S-Space College of Agriculture and Life Sciences (농업생명과학대학) Dept. of Plant Science (식물생산과학부) Journal Papers (저널논문_식물생산과학부)
7-hydroxymethyl chlorophyll a reductase functions in metabolic channeling of chlorophyll breakdown intermediates during leaf senescence
- Sakuraba, Yasuhito; Kim, Ye-Sol; Yoo, Soo-Cheul; Hortensteiner, Stefan; Paek, Nam-Chon
- Issue Date
- BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Vol.430 No.1, pp. 32-37
- 농수해양; chlorophyll degradation; STAY-GREEN; chlorophyll catabolic enzymes; 7-hydroxymethyl chlorophyll a reductase; SGR-CCE-LHCII complex
- Authors' final manuscript
- During natural or dark-induced senescence, chlorophyll degradation causes leaf yellowing. Recent evidence indicates that chlorophyll catabolic enzymes (CCEs) interact with the photosynthetic apparatus; for example, five CCEs (NYC1, NOL, PPH, PAO and RCCR) interact with LHCII. STAY-GREEN (SGR) and CCEs interact with one another in senescing chloroplasts; this interaction may allow metabolic channeling of potentially phototoxic chlorophyll breakdown intermediates. 7-hydroxymethyl chlorophyll a reductase (HCAR) also acts as a CCE, but HCAR functions during leaf senescence remain unclear. Here we show that in Arabidopsis, HCAR-overexpressing plants exhibited accelerated leaf yellowing and, conversely, hcar mutants stayed green during dark-induced senescence. Moreover, HCAR interacted with LHCII in in vivo pull-down assays, and with SGR, NYC1, NOL and RCCR in yeast two-hybrid assays, indicating that HCAR is a component of the proposed SGR-CCE-LHCII complex, which acts in chlorophyll breakdown. Notably, HCAR and NOL are expressed throughout leaf development and are drastically down-regulated during dark-induced senescence, in contrast with SGR, NYC1, PPH and PAO, which are up-regulated during dark-induced senescence. Moreover, HCAR and NOL are highly up-regulated during greening of etiolated seedlings, strongly suggesting a major role for NOL and HCAR in the chlorophyll cycle during vegetative stages, possibly in chlorophyll turnover.