Preharvest methyl jasmonate application delays cell wall degradation and upregulates phenolic metabolism and antioxidant activities in cold stored raspberries.

The effects of preharvest methyl jasmonate (MeJA) spray application on the physicochemical quality, metabolism of phenolics, and cell wall components in raspberries were investigated during a 10-day cold storage period. MeJA spray reduced firmness loss, decay incidence, and weight loss, while maintained higher levels of soluble solids content, ascorbic acid, anthocyanins and flavonoids in raspberries. Furthermore, MeJA application resulted in increased total pectin and protopectin levels, as well as lowered water-soluble pectin, and activities of pectin methyl esterase, polygalacturonase and cellulase enzymes. Additionally, MeJA treatment upregulated the phenylpropanoid pathway, leading to higher endogenous phenolics and activities of phenylalanine-ammonia lyase and shikimate dehydrogenase. In conclusion, preharvest MeJA spray application could be adopted to enhance the storage potential of cold-stored raspberries for 10 days by maintaining higher firmness, assuring better physicochemical quality, and increasing phenolic metabolism, while reducing cell wall hydrolysis.

In vivo assembly in tobacco cells to elucidate and engineer the biosynthesis of 4-hydroxydihydrocinnamaldehyde from Gloriosa superba.

KEY MESSAGE: This study described the biosynthesis of 4-hydroxydihydrocinnamaldehyde sharing with monolignol pathway and supplemented the biosynthesis of colchicine in G. superba, 4-hydroxydihydrocinnamaldehyde produced in tobacco BY2 cells provided an important stepstone. The precursor, 4-hydroxydihydrocinnamaldehyde (4-HDCA), participates in the biosynthesis of the carbon skeleton of colchicine, which is derived from L-phenylalanine. However, one hypothesis proposed that 4-HDCA is synthesized by sharing the early part of the monolignol pathway in G. superba. In this study, we validated this prediction and identified the enzymatic functions involved in this pathway. GsDBR1 is a crucial enzyme to illustrate 4-HDCA diverging from monolignol pathway, we first confirmed its reductase activity on 4-coumaraldehyde, an important intermediate compound in monolignol biosynthesis. Then, the biochemical function of recombinant enzymes belonging to the other four families were verified to elucidate the entire process of 4-HDCA biosynthesis from L-phenylalanine. After reconstruction, the 4-HDCA was 78.4 ng/g with fresh weight (FW) of transgenic tobacco cells, and the yield increased to 168.22 ng/g·FW after improved treatment with methyl jasmonate (MeJA). The elucidation of 4-HDCA biosynthesis sharing the monolignol pathway supplemented the biosynthesis of colchicine in G. superba, and the production of 4-HDCA in tobacco cells provides an important step in the development of plant cell cultures as heterologous bio-factories for secondary metabolite production.

Investigation of genes involved in scent and color production in Rosa damascena Mill.

Rosa damascena Mill., commonly known as the King Flower, is a fragrant and important species of the Rosaceae family. It is widely used in the perfumery and pharmaceutical industries. The scent and color of the flowers are significant characteristics of this ornamental plant. This study aimed to investigate the relative expression of MYB1, CCD1, FLS, PAL, CER1, GT1, ANS and PAR genes under two growth stages (S1 and S2) in two morphs. The CCD1 gene pathway is highly correlated with the biosynthesis of volatile compounds. The results showed that the overexpression of MYB1, one of the important transcription factors in the production of fragrance and color, in the Hot pink morph of sample S2 increased the expression of PAR, PAL, FLS, RhGT1, CCD1, ANS, CER1, and GGPPS. The methyl jasmonate (MeJA) stimulant had a positive and cumulative effect on gene expression in most genes, such as FLS in ACC.26 of the S2 sample, RhGT1, MYB1, CCD1, PAR, ANS, CER1, and PAL in ACC.1. To further study, a comprehensive analysis was performed to evaluate the relationship between the principal volatile compounds and colors. Our data suggest that the rose with pink flowers had a higher accumulation content of flavonoids and anthocyanin. To separate essential oil compounds, GC/MS analysis identified 26 compounds in four samples. The highest amount of geraniol, one of the main components of damask rose, was found in the Hot pink flower, 23.54%, under the influence of the MeJA hormone.

