MeJA (Methyl jasmonate) acts as a crucial regulatory phytohormone that mediates plant responses to biotic and abiotic stresses. Nevertheless, systematic studies on the effects and underlying regulatory mechanisms of MeJA on the postharvest quality of table grapes during low-temperature storage remain limited. In this study, physiological measurements combined with transcriptomic data demonstrated that MeJA treatment effectively maintained the postharvest quality of ‘Kyoho’ grapes under low-temperature storage. Physiological results showed that MeJA significantly enhanced the activities of antioxidant enzymes, inhibited the activities of cell wall softening-related enzymes PG and PE, promoted lignin accumulation, and delayed cellulose degradation. Furthermore, transcriptomic analysis verified that MeJA markedly upregulated the expression of genes associated with lignin biosynthesis. Collectively, MeJA maintains the postharvest quality of ‘Kyoho’ grapes during low-temperature storage by modulating antioxidant metabolism and cell wall metabolism, exhibiting great potential as an effective postharvest regulatory technique.

The mesophyll protoplast transient expression system is an essential and robust methodology for examining gene expression regulation. Despite its potential, it has not been effectively employed to elucidate the genetic regulatory pathways and networks underlying plant responses to nutrient starvation, such as those involving phosphorus (Pi) and iron (Fe). In this study, we identified differentially expressed genes in response to Pi starvation in Arabidopsis using transcriptome analysis and RT-qPCR validation. Our findings revealed that Pi starvation significantly upregulated the expression of Pi-starvation induced (PSI) genes, including SPX1, SPX3, IPS1, and PS2, while simultaneously downregulating the expression of Fe starvation-responsive genes, such as FIT, IRT1, and FRO2. Additionally, through a dual luciferase transient expression assay in mesophyll protoplasts, we demonstrated that the transcription factor PHR1 serves as a crucial transcriptional regulator, modulating the expression of phosphate starvation response (PSR) genes. This regulation significantly enhances the transcriptional activity of the SPX1, SPX2, SPX3, IPS1, PS2, and PHT1;4 promoters. Upon the addition of the SPX1 protein, the activation of these gene promoters by PHR1 were alleviated. Concurrently, the transcriptional regulator FIT, which governs the expression of genes responsive to Fe starvation, markedly increased the transcriptional activity of the IRT1 and FRO2 promoters. Based on these findings, we propose the mesophyll protoplast transient expression system as a rapid and reliable method for investigating complex genetic networks. Overall, our study provides substantial evidence for understanding the role of the mesophyll protoplast transient expression system in elucidating the genetic regulatory pathways and networks involved in plant responses to nutrient starvation.

Grapes are among the most widely cultivated fruit crops globally, yet their growth and yield are severely compromised by Colletotrichum viniferum, which causes a devastating disease that affects grape berries. The wall-associated kinase (WAK) gene family, a unique subfamily of receptor-like-kinases (RLKs), plays important roles in mediating plant responses to both abiotic and biotic stresses. However, the expression patterns and biological functions of grape WAKs in response to C. viniferum infection remain largely uncharacterized. In this study, a total of 57 VdWAK genes were identified and phylogenetically classified into twelve subgroups. Chromosomal localization and collinearity analyses further revealed that tandem duplication and segmental duplication events contributed to the expansion of the VdWAK gene family. Transcriptomic profiling identified VdWAK19 as a key responsive gene. It was predominantly expressed in mature berries but transcriptionally repressed upon C. viniferum infection. Virus-induced gene silencing assays in grape berries demonstrated that knockdown of VdWAK19 significantly reduced fruit resistance to C. viniferum infection. Overall, these findings advance our understanding of the functional roles of VdWAK genes during C. viniferum infection and provide a theoretical basis for the potential application of VdWAK19 in breeding grape varieties with enhanced resistance to ripe rot.

