Cloning and characterisation of JAZ gene family in Hevea brasiliensis

Mechanical wounding or treatment with exogenous jasmonates (JA) induces differentiation of the laticifer in Hevea brasiliensis. JA is a key signal for latex biosynthesis and wounding response in the rubber tree. Identification of JAZ (jasmonate ZIM‐domain) family of proteins that repress JA responses has facilitated rapid progress in understanding how this lipid‐derived hormone controls gene expression and related physiological processes in plants. In this work, the full‐length cDNAs of six JAZ genes were cloned from H. brasiliensis (termed HbJAZ). These HbJAZ have different lengths and sequence diversity, but all of them contain Jas and ZIM domains, and two of them contain an ERF‐associated amphiphilic repression (EAR) motif in the N‐terminal. Real‐time RT‐PCR analyses revealed that HbJAZ have different expression patterns and tissue specificity. Four HbJAZ were up‐regulated, one was down‐regulated, while two were less effected by rubber tapping treatment, suggesting that they might play distinct roles in the wounding response. A yeast two‐hybrid assay revealed that HbJAZ proteins interact with each other to form homologous or heterogeneous dimer complexes, indicating that the HbJAZ proteins may expand their function through diverse JAZ–JAZ interactions. This work lays a foundation for identification of the JA signalling pathway and molecular mechanisms of latex biosynthesis in rubber trees.     

Overexpression of a chrysanthemum transcription factor gene <Emphasis Type="Italic">DgNAC1</Emphasis> improves drought tolerance in chrysanthemum

Phenolic acids and tanshinones are two groups of pharmaceutical components present in Salvia miltiorrhiza Bunge. Methyl jasmonate (MeJA) has been reported to influence the accumulation of both phenolic acids and tanshinones in S. miltiorrhiza hairy roots. However, there is currently a lack of information regarding the comparison of how these two groups of bioactive compounds in S. miltiorrhiza respond to MeJA under the same conditions. In the present study, the effect of 100 µM MeJA on the biosynthesis of phenolic acids and tanshinones in S. miltiorrhiza hairy roots was investigated. The results showed that MeJA dramatically induced the accumulation of five different phenolic acids, especially rosmarinic acid and salvianolic acid B, which reached their highest contents at day 3 (20.3 mg/g DW, 1.5-fold of control) and day 6 (47.49 mg/g DW, 2.5-fold of control), respectively. The total production of phenolic acids was induced by as much as 3.3-fold of the control (day 9 after treatment), reaching 357.5 mg/L at day 6. However, tanshinone I was almost unaffected by MeJA treatment, and the accumulation of tanshinone IIA was inhibited. Furthermore, cryptotanshinone and dihydrotanshinone I were moderately induced by MeJA. The gene expression results indicated that MeJA probably induced the whole pathways, especially the tyrosine-derived pathway and the methylerythritol phosphate pathway, and finally resulted in the increased production of these metabolites. This study will help us to further understand how the different biosynthetic mechanisms of phenolic acids and tanshinones respond to MeJA and provide a reference for the future selection of elicitors for application to improving the production of targeted compounds.     

Genome-Wide Identification and Analysis of the TIFY Gene Family in Grape

Background

The TIFY gene family constitutes a plant-specific group of genes with a broad range of functions. This family encodes four subfamilies of proteins, including ZML, TIFY, PPD and JASMONATE ZIM-Domain (JAZ) proteins. JAZ proteins are targets of the SCF^COI1 complex, and function as negative regulators in the JA signaling pathway. Recently, it has been reported in both Arabidopsis and rice that TIFY genes, and especially JAZ genes, may be involved in plant defense against insect feeding, wounding, pathogens and abiotic stresses. Nonetheless, knowledge concerning the specific expression patterns and evolutionary history of plant TIFY family members is limited, especially in a woody species such as grape.

Methodology/Principal Findings

A total of two TIFY, four ZML, two PPD and 11 JAZ genes were identified in the Vitis vinifera genome. Phylogenetic analysis of TIFY protein sequences from grape, Arabidopsis and rice indicated that the grape TIFY proteins are more closely related to those of Arabidopsis than those of rice. Both segmental and tandem duplication events have been major contributors to the expansion of the grape TIFY family. In addition, synteny analysis between grape and Arabidopsis demonstrated that homologues of several grape TIFY genes were found in the corresponding syntenic blocks of Arabidopsis, suggesting that these genes arose before the divergence of lineages that led to grape and Arabidopsis. Analyses of microarray and quantitative real-time RT-PCR expression data revealed that grape TIFY genes are not a major player in the defense against biotrophic pathogens or viruses. However, many of these genes were responsive to JA and ABA, but not SA or ET.

