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The DELLA Proteins Serve as Central Regulators Integrating Multiple Signaling Pathways. (A) The DELLA proteins function as transcriptional repressors, physically interacting with bHLH (e.g. PIFs and ALC) thereby preventing their binding with their target genes. The GA-mediated degradation of the DELLA proteins releases bHLH, which, in turn, promotes the expression of SL patterning and light responses genes. (B) The DELLA proteins function as transcriptional activators. JAZ proteins interact with MYC2, thereby inhibiting the activity of MYC2. JA promotes the degradation of JAZ proteins to release MYC2. The DELLA proteins compete with MYC2 for binding to JAZ proteins, which, in turn, activates the expression of JA-responsive genes.
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Gibberellic acid (GA) regulates many aspects of plant growth and development. The DELLA proteins act to restrain plant growth, and GA relieves this repression by promoting their degradation via the 26S proteasome pathway. The elucidation of the crystalline structure of the GA soluble receptor GID1 protein represents an important breakthrough for un...
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Context 1
... GA, through its destabilization of the DELLA proteins, promotes the release of ALC, with a conse- quent effect on the SL (Arnaud et al., 2010). Here, the DELLA proteins function as a transcriptional repressor, preventing the binding of the bHLH proteins with their gene promoter target, and thereby inhibiting gene expression (Figure 2A). ...
Context 2
... GA promotes the degradation of the DELLA proteins, which promotes the binding of JAZ with MYC2 and increases the subsequent restraint on MYC2 activity ( Hou et al., 2010). Thus, a full model of DELLA protein function must include its role as a transcriptional activator pro- moting the expression of JA responsive genes ( Figure 2B). ...
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Citations
... In the first step, once the GID1 receptor recognizes GA signal, it forms a GA-GID1 complex. The GA-GID1 complex enhances the interaction of GID1 and DELLA, which results in the rapid degradation of DELLAs via the ubiquitin-proteasome pathway with the help of a specific ubiquitin E3 ligase complex S-phase kinase-associated protein 1 (SKP1)-cullin 1-F-box ubiquitin ligase (SCF SLY1/GID2 ) (Gao et al., 2011;Wallner et al., 2016). DELLA is a key component in GA-induced plant growth, repressing GA-signaling and restricting GA-mediated growth promotion through transcriptional reprogramming. ...
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... The conformation of GID1 protein changes when the GA signal is perceived (Ueguchi-Tanaka et al., 2007b;Hirano et al., 2008;Yoshida et al., 2018). The GID1-DELLA complex promotes the ubiquitination and degradation of DELLA proteins by the F-box protein component of SCF SLY1/GID2 complex through the 26S proteasome pathway, thereby releasing the inhibitory effect of DELLA on downstream regulators related to various biological processes Sun, 2010Sun, , 2011Gao et al., 2011). In addition to the GA-GID1-DELLA signaling pathway, DELLAindependent pathways have been reported (Maymon et al., 2009;Fuentes et al., 2012;Livne et al., 2015;Okada et al., 2017). ...
Although DELLA protein destabilization mediated by post‐translational modifications is essential for gibberellin (GA) signal transduction and GA‐regulated anthocyanin biosynthesis, the related mechanisms remain largely unknown. In this study, we report the ubiquitination and phosphorylation of an apple DELLA protein MdRGL2a in response to GA signaling and its regulatory role in anthocyanin biosynthesis.
MdRGL2a could interact with MdWRKY75 to enhance the MdWRKY75‐activated transcription of anthocyanin activator MdMYB1 and interfere with the interaction between anthocyanin repressor MdMYB308 and MdbHLH3 or MdbHLH33, thereby promoting anthocyanin accumulation.
A protein kinase MdCIPK20 was found to phosphorylate and protect MdRGL2a from degradation, and it was essential for MdRGL2a‐promoting anthocyanin accumulation. However, MdRGL2a and MdCIPK20 were ubiquitinated and degraded by E3 ubiquitin ligases MdSINA1 and MdSINA2, respectively, both of which were activated in the presence of GA.
Our results display the integration of SINA1/2 with CIPK20 to dynamically regulate GA signaling and will be helpful toward understanding the mechanism of GA signal transduction and GA‐inhibited anthocyanin biosynthesis. The discovery of extensive interactions between DELLA and SINA and CIPK proteins in apple will provide reference for the study of ubiquitination and phosphorylation of DELLA proteins in other species.