Cadmium (Cd), a highly toxic and mobile heavy metal, has emerged as a severe environmental concern in global agroecosystems, posing a substantial threat to human health. Although prior studies have established that ZAT6 and ZAT10 positively regulate Arabidopsis tolerance to Cd toxicity, the underlying molecular mechanisms remain largely elusive. The present study provides evidence that a class I TCP transcription factor, TCP9, significantly enhances Arabidopsis tolerance to Cd toxicity through the direct activation of ZAT6 and ZAT10 expression. The real-time quantitative PCR (RT-qPCR) analysis indicates that the expression of TCP9 was induced under Cd toxicity. Meanwhile, the tcp9 mutant exhibited heightened sensitivity to Cd toxicity, accompanied by elevated Cd accumulation in both shoots and roots. Notably, the complemented lines exhibited phenotypic characteristics analogous to those observed in the wild-type (WT) plants. Further physiological and biochemical analyses revealed that, in comparison to WT, the tcp9 mutant displayed elevated hydrogen peroxide (H2O2) accumulation and reduced contents of catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) under Cd toxicity. Furthermore, TCP9 directly interacted with the promoters of ZAT6 and ZAT10 in vitro, facilitating their transcription and consequently enhancing plant tolerance to Cd toxicity. Overall, our findings showed that TCP9 enhances Cd tolerance via modulating ZAT6 and ZAT10, thereby identifying TCP9 as a potential key target for improving plant tolerance to Cd toxicity.

Grape (Vitis vinifera) production globally faces significant challenges from grape ripe rot (Colletotrichum viniferum). MYB transcription factors (TFs) play a crucial role in mediating plant responses to biotic stresses. However, their involvement in grapevine responses to ripe rot remains unclarified. This study employed bioinformatics to identify MYB TF genes within the grapevine genome and assessed their expression profiles post C. viniferum infection via transcriptome analysis. Among the 121 R2R3-MYB genes identified, VdMYB31, predominantly expressed in mature fruits, was notably downregulated in responding to C. viniferum infection. Heterologous expression of VdMYB31 in tomato (Solanum lycopersicum) fruits increased susceptibility to C. acutatum by suppressing salicylic acid (SA)-related gene expression. Silencing MYB31 in grape berries conferred resistance to C. viniferum. Additionally, exogenous SA application bolstered grape resistance to C. viniferum infection. These findings underscore the involvement of R2R3-MYB TFs in defending against C. viniferum, positioning VdMYB31 as a promising target for breeding grape varieties with improved resistance to ripe rot in viticulture.

Seedlessness is one of the most valuable agronomic traits in grape. Embryo rescue technology, with its advantages of increasing the proportion of seedless progeny and shortening the breeding cycle, has been widely applied in seedless grape breeding. To improve the efficiency of embryo rescue breeding in seedless grape, this study focused on rescuing and reusing abnormal seedlings generated during the process. By analyzing the influence of parental genotypes from 19 cross combinations on the formation of abnormal seedlings and employing both direct transformation and somatic embryogenesis for their rescue, the study investigated the effects of different abnormal seedling types and parental genotypes on rescue efficiency. Additionally, using the secondary embryos differentiated from the hypocotyls of abnormal seedlings in 3 cross combinations as experimental materials, the aim is to establish a somatic embryo regeneration system. The results revealed that the average proportion of abnormal seedlings (46.25%) across the 19 cross combinations was significantly higher than that of normal seedlings (33.06%). Among the abnormal seedling types, leaves without roots and cotyledon albinism were the most prevalent. Using the direct transformation method, the polycotyledonous type exhibited the highest rescue efficiency at 53.06%, while the cross combination “Perlette × Huozhoucuiyu" achieved the highest abnormal seedling rescue rate of 81.11%. Furthermore, secondary embryos derived from the hypocotyl of abnormal seedlings were capable of developing into normal seedlings, enabling the rescue of some abnormal seedlings. A cyclic somatic embryogenesis system was established for grape hypocotyls in the crosses “Melissa Seedless × Lüzhoubaoshi" and “Zitian Seedless × Melissa Seedless". This approach not only significantly enhanced the efficiency of embryo rescue but also expanded the potential applications of abnormal seedlings in somatic regeneration research, providing valuable receptor materials for grape genetic transformation systems.

