2025-09-25 京都大学
BGH2破壊株では、正常な光環境への順応が行われず、黄化したまま枯死する。上段:野生型またはBGH2破壊株を暗所で生育させた後に連続光を照射したときの表現型。下段:野生型またはBGH2破壊株の光環境順応メカニズムの作業仮説。
<関連情報>
- https://www.kyoto-u.ac.jp/ja/research-news/2025-09-25-1
- https://www.kyoto-u.ac.jp/sites/default/files/2025-09/web_2509_Nakano-96ddcd1d4410403439de4df7330ad8de.pdf
- https://academic.oup.com/plcell/article-abstract/37/8/koaf180/8210543
暗誘導性BGH2はGLK転写因子を抑制し、プラスチドの恒常性を維持して光適応を促進する Dark-inducible BGH2 suppresses GLK transcription factors and maintains plastid homeostasis to promote light adaptation
Ryo Tachibana (立花 諒), Rino Akema (明間 莉乃), Akiko Yoshihara (吉原 晶子), Chihiro Ujihara (宇治原 千裕), Kaisei Nishida (西田 快世), Shunshu Ri (李 俊澍), Ayumi Yamagami (山上 あゆみ), Takuya Miyakawa (宮川 拓也), Koichi Kobayashi (小林 康一), Ryouichi Tanaka (田中 亮一) ,…
The Plant Cell Published:22 July 2025
DOI:https://doi.org/10.1093/plcell/koaf180
Abstract
Light is an essential energy source for plants, but it can cause harmful photooxidative damage that induces cell death. When dark-germinated plants are exposed to the light, etioplasts differentiate into chloroplasts, converting protochlorophyllide (Pchlide) into chlorophyll, while excessive free Pchlide accumulation in etioplasts causes reactive oxygen species (ROS) generation and cell death under light conditions. Despite this knowledge, the molecular mechanisms by which dark-germinated plants adapt to the light environment via transcriptional regulation of chlorophyll biosynthesis remain unclear. We previously identified BRZ-INSENSITIVE-PALE GREEN 4 (BPG4) as a light-inducible chloroplast homeostasis factor. Here, we identified the BPG4 paralog BPG4 HOMOLOGOUS GENE 2 (BGH2) as a nucleus-localized plastid regulator required for light adaptation in Arabidopsis thaliana. Dark-inducible BGH2 interacts with GOLDEN2-LIKE 1 (GLK1) and GLK2, master transcription factors regulating chlorophyll biosynthesis. This interaction suppresses excessive photosynthesis-associated nuclear gene (PhANG) expression, avoids Pchlide overaccumulation in the dark, prevents ROS generation, and promotes healthy cotyledon greening during de-etiolation. BPG4 and BGH2 expression is regulated by GLK and PHYTOCHROME-INTERACTING FACTOR transcription factors under light and dark conditions. Overall, our findings suggest that BGH2 plays an essential role in fine-tuning chlorophyll biosynthesis and etioplast homeostasis by inhibiting GLK transcriptional activity and excessive PhANG expression in the dark.
