链格孢菌Alternaria alternata对南疆骏枣果实的侵染机制

Jujube blackspot infected by Alternaria alternata is a new disease that outbreaks widespreadly in southern Xinjiang in recent years. The pathogen infects late fruits and seriously threats to the development of jujube industry in southern Xinjiang. The infection law is theoretical basis of the disease prevention. However, there was no report about the research on infection process and mechanism of jujube blackspot at home and abroad and brough the difficulty to make preventive countermeasures. In this study, the infection expansion of jujube blackspot pathogen, Alternaria alternata, in fruit tissue and the change of disease tissue infected by the pathogen will be observed by using the agrobacterium-mediated transformation technique (ATMT), serial sectioning technique and staining technique. Furthermore, the cell wall-degrading enzymes and the toxin produced by Alternaria alternata will be analysised to investigate the physiological and biochemical mechanism of Alternaria alternata in order to provide a theoretical basis to explore the molecular mechanism and establish the strategy of prevention and control black spot further more. It has significance to the sustainable development of jujube industry in southern Xinjiang both theoretically and practically.

由链格孢菌Alternaria alternata引起的枣黑斑病是南疆近几年暴发流行的一种新病害，给枣产业带来了重大损失。目前关于枣黑斑病菌的侵染致病机理尚无报道，为制定该病害有效防控对策带来了难度。本项目以南疆枣黑斑病菌（Alternaria alternata）为研究对象，采用根癌农杆菌介导遗传转化技术、连续切片和细胞染色技术研究Alternaria alternata在枣果组织细胞内的侵染过程及侵染后引起的病组织细胞的变化，明确该病菌侵染的形态变化机制；并对Alternaria alternata在侵染过程中产生的细胞壁降解酶和毒素进行分析，探讨Alternaria alternata侵染枣果的生理生化机制，以期为探究Alternaria alternata与寄主的互作及制定防控黑斑病策略提供理论基础。该项目的研究成果对保障南疆红枣产业的可持续发展具有重要的理论和实践意义.

枣黑斑病给南疆枣产业造成了极大的威胁。本项目以引起枣黑斑病的病原菌Alternaria alternata为研究对象，探明了A.alternata侵染枣果的形态变化机制和生化机制，为进一步探究A.alternata侵染枣果的分子机制及制定防控黑斑病策略提供理论基础。取得的研究成果如下：(1)依据病菌形态特征、ITS序列和β-tubulin序列分析结果，明确了引起枣黑斑病的病原菌为链隔孢菌A.alternata。（2）采用实时荧光定量PCR，检测不同时期枣花及枣果各部位带菌量，结果表明枣果黑斑病菌在开花期已经感染枣花，在枣果果肉中可潜伏侵染，显症期在枣果成熟中后期。研究结果为枣果黑斑病的药剂防治提供理论依据。（3）以链隔孢菌A.alternata为研究对象，优化了农杆菌EHA105介导的链格孢菌遗传转化体系。应用ATMT技术对实验室保存黑斑病菌的孢子进行GFP标记，获得性状稳定的具有致病力菌株的转化子。（4）以含有GFP标记的转化子接种枣果，观察了枣果的组织结构变化及侵染后引起的病组织细胞的形态差异，从组织病理学的角度明确了该病菌侵染枣果的形态结构变化过程，为链格孢菌-寄主互作关系提供依据。（5）研究了细胞壁降解酶和毒素在链格孢菌侵染枣果过程中的作用机制，研究结果明确了β-葡萄糖苷酶是链格孢菌致病过程中起关键作用的细胞壁降解酶；链格孢菌毒素处理枣组织抗氧化保护酶活力测定结果显示，CAT短时间内下降了67.06%，已知CAT的降低会导致H202的积累，最终加重对组织的损伤。结果中丙二醛含量的上升说明细胞生物膜损伤加剧，这种不可逆的伤害使细胞解体，组织溃烂，寄主死亡。