To investigate the effects of straight-line-shape (SL) and inverted-umbrella-shape (IU) training systems on sugar accumulation and metabolism in ‘Kyoho’ grape berries in Fujian, this study used 16-year-old ‘Kyoho’ grapevines trained in the two systems. Fruit samples were collected from 45 to 95 days after flowering (DAF) to measure soluble sugar content. Transcriptome sequencing was performed to analyze the differential expression of sugar metabolism-related genes, combined with KEGG enrichment analysis and RT-qPCR validation of key genes. The results showed that, at the same stage, the soluble sugar content in berries under the SL training system was significantly higher than that under the IU training system, especially from 45 to 65 DAF, where sugar accumulation was faster. Transcriptome analysis revealed that the SL training system showed 6274, 5597, and 2064 differentially expressed genes at 45, 65, and 95 DAF, respectively. Key sugar metabolism-related genes, such as fructokinase (FK), phosphofructokinase (PFK), and sucrose phosphate synthase (SPS), exhibited significantly higher expression levels in the SL training system than in the IU training system. KEGG enrichment analysis indicated that the SL training system significantly enriched sugar metabolism and transport pathways during the early fruit ripening stage. RT-qPCR validation confirmed that genes related to sugar metabolism and transport (such as FK7, SUS3, SPP1) were expressed at significantly higher levels in the SL training system than in the IU training system. In conclusion, the SL training system significantly promoted soluble sugar accumulation and accelerated fruit ripening in ‘Kyoho’ grapes by regulating the expression of sugar metabolism and transport-related genes, providing a theoretical basis for promoting the SL training system in production.

BACKGROUND:DIR (Dirigent) proteins play important roles in the biosynthesis of lignin and lignans and are involved in various processes such as plant growth, development, and stress responses. However, there is less information about VvDIR proteins in grapevine (Vitis vinifera L). RESULTS:In this study, we used bioinformatics methods to identify members of the DIR gene family in grapevine and identified 18 VvDIR genes in grapevine. These genes were classified into 5 subfamilies based on phylogenetic analysis. In promoter analysis, various plant hormones, stress, and light-responsive cis-elements were detected. Expression profiling of all genes following Colletotrichum gloeosporioides infection and phytohormones (salicylic acid (SA) and jasmonic acid (JA)) application suggested significant upregulation of 17 and 6 VvDIR genes, respectively. Further, we overexpressed the VvDIR4 gene in Arabidopsis thaliana and grapes for functional analysis. Ectopic expression of VvDIR4 in A. thaliana and transient expression in grapes increased resistance against C. gloeosporioides and C. higginsianum, respectively. Phenotypic observations showed small disease lesions in transgenic plants. Further, the expression patterns of genes having presumed roles in SA and JA signaling pathways were also influenced. Lignin contents were measured before and after C. higginsianum infection; the transgenic A. thaliana lines showed higher lignin content than wild-type, and a significant increase was observed after C. higginsianum infection. CONCLUSIONS:Based on the findings, we surmise that VvDIR4 is involved in hormonal and lignin synthesis pathways which regulate resistance against anthracnose. Our study provides novel insights into the function of VvDIR genes and new candidate genes for grapevine disease resistance breeding programs.

Pepper (Capsicum annuum L.) is frequently challenged by various pathogens, among which Phytophthora capsici is the most devastating to pepper production. Red light signal acts as a positive induction of plant resistance against multiple pathogens. However, little is known about how the red light signal affects pepper resistance to P. capsici infection (PCI). Here, we report that red light regulates salicylic acid (SA) accumulation by activating elongated hypocotyl5 (CaHY5), a basic leucine zipper (bZIP) transcription factor, thereby decreasing pepper susceptibility to PCI. Exogenous SA treatment reduced pepper susceptibility to PCI, while silencing of CaPHYB (a red light photoreceptor) increased its susceptibility. PCI significantly induced CaHY5 expression, and silencing of CaHY5 reduced SA accumulation, accompanied by decreases in the expression levels of phenylalanine ammonia-lyase 3 (CaPAL3), CaPAL7, pathogenesis-related 1 (CaPR1), and CaPR1L, which finally resulted in higher susceptibility of pepper to PCI. Moreover, CaHY5 was found to activate the expression of CaPAL3 and CaPAL7, which are essential for SA biosynthesis, by directly binding to their promoters. Further analysis revealed that exogenous SA treatment could restore the resistance of CaHY5-silenced pepper plants to PCI. Collectively, this study reveals a critical mechanism through which red light induces SA accumulation by regulating CaHY5-mediated CaPAL3 and CaPAL7 expression, leading to enhanced resistance to PCI. Moreover, red light-induced CaHY5 regulates pepper resistance to PCI, which may have implications for PCI control in protected vegetable production.

