Laboratory of Forest Pathology, Department of Plant Pathology, Universidade Federal de Viçosa, Minas Gerais State 36570-900, Brazil.
Laboratory of Molecular Genetics of Microorganisms, Department of Microbiology, Universidade Federal de Viçosa, Minas Gerais State 36570-900, Brazil.
Fungal Genet Biol. 2022 Sep;162:103728. doi: 10.1016/j.fgb.2022.103728. Epub 2022 Aug 3.
Ceratocystis fimbriata is an important pathogen that causes wilt in several plant species. Despite the importance of this pathogen, knowledge about its karyotypic polymorphism and genomic architecture is limited. The main objective of this study was to investigate the karyotype of isolates of the C. fimbriata species complex from different host plants and geographical origins in Brazil. First, the identity of the isolates was confirmed conducting multilocus sequence analysis (MLSA) phylogeny using β-tubulin (TUBB), translation elongation factor 1α (TEF-1α) and mating-type (MAT1 and MAT2) gene sequences. To investigate the chromosomal polymorphism, two conditions of pulsed-field gel electrophoresis (PFGE) were used and the karyotypes of the isolates obtained. The retrotransposon-microsatellite amplified polymorphism (REMAP) molecular marker was utilized to assess the genetic variability among isolates. In the MLSA utilizing the concatenated gene sequences, Ceratocystis cacaofunesta and C. fimbriata formed separate clades, but considerable variation among C. fimbriata isolates was observed. Polymorphism in chromosome number and size was found, indicating the existence of genomic differences among isolates and occurrence of chromosomal rearrangements in the species complex. The number of chromosomes varied from seven to nine and the estimated minimum chromosome sizes were estimated to be between 2.7 and 6.0 Mbp. Small polymorphic chromosomes ranging from 1.2 to 1.8 Mbp were observed in all isolates, raising the hypothesis that they could be supernumerary chromosomes. REMAP analysis revealed a high genetic variability and that isolates from the same host tend to group together in a same cluster. Our results bring new insights into the chromosomal diversity and genome organization of the C. fimbriata complex.
旋孢腔菌是一种重要的病原体，可引起多种植物物种的萎蔫。尽管该病原体很重要，但对其核型多态性和基因组结构的了解有限。本研究的主要目的是研究来自巴西不同宿主植物和地理起源的旋孢腔菌物种复合体分离物的核型。首先，通过β-微管蛋白（TUBB）、翻译延伸因子 1α（TEF-1α）和交配型（MAT1 和 MAT2）基因序列的多基因序列分析（MLSA）系统发育来确认分离物的身份。为了研究染色体多态性，使用了两种脉冲场凝胶电泳（PFGE）条件，并获得了分离物的核型。使用逆转座子-微卫星扩增多态性（REMAP）分子标记评估分离物之间的遗传变异性。在利用串联基因序列进行 MLSA 中，Ceratocystis cacaofunesta 和 C. fimbriata 形成了单独的分支，但在 C. fimbriata 分离物中观察到相当大的变异。发现染色体数目和大小的多态性，表明分离物之间存在基因组差异，并在物种复合体中发生染色体重排。染色体数从 7 到 9 不等，估计最小染色体大小在 2.7 到 6.0 Mbp 之间。所有分离物中都观察到大小在 1.2 到 1.8 Mbp 之间的小多态性染色体，这表明它们可能是超数染色体。REMAP 分析显示出很高的遗传变异性，并且来自同一宿主的分离物倾向于在同一聚类中聚集在一起。我们的研究结果为旋孢腔菌复合体的染色体多样性和基因组组织提供了新的见解。
