华北地区十字花科芸薹属蔬菜上立枯丝核菌的病原生物学研究

 由丝核菌引起的十字花科蔬菜叶腐和茎基腐病在中国华北地区普遍发生,其中以河北、内蒙以及北京较为严重。2011~2018年,从华北地区不同省份具有典型叶腐和茎基腐症状的芸苔属蔬菜上分离获得95个丝核菌(Rhizoctonia spp.)分离物,大多数分离自发病植株的叶部,少数分离自茎基部。通过细胞核染色,87株菌属于多核丝核菌,另外8株属于双核丝核菌;经菌丝融合鉴定、rDNA-ITS区及TEF-1α(translation elongation factor 1-alpha, TEF-1α)序列分析,大多数多核丝核菌属于立枯丝核菌(Rhizoctonia solani)AG-2-1(74％),其他少数分别属于AG-1-IB(16％)、AG-4-HG II(2％)和双核丝核菌AG-A(8％)。温室条件下进行寄主范围致病力测定,各分离物对原寄主都表现出致病力,呈现典型叶腐或茎基腐症状;对其他作物的致病力差异较大。不同融合群(Anastomosis group,AG)的菌株对寄主致病力大小存在差异,AG-2-1致病力最强,只有AG-A对叶部没有致病力。AG-2-1对寄主叶部的致病力和对茎基部的致病力呈显著正相关,AG-1-IB对寄主叶部的致病力和对茎基部的致病力无显著相关性。

Biological characteristics on Rhizoctonia solani isolated from Cruciferous-vegetables in North China

Leaf rot and stem rot caused by Rhizoctonia solani commonly occur in cruciferous vegetable-growing regions in North China, and become severe especially in Hebei, Inner Mongolia and Beijing. From 2011 to 2018, a total of 95 isolates of Rhizoctonia spp. were collected from different cultivation areas of cruciferous vegetables in North China, most of which were isolated from leaves, and others from stems. All of the isolates have been identified as 87 multinucleate Rhizoctonia and 8 binucleate Rhizoctonia by nuclear staining and were assigned to the anastomosis group (AG) by performing conventional PCR assays using previously published primers for amplifying ITS-rDNA and TEF-1α regions, as well as by observing hyphal interactions where appropriate. Most isolates were assigned to AG-2-1(74％), and several were assigned to AG-1-IB(16％), AG-4-HG II(2％)and AG-A(8％). A comparative assay of the pathogenicity in greenhouse conditions was conducted. The results showed that each isolate showed pathogenicity to the original host, presenting typical leaf rot or stem rot symptoms; there existed differences between AGs in pathogenicity to other plants. Specifically, AG-2-1 was more pathogenic, while AG-A was no pathogenic to leaves. Besides, there was a significant positive correlation of the disease indexes of AG-2-1 between leaf and stem while AG-1-IB had no significant correlation.