Bacterial wilt is a devastating disease of tomato (Solanum lycopersicum) caused by Ralstonia solanacearum that severely threatens tomato production. Group III WRKY transcription factors (TFs) are implicated in the plant response to pathogen infection; however, their roles in the response of tomato to R. solanacearum infection (RSI) remain largely unexplored. Here, we report the crucial role of SlWRKY30, a group III SlWRKY TF, in the regulation of tomato response to RSI. SlWRKY30 was strongly induced by RSI. SlWRKY30 overexpression reduced tomato susceptibility to RSI, and also increased H2O2 accumulation and cell necrosis, suggesting that SlWRKY30 positively regulates tomato resistance to RSI. RNA sequencing and reverse transcription-quantitative PCR revealed that SlWRKY30 overexpression significantly upregulated pathogenesis-related protein (SlPR-STH2) genes SlPR-STH2a, SlPR-STH2b, SlPR-STH2c, and SlPR-STH2d (hereafter SlPR-STH2a/b/c/d) in tomato, and these SlPR-STH2 genes were directly targeted by SlWRKY30. Moreover, four group III WRKY proteins (SlWRKY52, SlWRKY59, SlWRKY80, and SlWRKY81) interacted with SlWRKY30, and SlWRKY81 silencing increased tomato susceptibility to RSI. Both SlWRKY30 and SlWRKY81 activated SlPR-STH2a/b/c/d expression by directly binding to their promoters. Taking these results together, SlWRKY30 and SlWRKY81 synergistically regulate resistance to RSI by activating SlPR-STH2a/b/c/d expression in tomato. Our results also highlight the potential of SlWRKY30 to improve tomato resistance to RSI via genetic manipulations.

Cadmium (Cd) is a harmful heavy metal that is risky for plant growth and human health. The zinc-finger transcription factor ZAT10 is highly conserved with ZAT6 and ZAT12, which are involved in Cd tolerance in plants. However, the definite function of ZAT10 in Cd tolerance remains uncertain. Here, we demonstrated that ZAT10 negatively regulated Cd uptake and enhanced Cd detoxification in Arabidopsis. The expression of ZAT10 in plants is induced by Cd treatment. The zat10 mutant plants exhibited a greater sensitivity to Cd stress and accumulated more Cd in both shoot and root. Further investigations revealed that ZAT10 repressed the transcriptional activity of IRT1, which encodes a key metal transporter involved in Cd uptake. Meanwhile, ZAT10 positively regulated four heavy metal detoxification-related genes: NAS1, NAS2, IRT2, and MTP3. We further found that ZAT10 interacts with FIT, but their regulatory relationship is still unclear. In addition, ZAT10 directly bound to its own promoter and repressed its transcription as a negative feedback regulation. Collectively, our findings provided new insights into the dual functions of ZAT10 on Cd uptake and detoxification in plants and pointed to ZAT10 as a potential gene resource for Cd tolerance improvement in plants.

WRKY蛋白是植物中最大的转录因子家族之一,其家族成员广泛参与植物生长发育,特别在应答环境逆境胁迫中起重要的调节作用.开展WRKY家族成员在应答各种逆境胁迫中的作用及其机制研究,有利于阐明植物应答逆境胁迫的分子机制.本研究采用染色体步移技术,分离获得PsWRKY22的启动子,通过启动子5'端缺失体构建、拟南芥遗传转化和GUS酶活测定等方法研究pPsWRKY22及其缺失体在不同胁迫下(干旱,低温和高盐)以及外源激素(ABA,MeJA,SA和ETH)处理下的表达情况.研究结果表明,PsWRKY22启动子及其缺失片段在多种胁迫处理下都不同程度地抑制下游GUS蛋白的表达,尤其在外源SA胁迫处理下两者被抑制的效果最为明显,另外在低温和外源ABA处理下,pPsWRKY22及其缺失体的GUS酶活差异极其显著.本研究结果为进一步探究WRKY转录因子在非生物胁迫和外源激素作用下诱导油柰抗逆性基因表达的分子机制提供理论依据.