... Together with the function of JAZ, we noticed that two gibberellin-related genes were up-regulated and hop-interaction protein THI039 della protein (DELLAs) was down-regulated (Table 1). DELLAs were reported to repress GA signaling transmission and promote JA responses, and when GA were biosynthesized in plants, DELLAs will be degraded by ubiquitination, release GA-response-related transcription factors to activate GA response and hence promote plant photosynthetic growth (Gao et al. 2011). To further illustrate the interaction of significantly regulated plant hormones, the network of the interaction between ETH, JA and GA were made (Fig. 4). ...
The secondary compost products (SCP), originated from secondary composting process of the agriculture organic waste fermentation CO2 enrichment devices, can promote tomato plants growth, yield and fruit quality, while reducing the emission of greenhouse gas and organic wastes to the environment, which contributing to the building of carbon neutral and peak. However, the molecular mechanisms and metabolic pathways by which tomato plants responses to SCP treated soil are unknown. In this case, leaf metabolome and transcriptome were compared in the tomato plants grown under SCP, chemical fertilizer (CF) and organic fertilizer (OF). Results showed that SCP application improved primary metabolism especially TCA cycle, carbohydrate metabolism and amino acid metabolism, and also enhanced secondary metabolism especially phenylpropanoid metabolism in tomato leaves when compared with that of CF. Meanwhile, SCP induced significantly down-regulation in ethylene-related genes, while up-regulation in jasmonic acid and gibberellin related genes, which together with the increase of Jasmonate ZIM-domain protein and decrease of DELLA protein endow good balance between growth and environment adaptation ability of plants under SCP treatment. Our findings provide an insight into the molecular and metabolomic response to SCP treated tomato plants for the first time, contributing to the construction of climate-smart agriculture.
... Moreover, 750 mg L −1 uniconazole treatment can further lessen the yield gap between the sowing densities at 400 and 800 seeds per tray. However, as a well-known gibberellin inhibitor, excessive doses of uniconazole could have a negative impact on seed germination and even growth [45,46]. Hence, on safety grounds, we conservatively recommend 5 mL of 500-750 mg L −1 uniconazole polyvinyl alcohol solution per 100 g of seeds in production practice. ...
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... Both alleles carry mutations in the Rht-1 coding region that result in stop codons within the N-terminal DELLA protein domain (Phillips 2016), producing truncated DELLA proteins (Pearce et al. 2011). In the presence of gibberellic acid (GA), the GA receptor, gibberellin insensitive dwarf1 (GID1), binds to wild-type DELLA proteins, resulting in their ubiquitination and degradation through the 26S proteasome SCF complex (Gao et al. 2011). The truncated DELLA proteins encoded by Rht-B1b and Rht-D1b are unable to bind to GID1 and therefore do not undergo degradation but continue to suppress plant growth and result in a semidwarf phenotype (Phillips 2016). ...
Partial resistance to the biotrophic fungal pathogen Claviceps purpurea, causal agent of ergot, has been found that co-locates with mutant alleles of the wheat Reduced height (Rht) loci on chromosomes 4B and 4D. These Rht loci represent the wheat orthologues of the Arabidopsis Della genes. To investigate the role of the Rht mutant DELLA proteins in ergot resistance we assessed C. purpurea infection in wheat near-isogenic lines (NILs) carrying the gibberellic acid (GA)-insensitive semi-dwarf alleles Rht-B1b and Rht-D1b and the severe dwarf alleles Rht-B1c and Rht-D1c. NILs of the GA-sensitive alleles Rht8 (chromosome 2D) and Rht12 (chromosome 5A) were also included. A general trend towards increased resistance to C. purpurea, with smaller and lighter sclerotia, was observed on the NILs Rht-B1b, Rht-D1b, Rht-B1c and Rht-D1c, but also on Rht8. Levels of the bioactive GA4 and the auxin indole-3-acetic acid (IAA) increased following inoculation with C. purpurea, following similar patterns and implicating a potential auxin-mediated induction of GA biosynthesis. In contrast, jasmonic acid (JA) levels fell in the parental lines Mercia and Maris Huntsman following inoculation with C. purpurea, but increased in all the Rht-mutant NILs. Inoculation with C. purpurea did not show any informative changes in the levels of salicylic acid. Our results suggest that GA-mediated degradation of the DELLA proteins and down-regulation of JA-signalling pathways supports infection of wheat by C. purpurea. As these responses are generally associated with necrotrophic fungal pathogens, we propose that the biotroph C. purpurea may have a necrotrophic growth stage.
