Karrikin (KAR) signaling plays crucial roles in plant development, regulating key traits such as photomorphogenesis, root hair development, and arbuscular mycorrhizal symbiosis. SUPPRESSOR OF MAX2 1 (SMAX1), a key negative regulator of the KAR pathway, has been functionally studied in several plant species. However, the SMAX1 protein remains poorly understood in Medicago truncatula, an important model legume, which limits the comprehensive understanding and application of the KAR pathway in legumes. In this study, we identified the single SMAX1 ortholog MtSMAX1 in M. truncatula. Sequence alignment and structural modeling analyses revealed that MtSMAX1 is highly conserved with SMAX1 homologs from other plant species. Yeast two-hybrid assays demonstrated that MtSMAX1 interacts with two KAR signaling receptors KARRIKIN INSENSITIVE 2 (MtKAI2a/b). In addition, both MtKAI2a/b interact with the F-box protein MORE AXILLARY GROWTH 2 (MtMAX2), suggesting a conserved KAR signaling pathway in M. truncatula. To further investigate the biological functions of MtSMAX1, we generated two distinct CRISPR-edited mutant lines. The loss-of-function mutant Mtsmax1, which carries a premature termination mutation, displays defective phenotypes including reduced seed size, dwarfism, and delayed flowering. In contrast, the Mtsmax1ΔQ210 mutant, harboring a single glutamine deletion at position 210, exhibits specific defects only in seed development. These phenotypic differences indicate a previously unreported role of MtSMAX1 in regulating legume seed development, with the conserved Q210 residue potentially involved in this process. Furthermore, MtSMAX1 overexpression lines exhibit phenotypes opposite to those of the mutants, further validating the biological functions of MtSMAX1. Gene expression analysis of key developmental marker genes revealed altered expression levels in MtSMAX1 mutants, which are tightly consistent with the corresponding phenotypic variations. These results suggest that MtSMAX1 likely functions as an important transcriptional regulator to modulate the expression of downstream developmental genes. Collectively, our findings establish MtSMAX1 as a pivotal regulator of multiple developmental processes in legumes and provide a foundation for elucidating the broader biological functions and regulatory mechanisms of the KAR signaling pathway.

Strigolactones (SLs) and karrikins (KARs) are structurally related signaling molecules that regulate different aspects of plant development. In Arabidopsis, both SL and KAR signaling require the F box protein MAX2 but are perceived by different receptors, AtD14 and KAI2, respectively. These signals target distinct SMAX1-LIKE (SMXL) repressors, the SMXL7 and SMAX1 clade, respectively, for degradation. However, the mechanism underlying selective SMXL degradation remains elusive. Here, we propose that selective SMXL degradation arises from RGKT motif-dependent ternary protein complexes involving MAX2 and the respective receptors. Domain-swapping analysis between SMAX1 and SMXL7 indicates that the D1M (D1+M) and D2 domains contribute to hormone responsiveness in Arabidopsis through targeted degradation. Biochemical and structural analyses highlight the D2 domain and its RGKT motif as central to ternary complex formation. Our findings provide insights into how a single E3 ubiquitin ligase recruits distinct substrate proteins via different signaling receptors to achieve specific signal transduction.

Although both abscisic acid (ABA) and methyl jasmonate (MeJA) play significant roles in regulating the development and quality of grape (Vitis vinifera L.) berries, the regulatory effects and mechanisms of the combined application of ABA and MeJA remain unclear. To further explore the optimal combination of these hormones for regulating the development of grape quality, combined ABA and MeJA treatments were carried out in this study, with 'Jumeigui' grape used as the material. The results indicated that the combined treatment of high-ABA and low-MeJA (HA+LM) increased the sugar-acid ratio, promoted the accumulation of phenolic substances in grape skins, and resulted in anthocyanin content 168.9% higher than that of the control, significantly enhancing coloration. Additionally, the combined treatment of low-ABA and low-MeJA (LA+LM) was more conducive to the accumulation of phenols in grape, especially phenolic acid and resveratrol, as the total phenolic content increased by 38.96% relative to that of the control. Moreover, the expressions of aroma-related genes were upregulated by the combined high-MeJA treatments. The combined treatment of high-ABA and high-MeJA (HA+HM) markedly increased terpene biosynthesis, followed by the LA+HM treatment, increasing the intensity of the rose flavor characteristics of the 'Jumeigui' grape. Therefore, the combination of MeJA and ABA at different concentrations had distinct effects on fruit quality and appropriate combinations can be selected according to the specific needs for the targeted metabolites.

