Graduate School of Biostudies, Kyoto University, KItashirakawa-Oiwake-cho, Sakyo-ku, Kyoto, Japan.
Department of Biology, Ochanomizu University, Bunkyo-ku, Tokyo, Japan.
Biosci Biotechnol Biochem. 2022 Jul 22;86(8):1041-1048. doi: 10.1093/bbb/zbac071.
Brassinosteroids (BRs), a kind of phytohormone, have various biological activities such as promoting plant growth, increasing stress resistance, and chloroplast development. Though BRs have been known to have physiological effects on chloroplast, the detailed mechanism of chloroplast development and chlorophyll biosynthesis in BR signaling remains unknown. Here we identified a recessive pale green Arabidopsis mutant, Brz-insensitive-pale green1 (bpg1), which was insensitive to promoting of greening by BR biosynthesis-specific inhibitor Brz in the light. BPG1 gene encoded chlorophyll biosynthesis enzyme, 3, 8-divinyl protochlorophyllide a 8-vinyl reductase (DVR), and bpg1 accumulated divinyl chlorophylls. Chloroplast development was suppressed in bpg1. Brz dramatically increased the expression of chlorophyll biosynthesis enzyme genes, including BPG1. These results suggest that chlorophyll biosynthesis enzymes are regulated by BR signaling in the aspect of gene expression and BPG1 plays an important role in regulating chloroplast development.
油菜素内酯（BRs）是一种植物激素，具有促进植物生长、增强抗逆性和叶绿体发育等多种生物学活性。尽管 BRs 已被证明对叶绿体具有生理作用，但 BR 信号转导中叶绿体发育和叶绿素生物合成的详细机制尚不清楚。在这里，我们鉴定了一个隐性淡绿色拟南芥突变体 bpg1，其对 BR 生物合成特异性抑制剂 Brz 在光照下促进变绿不敏感。BPG1 基因编码叶绿素合成酶，3,8-二乙烯基原叶绿素酸 a 8-乙烯基还原酶（DVR），并且 bpg1 积累二乙烯基叶绿素。bpg1 中叶绿体发育受到抑制。Brz 显著增加了叶绿素合成酶基因的表达，包括 BPG1。这些结果表明，BR 信号转导在基因表达方面调节叶绿素合成酶，并且 BPG1 在调节叶绿体发育方面发挥重要作用。
