四川省红叶石楠炭疽病病原菌鉴定及其潜在侵染源测定

Identification of the pathogens causing anthracnose and determination of the potential infection source of Photinia×fraseri in Sichuan Province

为明确引起四川省红叶石楠炭疽病的病原菌及其潜在侵染源,采集疑似感染炭疽病的典型病叶进行分离获得纯化病原菌菌株,从中随机选取菌株HYSN3制成分生孢子悬浮液和菌饼,以无伤、刺伤、剪伤3种方式进行接种,筛选出效果最好的接种方式进行致病性测定,结合形态学特征与多基因序列分析将病原菌鉴定到种,并采用筛选出的接种方式将分离自其它19种寄主的23株炭疽菌接种到红叶石楠上,明确其潜在侵染源。结果表明,从红叶石楠病叶中共纯化得到14株菌株,基于形态特征和显微初步鉴定结果,从中选择8株代表菌株进行进一步鉴定。3种接种方式中,以刺伤后接种菌株HYSN3菌饼的效果最好,可用于致病性测定。基于形态学特征、致病性测定和多基因序列分析结果,将病原菌鉴定为胶孢炭疽菌Colletotrichum gloeosporioides(5株)、喀斯特炭疽菌C.karstii(1株)和暹罗炭疽菌C. siamense(2株),表明四川省红叶石楠炭疽病是由多种病原菌复合侵染引起的。来自其它寄主的23株炭疽菌菌株都能侵染红叶石楠,但致病力强弱不同,附近受炭疽菌侵染的植物都有可能成为红叶石楠炭疽病的潜在侵染源,园林植物养护过程中需予以一定的重视。

In order to figure out the pathogens and potential infection sources causing anthracnose of Photinia×fraseri, the leaves samples were collected with exhibited typical symptoms of anthracnose from Sichuan Province, the pathogen strains were obtained by tissue separation and single-spore purification, and the isolate HYSN3 was randomly selected to study the influence of different inoculation methods. Spore suspension or mycelial plugs of isolate HYSN3 were prepared and inoculated onto Photinia×fraseri using the non-wounded, wounded with needle and scissors methods. Combined with morphological characteristics and the phylogenetic analysis of multi-locus sequence, the pathogenic agents were identified at the species level. Twenty-three strains of Colletotrichum isolated from other 19 landscape plants were inoculated on Photinia×fraseri to figure out the potential infection source with the best inoculation methods. The results showed that 14 isolates were obtained, and eight representative isolates were selected based on morphological and microscopic characteristics to conduct further identify.Of the three inoculation methods, pretreatment by scratching with a needle prior to inoculate mycelial plugs of HYSN3 on the leaf was the best method for the pathogenicity test on Photinia×fraseri. Based on morphological characteristics, pathogenicity tests and the phylogenetic analysis of multi-locus sequence, strains were identified as Colletotrichum gloeosporioides(five isolates), C. karstii(one isolate),and C. siamense(two isolates), which indicated that the pathogens causing anthracnose of Photinia×fraseri in Sichuan Province were multiple pathogens. All tested of 23 strains from different sources could infect Photinia×fraseri with obvious differences in pathogenicity, indicating that the nearby plants which infected anthracnose were possibly to be the potential infection sources of Photinia×fraseri,some attention should be give at the process of landscape plant maintenance.