The majority of terrestrial plants can interact with arbuscular mycorrhizal fungi (AMF) to form symbiotic relationships. AMF colonization not only enhances the host plant’s uptake of mineral nutrients but also improves its tolerance to biotic and abiotic stresses. In return, the host plant supplies the AMF with carbon sources essential for completing its life cycle. How AMF overcome the plant immune system to successfully establish symbiosis has remained an unresolved question. During colonization, AMF also secrete effector proteins, similar to how pathogenic fungi utilize effectors to promote virulence. In this study, we employed machine learning models such as SignalP 6.0 and EffectorP 3.0 to predict potential effectors in Rhizophagus irregularis, leading to the identification of 227 effector candidates. Using EffectorP 3.0, ApoplastP, and LOCALIZER, most R. irregularis effectors were predicted to be localized in the cytoplasm rather than the apoplast, suggesting a functional role in regulating symbiotic development. Only 26% of the predicted effectors were annotated by Pfam, indicating that the majority are proteins of unknown function. Effector proteins from 14 microbial species representing five ecological types (Ectomycorrhizae, Ericoid mycorrhizae, Endophyte, Arbuscular mycorrhizae, and Pathogen) clustered distinctly by species, highlighting the high degree of species specificity among effectors. Two R. irregularis effectors containing the RxLR motif were identified. Although these effectors localized to the cytoplasm, they did not exhibit virulence factor activity. Additionally, we characterized a functionally conserved chitin deacetylase effector, RiPDA1, which localized to the apoplastic space. The Y2H assay indicated that RiPDA1 forms homodimers. The in vitro chitin-binding assay showed that RiPDA1 has an affinity for chitin. RiPDA1 may function as a secretory polysaccharide deacetylase that facilitates symbiosis by deacetylating chitin oligomers. In summary, this study systematically identified and characterized effector proteins in R. irregularis. Similar to pathogenic fungi, AMF appear to employ cell wall-modifying enzymes to overcome plant immune defenses.

Glyphosate is the most widely used herbicide globally, especially due to the extensive cultivation of genetically modified glyphosate-resistant crops. However, its intensive application has raised public concerns about the risks to food safety and human health. Identifying enzymes capable of metabolizing glyphosate in plants represents an ideal strategy for addressing this issue, but few are known. Here, we identified the rice variety Kitaake with natural tolerance to glyphosate and demonstrated that this tolerance is driven by glyphosate glycosylation metabolism. Seven up-regulated UDP-dependent glycosyltransferase (UGT) genes associated with glyphosate tolerance were identified in Kitaake. Molecular-docking analysis indicated that these UGT proteins have moderate binding affinity for glyphosate. Among these, a deletion of an adenine at position-803 in the promoter region of GLYPHOSATE RESPONSIVE GLYCOSYLTRANSFERASE 1 (GRGT1) enhances its expression in Kitaake. GRGT1 localizes to the endoplasmic reticulum and catalyzes glyphosate glycosylation both in vivo and in vitro. Rice lines complemented with GRGT1-GFP rescue the inability of grgt1 knockout mutants to produce glycosylated glyphosate derivatives. Overexpression of GRGT1 in the susceptible Nipponbare cultivar confers glyphosate tolerance by up-regulating glyphosate metabolism to produce glycosylated glyphosate derivatives M329, M331, and M345. This provides a strategy for developing herbicide-tolerant crops, but also offers a potential approach to consequently reduce glyphosate residues in crops.