Conclusion

The genome-wide identification, evolutionary and expression analyses of grape TIFY genes should facilitate further research of this gene family and provide new insights regarding their evolutionary history and regulatory control.     

丹参抗性基因SmORA1的克隆及诱导表达分析

该研究采用PCR方法从丹参中克隆出一条乙烯应答因子结合蛋白(ERF)转录因子编码基因,命名为SmORA1,GenBank登录号为KT359598。经分析发现该基因全长648bp,不包含内含子,编码206个氨基酸残基。编码蛋白SmORA1含有典型的AP2结合结构域。表达分析结果表明,SmORA1主要在丹参根中表达,且该基因的表达明显受到茉莉酸甲酯(MeJA)、脱落酸(ABA)、乙烯(ET)、机械创伤和病原菌等逆境信号的诱导,但低温和脱水情况下SmORA1表达下调。研究表明,SmORA1参与丹参生物胁迫反应,可整合JA、ABA、ET和病原菌等胁迫信号途径。     

Wound-induced expression of a tobacco peroxidase is not enhanced by ethephon and suppressed by methyl jasmonate and coronatine

In tobacco plants, wounding induces production of a set of defense-related proteins such as basic pathogenesis-related (PR) proteins and proteinase inhibitors (PIs) via the jasmonate/ethylene pathway. Although class III plant peroxidase (POX) is also wound-inducible, the regulatory mechanism for its wound-induced expression is not fully understood. Here, we describe that a tobacco POX gene (tpoxN1), which is constitutively expressed in roots, is induced locally 30 min after wounding and then systemically in tobacco plants. Infection of necrotizing virus also induced tpoxN1 gene. The wound-induced expression was not enhanced by known wound-signal compounds such as methyl jasmonate (MeJA) and ethephon in contrast to other wound-inducible genes such as basic PR-1 and PI-II genes. And treatment with MeJA and coronatine, biological analogs of jasmonate, rather suppressed the tpoxN1 expression. Salicylic acid, an antagonist of jasmonate-based wound signaling, did not suppress the wound-induced expression of tpoxN1. Only spermine, which is reported as an endogenous inducer for acidic PR genes in tobacco mosaic virus-infected tobacco leaves, could induce tpoxN1 gene expression. These results suggest that wound-induced expression of the tpoxN1 gene is regulated differently from that of the basic PR and PI-II genes.     

Class I chitinase and beta-1,3-glucanase are differentially regulated by wounding,methyl jasmonate,ethylene, and gibberellin in tomato seeds and leaves

Class I chitinase (Chi9) and beta-1,3-glucanase (GluB) genes are expressed in the micropylar endosperm cap of tomato (Lycopersicon esculentum) seeds just before radicle emergence through this tissue to complete germination. In gibberellin (GA)-deficient mutant (gib-1) seeds, expression of Chi9 and GluB mRNA and protein is dependent upon GA. However, as expression occurs relatively late in the germination process, we investigated whether the genes are induced indirectly in response to tissue wounding associated with endosperm cap weakening and radicle protrusion. Wounding and methyl jasmonate (MeJA) induced Chi9 expression, whereas ethylene, abscisic acid, sodium salicylate, fusicoccin, or beta-aminobutyric acid were without effect. Chi9 expression occurred only in the micropylar tissues when seeds were exposed to MeJA or were wounded at the chalazal end of the seed. Expression of Chi9, but not GluB, mRNA was reduced in germinating seeds of the jasmonate-deficient defenseless1 tomato mutant and could be restored by MeJA treatment. Chi9 expression during germination may be associated with "wounding" from cell wall hydrolysis and weakening in the endosperm cap leading to radicle protrusion, and jasmonate is involved in the signaling pathway for this response. Among these treatments and chemicals (other than GA), only MeJA and wounding induced a low level of GluB expression in gib-1 seeds. However, MeJA, wounding, and particularly ethylene induced both genes in leaves, whereas GA induced only Chi9 in leaves. Although normally expressed simultaneously during tomato seed germination, Chi9 and GluB genes are regulated distinctly and tissue specifically by hormones and wounding.