GA Signaling: Direct Targets of DELLA Proteins

Circadian clock circuitry intersects with a plethora of signaling pathways to adequately time physiological processes to occur at the most appropriate time of the day and year. However, our mechanistic understanding of how the clockwork is wired to its output is limited. Here we uncover mechanistic connections between the core clock component GIGANTEA (GI) and hormone signaling through the modulation of key components of the transduction pathways. Specifically, we show how GI modulates gibberellin (GA) signaling through the stabilization of the DELLA proteins, which act as negative components in the signaling of this hormone. GI function within the GA pathway is required to precisely time the permissive gating of GA sensitivity, thereby determining the phase of GA-regulated physiological outputs.

Download Full-text

Gibberellin DELLA signaling targets the retromer complex to redirect protein trafficking to the plasma membrane

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1721760115 ◽

2018 ◽

Vol 115 (14) ◽

pp. 3716-3721 ◽

Cited By ~ 24

Author(s):

Yuliya Salanenka ◽

Inge Verstraeten ◽

Christian Löfke ◽

Kaori Tabata ◽

Satoshi Naramoto ◽

...

Keyword(s):

Plasma Membrane ◽

Cell Surface ◽

Protein Trafficking ◽

Molecular Mechanisms ◽

Sorting Nexin ◽

Protein Traffic ◽

Della Proteins ◽

Retromer Complex ◽

Ga Signaling ◽

Multiple Processes

The plant hormone gibberellic acid (GA) is a crucial regulator of growth and development. The main paradigm of GA signaling puts forward transcriptional regulation via the degradation of DELLA transcriptional repressors. GA has also been shown to regulate tropic responses by modulation of the plasma membrane incidence of PIN auxin transporters by an unclear mechanism. Here we uncovered the cellular and molecular mechanisms by which GA redirects protein trafficking and thus regulates cell surface functionality. Photoconvertible reporters revealed that GA balances the protein traffic between the vacuole degradation route and recycling back to the cell surface. Low GA levels promote vacuolar delivery and degradation of multiple cargos, including PIN proteins, whereas high GA levels promote their recycling to the plasma membrane. This GA effect requires components of the retromer complex, such as Sorting Nexin 1 (SNX1) and its interacting, microtubule (MT)-associated protein, the Cytoplasmic Linker-Associated Protein (CLASP1). Accordingly, GA regulates the subcellular distribution of SNX1 and CLASP1, and the intact MT cytoskeleton is essential for the GA effect on trafficking. This GA cellular action occurs through DELLA proteins that regulate the MT and retromer presumably via their interaction partners Prefoldins (PFDs). Our study identified a branching of the GA signaling pathway at the level of DELLA proteins, which, in parallel to regulating transcription, also target by a nontranscriptional mechanism the retromer complex acting at the intersection of the degradation and recycling trafficking routes. By this mechanism, GA can redirect receptors and transporters to the cell surface, thus coregulating multiple processes, including PIN-dependent auxin fluxes during tropic responses.

Download Full-text

Sunflower ‘Sunspot’ is Hyposensitive to GA3 and has a Missense Mutation in the DELLA Motif of HaDella1

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.141.4.389 ◽

2016 ◽

Vol 141 (4) ◽

pp. 389-394 ◽

Cited By ~ 4

Author(s):

Norman B. Best ◽

Xingang Wang ◽

Scottie Brittsan ◽

Eric Dean ◽

Seth J. Helfers ◽

...

Keyword(s):

Helianthus Annuus ◽

Missense Mutation ◽

Reference Sequence ◽

Transcriptional Repressors ◽

Nucleotide Polymorphism ◽

Dwarf Phenotype ◽

Single Nucleotide ◽

Della Proteins ◽

Ga Signaling ◽

Genes Encoding

Gibberellins (GAs) are phytohormones that regulate plant height and flowering time in plants. Plants with reduced GA or disrupted in GA signaling exhibit a dwarf phenotype. DELLA proteins are transcriptional repressors that attenuate GA-mediated promotion of plant growth. Alleles in which the eponymous DELLA motif in these proteins is disrupted result in constitutive repression of GA signaling and a dominantly inherited dwarf phenotype. We found that the dwarf Helianthus annuus (sunflower) cultivar Sunspot is hyposensitive to GA3 as compared with the tall cultivar Mammoth Grey. Sequencing of the HaDella1 gene indicates that ‘Sunspot’ has a single nucleotide polymorphism resulting in a missense mutation in the DELLA motif as compared with ‘Mammoth Grey’ and the reference sequence. Helianthus annuus has five genes encoding DELLA proteins, including HaDella1. We propose that the DELLA motif alteration in the HaDella1 gene results in a dominant mutation in ‘Sunspot’ and is the cause of its dwarf phenotype.

Download Full-text

DELLA-NAC Interactions Mediate GA Signaling to Promote Secondary Cell Wall Formation in Cotton Stem

Frontiers in Plant Science ◽

10.3389/fpls.2021.655127 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yi Wang ◽

Wanting Yu ◽

Lingfang Ran ◽

Zhong Chen ◽

Chuannan Wang ◽

...

