花生丝核菌叶枯病的鉴定

Identification of peanut Rhizoctonia foliar blight

近年来在广东局部地区发现一种严重危害花生叶部的病害，该病害主要病症为在叶部形成水渍状病斑，并导致叶片枯死，严重影响花生植株生长。在病叶的病健交界处分离获得一真菌，该真菌菌丝宽度为5．5～12-3μm，近直角分枝，分枝处缢缩，近分枝处有隔膜；菌丝细胞核数目为3~9个，多为4～7个；产生褐色不规则形状菌核，外表粗糙，长宽范围为O．92～6．12minx0．74～4．96mm。该菌被鉴定为茄丝核菌（RhizoctoniasolaniKiihn，有性态为ThanatephoruscltculTteris（Genbank登录号分别为KF053534、KF053535和KF053536）），获得的序列与GenBank中已报道的茄丝核菌（R．sonaki）AG-1融合群的菌株E53、YN一1和H5—526（Genbank登录号分别为KC285892、KC285893和AY154301）同源性高达99％～100％。离体叶片和盆栽接种，均获得与田间相似的症状，并在罹病叶片上再次分离到同一种真菌。该病害被定名为花生丝核菌叶枯病。

In recent years, a serious disease of peanut occurred in Guangdong province. The typical symptoms were water soaked leaf lesions which lead to quickly foliar blight, and have a serious impact on growth of peanut. A fungus was consistently isolated between the diseased and health part. The width of hypha was 5.5 to 12.3 m. The hypha produced branches at right and acute angels to the main hypha, the branch hypha is slightly constricted at the branch origin, and there is often a septum near the branch origin. The nucleus of the hyphae ranged from 3~9, mostly were 4~7. The fungus produced irregular brown sclerotia. The surface of the sclerotium was rough and the size of the sclerotia ranged from 0.92~ 6.12 mm×0.74-4.96 ram. The fungus was identified as Rhizoctonia solani ktihn （teleomorph Thanatephorus cucumeris）. The ITS region of rDNA of three isolates （GDSH12, GDSH38, and JXWD5 ） were amplified with universal primers ITS1/ITS4 and sequenced （ GenBank Accession Nos. KF053534, KF053535 and KF053536 ）, and comparisons with GenBank showed 99%-100% similarity with R. solani AG-I isolates E53 ,YN-1 和H5~526（GenBank Accession Nos. KC285892, KC285893 and AY154301）. The pathogenicity was confirmed by inoculate the detached leaves and seedlings of peanut. Typical water soaked leaf lesions similar with the field plants were appeared and the fungus was re-isolated from the diseased leaves. The disease was named Rhizoctoniafoliar blight of peanut.