Integrative metabolome and transcriptome analysis characterized methyl jasmonate-elicited flavonoid metabolites of Blumea balsamifera.

As a commonly used medicinal plant, the flavonoid metabolites of Blumea balsamifera and their association with genes are still elusive. In this study, the total flavonoid content (TFC), flavonoid metabolites and biosynthetic gene expression patterns of B. balsamifera after application of exogenous methyl jasmonate (MeJA) were scrutinized. The different concentrations of exogenous MeJA increased the TFC of B. balsamifera leaves after 48 h of exposure, and there was a positive correlation between TFC and the elicitor concentration. A total of 48 flavonoid metabolites, falling into 10 structural classes, were identified, among which flavones and flavanones were predominant. After screening candidate genes by transcriptome mining, the comprehensive analysis of gene expression level and TFC suggested that FLS and MYB may be key genes that regulate the TFC in B. balsamifera leaves under exogenous MeJA treatment. This study lays a foundation for elucidating flavonoids of B. balsamifera, and navigates the breeding of flavonoid-rich B. balsamifera varieties.

Dual-Mediated Roles of H+-ATPase in Alleviating the Phytotoxicity of Imazethapyr to Nontarget Wheat.

The regulation solutions and mechanisms of reducing pesticide phytotoxicity to nontarget plants are not well-defined and detailed. Here, we have proposed a new detoxification strategy to control the toxic effects of herbicide imazethapyr (IM) induced in wheat seedlings from the perspective of the plasma membrane (PM) H+-ATPase. We found that the changes in PM H+-ATPase activity have a regulatory effect on the phytotoxic effects induced by IM in plants. Treatment with PM H+-ATPase activators restored the reduced auxin content and photosynthetic efficiency caused by IM, thereby promoting plant growth. Application of a PM H+-ATPase inhibitor further reduced phosphorus content and significantly increased 2,4-dihydroxy-7-methoxy-2H,1,4-benzoxazin-3(4H)one (DIMBOA) and jasmonic acid levels. These effects indicate that auxin and DIMBOA may regulate plant growth trends and detoxification effects mediated by PM H+-ATPase. This work opens a new strategy for regulating herbicide toxicity to nontarget plants from the PM H+-ATPase.

Characterization of the ZCTs, a subgroup of Cys2-His2 zinc finger transcription factors regulating alkaloid biosynthesis in Catharanthus roseus.

KEY MESSAGE: The C. roseus ZCTs are jasmonate-responsive, can be induced by CrMYC2a, and can act as significant regulators of the terpenoid indole alkaloid pathway when highly expressed. Catharanthus roseus is the sole known producer of the anti-cancer terpenoid indole alkaloids (TIAs), vinblastine and vincristine. While the enzymatic steps of the pathway have been elucidated, an understanding of its regulation is still emerging. The present study characterizes an important subgroup of Cys2-His2 zinc finger transcription factors known as Zinc finger Catharanthus Transcription factors (ZCTs). We identified three new ZCT members (named ZCT4, ZCT5, and ZCT6) that clustered with the putative repressors of the TIA pathway, ZCT1, ZCT2, and ZCT3. We characterized the role of these six ZCTs as potential redundant regulators of the TIA pathway, and their tissue-specific and jasmonate-responsive expression. These ZCTs share high sequence conservation in their two Cys2-His2 zinc finger domains but differ in the spacer length and sequence between these zinc fingers. The transient overexpression of ZCTs in seedlings significantly repressed the promoters of the terpenoid (pLAMT) and condensation branch (pSTR1) of the TIA pathway, consistent with that previously reported for ZCT1, ZCT2, and ZCT3. In addition, ZCTs significantly repressed and indirectly activated several promoters of the vindoline pathway (not previously studied). The ZCTs differed in their tissue-specific expression but similarly increased with jasmonate in a dosage-dependent manner (except for ZCT5). We showed significant activation of the pZCT1 and pZCT3 promoters by the de-repressed CrMYC2a, suggesting that the jasmonate-responsive expression of the ZCTs can be mediated by CrMYC2a. In summary, the C. roseus ZCTs are jasmonate-responsive, can be induced by CrMYC2a, and can act as significant regulators of the TIA pathway when highly expressed.

