• 中文核心期刊
  • CSCD来源期刊
  • 中国科技核心期刊
  • CA、CABI、ZR收录期刊

马铃薯早疫病病原菌茄链格孢菌 Alternaria solani线粒体基因组特征分析

Mitogenome Characterization of Potato Early Blight Pathogen Alternaria solani

  • 摘要:
    目的 茄链格孢菌(Alternaria solani)是引起马铃薯早疫病的主要病原菌。本研究拟对A. solani TA-0410菌株的线粒体基因组进行组装和遗传特征分析。
    方法 对A. solani TA-0410菌株进行DNA的提取及测序,并对其线粒体基因组进行结构特点及比较分析和聚类分析。
    结果 TA-0410线粒体基因组的总大小为58 494 bp,(G+C)含量为28.80%。各碱基含量分别为:A(35.40%)、T(35.80%)、G(13.90%)和C(14.90%)。基因组包含24个编码基因和25个转运RNA(tRNA)基因。在SSR分析中,共发现224个短重复序列,其长度为2~8 bp。出现频率最高的6种短重复序列依次为:AT(146次)、AAT(26次)、AG(25次)、AC(14次)、AAG(4次)和ACT(4次)。此外,在基因组位置29 387-29 419 bp处发现了1个8 bp的重复序列(AATTATAT),该序列在基因组中共有4个拷贝。系统发育分析基于28个完整线粒体基因组,结果显示A. solani与同属物种A. tenuissimaA. alternata具有最密切的亲缘关系,并与Stemphylium lycopersici、Curvularia clavate、Exserohilum rostratum、Exserohilum turcicum、Bipolaris cookie、Bipolaris oryzaeBipolaris sorokiniana等7个属于其他属的真菌具有较近的亲缘关系。此外,TA-0410线粒体基因组显示出显著的遗传密码子偏好性:47.62%的密码子的RSCU值大于1,其中90.63%以A或U结尾;而50.79%的密码子的RSCU值小于1,93.75%以C或G结尾,这主要由自然选择和驯化压力驱动。
    结论 茄链格孢菌线粒体基因组和链格孢属其他几个种存在大范围的共线性,系统发育分析关系较近,遗传密码子偏好性主要受自然选择与驯化影响。研究为解析A. solani的遗传多样性与进化特点提供了基因组学基础。

     

    Abstract:
    Objective The mitochondrial genome of a strain of Alternaria solani, the primary pathogen of early blight disease in potatoes, was assembled and characterized.
    Methods DNA was extracted and sequenced from A. solani TA-0410 to study the mitogenome structure to compare with other similar strains for a clustering analysis.
    Results The mitochondrial genome was 58,494bp with a GC content of 28.80% with 35.40% of A nucleotides, 35.80% of T, 13.90% of G, and 14.90% of C. It contained 24 protein-coding and 25 tRNA genes. The SSR analysis identified 224 short repeat sequences ranging from 2bp to 8bp in length. The 6 most frequently occurring short repeats were AT with 146 occurrences, followed by AAT with 26, AG with 25, AC with, AAG with 4, and ACT with 4 occurrences. In 29,387–29,419bp of the genome, 4 copies of 8bp repeat sequence of AATTATAT were found. A phylogenetic analysis based on 28 complete mitochondrial genomes indicated that A. solani was most closely related to the congeneric species, A. tenuissima and A. alternata, and relatively with 7 fungi from genera such as Stemphylium lycopersici, Curvularia clavate, Exserohilum rostratum, Exserohilum turcicum, Bipolaris cookie, Bipolaris oryzae and Bipolaris sorokiniana. The TA-0410 mitochondrial genome exhibited a significant codon usage bias that was primarily driven by natural selection and mutational pressure, as 47.62% of the codons had a RSCU greater than 1 with 90.63% ending in A or U, while 50.79% had the value less than 1 with 93.75% ending in C or G.
    Conclusion The mitogenome of A. solani displayed an extensive collinearity with those of several other Alternaria species. Phylogenetically, they were evolutionarily close despite the significant bias on genetic codon usage due primarily to natural selection and domestication.

     

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