白及锈病病原菌的鉴定及抗锈病资源筛选

为鉴定引起广西种植区白及锈病的病原菌种类且筛选抗锈病的白及资源,该研究对白及锈病病原菌进行分离,并采用形态学和分子生物学的方法对病原菌进行鉴定,同时通过人工接种病原菌法对23份白及进行锈病抗性评价以及筛选抗锈病的白及资源。结果表明:(1)从白及感病叶片中分离的锈病病原菌X2夏孢子呈金黄色,卵圆形或椭圆形,大小为(21.43～30.95)μm ×(13.10～19.05)μm; 冬孢子呈橘红色、红褐色,倒卵形或棍棒状,大小为(17.25～30)μm ×(5.5～6.65)μm。(2)把菌株X2全长689 bp的ITS序列(OQ826009)与GenBank 已登陆的序列进行相似性分析发现,菌株X2与Coleosporium sp.(KY783686.1)匹配度最高,序列一致性为95.86%,但系统发育树表明,X2与Coleosporium bletiae(MN108161.1,OP363680.1)聚为一类群; 结合形态学和分子生物学的方法,鉴定菌株X2为Coleosporium bletiae。(3)人工接种菌株X2 14 d后,23份白及的病情指数范围在0～70.7之间,并根据病情指数将 23 份白及划分为 6 个抗性等级,即表现为免疫的白及1份,病情指数为0; 表现为高抗的白及4份,病情指数为1.7～4.7; 表现为抗病的白及6份,病情指数为5.6～9.4; 表现为中抗的白及5份,病情指数为12.7～18.3; 表现为感病的白及5份,病情指数为32.0～49.1; 表现为高感的白及2份,病情指数为62.2～70.7。综上认为,表现为免疫和高抗的5份白及(分别来自云南红河、广西恭城、广西百色、贵州遵义、湖北宜昌)病情指数低、抗锈病能力强,可推广应用或作为培育抗锈病优良种质的亲本材料。该研究结果为后续开展白及锈病的有效防治与致病机理研究提供了支撑。

Identification of Bletilla striata rust pathogen and resistance resources screening

In order to identify the pathogen that caused rust of Bletilla striata in Guangxi Zhuang Autonomous Region and to screen resistance resources for B. striata, the rust pathogen was isolated from infected leaves of B. striata and identified using morphology and molecular methods. At the same time, the resistance of 23 B. striata from different regions was evaluated by artificial inoculation of pathogen. The results were as follows:(1)The urediopores of strain X2 isolated from diseased leaves in B. striata were golden yellow, oval,(21.43-30.95)μm ×(13.10-19.05)μm. The teleutospores were golden yellow, obovate or clavate,(17.25-30)μm ×(5.5-6.65)μm.(2)The length of ITS sequence of strain X2(OQ826009)was 689 bp, which were compared with other ITS sequences in the GenBank, and the similarity reached 95.86% compared with Coleosporium sp.(KY783686.1). But the phylogenetic tree showed that the sequence was clustered together with two sequences of Coleosporium bletiae (MN108161.1, OP363680.1). The strain X2 was identified as Coleosporium bletiae by combining morphology and molecular methods.(3)After 14 days of artificial inoculation with strain X2, the disease index of 23 Bletilla striata ranged from 0 to 70.7. And the resistance of strain X2 from 23 B. striata were divided into six different levels according to the disease index. Among them, one immune materials was identified for the disease index was 0. Four highly resistant materials were identified for the disease index was 1.7-4.7. Six disease-resistant materials were identified for the disease index was 5.6-9.4. Five medium-resistant materials were identified for the disease index was 12.7-18.3. Five susceptible materials were identified for the disease index was 32.0-49.1 and two highly susceptible materials were identified for the disease index was 62.2-70.7. In conclusion, five materials(one immune material and four highly resistant materials)of B. striata from different places(Honghe City in Yunnan Province, Gongcheng County and Baise City in Guangxi Zhuang Autonomous Region, Zunyi City in Guizhou Province and Yichang City in Hubei Province, respectively)can be promoted directly or applied as parent materials for creating excellent germplasm to resist the rust in B. striata for they express immune or highly resistance. This study provides the basis for further research on pathogenesis and control of rust in B. striata.