title: Glycosyltransferase-like protein ABI8/ELD1/KOB1 promotes Arabidopsis hypocotyl elongation through regulating cellulose biosynthesis.
abstract: Seedling de-etiolation (photomorphogenesis) is an important light-regulated developmental process in plants. Here, we showed that disruption of the gene encoding a glycosyltransferase-like protein, ABA INSENSITIVE 8 (ABI8)/ELONGATION EFFECTIVE 1 (ELD1)/KOBITO1 (KOB1), caused short-hypocotyl elongation under all light conditions examined and even in darkness. We found that the ABI8 transcript level was down-regulated by light in a phytochrome A-dependent manner. Furthermore, light destabilized ABI8 protein via the 26S proteasome degradation pathway. We showed that ABI8 promoted the expression of genes involved in cell elongation and cellulose synthesis. Consistently, the cellulose content was reduced in the abi8 mutants and application of 2, 6-dichlorobenzonitrile (an inhibitor of cellulose biosynthesis) mimicked the abi8 mutant phenotype. Moreover, we found that phytochrome and cryptochrome photoreceptors negatively, whereas CONSTITUTIVE PHOTOMORPHOGENIC 1 positively, regulated cellulose synthesis. We also showed that ELONGATED HYPOCOTYL 5 directly bound to the promoters of ABI8 and several cellulose synthesis genes and repressed their expression in light conditions. Taken together, our study reveals that ABI8 functions as a negative factor in light inhibition of hypocotyl elongation through modulating cellulose biosynthesis.
authors.affiliation: Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China; University of the Chinese Academy of Sciences, Beijing, 100049, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Jing
authors.forename: Baocai
authors.initials: B
authors.lastname: Zhang
authors.forename: Yihua
authors.initials: Y
authors.lastname: Zhou
authors.forename: Rongcheng
authors.initials: R
authors.lastname: Lin
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002482:Cellulose / Q000096:biosynthesis*; D056931:Cryptochromes / Q000378:metabolism; D003624:Darkness; D064527:Etiolation; D018506:Gene Expression Regulation, Plant; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism; D018546:Hypocotyl / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D008027:Light; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D051942:Phytochrome A / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D036226:Seedlings / Q000201:enzymology / Q000235:genetics / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; D002482:Cellulose; D056931:Cryptochromes; D016695:Glycosyltransferases; D008565:Membrane Proteins; D051942:Phytochrome A; D046988:Proteasome Endopeptidase Complex; C484234:ELD1 protein, Arabidopsis; C469256:KOB1 protein, Arabidopsis; C061553:ATP dependent 26S protease
keywords: cellulose synthesis; light; photomorphogenesis