Warm climate in Ningxia wine region commonly triggers excessive sugar accumulation, low organic acid and inadequate secondary metabolite synthesis in Marselan grapes, deteriorating grape and wine quality. This twoyear field trial was carried out to explore whether combined canopy height management and ethephon spraying could balance berry sugar-acid composition and promote phenolic accumulation. Three canopy heights (0.9, 1.2, 1.5 m) and two ethephon concentrations (300, 600 mg/L) were set with single and combined treatments. Results indicate that all three canopy height treatments reduced sugar content and increased acid content in grape fruit. Fruit treated with ethylene exhibited higher total phenolic content. Compared with control, independent 1.2 m canopy cut soluble sugar by 10%-11% and elevated titratable acid by 13%-14%. Single 300 mg/L ethephon increased berry total phenolics by 10%-23% and total anthocyanins by 10%-17%. The combination of 1.2 m canopy plus 300 mg/L ethephon reduced fruit sugar-acid ratio by around 14%, and increased total phenolics, tannins and flavanols by 11%-46%; meanwhile, contents of multiple monomeric anthocyanins and phenolic compounds in finished wine were significantly improved. In conclusion, 1.2 m canopy matched with 300 mg/L ethephon is an effective cultivation strategy to fix high-sugar low-acid problems and enhance phenolic richness for warm-climate Marselan production.

Strigolactones (SLs) are plant-specialized butenolide signaling molecules, recognized as endogenous plant hormones, that control plant development and environmental adaptation. In Arabidopsis (Arabidopsis thaliana), the repressor D53-like SMXLs regulate the expression of a vast number of genes in an EAR-motif-dependent manner to mediate SL signaling. However, it remains unclear how the SMXLs are recruited to specific genes and implement unique functions in vivo. Based on chromatin co-distribution analysis, we constructed a chromatin co-localization map of SMXL6 with 108 transcription factors. Among the candidate transcription factors, the Class II TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) family member TCP4 shows the highest frequency of chromatin co-localization with SMXL6. SMXL6 and TCP4 co‑localize at the promoter regions of 18 SL-induced SMXL6 target genes (SISGs), including BRC1. We confirmed that TCP4 interacts with SMXL6 and can bind directly to these co‑localized sites. The loss of CIN-TCPs function reduces the hormone responsiveness of the SL-induced genes. Introducing the tcp3/4/10 into SL‑deficient mutants restored the BRC1 expression to a level exceeding that of the wild type. However, the branching phenotype of the SL‑deficient mutant was only partially rescued, suggesting a limited role for BRC1 in SL‑mediated branching control and implicating the involvement of additional factors. An unexpected finding was that tcp3/4/10 rescued the dwarf phenotype of the SL‑deficient mutants, providing an opportunity to elucidate the mechanisms underlying SL‑regulated plant height. These findings demonstrate that TCP4 mediates SMXL6 chromatin recruitment during SL signaling, and provide a new understanding of how SMXL6 participates in SL signaling-mediated gene expression and plant development.

The overexpression of key biosynthetic genes involved in triptolide production through a metabolic engineering strategy significantly enhanced triptolide accumulation in Tripterygium wilfordii hairy roots. Triptolide, the representative bioactive compound in Tripterygium wilfordii, is renowned for its potent insecticidal and pharmacological properties. In order to increase the production of triptolide, this study overexpressed several key enzyme genes related to its biosynthesis in T. wilfordii hairy roots. Specifically, the content of triptolide in hairy roots overexpressing TwTPS9 and TwTPS27 individually was found to be 1.60-fold and 1.42-fold that of the control, respectively. Co-expression of both TwTPS9 and TwTPS27 resulted in significant increase in triptolide levels, reaching approximately 2.72 times that of the control. Furthermore, overexpressing TwGGPPS and TwDXS on the basis of the double gene overexpression led to the highest triptolide production, with a yield of 12.83 mg/L, increasing to 3.18-fold compared to the control. This study offers valuable examples into the efficient biosynthesis of triptolide and is expected to lay a foundation for future industrial-scale production by mitigating its resource constraints through metabolic engineering.

