The complete mitogenome of <i>Alternaria tenuissima</i> (Kunze) Wiltshire 1933 (Pleosporaceae), a fungus causing apple leaf blotch disease

<i>Alternaria tenuissima</i> (Kunze) Wiltshire 1933 is a plant pathogenic fungus mainly causing leaf blotch disease. Here, we de novo assembled mitochondrial genome of <i>A. tenuissima</i> isolate AT-1224. The total mitogenome size is 57,475 bp with 29.00% G + C content. The genome contained 12 coding genes and 15 hypothetical proteins, 34 transfer RNA (tRNA) genes and 2 ribosomal RNA (rRNA). There are 227 SSR repeats, range from 2 to 4 base pairs, most five repeats were AT (144), AAT (54), AG (33), AC (13) and AAG (5). The results also found 13 tandem repeats (&gt;100 bp), the largest repeat were forward 2 times located from 13,405 to 20,024 bp and 25,549 to 32,168 bp. Phylogenetic analysis based on 17 species complete mitogenomes indicated that <i>A. tenuissima</i> mitogenome was closest to 2 species, <i>A. solani</i> and <i>A. alternata,</i> sister clade to 6 species, representing <i>Curvularia clavate</i>, <i>Exserohilum rostratum</i>, <i>Exserohilum turcicum</i>, <i>Bipolaris cookie</i>, <i>Bipolaris oryzae</i> and <i>Bipolaris sorokiniana</i>. Further analysis among common fungus in local apple orchards using mitochondrial protein-coding genes revealed <i>A. tenuissima</i> were closing to 2 Alternaria fungi and a fungus representing <i>Phoma</i> sp. These results provide a basic reference for identification and evolution studies of <i>A. tenuissima</i> on apple trees.

细极链格孢（Alternaria tenuissima）(Kunze) Wiltshire 1933是一种植物病原真菌，主要引发叶斑病。本研究对细极链格孢菌株AT-1224的线粒体基因组进行了从头组装（de novo）。该线粒体基因组总长度为57475 bp，G+C含量为29.00%。基因组包含12个编码基因、15个假设蛋白（hypothetical protein）、34个转运RNA（transfer RNA, tRNA）基因以及2个核糖体RNA（ribosomal RNA, rRNA）基因。共检测到227个简单序列重复（simple sequence repeat, SSR），重复单元长度为2~4 bp，其中丰度最高的5种重复基序依次为AT（144个）、AAT（54个）、AG（33个）、AC（13个）和AAG（5个）。研究同时发现13个长度大于100 bp的串联重复序列，其中最大的两处正向重复分别位于13405~20024 bp和25549~32168 bp区域。基于17个物种的完整线粒体基因组进行的系统发育分析结果显示，细极链格孢的线粒体基因组与茄链格孢（Alternaria solani）和链格孢（Alternaria alternata）两个物种亲缘关系最近，与棒状弯孢（Curvularia clavata）、喙突长喙霉（Exserohilum rostratum）、高粱长喙霉（Exserohilum turcicum）、可可平脐蠕孢（Bipolaris cookie）、稻平脐蠕孢（Bipolaris oryzae）以及禾谷平脐蠕孢（Bipolaris sorokiniana）共6个物种形成姊妹支系。进一步利用当地苹果园常见真菌的线粒体蛋白编码基因开展的分析表明，细极链格孢与2种链格孢属真菌以及1株茎点霉属（Phoma）未知种亲缘关系较近。本研究结果可为苹果树细极链格孢的鉴定及进化研究提供基础参考依据。