... SLY1/GID2 relies on its C-terminal regulatory (GGF and LSL) domain to bind DELLA proteins via their C-terminal GRAS (VHIID and LHRII) domain Fu et al., 2004;Hirano et al., 2010;Ariizumi et al., 2011). DELLA proteins are subsequently ubiquitinated by the E2/E3 ubiquitin ligase pathway via the SCF SLY1/GID2 complex, and the ubiquitinated DELLA is then degraded via the 26S proteasome with the concomitant discharge of the ubiquitin moieties for reuse (Ariizumi et al., 2011;Gao et al., 2011;Sun, 2011). Although studies in Arabidopsis and rice have revealed a conserved GA signaling pathway across land plant lineages, the fact that each plant carries a distinct set of GA signaling paralogs adds extra complexity to GA response mechanisms. ...
Fruit development is orchestrated by a complex network of interactions between hormone-signaling pathways. The phytohormone, gibberellin (GA), is known to regulate a diverse range of developmental processes; however, the mechanisms of GA-action in perennial fruit species are yet to be elucidated. In the current study, a GA-signaling gene PslSLY1, encoding a putative F-box protein that belongs to the SLY1 (SLEEPY1)/GID2 (gibberellin-insensitive dwarf2) gene family was isolated from Japanese plum (Prunus salicina). PslSLY1 transcript abundance declined as fruit development progressed, along with potential negative feedback regulation of PslSLY1 by GA. Subcellular localization and protein-protein interaction assays suggested that PslSLY1 functions as an active GA-signaling component that interacts with the ASK1 (Arabidopsis SKP1) subunit of an SCF–ubiquitin ligase complex and with PslDELLA-repressors, in a GA-independent manner. By using a domain omission strategy, we illustrated that the F-box and C-terminal domains of PslSLY1 are essential for its interactions with the downstream GA-signaling components. PslSLY1–overexpression in WT and Arabidopsis sly1.10 mutant backgrounds resulted in a dramatic enhancement in overall plant growth, presumably due to triggered GA-signaling. This includes germination characteristics, stem elongation, flower structure, and fertility. Overall, our findings shed new light on the GA strategy and signaling network in commercially important perennial crops.
... However, since DELLA proteins do not contain a canonical DNA-binding domain, they may interact with other transcription factors and then regulate the target genes. DELLA proteins can interact with many transcription factors, including ABA INSE NSITIVE 3 (ABI3), ABI5, AUXIN RESPONSE FACTOR 6 (ARF6), PHYTOCHROME INTERACTING FACTORs (PIFs), BRASSINAZOLE-RESISTANT 1 (BZR1), ETHYLE NE-INSENSITIVE 3 (EIN3), JASMONATE-ZIM-DOMAIN PROTEINs (JAZs), DWARF 14 (D14), and FLOWERING LOCUS C (FLC), as well as brassinosteroid (BR) signaling, which are involved in multiple phytohormone signaling pathways, thus participating in complex crosstalk among plant hormones [11][12][13][14][15][16][17]. ...
Background:
DELLAs play key roles in plant gibberellin signaling pathways and are generally important in plant development and growth. However, DELLAs in many plant taxa have not yet been systematically analyzed.
