Gibberellin Signaling Pathway Research Articles

Histological, Transcriptomic, and Functional Analyses Reveal the Role of Gibberellin in Bulbil Development in Lilium lancifolium

Lily bulbils, advantageous axillary organs used for asexual reproduction, have an underexplored developmental mechanism. Gibberellins are known to participate in bulbil development, but the regulatory mechanisms remain unclear. In this study, exogenous gibberellin (GA3) significantly increased the bulbil length, width, and weight by raising the endogenous gibberellin levels and elongating the scale cells. Transcriptomic analysis identified LlGA20ox2, a key gibberellin biosynthesis gene, which was upregulated during bulbil development and significantly responsive to GA3 treatment. Given the similarities in bulbil and bulblet development, we determined the roles of LlGA20ox2 using a bulblet system. Silencing LlGA20ox2 in bulblets inhibited development by reducing the cell length, while overexpression increased the bulblet length and width. In the gibberellin signaling pathway, we identified two key genes, LlGID1C and LlCIGR2. Silencing these genes resulted in phenotypes similar to LlGA20ox2, inhibiting bulblet development. Further transcriptomic analysis revealed that gibberellin-responsive genes were enriched in the glucuronate pathway, pentose phosphate pathway and galactose metabolism pathways. Most of these differentially expressed genes responded to gibberellin and were highly expressed in later stages of bulbil development, suggesting their involvement in gibberellin-regulated bulbil growth. In conclusion, we preliminarily explored the mechanisms of gibberellin regulation in bulbil development, offering significant commercial potential for new lily reproductive organs.

Identification and analysis of gibberellin 2-oxidase (GA2ox) members in Cunninghamia lanceolate and the negative regulatory character of ClGA2ox12 in tree stature and xylem lignin deposits

Cunninghamia lanceolata (Lamb.) Hook (C. lanceolate) is a fast-growing evergreen coniferous tree species with high wood yield and fantabulous timber quality. To date, numerous studies have revealed that gibberellins (GAs) regulate the formation of plant wood (secondary xylem). Moreover, GA 2-oxidases (GA2oxs) are known as the major enzymes that deactivate GAs. However, a small or no number of the GA2oxs involved in xylem development and lignin biosynthesis mediated by the GA pathway in woody plants have been identified previously. In this study, 5 GA2oxs members were identified in C. lanceolate, including 4 ClGA2ox12s and one ClGA2ox8-like. Exogenous gibberellin not only promoted lignin deposition in the stem of C. lanceolate but also up-regulated the expression of the lignin biosynthesis gene ClCAD1 by 2–3 folds and one of ClGA2ox12s (designated ClGA2ox12) by 4 folds, suggesting that ClGA2ox12 may be involved in the modulation of lignin deposition by the gibberellin signaling pathway in C. lanceolate. Furthermore, transgenic Populus tomentosa overexpressing ClGA2ox12 exhibited growth retardation and a typical dwarfing phenotype, with a reduction of approximately 40 % in the number of xylem cell layers and a decrease of approximately 16.7 %-26.9 % in lignin content relative to wild-type plants. At the same time, the expression level of lignin biosynthetic genes and lignin content were down-regulated in transgenic plants. Together, these results suggested that ClGA2ox12 functioned as a GA 2oxs catabolic enzyme that plays pivotal roles in plant growth processes, xylem development, and lignin biosynthesis, which gives insights into producing dwarf and low-lignin varieties of C. lanceolate.

Functional characterization of WsPR-1 reveals its interplay with cytokinin and gibberellin signaling pathways

Pathogenesis-related protein 1 (PR-1) is an antimicrobial protein involved in systemic acquired resistance (SAR) in plants, but its regulatory role and interactions with other pathways remain unclear. In this study, we functionally characterize WsPR-1 gene of Withania somnifera in Nicotiana tabacum to elucidate its role in plant defense, growth, and development. Interestingly, transgenic tobacco plants with increased levels of cytokinin (CK) and decreased gibberellins (GAs) exhibited stunted shoot growth, an underdeveloped root system, modified leaf morphology, reduced seed pod production, and delayed leaf senescence. Transcriptional analysis revealed that WsPR-1 overexpression downregulated the GA 20-oxidase (GA20ox) gene involved in GA biosynthesis while upregulating GA 2-oxidase (GA2ox), a GA catabolic enzyme. Moreover, transcript levels of FRUITFULL (FUL) and LEAFY (NFL2) flowering genes exhibited a decrease in WsPR-1 plants, which could explain the delayed flowering and reduced seed pod development in transgenic plants. Confocal microscopy confirmed increased lignin deposition in stem cross-sections of WsPR-1 transgenic plants, supported by gene expression analysis and lignin content quantification. Additionally, our findings also suggest the involvement of Knotted1-like homeobox (KNOX) gene in enhancing cytokinin levels. This study highlights PR-1's regulatory role in plant growth and development, with potential to boost crop yields and enhance resilience.