Recent advances indicate that epigenetic regulators critically govern hormone signaling networks, such as abscisic acid, ethylene, jasmonate, gibberellin, and cytokinin pathways in plants. Nevertheless, whether strigolactone (SL) modulates chromatin dynamics and genome architecture through epigenetic mechanisms remains largely unexplored. Here, we demonstrate that SUPPRESSOR OF MAX2-LIKE7 (SMXL7), a repressor of SL signaling, restructures chromocenter organization through H3 trimethylation at K27 (H3K27me3)-mediated epigenetic regulation. Moreover, SMXL7 associates with histone H3K27me3-related heterochromatin and controls genome-wide H3K27me3 levels through incorporating the histone demethylases JUMNOJI 30 (JMJ30) into the SMXL7 condensates, modulating chromatin accessibility and genome architecture. Our findings provide evidence that SMXL7 influences higher order chromatin organization in planta and suggest a novel mode of SL signal transduction.

Perennial ryegrass is a widely cultivated cool-season forage and turf grass species whose growth and development are limited by drought and high temperature. MAX2 is an F-box leucine-rich repeat (LRR) protein, which serves as a central component of strigolactone (SL) and karrikin (KAR) signaling pathways, involved in multiple growth and developmental processes as well as stress response. Here, we identified LpMAX2, a perennial ryegrass (Lolium perenne L.) homolog of Arabidopsis MAX2 (AtMAX2) and rice D3. LpMAX2 can interact with AtD14 and LpD14 in an SL-dependent manner, implying functional conservation with AtMAX2. Overexpression of LpMAX2 in the Arabidopsis max2-3 mutant partially rescued leaf morphology, hypocotyl elongation, and branching phenotypes, while fully restoring drought tolerance, highlighting the evolutionarily conserved roles of MAX2 in plant growth and drought resistance. In conclusion, LpMAX2 is evolutionarily conserved in SL/KAR signaling pathways, highlighting its potential function in drought adaptation. In addition to elucidating the biological function of LpMAX2, this study identifies a promising genetic target for enhancing stress resilience in forage grasses through biotechnological approaches.

Recent advancements in our understanding of gene expression highlight the role of phase-separated condensates in modulating transcriptional regulation. While the mechanisms of transcriptional condensate formation and function have been well characterized in animal systems, plant studies are still in the early stages. Here, we show that SUPPRESSOR OF MORE AXILLARY GROWTH 2-LIKE 7 (SMXL7), a repressor of plant hormone strigolactone (SL) signaling, forms phase-separated nuclear condensates. As expected, SMXL7 enriches its interacting proteins, SL receptor DWARF14 (D14) and F box protein MORE AXILLARY GROWTH 2 (MAX2), within the condensates. Intrinsically disordered regions in SMXL7 are essential for condensate formation and transcription repression. Significantly, SMXL7 nuclear condensates act as active transcriptional repressors by sequestering transcription factors, such as DNAJ DOMAIN-CONTAINING PROTEIN 1 (DNAJ1), away from gene loci, thereby regulating plant development. Our findings provide evidence that SMXL7-formed condensates sequester certain cellular components to repress transcription in planta and suggest a novel mode of SL signal transduction.