WRKY transcription factors are key regulatory components of plant responses to both biotic and abiotic stresses. In pepper (Capsicum annuum), CaWRKY27 positively regulates resistance to the pathogenic bacterium Ralstonia solanacearum and negatively regulates thermotolerance. Here, we report that CaWRKY27 functions in the response to salinity and osmotic stress. CaWRKY27 transcription was induced by salinity, osmotic, and abscisic acid (ABA) treatments, as determined using qPCR and GUS assays. Transgenic Arabidopsis thaliana and tobacco (Nicotiana tabacum) plants heterologously expressing CaWRKY27 had an increased sensitivity to salinity and osmotic stress, with a higher inhibition of both root elongation and whole plant growth, more severe chlorosis and wilting, lower germination rates, and an enhanced germination sensitivity to ABA than the corresponding wild-type plants. Furthermore, most marker genes associated with reactive oxygen species (ROS) detoxification and polyamine and ABA biosynthesis, as well as stress-responsive genes NtDREB3, were downregulated in plants transgenically expressing CaWRKY27 upon exposure to salinity or osmotic stress. Consistently, silencing of CaWRKY27 using virus-induced gene silencing conferred tolerance to salinity and osmotic stress in pepper plants. These findings suggest that CaWRKY27 acts as a molecular link in the antagonistic crosstalk regulating the expression of defense-related genes in the responses to both abiotic and biotic stresses by acting either as a transcriptional activator or repressor in pepper.

WRKY transcription factors have been implicated in both plant immunity and plant responses to cadmium (Cd); however, the mechanism underlying the crosstalk between these processes is unclear. Here, we characterized the roles of CaWRKY41, a group III WRKY transcription factor, in immunity against the pathogenic bacterium Ralstonia solanacearum and Cd stress responses in pepper (Capsicum annuum). CaWRKY41 was transcriptionally up-regulated in response to Cd exposure, R. solanacearum inoculation, and H2O2 treatment. Virus-induced silencing of CaWRKY41 increased Cd tolerance and R. solanacearum susceptibility, while heterologous overexpression of CaWRKY41 in Arabidopsis impaired Cd tolerance, and enhanced Cd and zinc (Zn) uptake and H2O2 accumulation. Genes encoding reactive oxygen species-scavenging enzymes were down-regulated in CaWRKY41-overexpressing Arabidopsis plants, whereas genes encoding Zn transporters and enzymes involved in H2O2 production were up-regulated. Consistent with these findings, the ocp3 (overexpressor of cationic peroxidase 3) mutant, which has elevated H2O2 levels, displayed enhanced sensitivity to Cd stress. These results suggest that a positive feedback loop between H2O2 accumulation and CaWRKY41 up-regulation coordinates the responses of pepper to R. solanacearum inoculation and Cd exposure. This mechanism might reduce Cd tolerance by increasing Cd uptake via Zn transporters, while enhancing resistance to R. solanacearum.

Trihelix转录因子家族在植物生长发育、生物胁迫和非生物胁迫等方面具有重要的作用,但是目前关于谷子Trihelix转录因子家族研究鲜见报道.本试验共鉴定到34个谷子转录因子,对其进行染色体定位、系统进化树、保守基序、基因结构和不同组织的表达分析发现,该家族成员均含有高度保守的Trihelix结构域,分为5个亚族,同一亚族含有相同的保守基序,同一亚族含有相似的基因结构,在不同的亚族中,组织表达模式不同.本研究初步明确了谷子Trihelix转录因子家族成员进化关系和结构特点,为进一步研究谷子Trihelix转录因子家族的系统发育以及生物学功能奠定了基础,为谷子的分子育种提供科学依据.