BnVP1, a novel vacuolar H+ pyrophosphatase gene from Boehmeria nivea confers cadmium tolerance in transgenic Arabidopsis.

Plants have developed precise defense mechanisms against cadmium (Cd) stress, with vacuolar compartmentalization of Cd2+ being a crucial process in Cd detoxification. The transport of Cd into vacuoles by these cation / H+ antiporters is powered by the pH gradient created by proton pumps. In this study, the full-length cDNA of a vacuolar H+-pyrophosphatase (V-PPase) gene from Boehmeria nivea (ramie), BnVP1, was isolated using the rapid amplification of cDNA ends (RACE) method. The open reading frame (ORF) of BnVP1 is 2292 bp, encoding a 763 amino acid V-PPase protein with 15 predicted transmembrane domains. Sequence alignment and phylogenetic analysis revealed that BnVP1 belongs to the Type I V-PPase family. Quantitative RT-PCR assays demonstrated that BnVP1 expression was significantly higher in ramie roots than in shoots. Cd treatments markedly induced BnVP1 expression in both roots and leaves of ramie seedlings, with a more pronounced effect in roots. Additionally, BnVP1 expression was significantly upregulated by the plant hormone methyl jasmonate (MeJA). Heterologous expression of BnVP1 in transgenic Arabidopsis significantly enhanced V-PPase activity in the roots. The growth performance, root elongation, and total chlorophyll content of transgenic plants with high tonoplast H+-PPase (V-PPase) activity were superior to those of wild-type plants. Overexpression of BnVP1 reduced membrane lipid peroxidation and ion leakage, and significantly increased Cd accumulation in the roots of transgenic Arabidopsis seedlings. This study provides new genetic resources for the phytoremediation of Cd-contaminated farmland.

Effect of phytohormone on proliferation and accumulation of cellular metabolites of microalgae Isochrysis zhanjiangensis.

Phytohormones play a role in regulating microalgae cells tolerance to adversity. This paper examines the effects of different temperatures (20 °C, 25 °C, 30 °C and 35 °C) on the physiological characteristics and endogenous phytohormones of the Isochrysis Zhanjiangensis (IZ) and its mutagenic strain (3005). The results showed that the endogenous phytohormones indole acetic acid (IAA) and jasmonic acid (JA) exhibited significant differences (P<0.05) between the two strains. The addition of 0.5 mg·L-1 exogenous JA inhibitor ibuprofen (IBU) improved cell growth of IZ, and was extremely effective in the accumulation of polysaccharides, which accounted for 33.25 %. Transcriptomic analyses revealed that genes involved in photosynthesis, such as PetC and PsbO, exhibited significantly elevated expression of the strain IZ, while the pathways related to JA synthesis may be the factor affecting microalgae temperature tolerance. This study provides a theoretical foundation for elucidating the underlying mechanisms and potential applications for high temperature tolerance in IZ.

Phytohormone-induced changes in growth, physiology, and biochemistry of Aurantiochytrium sp. for sustainable bioproduction.