Melatonin Priming Promotes Crop Seed Germination and Seedling Establishment Under Flooding Stress by Mediating ABA, GA, and ROS Cascades.

Both seed germination and subsequent seedling establishment are key checkpoints during the life cycle of seed plants, yet flooding stress markedly inhibits both processes, leading to economic losses from agricultural production. Here, we report that melatonin (MT) seed priming treatment enhances the performance of seeds from several crops, including soybean, wheat, maize, and alfalfa, under flooding stress. Transcriptome analysis revealed that MT priming promotes seed germination and seedling establishment associated with changes in abscisic acid (ABA), gibberellin (GA), and reactive oxygen species (ROS) biosynthesis and signaling pathways. Real-time quantitative RT-PCR (qRT-PCR) analysis confirmed that MT priming increases the expression levels of GA biosynthesis genes, ABA catabolism genes, and ROS biosynthesis genes while decreasing the expression of positive ABA regulatory genes. Further, measurements of ABA and GA concentrations are consistent with these trends. Following MT priming, quantification of ROS metabolism-related enzyme activities and the concentrations of H2O2 and superoxide anions (O2 -) after MT priming were consistent with the results of transcriptome analysis and qRT-PCR. Finally, exogenous application of GA, fluridone (an ABA biosynthesis inhibitor), or H2O2 partially rescued the poor germination of non-primed seeds under flooding stress. Collectively, this study uncovers the application and molecular mechanisms underlying MT priming in modulating crop seed vigor under flooding stress.

Insights into the ameliorative effect of ZnONPs on arsenic toxicity in soybean mediated by hormonal regulation, transporter modulation, and stress responsive genes.

Arsenic (As) contamination of agricultural soils poses a serious threat to crop productivity and food safety. Zinc oxide nanoparticles (ZnONPs) have emerged as a potential amendment for mitigating the adverse effects of As stress in plants. Soybean crop is mostly grown on marginalized land and is known for high accumulation of As in roots than others tissue. Therefore, this study aimed to elucidate the underlying mechanisms of ZnONPs in ameliorating arsenic toxicity in soybean. Our results demonstrated that ZnOB significantly improved the growth performance of soybean plants exposed to arsenic. This improvement was accompanied by a decrease (55%) in As accumulation and an increase in photosynthetic efficiency. ZnOB also modulated hormonal balance, with a significant increase in auxin (149%), abscisic acid (118%), gibberellin (160%) and jasmonic acid content (92%) under As(V) stress assuring that ZnONPs may enhance root growth and development by regulating hormonal signaling. We then conducted a transcriptomic analysis to understand further the molecular mechanisms underlying the NPs-induced As(V) tolerance. This analysis identified genes differentially expressed in response to ZnONPs supplementation, including those involved in auxin, abscisic acid, gibberellin, and jasmonic acid biosynthesis and signaling pathways. Weighted gene co-expression network analysis identified 37 potential hub genes encoding stress responders, transporters, and signal transducers across six modules potentially facilitated the efflux of arsenic from cells, reducing its toxicity. Our study provides valuable insights into the molecular mechanisms associated with metalloid tolerance in soybean and offers new avenues for improving As tolerance in contaminated soils.

Transcriptomics analyses reveal the key genes involved in stamen petaloid formation in Alcea rosea L.

