Arabidopsis constitutive photomorphogenic mutant, bls1, displays altered brassinosteroid response and sugar sensitivity.
We have isolated an Arabidopsis mutant impaired in light- and brassinosteroid (BR) induced responses, as well as in sugar signalling. The bls1 (brassinosteroid, light and sugar1) mutant displays short hypocotyl, expanded cotyledons, and de-repression of light-regulated genes in young seedlings, and leaf differentiation and silique formation on prolonged growth in dark. In light, the bls1 mutant is dwarf and develops a short root, compact rosette, with reduced trichome number, and exhibits delayed bolting. The activity of the BR inducible TCH4 and auxin inducible SAUR promoters, fused with GUS gene, is also altered in seedlings harbouring bls1 mutant background. In addition, the bls1 mutant is hypersensitive to metabolizable sugars. The short hypocotyl phenotype in dark, short root phenotype in light and sugar hypersensitivity could be rescued with BR application. Moreover, the bls1 mutant also showed higher expression of a BR biosynthetic pathway gene CPD, which is known to be feedback-regulated by BR. Using a genome-wide AFLP mapping strategy, the bls1 mutant has been mapped to a 1.4 Mb region of chromosome 5. Since no other mutant with essentially a similar phenotype has been assigned to this region, we suggest that the bls1 mutant defines a novel locus involved in regulating endogenous BR levels, with possible ramifications in integrating light, hormone and sugar signalling.
Laxmi
Ashverya
A
Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India.
Paul
Laju K
LK
Peters
Janny L
JL
Khurana
Jitendra P
JP
D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics; D060406:Brassinosteroids; D002241:Carbohydrates / Q000494:pharmacology*; D002777:Cholestanols / Q000494:pharmacology*; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D003433:Crosses, Genetic; D003624:Darkness; D004305:Dose-Response Relationship, Drug; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D005838:Genotype; D005875:Gibberellins / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D018546:Hypocotyl / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D007210:Indoleacetic Acids / Q000494:pharmacology; D008027:Light; D009024:Morphogenesis / Q000187:drug effects / Q000528:radiation effects; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013260:Steroids, Heterocyclic / Q000494:pharmacology*; D013395:Sucrose / Q000494:pharmacology
D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D002241:Carbohydrates; D002777:Cholestanols; D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; D013260:Steroids, Heterocyclic; D013395:Sucrose; D000040:Abscisic Acid; D005966:Glucuronidase; D005947:Glucose; C023623:brassinolide