Porocercospora seminalis gen. et comb. nov., the causal organism of buffalo grass false smut
Porocercospora seminalis gen. et comb. nov., the causal organism of buffalo grass false smut
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DOI：
10.3852/13-147
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发表时间：
2014-01-01
期刊：
影响因子：
2.8
通讯作者：
Amundsen, Keenan
中科院分区：
文献类型：
--
作者：
Amaradasa, Bimal S.;Madrid, Hugo;Amundsen, Keenan
黑穗病是影响牧草种子生产的一种重要病害。该病原菌阻碍颖果的正常发育，造成相当大的产量损失和种子萌发能力的降低。根据其形态特征和DNA系统发育，目前将黑粉病病原菌归入尾孢属的分类是不正确的。本研究基于三个基因座的DNA序列分析，即内转录间隔区(ITS)、部分核糖体大亚基(LSU)和RNA聚合酶II第二大亚基(RPB2)的部分序列，明确了精原丝虫的系统发育地位。从内布拉斯加州林肯附近的水牛草遗址收集了一批精原丝虫分离物。DNA序列分析表明，该属在系统发育上与双极孢属和弯孢霉属(Pleosporaceae，Pleosporales)的种类相近，但又不同。分生尾孢菌具有独特的形态特征，即棕色气孔分生孢子梗密集聚集，分生孢子梗重复分枝，分生孢子细胞单列，分生孢子细胞位置不明显，分生孢子具菌丝，分生孢子具鳞片，菌丝变厚变暗。孔孢霉是为适应水牛草黑粉病病原菌而引入的一个新属。
False smut caused by Cercospora seminalis is an important disease of buffalograss (Buchloe dactyloides) affecting seed production. The pathogen prevents normal caryopsis development and causes considerable yield loss and reduced seed germinadon. The current taxonomic placement of the false-smut causal pathogen in the genus Cercospora is incorrect based on its morphological characteristics and DNA phylogeny. In the present study the phylogenetic position of C. seminalis is clarified based on DNA sequence analysis of three loci namely the internal transcribed spacer (ITS) region, partial nuclear ribosomal large subunit (LSU) and partial sequences of the RNA polymerase II second largest subunit (RPB2). A collection of C. seminalis isolates was made from buffalograss sites near Lincoln, Nebraska. DNA sequence data indicated that Cercospora seminalis is phylogenetically close to but distinct from species of Bipolaris and Curvularia (Pleosporaceae, Pleosporales). Cercospora seminalis morphologically had unique characteristics, namely densely aggregated and repeatedly branched conidiophores arising from a brown stoma, monotretic conidiogenous cells with inconspicuous loci, and scolecosporous conidia with distosepta, and thickened, darkened hila. Porocercospora is introduced as a new genus to accommodate the buffalograss false-smut pathogen.