【作者】 严琰；

【导师】 张绍升；

【作者基本信息】 福建农林大学 ， 植物病理学， 2009， 硕士

【摘要】 本实验对香蕉不同品种通过伤根后用香蕉枯萎病菌4号生理小种的孢子悬浮液接种和用病菌发酵无菌滤液浸根处理,观察香蕉枯萎病菌及其发酵无菌滤液对香蕉不同品种的致病性。香蕉枯萎病菌发酵液经细菌过滤器过滤获得的无菌滤液的浓度用标准镰刀菌酸标定。用香蕉枯萎病菌接种后香蕉不同品种抗性程度由大到小依次排列表现为:抗枯5号,马来西亚蕉和抗枯1号,粉蕉,巴西蕉;病菌发酵无菌滤液处理后的抗性程度由大到小依次排列表现为:马来西亚蕉,粉蕉和巴西蕉,抗枯1号,抗枯5号。与病菌孢子接种相比用病菌发酵滤液处理后蕉苗的发病程度较重且发病速度较快,显示出香蕉枯萎病菌发酵滤液可能用于香蕉品种的抗病性鉴定和抗病品种筛选。将发病植株的根部组织切片染色处理后显微观察,表明香蕉枯萎病菌由受伤的寄主根部侵入,在木质部导管内,病菌菌丝伸长并分枝,并大量繁殖小型分生孢子。在褐变的寄主球茎细胞内,菌丝可以在皮层薄壁细胞内扩展,病菌菌丝有分隔和分枝,并产生分生孢子;病原菌孢子也能穿透细胞连接部位,侵入细胞间隙;病菌的厚垣孢子,分散或成串排列,充塞于木质部导管内。在香蕉枯萎病症状显现时,香蕉细胞组织发生病变。病原菌侵入后引起寄主细胞内含物颗粒化,原生质收缩,细胞组织褐变;与寄主细胞壁紧连的病原菌菌丝表面也随即被褐变物质包围,菌丝细胞褐变坏死;受侵染的香蕉组织细胞壁和导管壁木栓化;球茎组织的淀粉粒的含量变化,根-茎部氧化酶(主要包括过氧化物酶和过氧化氢酶)的活性增加;根部木质部导管内充满褐色胶状物和假茎组织气腔内有侵填体的形成。更多还原

【Abstract】 Banana cultivars (Musa spp.) were injured at root tips, followed by the inoculation of Foc4 spore suspension and treatment with fermented filtrate of Fusarium oxysporum f.sp. cubense race 4 (Foc4). The experiment result indicates the pathogenicity evaluation of the two treatment method upon banana cultivars. The pathogen fermenting liquor was filtered through cheesecloth and a membrane filter. Pure fusaric acid was used to estimate the concentration of fermented filtrate. Observation after 20 days’infection process, banana cultivars treated with fermented filtrate show the more severe symptom compared to the level observed 20 days after Foc4 inoculation. Under Foc4 inoculation, banana cultivars manifest differences in degree of resistance to Fusarium wilt, which is shown in a descending order as follows: Resistance FOC No.5 banana, Malaysia banana and Resistance FOC No.1 banana, Drawf banana, Banana Brazil. While banana cultivars treated with fermented filtrate, which result is given in a descending order as follows: Malaysia banana, Drawf banana and Banana Brazil, Resistance FOC No.1 banana, Resistance FOC No.5 banana. Foc4 fermented filtrate treatment increased the symptom severity, and was shown a speed-up in the appearance of the typical FOC symptoms. It appears that the use of Foc4 fermented filtrate to evaluate banana resistance and screen for banana resistant varieties to Fusarium wilt may be potential.The microscopic observations of staining root-tissue sections from Foc4-inoculated banana plants revealed that successful fungal penetration of the host cell was achieved through localized vascular steles of the injured roots. Hyphae of the pathogen grew and multiplied small conidia or chlamydospore, which occurred mainly in xylem vessels of root-tissue and corm-tissue. At this stage of infection, mycelial growth occurred both intercellularly and intracellularly on brown lesions from the corm tissue.Pathogen ingress toward the host cell was accompanied by severe host cell alterations ranging from the granulation and yellowing of cytoplasm to protoplasm retraction; the deposition of lignin and (or) phellem in both host cell walls and vascular stele cell; a decrease of faecula granule; an increase in oxidase activity in root-tissue and corm-tissue; the occlusion of root-tissue xylem vessels space with brown gel and the formation of tylose in vessel cavities of pseudostem-tissue. The polymorphic brown material frequently established close contact with the invading hyphae. The fungal cells become browning necrotic.更多还原