title: Chlorophyll b reductase plays an essential role in maturation and storability of Arabidopsis seeds.
abstract: Although seeds are a sink organ, chlorophyll synthesis and degradation occurs during embryogenesis and in a manner similar to that observed in photosynthetic leaves. Some mutants retain chlorophyll after seed maturation, and they are disturbed in seed storability. To elucidate the effects of chlorophyll retention on the seed storability of Arabidopsis (Arabidopsis thaliana), we examined the non-yellow coloring1 (nyc1)/nyc1-like (nol) mutants that do not degrade chlorophyll properly. Approximately 10 times more chlorophyll was retained in the dry seeds of the nyc1/nol mutant than in the wild-type seeds. The germination rates rapidly decreased during storage, with most of the mutant seeds failing to germinate after storage for 23 months, whereas 75% of the wild-type seeds germinated after 42 months. These results indicate that chlorophyll retention in the seeds affects seed longevity. Electron microscopic studies indicated that many small oil bodies appeared in the embryonic cotyledons of the nyc1/nol mutant; this finding indicates that the retention of chlorophyll affects the development of organelles in embryonic cells. A sequence analysis of the NYC1 promoter identified a potential abscisic acid (ABA)-responsive element. An electrophoretic mobility shift assay confirmed the binding of an ABA-responsive transcriptional factor to the NYC1 promoter DNA fragment, thus suggesting that NYC1 expression is regulated by ABA. Furthermore, NYC1 expression was repressed in the ABA-insensitive mutants during embryogenesis. These data indicate that chlorophyll degradation is induced by ABA during seed maturation to produce storable seeds.
authors: Institute of Low Temperature Science, Hokkaido University, Kita-ku, Sapporo 060-0819, Japan.
authors: Saori
authors: S
authors: Nakajima
authors: Hisashi
authors: H
authors: Ito
authors: Ryouichi
authors: R
authors: Tanaka
authors: Ayumi
authors: A
authors: Tanaka
mesh_terms: D000040:Abscisic Acid; D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D018548:Cotyledon / Q000378:metabolism / Q000648:ultrastructure; D018744:DNA, Plant / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D018506:Gene Expression Regulation, Plant; D018525:Germination; D010938:Plant Oils / Q000378:metabolism; D011401:Promoter Regions, Genetic; D055314:Seed Storage Proteins / Q000378:metabolism; D012639:Seeds / Q000201:enzymology* / Q000235:genetics; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D018744:DNA, Plant; D010938:Plant Oils; D055314:Seed Storage Proteins; D002734:Chlorophyll; D000040:Abscisic Acid; D000429:Alcohol Oxidoreductases; C102575:chlorophyll b reductase