Switching the Direction of Stem Gravitropism by Altering Two Amino Acids in AtLAZY1

Yoshihara, Takeshi; Spalding, Edgar P.

doi:10.1104/pp.19.01144

Cited by 45 publications

(74 citation statements)

References 59 publications

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“…To assay this, we overexpressed LAZY1, DRO1, or LAZY6 in the lazy1 background, and compared the phenotypes in response to light conditions. It was recently reported that expressing LAZY1 under its native promoter in a lazy1 mutant background only partially rescued the mutant branch angle phenotype (Yoshihara and Spalding, 2019). We found this to be true when overexpressing LAZY1 in a lazy1 mutant background as well (Fig.…”

Section: Lazy and Dro Gene Expression Responds Differentially To Lighsupporting

confidence: 74%

IGT/LAZY family genes are differentially influenced by light signals and collectively required for light-induced changes to branch angle

Waite

Dardick

2020

Preprint

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Plants adjust their growth orientations in response to environmental signals such as light and gravity in order to optimize photosynthesis and access to nutrients. However, given the fixed nature of gravity, understanding how light and gravity signals are integrated is challenging. Branch orientation, or gravitropic set point angle, is a key aspect of plant architecture, set with respect to gravity and shown to be altered by changes in light conditions. The IGT gene family, also known as the LAZY family, contains important components for branch angle and gravity responses, including three gene clades: LAZY, DEEPER ROOTING (DRO), and TILLER ANGLE CONTROL (TAC). LAZY and DRO genes promote upward branch orientations downstream of amyloplast sedimentation, and upstream of auxin redistribution in response to gravity. In contrast, TAC1 promotes downward branch angles in response to photosynthetic signals. Here, we investigated the influence of different light signaling pathways on LAZY and DRO gene expression, and their role in light regulation of branch angle responses. We found differential effects of continuous light and dark, circadian clock, photoreceptor-mediated signaling, and photosynthetic signals on LAZY and DRO gene expression. Phenotypic analysis revealed that LAZY and DRO genes are collectively required for branch angle responses to light.HighlightLAZY and DRO gene expression responds differentially to changes in light regime and signaling. Loss of multiple LAZY and DRO genes leads to loss of branch angle response to light.

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Section: Lazy and Dro Gene Expression Responds Differentially To Lighsupporting

confidence: 74%

IGT/LAZY family genes are differentially influenced by light signals and collectively required for light-induced changes to branch angle

Waite

Dardick

2020

Preprint

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“…Yet, the importance or specific role of each domain may vary between species. Heterologously expressed GFP-tagged full-length and truncated LAZY1 proteins, along with in vitro assays, indicated monocot and dicot LAZY1 proteins, as well as Arabidopsis AtLAZY2, 3 and 4, associate with the plasma membrane and, in some cases, microtubules and nuclei 4,5,20,28,29 . The LAZY1 TMD was needed for membrane localization of transiently expressed rice and maize LAZY1-GFP in onion 20,27 .…”

mentioning

confidence: 99%

“…Interestingly, in Arabidopsis, nuclear localization is not needed for LAZY1-mediated branch angle control 4 . The lazy1 shoot phenotype was rescued by overexpressing a LAZY1 sequence containing a mutation in the NLS, which was shown to prevent nuclear localization in tobacco 4 .The last ~14 amino acids of the LAZY protein C-terminus (which is also called domain/region V, the Conserved C-terminus in LAZY1, or the CCL, as well as peptide VI) contains an Ethylene-responsive Amphiphilic Repression (EAR) transcriptional repressor motif and this region seems to be important for LAZY protein function in many species 3,5,8,29 . It was required to rescue Arabidopsis lazy1;lazy2;lazy4 mutant root gravitropism phenotypes 8 .…”

mentioning

confidence: 99%

Opposing influences of TAC1 and LAZY1 on Lateral Shoot Orientation in Arabidopsis

