AtBBX21 and COP1 genetically interact in the regulation of shade avoidance
Plants grown at high densities perceive the reduction in the ratio of red [R] to far-red [FR] light as a warning of competition. This light signal triggers morphological responses such as hypocotyl and stem elongation, and acceleration of flowering, which are known collectively as the shade-avoidance syndrome [SAS]. Mutations in the photomorphogenic repressor COP1 suppress the SAS, but how COP1 modulates these responses is uncertain. We identified a new mutant with altered responses to natural shade, named lhus [long hypocotyl under shade]. lhus seedlings have longer hypocotyls than wild-type under a low R:FR ratio, but not under sunlight or darkness. The lhus phenotype is due to a mutation affecting a B-box zinc finger transcription factor encoded by At1g75540, a gene previously reported as AtBBX21 that interacts with COP1 to control de-etiolation. Mutations in genes encoding other members of this protein family also result in impaired SAS regulation. Under short-term canopy shade, LHUS/BBX21 acts as positive regulator of SAS genes such as PAR1, HFR1, PIL1 and ATHB2. In contrast, global expression analysis of wild-type and lhus/bbx21 seedlings revealed that a large number of genes involved in hormonal signalling pathways are negatively regulated by LHUS/BBX21 in response to long-term canopy shade, and this observation fits well with the phenotype of lhus/bbx21 seedlings grown under a low R:FR ratio. Moreover, the bbx21 bbx22 double mutation restored the SAS in the cop1 background. We propose that LHUS/BBX21 and other B-box-containing proteins, such as BBX22, act downstream of COP1, and play a central role in early and long-term adjustment of the SAS in natural environments.
| Main Authors: | , , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Subjects: | ARABIDOPSIS, B-BOX ZINC FINGER PROTEINS, CANOPY LIGHT, PAR GENES, SHADE-AVOIDANCE SYNDROME, T-DNA MUTANTS, GENES, SEED, TRANSCRIPTION FACTORS, ZINC, TRANSCRIPTION, ARABIDOPSIS PROTEIN, BASIC HELIX LOOP HELIX TRANSCRIPTION FACTOR, BBX21 PROTEIN, ARABIDOPSIS, COP1 PROTEIN, ARABIDOPSIS, PAR1 PROTEIN, ARABIDOPSIS, TRANSCRIPTION FACTOR, UBIQUITIN PROTEIN LIGASE, GENE EXPRESSION PROFILING, GENE EXPRESSION REGULATION, GENETICS, GROWTH, DEVELOPMENT AND AGING, METABOLISM, MUTATION, PHOTOTROPISM, PLANT GENE, SUNLIGHT, UPREGULATION, ARABIDOPSIS PROTEINS, BASIC HELIX-LOOP-HELIX TRANSCRIPTION FACTORS, GENE EXPRESSION REGULATION, PLANT, GENES, PLANT, UBIQUITIN-PROTEIN LIGASES, UP-REGULATION, , |
| Online Access: | http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=46668 |
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