Alcea rosea L. is a traditional flower with a long cultivation history. It is extensively cultivated in China and is widely planted in green belt parks or used as cut flowers and potted ornamental because of its rich colors and flower shapes. Double-petal A. rosea flowers have a higher aesthetic value compared to single-petal flowers, a phenomenon determined by stamen petaloid. However, the underlying molecular mechanism of this phenomenon is still very unclear. In this study, an RNA-based comparative transcriptomic analysis was performed between the normal petal and stamen petaloid petal of A. rosea. A total of 3,212 differential expressed genes (DEGs), including 2,620 up-regulated DEGs and 592 down-regulated DEGs, were identified from 206,188 unigenes. Numerous DEGs associated with stamen petaloid were identified through GO and KEGG enrichment analysis. Notably, there were 63 DEGs involved in the plant hormone synthesis and signal transduction, including auxin, cytokinin, gibberellin, abscisic acid, ethylene, brassinosteroid, jasmonic acid, and salicylic acid signaling pathway and 56 key transcription factors (TFs), such as MADS-box, bHLH, GRAS, and HSF. The identification of these DEGs provides an important clue for studying the regulation pathway and mechanism of stamen petaloid formation in A. rosea and provides valuable information for molecular plant breeding.

Identification of male sterility-related genes in Saccharum officinarum and Saccharum spontaneum.

Candidate male sterility genes were identified in sugarcane, which interacts with kinase-related proteins, transcription factors, and plant hormone signaling pathways to regulate stamen and anther development. Saccharum officinarum is a cultivated sugarcane species that its predominant feature is high sucrose content in stems. Flowering is necessary for breeding new cultivars but will terminate plant growth and reduce sugar yield. The wild sugarcane species Saccharum spontaneum has robust and viable pollen, whereas most S. officinarum accessions are male sterile, which isa desirable trait of a maternal parent in sugarcane breeding. To study male sterility and related regulatory pathways in sugarcane, we carried out RNAseq using flowers in different developmental stages between male-sterile S. officinarum accession 'LA Purple' and fertile S. spontaneum accession 'SES208'. Gene expression profiles were used to detect how genes are differentially expressed between male sterile and fertile flowers and to identify candidate genes for male sterility. Weighted gene correlation networks analysis (WGCNA) was conducted to investigate the regulatory networks. Transcriptomic analyses showed that 988 genes and 2888 alleles were differentially expressed in S. officinarum compared to S. spontaneum. Ten differentially expressed genes and thirty alleles were identified as candidate genes and alleles for male sterility in sugarcane. The gene Sspon.03G0007630 and two alleles of the gene Sspon.08G0002270, Sspon.08G0002270-2B and Sspon.08G0014700-1A, were involved in the early stamen or carpel development stages, while the remaining genes were classified into the post-meiosis stage. Gibberellin, auxin, and jasmonic acid signaling pathways are involved in the stamen development in sugarcane. The results expanded our knowledge of male sterility-related genes in sugarcane and generated genomic resources to facilitate the selection of ideal maternal parents to improve breeding efficiency.

OsWRKY78 regulates panicle exsertion via gibberellin signaling pathway in rice.

Panicle exsertion is one of the crucial agronomic traits in rice (Oryza sativa). Shortening of panicle exsertion often leads to panicle enclosure and severely reduces seed production. Gibberellin (GA) plays important roles in regulating panicle exsertion. However, the underlying mechanism and the relative regulatory network remain elusive. Here, we characterized the oswrky78 mutant showing severe panicle enclosure, and found that the defect of oswrky78 is caused by decreased bioactive GA contents. Biochemical analysis demonstrates that OsWRKY78 can directly activate GA biosynthesis and indirectly suppress GA metabolism. Moreover, we found OsWRKY78 can interact with and be phosphorylated by mitogen-activated protein kinase (MAPK) kinase OsMAPK6, and this phosphorylation can enhance OsWRKY78 stability and is necessary for its biological function. Taken together, these results not only reveal the critical function of OsWRKY78, but also reveal its mechanism via mediating crosstalk between MAPK and the GA signaling pathway in regulating panicle exsertion.

Comparative transcriptome analysis of resistant and susceptible watermelon genotypes reveals the role of RNAi, callose, proteinase, and cell wall in squash vein yellowing virus resistance.