Hollender

Hill

Waite

et al. 2020

Sci Rep

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TAC1 and LAZY1 are members of a gene family that regulates lateral shoot orientation in plants. TAC1 promotes outward orientations in response to light, while LAZY1 promotes upward shoot orientations in response to gravity via altered auxin transport. We performed genetic, molecular, and biochemical assays to investigate possible interactions between these genes. In Arabidopsis they were expressed in similar tissues and double mutants revealed the wide-angled lazy1 branch phenotype, indicating it is epistatic to the tac1 shoot phenotype. Surprisingly, the lack of TAC1 did not influence gravitropic shoot curvature responses. Combined, these results suggest TAC1 might negatively regulate LAZY1 to promote outward shoot orientations. However, additional results revealed that TAC1-and LAZY1 influence on shoot orientation is more complex than a simple direct negative regulatory pathway. Transcriptomes of Arabidopsis tac1 and lazy1 mutants compared to wild type under normal and gravistimulated conditions revealed few overlapping differentially expressed genes. Overexpression of each gene did not result in major branch angle differences. Shoot tip hormone levels were similar between tac1, lazy1, and Col, apart from exceptionally elevated levels of salicylic acid in lazy1. The data presented here provide a foundation for future study of TAC1 and LAZY1 regulation of shoot architecture.Lateral organ orientation in both shoots and roots plays a key role in a plant's interaction with the environment and its ability to access resources such as light and water. The IGT gene family members TILLER ANGLE CONTROL 1 (TAC1) and the related set of LAZY genes are important regulators of lateral organ orientation 1,2 . These genes share four conserved amino acid regions or domains, and LAZY genes share an additional C-terminal domain 3,4 . TAC1 generally occurs as a single copy gene, but many species possess multiple LAZY genes, with six identified in Arabidopsis 2-8 . While the LAZY1 gene of Arabidopsis thaliana (Arabidopsis) contributes almost exclusively to shoot architecture, the remaining Arabidopsis LAZY genes primarily control root architecture 7,8 . However, GUS reporter activity and additive shoot phenotypes in plants with combinatorial lazy1, lazy2, and lazy4 mutations suggest LAZY2 and LAZY4 also have a role in regulating shoot orientation 7,8 . LAZY2, 3, and 4 are also known as DEEPER ROOTING (DRO3, 2, & 1) and NEGATIVE GRAVITROPIC RESPONSE OF ROOTS (NGR1, 3, & 2), respectively, as they were separately identified as regulators of lateral root orientation 6,9-12 . Further, an alternate LAZY gene nomenclature denotes LAZY3 as LZY2 and LAZY4 as LZ3Y 8 .Lateral branches, tillers, leaves, and flower buds of plants with loss-of-function tac1 mutations or reduced TAC1 expression exhibit upright orientations 3,13-19 . In contrast, lazy1 mutants have wider branch or tiller angles and lazy4/dro1 mutants display prostrate lateral root orientations 4-9,20-24 . Plants with multiple lazy/dro mutations exhibit even wider lateral shoot/root...

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“…The AtDRO1 promoter has been shown to drive expression of GFP, VENUS, and GUS reporter proteins in root tips, columella cells, and more distally in primary roots and older lateral roots (Yoshihara and Spalding 2017;Guseman et al 2017;Ge and Chen 2019). The AtDRO1 protein contains all 5 domains conserved among the IGT gene family (Dardick et al 2013;Yoshihara et al 2013;Yoshihara and Spalding 2019). The only recognizable motif among these includes an ethylene-responsive element binding factor associated amphiphilic repression-like motif, or EAR-like motif, associated with transcriptional repression (Kagale and Rozwadowski 2010).…”

Section: Introductionmentioning

confidence: 99%

“…This motif has been shown in wheat DRO1 to facilitate interaction with the TOPLESS protein at the plasma membrane and nucleus (Ashraf et al 2019). Other conserved domains have been characterized within the similar LAZY1 protein to be important for nuclear localization, plasma membrane localization, and association with microtubules using transient assays in protoplasts, and Arabidopsis and N. benthamiana leaves (Yoshihara et al 2013;Sasaki and Yamamoto 2015;Yoshihara and Spalding 2019). AtDRO1 protein driven by an estradiol-inducible promoter, was found to localize to the membranes of root epidermal and lateral root cap cells (Ge and Chen 2019).…”

Section: Introductionmentioning

confidence: 99%

AtDRO1 is nuclear localized in root tips under native conditions and impacts auxin localization

2020

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DEEPER ROOTING 1 (DRO1) contributes to the downward gravitropic growth trajectory of roots upstream of lateral auxin transport in monocots and dicots. Loss of DRO1 function leads to horizontally oriented lateral roots and altered gravitropic set point angle, while loss of all three DRO family members results in upward, vertical root growth. Here, we attempt to dissect the roles of AtDRO1 by analyzing expression, protein localization, auxin gradient formation, and auxin responsiveness in the atdro1 mutant. Current evidence suggests AtDRO1 is predominantly a membrane-localized protein. Here we show that VENUS-tagged AtDRO1 driven by the native AtDRO1 promoter complemented an atdro1 Arabidopsis mutant and the protein was localized in root tips and detectable in nuclei. atdro1 primary and lateral roots showed impairment in establishing an auxin gradient upon gravistimulation as visualized with DII-VENUS, a sensor for auxin signaling and proxy for relative auxin distribution. Additionally, PIN3 domain localization was not significantly altered upon gravistimulation in atdro1 primary and lateral roots. RNA-sequencing revealed differential expression of known root development-related genes in atdro1 mutants. atdro1 lateral roots were able to respond to exogenous auxin and AtDRO1 gene expression levels in root tips were unaffected by the addition of auxin. Collectively, the data suggest that nuclear localization may be important for AtDRO1 function and suggests a more nuanced role for DRO1 in regulating auxin-mediated changes in lateral branch angle. Key message DEEPER ROOTING 1 (DRO1) when expressed from its native promoter is predominately localized in Arabidopsis root tips, detectable in nuclei, and impacts auxin gradient formation.

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Switching the Direction of Stem Gravitropism by Altering Two Amino Acids in AtLAZY1

Cited by 45 publications

References 59 publications

IGT/LAZY family genes are differentially influenced by light signals and collectively required for light-induced changes to branch angle

IGT/LAZY family genes are differentially influenced by light signals and collectively required for light-induced changes to branch angle

Opposing influences of TAC1 and LAZY1 on Lateral Shoot Orientation in Arabidopsis

AtDRO1 is nuclear localized in root tips under native conditions and impacts auxin localization

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