The study aimed to assess the effects of nine combinations of phytohormones, salicylic acid (SA), gibberellic acid (GA), and jasmonic acid (JA) on the growth, physiology, and biochemistry of Aurantiochytrium sp. Parameters like optical density (OD), biomass, protein content, hydrogen peroxide (H2O2), malondialdehyde (MDA), catalase activity (CAT), and gene expression (malic enzyme (ME) and acetyl-CoA carboxylase (ACCase)) were assessed at various cultivation stages (24, 48, 72, and 96 h). The research also analyzed fatty acid composition, unsaturated fatty acids (UFA), saturated fatty acids (SFA), and the UFA to SFA ratio (USS) to understand the biochemical changes induced by phytohormones. Results demonstrated that modifying phytohormone concentrations significantly affected the characteristics of the microalgae, particularly in correlation with different growth stages, emphasizing the necessity of precise control of phytohormone levels for optimizing cultivation conditions and enhancing bioactive compound production in Aurantiochytrium sp.

Gossypium arboreum PPD2 facilitates root architecture development to increase plant resilience to salt stress.

The jasmonic acid (JA) signaling pathway plays an important role in plant responses to abiotic stresses. The PEAPOD (PPD) and jasmonate ZIM-domain (JAZ) protein in the JA signaling pathway belong to the same family, but their functions in regulating plant defense against salt stress remain to be elucidated. Here, Gossypium arboreum PPD2 was overexpressed in Arabidopsis thaliana and systematically silenced in cotton for exploring its function in regulating plant defense to salt stress. The GaPPD2-overexpressed Arabidopsis thaliana plants significantly increased the tolerance to salt stress compared to the wild type in both medium and soil, while the GaPPD2-silenced cotton plants showed higher sensitivity to salt stress than the control in pots. The antioxidant activities experiment showed that GaPPD2 may mitigate the accumulation of reactive oxygen species by promoting superoxide dismutase accumulation, consequently improving plant resilience to salt stress. Through the exogenous application of MeJA (methy jasmonate) and the protein degradation inhibitor MG132, it was found that GaPPD2 functions in plant defense against salt stress and is involved in the JA signaling pathway. The RNA-seq analysis of GaPPD2-overexpressed A. thaliana plants and receptor materials showed that the differentially expressed genes were mainly enriched in antioxidant activity, peroxidase activity, and plant hormone signaling pathways. qRT-PCR results demonstrated that GaPPD2 might positively regulate plant defense by inhibiting GH3.2/3.10/3.12 expression and activating JAZ7/8 expression. The findings highlight the potential of GaPPD2 as a JA signaling component gene for improving the cotton plant resistance to salt stress and provide insights into the mechanisms underlying plant responses to environmental stresses.

Improved pokeweed genome assembly and early gene expression changes in response to jasmonic acid.

BACKGROUND: Jasmonic acid (JA) is a phytohormone involved in regulating responses to biotic and abiotic stress. Although the JA pathway is well characterized in model plants such as Arabidopsis thaliana, less is known about many non-model plants. Phytolacca americana (pokeweed) is native to eastern North Americana and is resilient to environmental stress. The goal of this study was to produce a publicly available pokeweed genome assembly and annotations and use this resource to determine how early response to JA changes gene expression, with particular focus on genes involved in defense. RESULTS: We assembled the pokeweed genome de novo from approximately 30 Gb of PacBio Hifi long reads and achieved an NG50 of ~ 13.2 Mb and a minimum 93.9% complete BUSCO score for gene annotations. With this reference, we investigated the early changes in pokeweed gene expression following JA treatment. Approximately 5,100 genes were differentially expressed during the 0-6 h time course with almost equal number of genes with increased and decreased transcript levels. Cluster and gene ontology analyses indicated the downregulation of genes associated with photosynthesis and upregulation of genes involved in hormone signaling and defense. We identified orthologues of key transcription factors and constructed the first JA gene response network integrated with our transcriptomic data from orthologues of Arabidopsis genes. We discovered that pokeweed did not use leaf senescence as a means of reallocating resources during stress; rather, most secondary metabolite synthesis genes were constitutively expressed, suggesting that pokeweed directs its resources for survival over the long term. In addition, pokeweed synthesizes several RNA N-glycosylases hypothesized to function in defense, each with unique expression profiles in response to JA. CONCLUSIONS: Our investigation of the early response of pokeweed to JA illustrates patterns of gene expression involved in defence and stress tolerance. Pokeweed provides insight into the defense mechanisms of plants beyond those observed in research models and crops, and further study may yield novel approaches to improving the resilience of plants to environmental changes. Our assembled pokeweed genome is the first within the taxonomic family Phytolaccaceae to be publicly available for continued research.