Watermelon (Citrullus lanatus) is the third largest fruit crop in the world in term of production. However, it is susceptible to several viruses. Watermelon vine decline (WVD), caused by whitefly-transmitted squash vein yellowing virus (SqVYV), is a disease that has caused over $60 million in losses in the US and continues to occur regularly in southeastern states. Understanding the molecular mechanisms underlying resistance to SqVYV is important for effective disease management. A time-course transcriptomic analysis was conducted on resistant (392291-VDR) and susceptible (Crimson Sweet) watermelon genotypes inoculated with SqVYV. Significantly higher levels of SqVYV were observed over time in the susceptible compared to the resistant genotype. The plasmodesmata callose binding protein (PDCB) gene, which is responsible for increased callose deposition in the plasmodesmata, was more highly expressed in the resistant genotype than in the susceptible genotype before and after inoculation, suggesting the inhibition of cell-to-cell movement of SqVYV. The potential role of the RNA interference (RNAi) pathway was observed in the resistant genotype based on differential expression of eukaryotic initiation factor (eIF), translin, DICER, ribosome inactivating proteins, RNA-dependent RNA polymerase (RDR), and Argonaute (AGO) genes after inoculation. The significant differential expression of hormone-related genes, including those involved in the ethylene, jasmonic acid, auxin, cytokinin, gibberellin, and salicylic acid signaling pathways, was observed, emphasizing their regulatory roles in the defense response. Genes regulating pectin metabolism, cellulose synthesis, cell growth and development, xenobiotic metabolism, and lignin biosynthesis were overexpressed in the susceptible genotype, suggesting that alterations in cell wall integrity and growth processes result in disease symptom development. These findings will be helpful for further functional studies and the development of SqVYV-resistant watermelon cultivars.

Overexpression of SlCRF6 in tomato inhibits leaf development and affects plant morphology

Cytokinin response factors (CRFs) are transcription factors (TFs) that are specific to plants and have diverse functions in plant growth and stress responses. However, the precise roles of CRFs in regulating tomato plant architecture and leaf development have not been comprehensively investigated. Here, we identified a novel CRF, SlCRF6, which is involved in the regulation of plant growth via the gibberellin (GA) signaling pathway. SlCRF6-overexpressing (SlCRF6-OE) plants displayed pleiotropic phenotypic changes, including reduced internode length and leaf size, which caused dwarfism in tomato plants. This dwarfism could be alleviated by application of exogenous GA3. Remarkably, quantitative real-time PCR (qRTPCR), a dual luciferase reporter assay and a yeast one-hybrid (Y1H) assay revealed that SlCRF6 promoted the expression of SlDELLA (a GA signal transduction inhibitor) in vivo. Furthermore, transgenic plants displayed variegated leaves and diminished chlorophyll content, resulting in decreased photosynthetic efficiency and less starch than in wild-type (WT) plants. The results of transient expression assays and Y1H assays indicated that SlCRF6 suppressed the expression of SlPHAN (leaf morphology-related gene). Collectively, these findings suggest that SlCRF6 plays a crucial role in regulating tomato plant morphology, leaf development, and the accumulation of photosynthetic products.

Transcriptome Analysis and Novel EST-SSR Marker Development for Pinus tabuliformis Seedlings from Four Provenances

Chinese pine (Pinus tabuliformis) is a conifer species endemic to the temperate, warm temperate, and semi-arid regions of China. It has important ecological and economic values, but lacks suitable molecular markers for genetic studies. In this study, we collected open-pollinated progeny seeds from four provenances: Ningcheng (Nc), Qinyuan (Qy), Weichang (Wc), and Pingquan (Pq). We sequenced the transcriptomes of open-pollinated progeny seedlings from four provenances and annotated 18,244 unigenes. We analyzed the expression of genes involved in the auxin indole-3-acetic acid (IAA), cytokinin (CTK), and gibberellin (GA) signaling pathways among the provenances. Additionally, we detected 2811 expressed sequence tag simple sequence repeat (EST-SSR) loci in 2360 unigenes, with a frequency of 14.83% and an average of one locus per 14,556 base pairs (bp). We developed 10 polymorphic primers from 67 pairs and tested them on 56 samples from the four provenances. These primers exhibited moderate to high polymorphism and distinguished all samples clearly. Our study reveals variation in growth and development among open-pollinated progeny seedlings from different provenances of Chinese pine and provides novel markers for its genetic diversity study and marker-assisted breeding.