Heat stress, an important and damaging abiotic stress, regulates numerous WRKY transcription factors, but their roles in heat stress responses remain largely unexplored. Here, we show that pepper (Capsicum annuum) CaWRKY27 negatively regulates basal thermotolerance mediated by H2O2 signaling. CaWRKY27 expression increased during heat stress and persisted during recovery. CaWRKY27 overexpression impaired basal thermotolerance in tobacco (Nicotiana tabacum) and Arabidopsis thaliana, CaWRKY27-overexpressing plants had a lower survival rate under heat stress, accompanied by decreased expression of multiple thermotolerance-associated genes. Accordingly, silencing of CaWRKY27 increased basal thermotolerance in pepper plants. Exogenously applied H2O2 induced CaWRKY27 expression, and CaWRKY27 overexpression repressed the scavenging of H2O2 in Arabidopsis, indicating a positive feedback loop between H2O2 accumulation and CaWRKY27 expression. Consistent with this, CaWRKY27 expression was repressed under heat stress in the presence H2O2 scavengers and CaWRKY27 silencing decreased H2O2 accumulation in pepper leaves. These changes may result from changes in levels of reactive oxygen species (ROS)-scavenging enzymes, since the heat stress-challenged CaWRKY27-silenced pepper plants had significantly higher expression of multiple genes encoding ROS-scavenging enzymes, such as CaCAT1, CaAPX1, CaAPX2, CaCSD2, and CaSOD1. Therefore, CaWRKY27 acts as a downstream negative regulator of H2O2-mediated heat stress responses, preventing inappropriate responses during heat stress and recovery.

Tandem CCCH zinc finger (TZnF) proteins have been implicated in plant defence, but their role in pepper (Capsicum annuum) is unclear. In the present study, the role of CaC3H14, a pepper TZnF protein, in the immune response of pepper plants to Ralstonia solanacearum infection was characterized. When fused to the green fluorescent protein, CaC3H14 was localized exclusively to the nuclei in leaf cells of Nicotiana benthamiana plants transiently overexpressing CaC3H14. Transcript abundance of CaC3H14 was up-regulated by inoculation with R. solanacearum. Virus-induced silencing of CaC3H14 increased the susceptibility of the plants to R. solanacearum and down-regulated the genes associated with the hypersensitive response (HR), specifically HIR1 and salicylic acid (SA)-dependent PR1a. By contrast, silencing resulted in the up-regulation of jasmonic acid (JA)-dependent DEF1 and ethylene (ET) biosynthesis-associated ACO1. Transient overexpression of CaC3H14 in pepper triggered an intensive HR, indicated by cell death and hydrogen peroxide (H2 O2 ) accumulation, up-regulated PR1a and down-regulated DEF1 and ACO1. Ectopic overexpression of CaC3H14 in tobacco plants significantly decreased the susceptibility of tobacco plants to R. solanacearum. It also up-regulated HR-associated HSR515, immunity-associated GST1 and the SA-dependent marker genes NPR1 and PR2, but down-regulated JA-dependent PR1b and ET-dependent EFE26. The CaC3H14 promoter and was bound and its transcription was up-regulated by CaWRKY40. Collectively, these results indicate that CaC3H14 is transcriptionally targeted by CaWRKY40, is a modulator of the antagonistic interaction between SA and JA/ET signalling, and enhances the defence response of pepper plants to infection by R. solanacearum.

明确枣WRKY转录因子家族生物学特征,为深入研究枣WRKY家族基因的功能提供科学依据.通过DNAMAN6、MEGA5、Mapdarw和MEME Suite 4.12.0等软件对枣WRKY转录因子的数目、基因分类、染色体定位、系统进化关系和保守基序进行了分析.结果表明:枣中包含92个WRKY基因,根据WRKY结构域数量及其锌指结构的特征可将其分为Group Ⅰ、GroupⅡ和GroupⅢ,GroupⅡ又可分为Ⅱa、Ⅱb、Ⅱc、Ⅱd和Ⅱe5个亚组.枣12条假染色体上除了第7条染色体上没有查到枣WRKY基因分布外,其它1 1条染色体都有WRKY基因分布,其中第11条染色体上分布最多,有10个WRKY基因,第2条、第5条和第8条染色体分布最少,仅有2个WRKY基因.枣Ⅲ、Ⅱd和Ⅱe处在同一分支,Ⅰ、Ⅱa、Ⅱb和Ⅱc在同一分支.枣WRKY转录因子在同一类或亚类中含有相同的保守Motif,Motif最长为50,最短为21.枣WRKY转录因子蛋白在67～758个氨基酸范围之间,平均氨基酸个数为384,等电点为4.130 8～10.221 1不等.本研究对进一步探究枣WRKY基因的功能、进化以及分子育种具有重要的现实意义.

