Dataset Information

Dissection of HY5/HYH expression in Arabidopsis reveals a root-autonomous HY5-mediated photomorphogenic pathway.

ABSTRACT: ELONGATED HYPOCOTYL 5 (HY5), a member of the bZIP gene family, is a positive regulator of the light signaling pathway in Arabidopsis thaliana. Whereas the hy5 mutant exhibits an elongated hypocotyl when grown in the light, the hy5 homolog (hyh) mutant does not. Although the functions of HY5 and HYH in light-mediated seedling development have been revealed, the tissue-specific expression patterns of HY5 and HYH and their interconnected regulation are largely unknown. Here, we report that HY5 regulates HYH expression in roots and contributes to root growth under different light conditions. We generated HY5 and HYH transcriptional and translational fusion reporter lines to investigate their expression patterns. HY5 was constitutively expressed in all root tissues, while HYH was predominantly expressed in root xylem cells. Root growth after a dark-to-light transition was perturbed in the hy5 and hy5hyh mutant lines, but not in the hyh mutant line, indicating that HY5 plays a major role in light-regulated root growth. Light-induced HY5/HYH expression occurred autonomously in roots. HYH expression in roots was decreased in the hy5 mutant, suggesting that HY5 regulates HYH expression. Collectively, these results indicate that an organ-specific HY5-mediated pathway controls root photomorphogenic development independently of light signaling in the shoot.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC5500333 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Dissection of HY5/HYH expression in Arabidopsis reveals a root-autonomous HY5-mediated photomorphogenic pathway.

Zhang Yonghong Y Li Chen C Zhang Jingxuan J Wang Jiajing J Yang Jingwei J Lv Yanxia Y Yang Nian N Liu Jianping J Wang Xuanbin X Palfalvi Gergo G Wang Guodong G Zheng Lanlan L

PloS one 20170706 7

ELONGATED HYPOCOTYL 5 (HY5), a member of the bZIP gene family, is a positive regulator of the light signaling pathway in Arabidopsis thaliana. Whereas the hy5 mutant exhibits an elongated hypocotyl when grown in the light, the hy5 homolog (hyh) mutant does not. Although the functions of HY5 and HYH in light-mediated seedling development have been revealed, the tissue-specific expression patterns of HY5 and HYH and their interconnected regulation are largely unknown. Here, we report that HY5 regu ...[more]

PMID: 28683099

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Project description:The Arabidopsis transcription factor HY5 controls light-induced gene expression downstream of photoreceptors and plays an important role in the switch of seedling shoots from dark-adapted to light-adapted development. In addition, HY5 has been implicated in plant hormone signaling, accounting for the accelerated root system growth phenotype of hy5 mutants. Mutants in the close HY5 homolog HYH resemble wild-type, despite the largely similar expression patterns and levels of HY5 and HYH, and the functional equivalence of the respective proteins. Moreover, the relative contribution of HYH to the overall activity of the gene pair is increased by an alternative HYH transcript, which encodes a stabilized protein. Consistent with the enhanced root system growth observed in hy5 loss-of-function mutants, constitutively overexpressed alternative HYH inhibits root system growth. Paradoxically, however, in double mutants carrying hy5 and hyh null alleles, the hy5 root growth phenotype is suppressed rather than enhanced. Even more surprisingly, compared to wild-type, root system growth is diminished in hy5 hyh double mutants. In addition, the double mutants display novel shoot phenotypes that are absent from either single mutant. These include cotyledon fusions and defective vasculature, which are typical for mutants in genes involved in the transcriptional response to the plant hormone auxin. Indeed, many auxin-responsive and auxin signaling genes are misexpressed in hy5 mutants, and at a higher number and magnitude in hy5 hyh mutants. Therefore, auxin-induced transcription is constitutively activated at different levels in the two mutant backgrounds. Our data support the hypothesis that the opposite root system phenotypes of hy5 single and hy5 hyh double mutants represent the morphological response to a quantitative gradient in the same molecular process, that is gradually increased constitutive auxin signaling. The data also suggest that HY5 and HYH are important negative regulators of auxin signaling amplitude in embryogenesis and seedling development.

Dataset Information

Dissection of HY5/HYH expression in Arabidopsis reveals a root-autonomous HY5-mediated photomorphogenic pathway.

Publications

Dissection of HY5/HYH expression in Arabidopsis reveals a root-autonomous HY5-mediated photomorphogenic pathway.

Similar Datasets

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