title: A chemical genetics approach reveals a role of brassinolide and cellulose synthase in hypocotyl elongation of etiolated Arabidopsis seedlings.
abstract: The development of juvenile seedlings after germination is critical for the initial establishment of reproductive plants. Ethylene plays a pivotal role in the growth of seedlings under light or dark during early development. Previously, we identified small molecules sharing a quinazolinone backbone that suppressed the constitutive triple response phenotype in dark-grown eto1-4 seedlings. We designated these small molecules as ACSinhibitor quinazolinones (acsinones), which were uncompetitive inhibitors of 1-aminocyclopropane-1-carboxylic acid synthase. To explore the additional roles of acsinones in plants, we screened and identified 19 Arabidopsis mutants with reduced sensitivity to acsinone7303, which were collectively named revert to eto1 (ret) because of their recovery of the eto1 phenotype. A map-based cloning approach revealed that CELLULOSE SYNTHASE6 (CESA6) and DE-ETIOLATED2 (DET2) were mutated in ret8 (cesa6(ret8);eto1-4) and ret41 (det2(ret41);eto1-5), respectively. Etiolated seedlings of both ret8 and ret41 exhibit short hypocotyls and roots. Ethylene levels were similar in etiolated cesa6(ret8) and det2-1 and in eto1 mutants treated with acsinone7303. Chemical inhibitors of ethylene biosynthesis and perception did not significantly suppress the etiolated phenotype of cesa6(ret8) and det2(ret41). However, together with eto1, cesa6(ret8) and det2(ret41) exhibited an enhanced phenotype in the hypocotyls and apical hooks of etiolated seedlings. These results confirm that, in addition to ethylene, cellulose synthesis and brassinolides can independently contribute to modulate hypocotyl development in young seedlings.
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan, ROC.
authors.forename: I-Ju
authors.initials: IJ
authors.lastname: Chen
authors.forename: Wan-Sheng
authors.initials: WS
authors.lastname: Lo
authors.forename: Jung-Yun
authors.initials: JY
authors.lastname: Chuang
authors.forename: Chiao-Mei
authors.initials: CM
authors.lastname: Cheuh
authors.forename: Yu-Shan
authors.initials: YS
authors.lastname: Fan
authors.forename: Lee-Chung
authors.initials: LC
authors.lastname: Lin
authors.forename: Shaw-Jye
authors.initials: SJ
authors.lastname: Wu
authors.forename: Long-Chi
authors.initials: LC
authors.lastname: Wang
mesh_terms: D000598:Amino Acids, Cyclic / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D060406:Brassinosteroids / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism; D064527:Etiolation / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D018546:Hypocotyl / Q000254:growth & development / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D063245:Plant Development / Q000235:genetics / Q000502:physiology*; D010937:Plant Growth Regulators / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D052999:Quinazolinones / Q000378:metabolism / Q000494:pharmacology; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D013260:Steroids, Heterocyclic / Q000378:metabolism*
chemical_list: D000598:Amino Acids, Cyclic; D029681:Arabidopsis Proteins; D060406:Brassinosteroids; C098907:DET2 protein, Arabidopsis; C485242:ETO1 protein, Arabidopsis; D005030:Ethylenes; D010937:Plant Growth Regulators; D052999:Quinazolinones; D013260:Steroids, Heterocyclic; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene; D005964:Glucosyltransferases; C457769:PRC1 protein, Arabidopsis; C478648:cellulose synthase; C023623:brassinolide