutant , biology , brassinosteroid , arabidopsis , biogenesis , thylakoid , microbiology and biotechnology , gene , biochemistry
Summary Brassinazole (Brz) is a specific inhibitor of the biosynthesis of brassinosteroids (BRs), which regulate plant organ and chloroplast development. We identified a recessive pale green Arabidopsis mutant, bpg2‐1 ( Brz‐insensitive‐pale green 2‐1 ) that showed reduced sensitivity to chlorophyll accumulation promoted by Brz in the light. BPG2 encodes a chloroplast‐localized protein with a zinc finger motif and four GTP‐binding domains that are necessary for normal chloroplast biogenesis. BPG2 ‐homologous genes are evolutionally conserved in plants, green algae and bacteria. Expression of BPG2 is induced by light and Brz. Chloroplasts of the bpg2‐1 mutant have a decreased number of stacked grana thylakoids. In bpg2‐1 and bpg2‐2 mutants, there was no reduction in expression of rbcL and psbA , but there was abnormal accumulation of precursors of chloroplast 16S and 23S rRNA. Chloroplast protein accumulation induced by Brz was suppressed by the bpg2 mutation. These results indicate that BPG2 plays an important role in post‐transcriptional and translational regulation in the chloroplast, and is a component of BR signaling.