Winter dormancy and bud break are crucial to the viability, adaptability and yield of fruit trees, but not all metabolic activities or regulatory factors involved in maintaining and breaking dormancy are known. Here, winter buds, spanning from natural dormancy to bud break, were collected from 'Cabernet Sauvignon' grapevines maintained outdoors or forced indoors. The transcriptomes, proteomes and plant hormone contents were analysed across several bud stages. The winter buds presented three main stages, dormancy, dormancy release and bud development, whether grown in or outdoors. Weighted Correlation Network Analysis (WGCNA) and Gene Ontology (GO) analysis of the omics data revealed that the different stages were enriched for different biological processes. Analysis of the differentially expressed genes (DEGs) identified seven candidate genes that may affect grape dormancy and bud break. Transient transformation of these seven genes showed that VvDOGL4, VvAGL65 and VvMARD could promote maintenance of winter bud dormancy in grapevine. Subcellular localization showed that these three proteins all located to the nucleus, and yeast two-hybrid screening showed that they may interact with proteins related to plant hormone signal transduction, respiration, energy metabolism and transcription regulation to affect winter bud break in grapevine. Overall, these findings contribute to a better understanding of the regulatory dynamics of bud dormancy in a perennial fruit crop and lay a foundation for exploring key genes and regulatory mechanisms that can be manipulated to improve fruit quality and yields as the global climate shifts growing regions.

High temperature reduces anthocyanin accumulation in various horticultural plants. However, the molecular mechanisms underlying the high-temperature-induced reduction of anthocyanin in grape (Vitis vinifera) remain poorly understood. In this study, VvMYB44-1 was identified as a transcriptional repressor of anthocyanin biosynthesis in grape berries, and its gene expression was strongly induced by high-temperature treatment. Overexpression of VvMYB44-1 inhibited anthocyanin accumulation in both grape berries and tobacco (Nicotiana tabacum) by repressing the transcription of the anthocyanin biosynthesis genes dihydroflavonol-4-reductase (VvDFR) and UDP-glucose flavonoid-3-O-glucosyltransferase (VvUFGT). Furthermore, the interaction between VvMYB44-1 and VvWDR2 competitively inhibited the formation of the MYB-bHLH-WD40 (MBW) activation complex and weakened the transcriptional activity of the complex, thereby decreasing anthocyanin accumulation. Additionally, VvMYB44-1 facilitated cytokinin (CK) accumulation by upregulating the expression of the CK synthesis gene lonely guy 8 (VvLOG8) and inhibiting the CK degradation gene CK oxidase 4(VvCKX4), thus contributing to CK-mediated anthocyanin inhibition in grape berries. Moreover, the inhibitory effect of VvMYB44-1 on anthocyanin biosynthesis and its downstream target genes was weakened with the deletion of the ethylene-responsive element binding factor-associated amphiphilic repression (EAR) motif, indicating that the EAR motif is indispensable for the inhibitory effect of VvMYB44-1 on anthocyanin biosynthesis in grapes. These results provide insights into the regulatory network of VvMYB44-1 in high-temperature-mediated anthocyanin biosynthesis in grapes. Transcription factor VvMYB44-1 negatively regulates high-temperature-mediated anthocyanin biosynthesis in grapevine.

Composting is not only a green and sustainable way to treat and reuse agricultural waste but also an effective method for passivating heavy metals. However, there is no research on the co-composting of the by-products of Camellia oleifera and sediment to simultaneously achieve the remediation of heavy metal and resource utilization of Camellia oleifera by-products. Moreover, MnO2 and biochar have been widely used to promote humification in the composting process. However, few studies have investigated the efficiency of MnO2-loaded biochar in promoting the passivation of heavy metals in the co-composting system of Camellia oleifera by-products and sediment, and its effects on composting biological characteristics are often ignored. Therefore, this study investigated the changes in the heavy metal bioavailability and the microbial communities in sediment and Camellia oleifera by-products co-composting with the additives of MnO2-loaded biochar. The results showed that the MnO2-loaded biochar effectively passivated heavy metals and improved microbial diversity and structure, which increased the Copper and Lead residual fractions (RES-Cu and RES-Pb) by 14.01 % and 17.57 %, respectively, while the Cadmium exchangeable fraction (EXC-Cd) and the Zinc bioavailability fraction (BF-Zn) decreased by 24.72 % and 10.99 %, respectively. pH, temperature, and bacterial community were the critical regulators for heavy metals passivation by MnO2-loaded biochar. This study not only provides a promising resource utilization approach for Camellia oleifera by-products but also provides a new perspective and theoretical reference for the remediation of heavy metals contaminated sediment by composting.