QTL-seq identifies genomic region associated with the crown root development under Jasmonic acid response.

Rice root system plays a crucial role in plant adaptation under adverse conditions, particularly drought stress. However, the regulatory gene networks that govern rice root development during stress exposure remain largely unexplored. In this study, we applied a QTL sequencing method to identify QTL/gene controlling the crown root development under Jasmonic acid simulation using the Bulk-segregant analysis. Two rice cultivars with contrasting phenotypes from the Vietnamese traditional rice collection were used as parent pairs for crossing. The single-seed descent method was employed to generate an F2 population of progenies. This F2/3 population was further segregated based on root count under JA stress. Pooled DNA from the two extreme groups in this population was sequenced, and SNP indexes across all loci in these pools were calculated. We detected a significant genomic region on chromosome 10, spanned from 20.39-20.50 Mb, where two rice RLKs were located, OsPUB54 and OsPUB58. Receptor-like kinases (RLKs) are pivotal in regulating various aspects of root development in plants, and the U-box E3 ubiquitination ligase class was generally known for its degradation of some protein complexes. Notably, OsPUB54 was strongly induced by JA treatment, suggesting its involvement in the degradation of the Aux/IAA protein complex, thereby influencing crown root initiation. Besides, the Eukaryotic translation initiation of factor 3 subunit L (eIF3l) and the Mitogen-activated protein kinase kinase kinase 37 (MAPKKK 37) proteins identified from SNPs with high score index which suggests their significant roles in the translation initiation process and cellular signaling pathways, respectively. This information suggests several clues of how these candidates are involved in modifying the rice root system under stress conditions.

Methyl jasmonate advances fruit ripening, colour development, and improves antioxidant quality of 'Yoho' and 'Jiro' persimmon.

Methyl jasmonate (MJ) has potential to regulate fruit ripening and quality. 'Yoho' and 'Jiro' persimmons were sprayed with MJ (0, 2, 4, and 6 mM), four weeks before anticipated harvest to evaluate its effects on fruit colour and bioactive compounds. Preharvest MJ application significantly improved fruit colour with increased a*, b*, chroma, and colour index. The MJ 6 mM application had significantly enhanced soluble solids content (SSC), reduced total chlorophyll content in peel and pulp, and soluble and total tannins in persimmons. MJ treatments exhibited higher contents of total phenolics, flavonoids, carotenoids, and antioxidant activities. Additionally, MJ treatments enhanced the activities of shikimate dehydrogenase (SKDH), phenylalanine ammonia-lyase (PAL), catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and lipoxygenase (LOX) enzymes. Overall, pre-harvest MJ application at 6 mM four weeks before anticipated harvest could be useful for advancing colour and improving bioactive compounds in 'Yoho' and 'Jiro' persimmons.

Jasmonate-insensitive mutant jar1b prevents petal elongation and flower opening coupling with parthenocarpic fruit development in Cucurbita pepo.

