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

Zhang, Yonghong; Li, Chen; Zhang, Jingxuan; Wang, Jiajing; Yang, Jingwei; Lv, Yanxia; Yang, Ning; Liu, Jianping; Wang, Xuanbin; Pálfalvi, Gergo; Wang, Guodong; Zheng, Lanlan

doi:10.1371/journal.pone.0180449

Cited by 38 publications

(36 citation statements)

References 45 publications

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“…Given that HY5 has the potential to regulate STOM expression we next examined expression of HY5 using confocal microscopy to study the localisation of HY5:CFP in HY5proHY5: CFP transgenic plants. It should be noted that previous studies have shown that HY5 is expressed widely throughout the plant including leaf tissue and that HY5 protein is mobile, therefore this already indicates that HY5 has the potential to regulate STOM expression in the mesophyll [32,33]. Our analysis confirmed the results of previous studies and HY5:CFP signal was clearly detected in the epidermis and stomatal lineage cells as well as the mesophyll ( Fig 1C and 1D).…”

Section: Resultssupporting

confidence: 91%

HY5 is not integral to light mediated stomatal development in Arabidopsis

et al. 2020

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Light is a crucial signal that regulates many aspects of plant physiology and growth including the development of stomata, the pores in the epidermal surface of the leaf. Light signals positively regulate stomatal development leading to changes in stomatal density and stomatal index (SI; the proportion of cells in the epidermis that are stomata). Both phytochrome and cryptochrome photoreceptors are required to regulate stomatal development in response to light. The transcription factor ELONGATED HYPOCOTYL 5 (HY5) is a key regulator of light signalling, acting downstream of photoreceptors. We hypothesised that HY5 could regulate stomatal development in response to light signals due to the putative presence of HY5 binding sites in the promoter of the STOMAGEN (STOM) gene, which encodes a peptide regulator of stomatal development. Our analysis shows that HY5 does have the potential to regulate the STOM promoter in vitro and that HY5 is expressed in both the epidermis and mesophyll. However, analysis of hy5 and hy5 hyh double mutants (HYH; HY5-HOMOLOG), found that they had normal stomatal development under different light conditions and the expression of stomatal developmental genes was not perturbed following light shift experiments. Analysis of stable lines overexpressing HY5 also showed no change in stomatal development or the expression of stomatal developmental genes. We therefore conclude that whilst HY5 has the potential to regulate the expression of STOM, it does not have a major role in regulating stomatal development in response to light signals. OPEN ACCESSCitation: Zoulias N, Brown J, Rowe J, Casson SA (2020) HY5 is not integral to light mediated stomatal development in Arabidopsis. PLoS ONE 15(1): e0222480. https://doi.org/10.

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Section: Resultssupporting

confidence: 91%

HY5 is not integral to light mediated stomatal development in Arabidopsis

et al. 2020

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“…Since HY5-GFP was shown to be mobile despite the increased size of the HY5-GFP protein compared with HY5 itself, we expect that HY5-YFP (38 kD) can also be mobile via the phloem. HY5 can induce transcription of its own gene in the root (Supplemental Figure 3); thus, an increase in HY5 protein can lead to an increase in HY5 expression (Lee et al, 2007;Binkert et al, 2014;Campos et al, 2016;Zhang et al, 2017). It is possible that HY5 unloaded at the root tip remains in the cells close to where LRPs are initiated and then upregulates their own expression, leading to increased HY5 in the LRP.…”

Section: Discussionmentioning

confidence: 99%

Far-Red Light Detection in the Shoot Regulates Lateral Root Development through the HY5 Transcription Factor

et al. 2018

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Plants in dense vegetation compete for resources and detect competitors through reflection of far-red (FR) light from surrounding plants. This reflection causes a reduced red (R):FR ratio, which is sensed through phytochromes. Low R:FR induces shade avoidance responses of the shoot and also changes the root system architecture, although this has received little attention so far. Here, we investigate the molecular mechanisms through which light detection in the shoot regulates root development in We do so using a combination of microscopy, gene expression, and mutant study approaches in a setup that allows root imaging without exposing the roots to light treatment. We show that low R:FR perception in the shoot decreases the lateral root (LR) density by inhibiting LR emergence. This decrease in LR emergence upon shoot FR enrichment is regulated by phytochrome-dependent accumulation of the transcription factor ELONGATED HYPOCOTYL5 (HY5) in the LR primordia. HY5 regulates LR emergence by decreasing the plasma membrane abundance of PIN-FORMED3 and LIKE-AUX1 3 auxin transporters. Accordingly, FR enrichment reduces the auxin signal in the overlaying cortex cells, and this reduces LR outgrowth. This shoot-to-root communication can help plants coordinate resource partitioning under competition for light in high density fields.

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“…The role for HY5 in Arabidopsis root development has been known for a long time, as HY5-deficient mutants show defects in root hair development, gravitropism, lateral root outgrowth, and elongation (Oyama et al, 1997;Sibout et al, 2006). The HY5 protein is, as was discovered recently, translocated via the phloem toward the root, with root-specific HY5 and HYH transcription, and promoted root development as a consequence (Chen et al, 2016;Zhang et al, 2017; Fig. 3D).…”

Section: The Rootsmentioning

confidence: 93%