Results:
In our study, we searched for DELLA genes across 58 green plant genomes and found 181 DELLAs. Structure analysis showed some DELLA domains do not contain "D-E-L-L-A" sequences and instead contain similar domains, including DGLLA and DSLLH domains. "VHYNP" motifs in plant DELLAs comprise 23 types of sequences, while some DELLAs did not contain GRAS domains. In grape, we found that the DELLA protein GSVIVT01015465001 contains an F-box domain, while apple DELLA proteins MDP0000220512 and MDP0000403162 contain a WW domain and a BCIP domain, respectively. These DELLAs can be divided into 22 homologous groups and 17 orthologous groups, and 35 paralogous genes were identified. In total, 35 positively selected genes (PSGs) and 121 negatively selected genes (NSGs) were found among DELLAs based on selective pressure analysis, with an average Ks of NSGs that was significantly higher than that of PSGs (P < 0.05). Among the paralogous groups, CBI and Fop were significantly positively correlated with GC, GC1, GC2, GC12, and GC3, while CAI was significantly positively correlated with GC, GC1, GC12, and GC. The paralogous groups with ω values exceeding 1 had significantly higher Ka values. We also found some paralogous groups with ω values exceeding 1 that differed in their motifs.
Conclusions:
This study provides helpful insights into the evolution of DELLA genes and offers exciting opportunities for the investigation of DELLA functions in different plants.
... Under increased GA levels, GA binds to its nuclear receptor GID1 (GA insensitive dwarf1) and changes its conformation, leading to its interaction with the N-terminal end of DELLA proteins [9][10][11]. The interaction of DELLA proteins with GID1 causes its ubiquitination and subsequent degradation by the 26S proteasome, leading to the activation of GA responses [12,13]. DELLA proteins are involved in most GA-mediated plant growth and environmental stresses, including dehydration stress. ...
DELLA (GAI/RGA/RGL1/RGL2/RGL3) proteins are key negative regulators in GA (gibberellin) signaling and are involved in regulating plant growth as a response to environmental stresses. It has been shown that the DELLA protein PROCERA (PRO) in tomato promotes drought tolerance, but its molecular mechanism remains unknown. Here, we showed that the gai-1 (gibberellin insensitive 1) mutant (generated from the gai-1 (Ler) allele (with a 17 amino acid deletion within the DELLA domain of GAI) by backcrossing gai-1 (Ler) with Col-0 three times), the gain-of-function mutant of GAI (GA INSENSITIVE) in Arabidopsis, increases drought tolerance. The stomatal density of the gai-1 mutant was increased but its stomatal aperture was decreased under abscisic acid (ABA) treatment conditions, suggesting that the drought tolerance of the gai-1 mutant is a complex trait. We further tested the interactions between DELLA proteins and ABF2 (abscisic acid (ABA)-responsive element (ABRE)-binding transcription factors) and found that there was a strong interaction between DELLA proteins and ABF2. Our results provide new insight into DELLA proteins and their role in drought stress tolerance.
... GAs belong to a large family of tetracyclic diterpenoids which promote various processes related to growth and development of organs and tissues (Hedden and Kamiya, 1997;Olszewski et al., 2002;Sakamoto et al., 2004;Sun and Gubler, 2004;Zhu et al., 2006;Gao et al., 2011;Ribeiro et al., 2012a). The regulation of GA biosynthesis is fundamental for plant development and adaptation (Hedden and Kamiya, 1997). ...
... Plant hormones play an important role in plant growth and stress response. Among them, gibberellin is a kind of biguanide compound, which is one of the essential hormones for plant growth and development (Achard et al. 2009;Ubeda-Tomás et al. 2009;Gao et al. 2011;Wang et al. 2015a;Zhuang et al. 2015). Up to now, more than 130 different types of gibberellins have been discovered and identified from different plants, but only a few have physiological activity (Silverstone and Sun 2000). ...
Gibberellins (GAs), as one of the important hormones in regulating the growth and development of higher plants, can significantly promote cell elongation and expansion. Celery is a widely grown leafy vegetable crop with rich nutritional value. However, the effect of gibberellins on celery leaves is unclear. In this paper, the celery variety “Jinnan Shiqin” plants were treated with gibberellic acid (GA3) and paclobutrazol (PBZ, a gibberellin inhibitor). Our results showed that GA3 treatment promoted the growth of celery leaves and caused lignification of celery leaf tissue. In addition, the transcript levels of genes associated with gibberellins, auxin, cytokinins, ethylene, jasmonic acid, abscisic acid, and brassinolide were altered in response to increased or decreased exogenous gibberellins or inhibitor. GA3 may regulate celery growth by interacting with other hormones through crosstalk mechanisms. This study provided a reference for further study of the regulation mechanism of gibberellins metabolism, and exerted effects on understanding the role of gibberellins in the growth and development of celery.