Jasmonates are growth regulators that play a key role in flower development, fruit ripening, root growth, and plant defence. The study explores the coordination of floral organ maturation to ensure proper flower opening for pollination and fertilization. A new mutant (jar1b) was discovered, lacking petal elongation and flower opening but showing normal pistil and stamen development, leading to parthenocarpic fruit development. The mutation also enhanced the elongation of roots while reducing the formation of root hairs. BSA sequencing showed that jar1b is a missense mutation in the gene CpJAR1B, which encodes the enzyme that catalyzes the conjugation between JA and the amino acid isoleucine. The loss of function mutation in CpJAR1B produced a deficiency in biologically active (+) -7-iso-jasmonoyl-L-isoleucine (JA-Ile), which was not complemented by the paralogous gene CpJAR1A or any other redundant gene. Exogenous application of methyl jasmonate (MeJA) demonstrated that jar1b is partially insensitive to JA in both flowers and roots. Further experimentation involving the combination of JA-Ile deficient and ethylene-deficient, and ET insensitive mutations in double mutants revealed that CpJAR1B mediated ET action in female petal maturation and flower opening, but JA and ET have independent additive effects as negative regulators of the set and development of squash fruits. CpJAR1B also regulated the aperture of male flowers in an ethylene-independent manner. The root phenotype of jar1b and effects of external MeJA treatments indicated that CpJAR1B has a dual role in root development, inhibiting the elongation of primary and secondary roots, but promoting the formation of root hairs.

Less Frequently Used Growth Regulators in Plant Tissue Culture.

Plant growth regulators are routinely added to in vitro culture media to foster the growth and differentiation of the cells, tissues, and organs. However, while the literature on usage of the more common auxins, cytokinins, gibberellins, abscisic acid, and ethylene is vast, other compounds that also have shown a growth-regulating activity have not been studied as frequently. Such substances are also capable of modulating the responses of plant cells and tissues in vitro by regulating their growth, differentiation, and regeneration competence, but also by enhancing their responses toward biotic and abiotic stress agents and improving the production of secondary metabolites of interest. This chapter will discuss the in vitro effects of several of such less frequently added plant growth regulators, including brassinosteroids (BRS), strigolactones (SLs), phytosulfokines (PSKs), methyl jasmonate, salicylic acid (SA), sodium nitroprusside (SNP), hydrogen sulfite, various plant growth retardants and inhibitors (e.g., ancymidol, uniconazole, flurprimidol, paclobutrazol), and polyamines.

Genome-Wide Analysis of the SRPP/REF Gene Family in Taraxacum kok-saghyz Provides Insights into Its Expression Patterns in Response to Ethylene and Methyl Jasmonate Treatments.

Taraxacum kok-saghyz (TKS) is a model plant and a potential rubber-producing crop for the study of natural rubber (NR) biosynthesis. The precise analysis of the NR biosynthesis mechanism is an important theoretical basis for improving rubber yield. The small rubber particle protein (SRPP) and rubber elongation factor (REF) are located in the membrane of rubber particles and play crucial roles in rubber biosynthesis. However, the specific functions of the SRPP/REF gene family in the rubber biosynthesis mechanism have not been fully resolved. In this study, we performed a genome-wide identification of the 10 TkSRPP and 2 TkREF genes' family members of Russian dandelion and a comprehensive investigation on the evolution of the ethylene/methyl jasmonate-induced expression of the SRPP/REF gene family in TKS. Based on phylogenetic analysis, 12 TkSRPP/REFs proteins were divided into five subclades. Our study revealed one functional domain and 10 motifs in these proteins. The SRPP/REF protein sequences all contain typical REF structural domains and belong to the same superfamily. Members of this family are most closely related to the orthologous species T. mongolicum and share the same distribution pattern of SRPP/REF genes in T. mongolicum and L. sativa, both of which belong to the family Asteraceae. Collinearity analysis showed that segmental duplication events played a key role in the expansion of the TkSRPP/REFs gene family. The expression levels of most TkSRPP/REF members were significantly increased in different tissues of T. kok-saghyz after induction with ethylene and methyl jasmonate. These results will provide a theoretical basis for the selection of candidate genes for the molecular breeding of T. kok-saghyz and the precise resolution of the mechanism of natural rubber production.

Functional characterization of AcWRKY94 in response to Pseudomonas syringae pv. actinidiae in kiwifruit.