Multiple plant hormones, including strigolactone (SL), play key roles in regulating flowering time. The Arabidopsis (Arabidopsis thaliana) DWARF14 (AtD14) receptor perceives SL and recruits F-box protein MORE AXILLARY GROWTH2 (MAX2) and the SUPPRESSOR OF MAX2-LIKE (SMXL) family proteins. These interactions lead to the degradation of the SMXL repressor proteins, thereby regulating shoot branching, leaf shape, and other developmental processes. However, the molecular mechanism by which SL regulates plant flowering remains elusive. Here, we demonstrate that intact strigolactone biosynthesis and signaling pathways are essential for normal flowering in Arabidopsis. Loss-of-function mutants in both SL biosynthesis (max3) and signaling (Atd14 and max2) pathways display earlier flowering, whereas the repressor triple mutant smxl6/7/8 (s678) exhibits the opposite phenotype. Retention of AtD14 in the cytoplasm leads to its inability to repress flowering. Moreover, we show that nuclear-localized AtD14 employs dual strategies to enhance the function of the AP2 transcription factor TARGET OF EAT1 (TOE1). AtD14 directly binds to TOE1 in an SL-dependent manner and stabilizes it. In addition, AtD14-mediated degradation of SMXL7 releases TOE1 from the repressor protein, allowing it to bind to and inhibit the FLOWERING LOCUS T (FT) promoter. This results in reduced FT transcription and delayed flowering. In summary, AtD14 perception of SL enables the transcription factor TOE1 to repress flowering, providing insights into hormonal control of plant flowering.

Plants rely on strigolactones (SLs) to regulate their development and form symbiotic relationships with microbes as part of the adaptive phosphorus (P) efficiency strategies. However, the impact of SLs on root-associated microbial communities in response to P availability remains unknown. Here, root microbiota of SL biosynthesis (max3-11) and perception (d14-1) were compared to wild-type Col-0 plants under different P concentrations. Using high-throughput sequencing, the relationship between SLs, P concentrations, and the root-associated microbiota was investigated to reveal the variation in microbial diversity, composition, and interaction. Plant genotypes and P availability played important but different roles in shaping the root-associated microbial community. Importantly, SLs were found to attract Acinetobacter in low P conditions, which included an isolated CP-2 (Acinetobacter soli) that could promote plant growth in cocultivation experiments. Moreover, SLs could change the topologic structure within co-occurrence networks and increase the number of keystone taxa (e.g., Rhizobiaceae and Acidobacteriaceae) to enhance microbial community stability. This study reveals the key role of SLs in mediating root-associated microbiota interactions.IMPORTANCEStrigolactones (SLs) play a crucial role in plant development and their symbiotic relationships with microbes, particularly in adapting to phosphorus levels. Using high-throughput sequencing, we compared the root microbiota of plants with SL biosynthesis and perception mutants to wild-type plants under different phosphorus concentrations. These results found that SLs can attract beneficial microbes in low phosphorus conditions to enhance plant growth. Additionally, SLs affect microbial network structures, increasing the stability of microbial communities. This study highlights the key role of SLs in shaping root-associated microbial interactions, especially in response to phosphorus availability.