Despite the greatly agricultural importance of pepper (Capsicum annuum) and the ubiquitously involvement of MAPK (mitogen-activated protein kinases) cascades in a broad range of plant biological processes,the roles of MAPK cascades in pepper remain unclearly.In the present study,a MAPK of pepper,designated as CaMAPK9 (Accession no.:CA04g21490),was expressed and functionally characterized.The results showed that CaMAPK9 shared more than 95％ deduced amino acid sequence identity with its homologues in other plant species including tobacco (Nieotiana tabacum),tomato (Solanum lycopersicum) and potato(Solanum tuberosum).By subcellular localization assay through transient overexpression of CaMAPK9-GFP (Green Fluorescent Protein) in leaves of Nicotiana benthamiana plants,CaMAPK9 was found to target to the nuclei.Total RNA was extracted from abiotic stresses imposed pepper plants,as salt,mannitol and foliar application of salicylic acid (SA),methyl jasmonate (MeJA) or abscisic acid (ABA) and used for first-stand cDNA synthesis,cDNA RT-PCR showed that CaMAPK9 was induced under salt or mannitol and foliar application of SA or ABA stresses but impeded by SA,showing that CaMAPK9 may be involved in salt stress pepper response.In addition,two T3 transgenic Arabidopsis lines were developed and the ectopic overexpression of CaMAPK9 was confirmed.The 2 transgenic lines consistently showed a enhanced tolerance to salt stress manifested by the higher germination rate and longer root length under salt stress compared to that of the wild type seeds of seedlings.The transcriptional expression of ABI5,an ABA maker gene which was responsive to signaling in plant under salt-stress tolerance,was higher in two transgenic Arabidopsis types that in wild plants under salt-stress.All these results collectively suggested that CaMAPK9 acted as a positive regulator in the response of pepper to salt stress possibly regulated by signaling mediated by ABA and JA.This study provides a theoretical basis for further research on the molecular breeding mechanism of salt stress response in pepper

ETHYLENE RESPONSE FACTORs (ERF) transcription factors (TFs) constitute a large transcriptional regulator family belonging to the AP2/ERF superfamily and are implicated in a range of biological processes. However, the specific roles of individual ERF family members in biotic or abiotic stress responses and the underlying molecular mechanism still need to be elucidated. In the present study, a cDNA encoding a member of ethylene response factor (ERF) transcription factor, CaERF5, was isolated from pepper. Sequence analysis showed that CaERF5 contains a typical 59 amino acid AP2/ERF DNA-binding domain, two highly conserved amino acid residues (14th alanine (A) and 19th aspartic acid (D)), a putative nuclear localisation signal (NLS), a CMIX-2 motif in the N-terminal region and two putative MAP kinase phosphorylation site CMIX-5 and CMIX-6 motifs. It belongs to group IXb of the ERF subfamily. A CaERF5-green fluorescence protein (GFP) fusion transiently expressed in onion epidermal cells localised to the nucleus. CaERF5 transcripts were induced by Ralstonia solanacearum infection, salicylic acid (SA), methyl jasmonate (MeJA) and ethephon (ETH) treatments. Constitutive expression of the CaERF5 gene in tobacco plants upregulated transcript levels of a set of defence- related genes and enhanced resistance to R. solanacearum infection. Our results suggest that CaERF5 acts as a positive regulator in plant resistance to R. solanacearum infection and show that overexpression of this transcription factor can be used as a tool to enhance disease resistance in crop species.