Transcript-wide identification and expression pattern analysis to comprehend the roles of AP2/ERF genes under development and abiotic stress in Trichosanthes kirilowii

BackgroundThe APETALA 2/ ethylene-responsive element binding factors (AP2/ERF), are thought to be associated with plant abiotic stress response, and involved in some plant hormone signaling pathways. Trichosanthes kirilowii is an important edible and medicinal crop, so far no research has been conducted on the TkAP2/ERF genes.ResultIn this study, a total of 135 TkERFs were identified, these genes were divided into 4 subfamilies and clustered into 13 groups. Moreover, 37 paralogous pairs were identified, with only two having Ka/Ks values greater than 1, proving that most TkERF genes underwent purifying selection during evolution. Co-expression networks constructed using transcriptome data at various flowering stages revealed that 50, 64, and 67 AP2/ERF genes correlated with members of the ethylene, gibberellin, and abscisic acid signaling pathways, respectively. When tissue cultured seedlings were treated with ETH, GA3 and ABA, 11, 12 and 17 genes were found to be up-regulated, respectively, suggesting that some members of the TkERF gene family may be involved in plant hormone signaling pathways. And under 4 ℃, PEG and NaCl treatment, 15, 20 and 19 genes were up-regulated, respectively, this suggested that these selected genes might be involved in plant abiotic stresses.ConclusionsOverall, we identified 135 AP2/ERF family members, a comprehensive analysis of AP2/ERF gene expression patterns by RNA-seq and qRT-PCR showed that they played important roles in flower development and abiotic stress. This study provided a theoretical basis for the functional study of TkAP2/ERF genes and the genetic improvement of T. kirilowii.

Transcriptome-Based Construction of the Gibberellin Metabolism and Signaling Pathways in Eucalyptus grandis × E. urophylla, and Functional Characterization of GA20ox and GA2ox in Regulating Plant Development and Abiotic Stress Adaptations.

Gibberellins (GAs) are the key regulators controlling plant growth, wood production and the stress responses in perennial woody plants. The role of GA in regulating the above-mentioned processes in Eucalyptus remain largely unclear. There is still a lack of systematic identification and functional characterization of GA-related genes in Eucalyptus. In this study, a total of 59,948 expressed genes were identified from the major vegetative tissues of the E. grandis × E. urophylla using transcriptome sequencing. Then, the key gene families in each step of GA biosynthesis, degradation and signaling were investigated and compared with those of Arabidopsis, rice, and Populus. The expression profile generated using Real-time quantitative PCR showed that most of these genes exhibited diverse expression patterns in different vegetative organs and in response to abiotic stresses. Furthermore, we selectively overexpressed EguGA20ox1, EguGA20ox2 and EguGA2ox1 in both Arabidopsis and Eucalyptus via Agrobacterium tumefaciens or A. rhizogenes-mediated transformation. Though both Arabidopsis EguGA20ox1- and EguGA20ox2-overexpressing (OE) lines exhibited better vegetative growth performance, they were more sensitive to abiotic stress, unlike EguGA2ox1-OE plants, which exhibited enhanced stress resistance. Moreover, overexpression of EguGA20ox in Eucalyptus roots caused significantly accelerated hairy root initiation and elongation and improved root xylem differentiation. Our study provided a comprehensive and systematic study of the genes of the GA metabolism and signaling and identified the role of GA20ox and GA2ox in regulating plant growth, stress tolerance, and xylem development in Eucalyptus; this could benefit molecular breeding for obtaining high-yield and stress-resistant Eucalyptus cultivars.

OsNF-YA3 regulates plant growth and osmotic stress tolerance by interacting with SLR1 and SAPK9 in rice.

The antagonism between gibberellin (GA) and abscisic acid (ABA) signaling pathways is vital to balance plant growth and stress response. Nevertheless, the mechanism by which plants determine the balance remains to be elucidated. Here, we report that rice NUCLEAR FACTOR-Y A3 (OsNF-YA3) modulates GA- and ABA-mediated balance between plant growth and osmotic stress tolerance. OsNF-YA3 loss-of-function mutants exhibit stunted growth, compromised GA biosynthetic gene expression, and decreased GA levels, while its overexpression lines have promoted growth and enhanced GA content. Chromatin immunoprecipitation-quantitative polymerase chain reaction analysis and transient transcriptional regulation assays demonstrate that OsNF-YA3 activates GA biosynthetic gene OsGA20ox1 expression. Furthermore, the DELLA protein SLENDER RICE1 (SLR1) physically interacts with OsNF-YA3 and thus inhibits its transcriptional activity. On the other side, OsNF-YA3 negatively regulates plant osmotic stress tolerance by repressing ABA response. OsNF-YA3 reduces ABA levels by transcriptionally regulating ABA catabolic genes OsABA8ox1 and OsABA8ox3 by binding to their promoters. Furthermore, OSMOTIC STRESS/ABA-ACTIVATED PROTEIN KINASE 9 (SAPK9), the positive component in ABA signaling, interacts with OsNF-YA3 and mediates OsNF-YA3 phosphorylation, resulting in its degradation in plants. Collectively, our findings establish OsNF-YA3 as an important transcription factor that positively modulates GA-regulated plant growth and negatively controls ABA-mediated water-deficit and salt tolerance. These findings shed light on the molecularmechanism underlying the balance between the growth and stress response of the plant.