WRKY transcription factors are essential for coping with various biotic stresses. Pseudomonas syringae pv. actinidiae (Psa)-induced kiwifruit canker is a major problem restricting kiwifruit yield. Nevertheless, it's unclear how the kiwifruit WRKY genes respond to Psa. Through genome-wide identification, 112 WRKY members were found in 'Hongyang' genome in this work. Promoter analysis revealed that there were many cis-acting elements associated with stress responses in the AcWRKY gene's promoter region. According to transcriptomic analysis, 90 of the AcWRKY genes were differently expressed following Psa, salicylic acid (SA), or methyl jasmonate (MeJA) treatments. Almost all group III WRKYs were responsive to at least one of these treatments, with tissue-specific expression patterns. Quantitative RT-PCR study provided more evidence that Psa and SA treatments significantly induced the expression of the group III WRKY gene AcWRKY94, whereas MeJA treatment repressed it. AcWRKY94 was a transcriptionally active protein localized in the nucleus. Transient overexpression of AcWRKY94 in the leaves of 'Hongyang' enhanced the resistance of kiwifruit to Psa. Overexpression of AcWRKY94 in kiwifruit callus remarkably promoted the expression of PR and JAZ genes associated with SA and JA signals, respectively. These data imply that AcWRKY94 controls the signaling pathway dependent on SA and JA, thereby enhancing resistance to Psa. Taken together, this study establishes the basis for functional research on WRKY genes and provides important information for elucidating the resistance mechanism of kiwifruit canker disease.

Genome-wide analysis of R2R3-MYB transcription factors in poplar and functional validation of PagMYB147 in defense against Melampsora magnusiana.

MAIN CONCLUSION: Transcription of PagMYB147 was induced in poplar infected by Melampsora magnusiana, and a decline in its expression levels increases the host's susceptibility, whereas its overexpression promotes resistance to rust disease. Poplars are valuable tree species with diverse industrial and silvicultural applications. The R2R3-MYB subfamily of transcription factors plays a crucial role in response to biotic stresses. However, the functional studies on poplar R2R3-MYB genes in resistance to leaf rust disease are still insufficient. We identified 191 putative R2R3-MYB genes in the Populus trichocarpa genome. A phylogenetic analysis grouped poplar R2R3-MYBs and Arabidopsis R2R3-MYBs into 33 subgroups. We detected 12 tandem duplication events and 148 segmental duplication events, with the latter likely being the main contributor to the expansion of poplar R2R3-MYB genes. The promoter regions of these genes contained numerous cis-acting regulatory elements associated with response to stress and phytohormones. Analyses of RNA-Seq data identified a multiple R2R3-MYB genes response to Melampsora magnusiana (Mmag). Among them, PagMYB147 was significantly up-regulated under Mmag inoculation, salicylic acid (SA) and methyl jasmonate (MeJA) treatment, and its encoded product was primarily localized to the cell nucleus. Silencing of PagMYB147 exacerbated the severity of Mmag infection, likely because of decreased reactive oxygen species (ROS) production and phenylalanine ammonia-lyase (PAL) enzyme activity, and up-regulation of genes related to ROS scavenging and down-regulation of genes related to PAL, SA and JA signaling pathway. In contrast, plants overexpressing PagMYB147 showed the opposite ROS accumulation, PAL enzyme activity, SA and JA-related gene expressions, and improved Mmag resistance. Our findings suggest that PagMYB147 acts as a positive regulatory factor, affecting resistance in poplar to Mmag by its involvement in the regulation of ROS homeostasis, SA and JA signaling pathway.

Jasmonic Acid and Salicylic Acid improved resistance against Spodoptera frugiperda Infestation in maize by modulating growth and regulating redox homeostasis.

