共查询到20条相似文献,搜索用时 15 毫秒
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In Arabidopsis, SHY2 encodes IAA3, a member of the auxin-induced Aux/IAA family. Gain-of-function mutations in SHY2/IAA3 cause enlarged cotyledons, short hypocotyls, and altered auxin-regulated root development. Here we show that the gain-of-function mutation shy2-2 decreases both the induction and repression of auxin-regulated genes, suggesting that SHY2/IAA3 acts as a negative regulator in auxin signaling. shy2-2 affects auxin induction of many previously characterized primary response genes, implying that it might repress primary auxin responses. In addition, shy2-2 also affects expression of multiple auxin-nonresponsive genes. Light regulates expression of SHY2/IAA3, suggesting a possible link between light and auxin response pathways. 相似文献
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Regulation of Arabidopsis SHY2/IAA3 protein turnover 总被引:1,自引:0,他引:1
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Roles and activities of Aux/IAA proteins in Arabidopsis. 总被引:12,自引:0,他引:12
J W Reed 《Trends in plant science》2001,6(9):420-425
Auxin induces various distinct developmental responses, partly by regulating gene expression. The Aux/IAA genes are a large gene family, many of which are induced by auxin. Work on Arabidopsis Aux/IAA genes has begun to reveal that they can regulate development and auxin-induced gene expression. Furthermore, auxin responses require Aux/IAA protein turnover. Finally, recent evidence suggests that Aux/IAA proteins can mediate light responses. Work in the near future should test whether Aux/IAA proteins are antennae that connect auxin and light signals to endogenous developmental responses. 相似文献
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A semi-dominant mutant suppressor of hy2 (shy2-1D) of Arabidopsis thaliana, originally isolated as a photomorphogenesis mutant, shows altered auxin responses. Recent molecular cloning revealed that the SHY2 gene is identical to the IAA3 gene, a member of the primary auxin-response genes designated the Aux/IAA gene family. Because Aux/IAA proteins are reported to interact with auxin response factors, we investigated the pattern of expression of early auxin genes in the iaa3/shy2-1D mutant. RNA hybridization analysis showed that levels of mRNA accumulation of the early genes were reduced dramatically in the iaa3/shy2-1D mutants, although auxin still enhanced gene expression in the iaa3/shy2-1D mutant. Histochemical analysis using a fusion gene of the auxin responsive domain (AuxRD) and the GUS gene showed no IAA-inducible GUS expression in the root elongation zone of the iaa3/shy2-1D mutant. On the other hand, ectopic GUS expression occurred in the hypocotyl, cotyledon, petiole and root vascular tissues in the absence of auxin. These results suggest that IAA3/SHY2 functions both negatively and positively on early auxin gene expression. 相似文献
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Funneling auxin action: specificity in signal transduction 总被引:11,自引:0,他引:11
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The Aux/IAA genes are rapidly and specifically induced by the plant hormone auxin. The proteins encoded by this gene family are short-lived nuclear proteins that are capable of homodimerizing and heterodimerizing. Molecular, biochemical, and genetic data suggest that these proteins are involved in auxin signaling. The pleiotropic morphological phenotype and altered auxin responses of the semidominant axr3-1 mutant of Arabidopsis result from a single amino acid change in the conserved domain II of the Aux/IAA protein IAA17. Here, we show that the biochemical effect of this gain-of-function mutation is to increase the half-life of the iaa17/axr3-1 protein by sevenfold. Intragenic mutations that suppress the iaa17/axr3-1 phenotype have been described. The iaa17/axr3-1R3 revertant contains a second site mutation in domain I and the iaa17/axr3-1R2 revertant contains a second site mutation in domain III. Transient expression assays show that the mutant forms of IAA17/AXR3 retain the ability to accumulate in the nucleus. Using the yeast two hybrid system, we show that the iaa17/axr3-1 mutation does not affect homodimerization. However, the iaa17/axr3-1 revertants counteract the increased levels of iaa17/axr3-1 protein by decreasing the capacity of the mutant protein to homodimerize. Interestingly, heterodimerization of the revertant forms of IAA17/AXR3 with IAA3/SHY2, another Aux/IAA protein, and ARF1 or ARF5/MP proteins is affected only by changes in domain III. Collectively, the results provide biochemical evidence that the revertant mutations in the IAA17/AXR3 gene affect the capacity of the encoded protein to dimerize with itself, other members of the Aux/IAA protein family, and members of the ARF protein family. By extension, these findings may provide insight into the effects of analogous mutations in other members of the Aux/IAA gene family. 相似文献