SCL14 Inhibits the Functions of the NAC043–MYB61 Signaling Cascade to Reduce the Lignin Content in Autotetraploid Populus hopeiensis

Whole-genome duplication often results in a reduction in the lignin content in autopolyploid plants compared with their diploid counterparts. However, the regulatory mechanism underlying variation in the lignin content in autopolyploid plants remains unclear. Here, we characterize the molecular regulatory mechanism underlying variation in the lignin content after the doubling of homologous chromosomes in Populus hopeiensis. The results showed that the lignin content of autotetraploid stems was significantly lower than that of its isogenic diploid progenitor throughout development. Thirty-six differentially expressed genes involved in lignin biosynthesis were identified and characterized by RNA sequencing analysis. The expression of lignin monomer synthase genes, such as PAL, COMT, HCT, and POD, was significantly down-regulated in tetraploids compared with diploids. Moreover, 32 transcription factors, including MYB61, NAC043, and SCL14, were found to be involved in the regulatory network of lignin biosynthesis through weighted gene co-expression network analysis. We inferred that SCL14, a key repressor encoding the DELLA protein GAI in the gibberellin (GA) signaling pathway, might inhibit the NAC043-MYB61 signaling functions cascade in lignin biosynthesis, which results in a reduction in the lignin content. Our findings reveal a conserved mechanism in which GA regulates lignin synthesis after whole-genome duplication; these results have implications for manipulating lignin production.

Aged sweet corn (Zea mays L. saccharata Sturt) seeds trigger hormone and defense signaling during germination

Abstract: Seed ageing during storage or shipping can affect the yield and cost of agricultural production. Sweet corn is a naturally mutated corn cultivar with weak seed vitality during storage. In this study, we have shown that endogenous hormone level dynamics of fresh and aged sweet corn seeds were different during early geminating process. Transcriptomic assembling uncovered several novel transcripts during early stage of sweet corn germination in signal transduction and RNA processing pathways. Comparative transcriptomic profiling revealed that expression of many genes was activated earlier in aged seeds than fresh ones. Functional analyses showed that, as two major networks, plant hormone signaling and defense pathways were different between fresh and aged sweet corn seeds. Auxin, cytokinin, gibberellin, salicylic acid and jasmonic acid signaling pathways were activated earlier in aged seeds than fresh ones on the first day after imbibition. These results provided knowledge for understanding the ageing process of sweet corn seeds and several candidate genes for genetic study of seed ageing mechanism.

GA-Mediated Disruption of RGA/BZR1 Complex Requires HSP90 to Promote Hypocotyl Elongation

Circuitries of signaling pathways integrate distinct hormonal and environmental signals, and influence development in plants. While a crosstalk between brassinosteroid (BR) and gibberellin (GA) signaling pathways has recently been established, little is known about other components engaged in the integration of the two pathways. Here, we provide supporting evidence for the role of HSP90 (HEAT SHOCK PROTEIN 90) in regulating the interplay of the GA and BR signaling pathways to control hypocotyl elongation of etiolated seedlings in Arabidopsis. Both pharmacological and genetic depletion of HSP90 alter the expression of GA biosynthesis and catabolism genes. Major components of the GA pathway, like RGA (REPRESSOR of ga1-3) and GAI (GA-INSENSITIVE) DELLA proteins, have been identified as physically interacting with HSP90. Interestingly, GA-promoted DELLA degradation depends on the ATPase activity of HSP90, and inhibition of HSP90 function stabilizes the DELLA/BZR1 (BRASSINAZOLE-RESISTANT 1) complex, modifying the expression of downstream transcriptional targets. Our results collectively reveal that HSP90, through physical interactions with DELLA proteins and BZR1, modulates DELLA abundance and regulates the expression of BZR1-dependent transcriptional targets to promote plant growth.