Exploring host plant resistance and elevating plant defense mechanisms through the application of exogenous elicitors stands as a promising strategy for integrated pest management. The fall armyworm, a pernicious menace to grain crops in tropical and subtropical regions, stands as a formidable threat due to its capacity for devastation and a wide-ranging spectrum of host plants. There is no literature regarding artificially induced resistance in maize against fall armyworm (Spodoptera frugiperda) by exogenous application of phytohormones. The present investigation was performed to evaluate the role of jasmonic acid (JA) and salicylic acid (SA) on two maize hybrids namely FH-1046 and YH-1898 against fall armyworm. Results showed that plant height, biomass and lengths, fresh and dry weight of root shoot which decreased with armyworm infestation improved with phytohormonal application. JA treatment resulted in a higher increase in all attributes as compared to SA treatment. Improvement in relative water contents, photosynthetic pigments and pronounced levels of phenol and proline accumulation were observed in infested plants after JA treatment. Infested plants recovered from oxidative stress as JA application activated and increased the antioxidant enzyme activity of superoxide dismutase, peroxidase and polyphenol oxidase activity in both FH-1046 and YH-1898 . The oxidative stress reduction in infested plants after JA treatment was also evident from a fair decrease in MDA and H2O2 in both varieties. The SA and JA mediated genes expression was studied and it was found that in FH1046 maize cultivar, JA dependent genes, particularly marker genes PR1 and Lox5 were highly expressed along with TPS10 and BBT12. Whereas SPI, WRKY28, ICS and PAL were shown to be activated upon SA application. Evidently, both JA and SA elicited a robust defensive response within the maize plants against the voracious S. frugiperda, which in consequence exerted a discernible influence over the pest's developmental trajectory and physiological dynamics. A decrease in detoxification enzyme activity of the insects was observed after feeding on treated plants. Moreover, it was recorded that the survival and weight gain of FAW feeding on phytohormone treated maize plants also decelerated. In conclusion, FH-1046 was found to be more tolerant than YH-1898 against fall armyworm infestation and 1 mM JA was more effective than 1 mM SA for alleviation of fall armyworm stress. Therefore, it was inferred that phytohormones regulated redox homeostasis to circumvent oxidative damage and mediate essential metabolic events in maize under stress. To our current understanding, this study is the very first presentation of induced resistance in maize against S. frugiperda with the phytohormonal application (JA and SA).

Genome-wide identification and characterization of the JAZ gene family in Gynostemma pentaphyllum reveals the COI1/JAZ/MYC2 complex potential involved in the regulation of the MeJA-induced gypenoside biosynthesis.

The Jasmonate ZIM domain (JAZ) proteins, functioning as critical suppressors for jasmonic acid (JA) signal transduction in plants, occupy crucial roles in multiple biological processes, particularly in the orchestration of secondary metabolic pathways. However, the mechanism underlying the JA-induced gypenosides accumulation in Gynostemma pentaphyllum remains poorly elucidated. Our research led to the identification of 11 distinct JAZ members in G. pentaphyllum (GpJAZs). According to the classification approach of AtJAZ, we allocated these members into five subgroups that shared similar conserved motif compositions. Subsequently, we identified the presence of various cis-acting elements associated with light stimuli, hormone responses, and stress signals within the promoter regions of the GpJAZ gene family. The expression levels of GpJAZ genes in different tissues were quite different, and the majority of GpJAZ genes exhibited varying degrees of response to methyl jasmonate (MeJA) induction. Yeast two-hybrid (Y2H) assays revealed interactions between GpJAZ1/2/4/5/7/9/10 and GpMYC2, whereas GpCOI1 protein was found to interact with GpJAZ1/2/4/5, thereby forming the COI1/JAZ/MYC2 complex. Furthermore, as an activator of gypenoside metabolic pathway, GpMYC2 could activate the promoter activity of the gypenoside metabolism-related genes to varying degrees by binding to their promoters, indicating that the COI1/JAZ/MYC2 module involved in the MeJA-induced regulation of gypenosides. In summary, our findings present an exhaustive examination of the JAZ gene family, furnishing a significant lead for delving deeper into the molecular mechanisms that drive the MeJA-induced enhancement of gypenosides accumulation in G. pentaphyllum.