MADS-box protein SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) were certified as key regulators of flowering and other developmental traits that are important for agricultural production in various plant species. Legumes are one of the most important industrial crops, commonly used for food, feed, and fuel production. Therefore, to fill the gap of the functions for SOC1 homologs in legume (Medicago truncatula) were of great values in increasing productions. Here, a SOC1-like gene in M. truncatula, MtSOC1c, was functionally characterized. In MtSOC1c-overexpressing plants, it had a considerably earlier flowering time and reduced biomass. Additionally, the ectopic expression of MtSOC1c had an obvious effect on seed development, resulting in smaller pods, lesser thorns, smaller embryo cells and seeds, darker color, and delayed germination. Further, RNA-seq analysis identified 416 differentially expressed genes (DEGs), including 230 upregulated and 186 downregulated DEGs. Enrichment analysis showed that 23 DEGs were enriched in the photosynthesis process. Among the 11 DEGs enriched in “plant hormone signaling transduction”, eight DEGs were involved in abscisic acid signaling pathway, including HVA22 and ATHB. Moreover, MtSOC1c could physically interact with other three MADS-box factors, MtAGL15 and MtAGL16a/b, whose Arabidopsis homologs also participate in seed development regulation. Concludingly, our findings certificated MtSOC1 also had crucial roles mainly in flowering and seed development by affecting ABA transduction, probably mediated by interacting with other functional MADS factors in M. truncatula. These findings provide insights into SOC1 function and its underlying mechanism in M. truncatula.

Jasmonates (JAs) are the most effective inducers for the biosynthesis of various secondary metabolites. Currently, jasmonate ZIM domain (JAZ) and its interactors, such as MYC2, constitute the main JA signal transduction cascade, and such a cascade fails to directly regulate all the taxol biosynthesis genes, especially the rate-limit gene, DBAT. Another JA signaling branch, JAV and WRKY, would probably fill the gap. Here, TcJAV3 was the closest VQ-motif-containing protein in Taxus chinensis to AtJAV1. Although TcJAV3 was overexpressed in AtJAV1 knockdown mutant, JAVRi17, the enhanced disease resistance to Botrytis cinerea caused by silencing AtJAV1 was completely recovered. The results indicated that TcJAV3 indeed transduced JA signal as AtJAV1. Subsequently, TcWRKY26 was screened out to physically interact with TcJAV3 by using a yeast two-hybrid system. Furthermore, bimolecular fluorescence complementation and luciferase complementary imaging also confirmed that TcJAV3 and TcWRKY26 could form a protein complex in vivo. Our previous reports showed that transient TcWRKY26 overexpression could remarkably increase DBAT expression. Yeast one-hybrid and luciferase activity assays revealed that TcWRKY26 could directly bind with the wa-box of the DBAT promoter to activate downstream reporter genes. All of these results indicated that TcWRKY26 acts as a direct regulator of DBAT, and the TcJAV3–TcWRKY26 complex is actually another JA signal transduction mode that effectively regulates taxol biosynthesis in Taxus. Our results revealed that JAV–WRKY complexes directly regulated DBAT gene in response to JA stimuli, providing a novel model for JA-regulated secondary metabolism. Moreover, JAV could also transduce JA signal and function non-redundantly with JAZ during the regulation of secondary metabolisms.

In grapevines, the frequent germination of prompt buds always leads to tedious task during summer management in vineyards. Strigolactones have been discovered to play an essential role in regulating shoot branching in different plant species. We investigated the effect of strigolactones (SLs) on grapevine prompt bud outgrowth. Two-year-old grape cuttings (Vitis vinifera L.) with non-burst prompt buds were used as material and subjected to decapitation (control group), or decapitation with subsequent GR24 (Germination releaser 24) treatment (GR), an analog of exogenous SLs. Results showed that grapevine bud growth was significantly induced at nodes 1 and 2, but was largely inhibited by GR24 after decapitation. Transcriptome results revealed the involvement of numerous genes associated with hormone synthesis and signal transduction. GR24 treatment could modulate IAA content and inhibit NCED decrease caused by decapitation, which is the key gene involved in ABA biosynthesis, possibly via BRC1-mediated pathway. Key genes participating in BR biosynthesis were largely modulated. The regulation of different hormones (CTK and BR) on cell cycle genes may be another important mechanism of GR24 regulation on grapevine bud outgrowth. Our results could provide new avenues for research and reveal hormone (IAA, ABA, CTK, and BR) signaling response to SLs in managing shoot branching in grapevines.