水培致病测定体系在Foc致病机理分析与香蕉品种抗性评价中的应用
Application of the hydroponic virulence test system to pathogenic mechanism analysis of Fusarium oxysporum f. sp. cubense strains and resistance evaluation

为验证已建立的水培苗直接浇菌法的准确性与适用范围,利用此方法分析了5个致病相关基因敲除突变体对巴西蕉的致病力,评价了巴西蕉、皇帝蕉、粉蕉、宝岛蕉4个香蕉品种对4株尖镰孢菌古巴专化型病原菌株的抗性,并观察了接菌后巴西蕉根部与球茎组织的病原菌入侵过程。结果表明,foste12基因敲除突变株△Foste12菌株对巴西蕉的致病力与野生型菌株相比下降41%,且与传统的盆栽苗伤根淋菌法测试的下降趋势基本一致;皇帝蕉、宝岛蕉对4株病原菌均表现为中抗或高抗,粉蕉均表现为感病或高感;且观察到病原菌孢子附着根部、菌丝入侵根细胞间隙、维管束组织内的菌丝纵向生长及球茎组织内的菌丝侵入定殖等入侵过程。研究证实水培苗直接浇菌法可用于病原菌致病机理分析及与不同香蕉种质资源对尖镰孢菌古巴专化型的室内抗性评价。
To identify the accuracy and application range of Fusarium oxysporum f. sp. cubense (Foc) strains' virulence test method, in which hydroponics seedlings were inoculated with Foc directly under the hydroponic system, several virulence-related gene knockout mutants' virulence to 'Bax' banana (Musa acuminata AAA) were analyzed, and the resistance of four banana cultivars ('Bax' banana, M. acuminata AA cv. Mas, Musa ABB Pisang Awak and M. acuminata AAA Cavendish cv. Formosana) to different Foc strains were evaluated, and the roots and corm tissues during the invasion processes were examined with confocal laser scanning microscope (CLSM). The results indicated that the pathogenic ability of △Foste12 transformant was declined significantly compared to the wild type strain in terms of relative disease index (RDI), and the RDI trend was the same as that with potted seedlings inoculated with Foc after root injury. M. acuminate AA cv. Mas and M. acuminata AAA Cavendish cv. Formosana cultivar showed medium or high resistance to the four tested Foc isolates, and Musa ABB Pisang Awak was sensitive or very sensitive to the four tested Foc isolates. These results were consistent with the results from actual field observation and the results reported by others. Images of histological invasion process with CLSM observation were clear, with spores attached to the banana root epidermis cells, with hyphal invasion roots along the junctions of adjacent epidermal cells, and massive infectious hyphae growing longitudinally in the xylem vessels of banana root and hyphal invasion and colonization in corm tissues. Thus, the Foc virulence evaluation method used by the authors could be applied to analyze pathogenic mechanism and evaluate banana germplasm resistance to Foc.