Independently evolved viral effectors convergently suppress DELLA protein SLR1-mediated broad-spectrum antiviral immunity in rice

Plant viruses adopt diverse virulence strategies to inhibit host antiviral defense. However, general antiviral defense directly targeted by different types of plant viruses have rarely been studied. Here, we show that the single rice DELLA protein, SLENDER RICE 1 (SLR1), a master negative regulator in Gibberellin (GA) signaling pathway, is targeted by several different viral effectors for facilitating viral infection. Viral proteins encoded by different types of rice viruses all directly trigger the rapid degradation of SLR1 by promoting association with the GA receptor OsGID1. SLR1-mediated broad-spectrum resistance was subverted by these independently evolved viral proteins, which all interrupted the functional crosstalk between SLR1 and jasmonic acid (JA) signaling. This decline of JA antiviral further created the advantage of viral infection. Our study reveals a common viral counter-defense strategy in which different types of viruses convergently target SLR1-mediated broad-spectrum resistance to benefit viral infection in the monocotyledonous crop rice.

Interaction of MdWRKY24 and MdRGL in Response to Tree Dwarfing in Malus domestica

In apple cultivation, dwarf rootstocks are chosen for dense planting and intensive cultivation, which is beneficial to production management. Dwarf rootstocks are widely used in apple production in China. However, the dwarfing mechanisms of dwarf interstock are still unclear. Here, M9 and SH40 were selected as the dwarf interstocks for potted Fuji apples. The key transcription factor MdWRKY24 was screened via transcriptional sequencing. The open reading frame sequence of the MdWRKY24 gene was 657 bp in length, encoded 218 amino acids, and was located on the cell membrane. The MdWRKY24-overexpressing Arabidopsis line showed a dwarf phenotype and delayed flowering. The DELLA protein RGA-like (RGL) gene is a repressor of the gibberellin signaling pathway. Yeast two-hybrid analysis revealed that MdWRKY24 could interact with MdRGL1/2/3. The results indicated that MdWRKY24 might affect plant dwarfing through the synergistic effect of MdRGL1/2/3. The MdWRKY24-MdRGL may be an important pathway underlying the gibberellin-mediated regulation of apple dwarfing.

RNA-Seq and Gene Ontology Analysis Reveal Differences Associated With Low R/FR-Induced Shade Responses in Cultivated Lentil and a Wild Relative.

Lentil is an important pulse crop not only because of its high nutrient value but also because of its ecological advantage in a sustainable agricultural system. Our previous work showed that the cultivated lentil and wild lentil germplasm respond differently to light environments, especially to low R/FR-induced shade conditions. Little is known about how cultivated and wild lentils respond to shade at the level of gene expression and function. In this study, transcriptomic profiling of a cultivated lentil (Lupa, L. culinaris) and a wild lentil (BGE 016880, L. orientalis) at several growth stages is presented. De novo transcriptomes were assembled for both genotypes, and differential gene expression analysis and gene ontology enrichment analysis were performed. The transcriptomic resources generated in this study provide fundamental information regarding biological processes and genes associated with shade responses in lentils. BGE 016880 and Lupa shared a high similarity in their transcriptomes; however, differential gene expression profiles were not consistent between these two genotypes. The wild lentil BGE 016880 had more differentially expressed genes than the cultivated lentil Lupa. Upregulation of genes involved in gibberellin, brassinosteroid, and auxin synthesis and signaling pathways, as well as cell wall modification, in both genotypes explains their similarity in stem elongation response under the shade. Genes involved in jasmonic acid and flavonoid biosynthesis pathways were downregulated in BGE 016880 only, and biological processes involved in defense responses were significantly enriched in the wild lentil BGE 016880 only. Downregulation of WRKY and MYB transcription factors could contribute to the reduced defense response in BGE 016880 but not in Lupa under shade conditions. A better understanding of shade responses of pulse crop species and their wild relatives will play an important role in developing genetic strategies for crop improvement in response to changes in light environments.