摘要
【目的】从细胞壁降解酶的角度开展其致病机制的研究,探讨杧果细菌性角斑病在发病过程中产生细胞壁降解酶的种类及其在致病过程中的作用,以期为对该病害的有效监测和研发防控新技术提供理论依据。【方法】采用活体外诱导培养和病原菌接种处理,利用3,5-二硝基水杨酸法（DNS法）和紫外分光光度计法检测病原菌侵染过程中细胞壁降解酶活性变化,DDS-ⅡA型电导率仪测定叶片组织浸出液的电导率,并观测细胞壁降解酶对杧果叶片的致病作用。【结果】病原菌在改良的Marcus培养液和罹病组织中均能产生6种主要细胞壁降解酶,其中羧甲基纤维素酶（Cx）活性较高,多聚半乳糖醛酸酶（PG）、果胶甲基半乳糖醛酸酶（PMG）和β-葡萄糖苷酶次之,果胶甲基反式消除酶（PMTE）和多聚半乳糖醛酸反式消除酶（PGTE）较低。病原菌接种杧果叶片后,6种酶活性显著升高,在病菌侵染前期（0-4 d）,PMG接种后2 d达到最大活性高峰,酶活值为8.470 U·mg^-1,以未含致病菌株的培养基接种杧果叶片作为对照,此时接种处理酶活值是对照的3.805倍;β-葡萄糖苷酶接种后4 d酶活性值最大,为15.190 U·mg^-1,是对照的4.388倍。在病菌侵染后期（4-14 d）,Cx、PG、PMTE和PGTE均在接种后的10 d达到最高峰,酶活性值分别为25.941、14.605、0.009、0.014 U·mg^-1,是对照的2.672、14.634、12.571和4.121倍,在整个测定过程中,对照始终处于较低水平。此外,细胞壁降解酶对杧果叶片具有浸解作用,且浸解损伤程度与酶浓度成正比。【结论】细胞壁降解酶在病原菌的入侵和致病过程中起重要作用。果胶酶在病原菌侵染初期最早分泌并起作用,纤维素酶主要降解次生壁,致病作用发生在后期,并且果胶酶比纤维素酶对杧果叶片的致病作用明显。
【Objective】Mango（Mangifera indaca L.） fruit is cultivated throughout the tropics and also in subtropical areas such as Israel, North Africa, Spain, Florida and Japan, and ranks the fifth in production worldwide. Major producers are India, China, Mexico, Thailand, Pakistan, and the Philippines. Mango bacterial leaf spot, a bacterial disease caused by Xanthomonas campestris pv. mangiferaeindicae, can be very destructive in areas where high temperatures and rainfalls occur concomitantly, and seriously affects mango yield and fruit commodity value. It is one of the main diseases in mango under quarantine check. The disease results in abnormal decomposition in infected leaves and fruit. It also causes black cross-crack spots on the surface of the infected tissue. The infected parts in the leaves initially develop water-soaked brown yellow halo spots which gradually develop into large black spots. In the infected branches, the adhesive material from crap gap faded out, and green evolved into black gradually. Dark green star spots emerge early and turn black later with a large number of bacteria that spilled out of the infected site of fruit from the middle crack, which formed slightly viscous strip blotch on its surface, and the fruit with serious disease proned to drop. The disease fruit was got, that aggravated the spread of the epidemic in transit easily. Pathological mechanisms of the mango bacterial leaf spot include cell wall degrading enzymes（CWDEs）, toxic extracellular polysaccharides and hormones, etc. The CWDEs are the enzymes secreted by the plant pathogens into plant cell walls. The objective of the study was to explore the cell wall degradation enzymes produced by pathogens, and their pathogenic effect were studied during the development of the disease based on the characteristics of the decomposition of the host tissue by the pathogen. The study aims to clarify the epidemic characters of the disease and to provide the theoretical basis for effective disease control.【Methods】This research w
出处
《果树学报》
CAS
CSCD
北大核心
2016年第5期585-593,共9页
Journal of Fruit Science
基金
海南自然科学基金(20163109)
中央级非盈利性研究机构基本科研业务费研究专项(1630062014007)
农业行业科研专项(201203092-3)
关键词
杧果细菌性角斑病
细胞壁降解酶
酶活性
致病作用
Mango bacterial leaf spot
Cell wall degrading enzymes
Enzyme activity
Pathogenic effect
