山东省危害核桃的链格孢属真菌鉴定及其系统发育

为了明确危害核桃的链格孢属Alternaria真菌种类,对34个供试菌株在PCA培养基上的培养特征、产孢表型、分生孢子特征等进行了研究,并采用ITS、OPA2-1和OPA1-3序列分析其系统发育。其中33个菌株为链格孢A.alternata,1个为细极链格孢A.tenuissima。链格孢:菌落灰色;孢子链短、分枝频繁,每条分枝含4～10个孢子;分生孢子多倒梨形,孢身平均25.6μm×7.4μm,横隔膜2～8个。细极链格孢:菌落褐色;孢子链长、少分枝,孢子链约含10个孢子;分生孢子多长椭圆形,孢身平均26.3μm×13.5μm,具柱状喙及假喙,主横隔膜1～6个,孢身中部的隔膜较粗。链格孢属真菌在遗传上有较大差异,ITS、OPA2-1和OPA1-3序列对链格孢小孢子种具有一定的区分作用,链格孢是危害核桃的主要链格孢属种。

Identification and phylogenetic analysis of walnut-associated Alternaria spp. in Shandong Province, China

To identify walnut-associated Alternaria spp.,the cultural characteristics,sporulation phenotypes and conidial characteristics were described from cultures grown on potato carrot agar(PCA).Meanwhile,the phylogenetic analysis was carried out based on the sequences of ITS,OPA2-1 and OPA1-3 anonymous genomic regions.The results released that 33 isolates of total 34 tested isolates were A.alternata and only one isolate ’10-19’ was A.tenuissima.Sporulation pattern of A.alternata isolates appeared as low bushy clumps of well-branched conidial chains(4 to 10 spores);conidia varied from obpyriform to ovate,the average size of spore body 25.6μm×7.4μm,with 2-8 transverse.A.tenuissima isolate produced long conidial chains(about 10 spores) with occasional branching forming secondary chains(1-5 spores);Conidia were obclavate or ellipsoidal with 1-6 transverse septa,central 1-2 septa often thicker and darker than the others,with the average size of spore body 26.3μm×13.5μm.The phylogenetic analysis was showed the sequences of ITS,OPA2-1 and OPA1-3 anonymous genomic regions can be used to distinguish the small-spores Alternaria species to some extent.A.alternata was dominant species of walnut-associated Alternaria spp.