桃响应LASIODIPLODIA THEOBROMAE侵染的基因表达变化及桃流胶病菌的侵染特性研究

发布时间：2018-10-05 16:58

【摘要】：桃树流胶病在我国桃产区广泛分布,尤其以长江流域及以南地区发病严重,可导致树势衰弱甚至树体死亡,严重危害桃树的栽培和生产。研究报道,桃流胶病的病原菌属于葡萄座腔菌属(Botryosphaeria spp.)真菌,主要包括Fusicoccum aesculi,Diplodia seriata和Lasiodiplodia theobromae三个种。桃胶的主要成分为多糖,因此研究认为胶体形成与树体内的糖代谢关系密切。本研究利用RNA-Seq,研究了桃树响应L.theobromae侵染后的基因表达变化,探讨了乙烯和茉莉酸在流胶病发病过程中作用,同时从病原菌的分离鉴定和组织病理学方面研究了皮孔流胶现象,分析了流胶病菌的侵染特性并鉴定了一株新的桃流胶病病原菌。主要结果如下:1.RNA-Seq分析结果表明,L.theobromae诱导了桃枝条组织的衰老和一系列防御反应,促进了新的多糖合成并抑制了一些多糖的降解。RNA-Seq共检出20772个基因,其中4231、3750、3453和3612个基因分别在接种后12 h、24 h、48 h和60 h时差异表达。共差异表达基因为920个,其中515个上调表达,405个下调表达。GO分析显示,接种L.theobromae后,桃枝条的苯丙素合成代谢、尿苷二磷酸(UDP)糖基转移酶相关基因显著上调表达,而光合作用相关基因表达受到明显抑制。糖代谢途径中的差异基因表达分析显示,细胞壁降解被促进,但是果胶和纤维素的降解也伴随着新的合成;与淀粉和蔗糖分解相关的基因上调表达,葡萄糖-6-磷酸转运蛋白的表达增强;接种后,UDP-半乳糖、UDP-木糖与UDP-D-甘露糖合成相关基因的表达被促进,这些物质都是多糖合成的前体;粘多糖降解相关基因的表达被抑制。桃枝条接种L.theobromae后促进了乙烯的释放,乙烯合成与信号转导相关基因的表达水平也显著提高;接种后12 h,茉莉酸合成相关基因显著上调表达。2%的茉莉酸甲酯(茉莉酸甲酯/羊毛脂,m/m)可稳定诱导桃一年生离体枝条流胶,促进了枝条乙烯的释放,降低了可溶性糖的含量;外源茉莉酸甲酯在早期抑制了桃枝条茉莉酸合成相关基因的表达,但在后期起促进作用。2.从桃树皮孔组织中可以稳定的分离到F.aesculi,F.aesculi在田间表现出潜伏侵染特性,分离到的Neofusicoccum parvum(有性型Botryosphaeria parva)鉴定为一株新的桃流胶病菌。F.aesculi在健康的皮孔组织中也能分离到;F.aesculi产生的分生孢子器位于枝条韧皮部,L.theobromae产生的分生孢子器位于外表皮;N.parvum的分生孢子呈纺锤形或椭圆形,透明,有些孢子有双隔,隔中间颜色变深。人工接种发现N.parvum的致病力较强,枝条接种后可产生明显的褐色病斑和流胶反应。
[Abstract]:Peach gum disease is widely distributed in peach growing areas in China, especially in the Yangtze River valley and south of China, which can lead to the decline of tree potential and even the death of tree body, thus seriously endangering the cultivation and production of peach trees. It is reported that the pathogen of peach gum disease belongs to (Botryosphaeria spp.). Fungi, mainly including Fusicoccum aesculi,Diplodia seriata and Lasiodiplodia theobromae three species. The main component of peach gum is polysaccharide, so it is considered that colloid formation is closely related to sugar metabolism in tree. In this study, RNA-Seq, was used to study the changes of gene expression in peach trees in response to L.theobromae infection, to explore the role of ethylene and jasmonic acid in the pathogenesis of Glutamosis, and to study the phenomenon of pipette in the aspects of isolation and identification of pathogenic bacteria and histopathology. In this paper, the infection characteristics and a new pathogen of peach gum disease were analyzed. The main results were as follows: 1. RNA-Seq analysis showed that L. theobromae induced senescence and a series of defense responses in peach branches, promoted the synthesis of new polysaccharides and inhibited the degradation of some polysaccharides. RNA-Seq detected a total of 20772 genes. The differential expression of 4231r-3750h-3453 and 3612 genes were observed at 24 h and 60 h after inoculation, respectively. There were 920 differentially expressed bases, of which 515 were up-regulated and 405 were down-regulated. Go analysis showed that after inoculation with L.theobromae, phenylpropanin synthesis and uridine diphosphate (UDP) glycosyltransferase related genes were significantly up-regulated in peach branches. However, the expression of photosynthesis-related genes was significantly inhibited. Analysis of differentially expressed genes in glucose metabolism pathway showed that cell wall degradation was promoted, but degradation of pectin and cellulose was accompanied by new synthesis; genes related to starch and sucrose decomposition were up-regulated. The expression of glucose-6-phosphate transporter was enhanced, and the expression of UDP-galactose-xylose and UDP-D- mannose biosynthesis genes were promoted after inoculation, which were all precursors of polysaccharide synthesis, and the expression of mucopolysaccharide degradation related genes was inhibited. Peach branches were inoculated with L.theobromae to promote ethylene release and the expression level of ethylene synthesis and signal transduction related genes were also significantly increased. 12 h after inoculation, the expression of 0.2% methyl jasmonate (methyl jasmonate / lanolin) was significantly up-regulated, which could stably induce the annual branch flow gum, promote the release of ethylene and decrease the content of soluble sugar. Exogenous methyl jasmonate inhibited the expression of genes related to the biosynthesis of jasmonic acid in peach branches at the early stage, but promoted it at a later stage. It was found that F. aesculium F. aesculi showed latent infection in the field. The Neofusicoccum parvum (sex type Botryosphaeria parva) was identified as a new Peach Streptococcus spp. F. aesculi could also be isolated from healthy lenticular tissue. The conidial organ produced by F. aesculi was located in the trunk phloem L. theobromae. The conidial organ was located in the outer epidermis of N. parvum. The conidia are spindle-shaped or elliptical. Transparent, some spores have double septum, the middle of the septum color darkened. The pathogenicity of N.parvum was found to be strong after inoculation.
【学位授予单位】：华中农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S436.621

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