Keyword(s):

Cell Wall ◽

Gene Silencing ◽

Secondary Cell Wall ◽

Cell Wall Formation ◽

Virus Induced Gene Silencing ◽

Secondary Cell Wall Formation ◽

Della Proteins ◽

Ga Signaling ◽

Wide Range ◽

New System

Gibberellins (GAs) promote secondary cell wall (SCW) development in plants, but the underlying molecular mechanism is still to be elucidated. Here, we employed a new system, the first internode of cotton, and the virus-induced gene silencing method to address this problem. We found that knocking down major DELLA genes via VIGS phenocopied GA treatment and significantly enhanced SCW formation in the xylem and phloem of cotton stems. Cotton DELLA proteins were found to interact with a wide range of SCW-related NAC proteins, and virus-induced gene silencing of these NAC genes inhibited SCW development with downregulated biosynthesis and deposition of lignin. The findings indicated a framework for the GA regulation of SCW formation; that is, the interactions between DELLA and NAC proteins mediated GA signaling to regulate SCW formation in cotton stems.

Download Full-text

Mechanism of auxin and GA crosstalk in diploid strawberry fruit initiation

10.1101/2020.03.30.016188 ◽

2020 ◽

Author(s):

Junhui Zhou ◽

John Sittmann ◽

Lei Guo ◽

Xiaolong Huang ◽

Anuhya Pulapaka ◽

...

Keyword(s):

Fruit Development ◽

Receptor Gene ◽

Auxin Signaling ◽

Parthenocarpic Fruit ◽

Strawberry Fruit ◽

Functional Studies ◽

Della Proteins ◽

Ga Signaling ◽

Future Production ◽

Wild Strawberry

AbstractStrawberry, a high value fruit crop, has recently become amenable for genetic studies due to genomic resources and CRISPR/CAS9 tools. Unlike ovary-derived botanical fruits, strawberry is an accessory fruit derived from receptacle, the stem tip subtending floral organs. Although both botanical and accessory fruits initiate development in response to auxin and GA released from seeds, the downstream auxin and GA signaling mechanisms underlying accessory fruit development remain unknown. Using wild strawberry, we performed in depth molecular characterizations of accessory fruit development. We show that auxin signaling proteins FveARF8/FveARF6 are bound and hence inhibited by FveIAA4 and FveRGA1, repressors in auxin and GA signaling pathways. This inhibition is relieved post-fertilization or by the application of GA or auxin. Mutants of FveRGA1 developed parthenocarpic fruit suggesting a conserved function of DELLA proteins in fruit set. Further, FveARF8 was found to repress the expression of a GA receptor gene GID1c to control fruit’s sensitivity to GA, revealing a novel crosstalk mechanism. We demonstrate that consensus co-expression network provides a powerful tool for non-model species in the selection of interacting genes for functional studies. These findings will facilitate the improvement of strawberry fruit productivity and quality by guiding future production of parthenocarpic fruit.One sentence summaryGenome editing and network analysis are applied to investigating the mechanism of accessory fruit initiation in the wild strawberry, revealing conserved as well as novel crosstalk mechanisms.The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) is: Zhongchi Liu ([email protected])

Download Full-text

The blue-light receptor CRY1 interacts with GID1 and DELLA proteins to repress GA signaling during photomorphogenesis in Arabidopsis

Molecular Plant ◽

10.1016/j.molp.2021.05.011 ◽

2021 ◽

Author(s):

Ming Zhong ◽

Bingjie Zeng ◽

Dongying Tang ◽

Jiaxing Yang ◽

Lina Qu ◽

...

Keyword(s):

Blue Light ◽

Della Proteins ◽

Blue Light Receptor ◽

Ga Signaling ◽

Light Receptor

Download Full-text

DELLA proteins physically interact with CONSTANS to regulate flowering under long days inArabidopsis

FEBS Letters ◽

10.1002/1873-3468.12076 ◽

2016 ◽

Vol 590 (4) ◽

pp. 541-549 ◽

Cited By ~ 33

Author(s):

Feng Xu ◽

Ting Li ◽

Peng-Bo Xu ◽

Ling Li ◽

Sha-Sha Du ◽

...

Keyword(s):

Della Proteins

Download Full-text

Enhanced sustainable green revolution yield via nitrogen-responsive chromatin modulation in rice

Science ◽

10.1126/science.aaz2046 ◽

2020 ◽

Vol 367 (6478) ◽

pp. eaaz2046 ◽

Cited By ~ 26

Author(s):

Kun Wu ◽

Shuansuo Wang ◽

Wenzhen Song ◽

Jianqing Zhang ◽

Yun Wang ◽

...

Keyword(s):

Nitrogen Use Efficiency ◽

Green Revolution ◽

Agricultural Sustainability ◽

Nitrogen Use ◽

Polycomb Repressive Complex 2 ◽

Della Proteins ◽

Genome Wide ◽

Use Efficiency ◽

Low Nitrogen ◽

Cereal Yields

Because environmentally degrading inorganic fertilizer use underlies current worldwide cereal yields, future agricultural sustainability demands enhanced nitrogen use efficiency. We found that genome-wide promotion of histone H3 lysine 27 trimethylation (H3K27me3) enables nitrogen-induced stimulation of rice tillering: APETALA2-domain transcription factor NGR5 (NITROGEN-MEDIATED TILLER GROWTH RESPONSE 5) facilitates nitrogen-dependent recruitment of polycomb repressive complex 2 to repress branching-inhibitory genes via H3K27me3 modification. NGR5 is a target of gibberellin receptor GIBBERELLIN INSENSITIVE DWARF1 (GID1)–promoted proteasomal destruction. DELLA proteins (characterized by the presence of a conserved aspartate-glutamate-leucine-leucine-alanine motif) competitively inhibit the GID1-NGR5 interaction and explain increased tillering of green revolution varieties. Increased NGR5 activity consequently uncouples tillering from nitrogen regulation, boosting rice yield at low nitrogen fertilization levels. NGR5 thus enables enhanced nitrogen use efficiency for improved future agricultural sustainability and food security.

Download Full-text