Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, 784028, India.
Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
Comput Biol Chem. 2021 Jun;92:107496. doi: 10.1016/j.compbiolchem.2021.107496. Epub 2021 Apr 24.
Exobasidium vexans, a basidiomycete pathogen, is the causal organism of blister blight disease in tea. The molecular identification of the pathogen remains a challenge due to the limited availability of genomic data in sequence repositories and cryptic speciation within its genus Exobasidium. In this study, the nuclear internal transcribed spacer rDNA region (ITS) based DNA barcode was developed for E. vexans, to address the problem of molecular identification within the background of cryptic speciation. The isolation of E. vexans strain was confirmed through morphological studies followed by molecular identification utilizing the developed ITS barcode. Phylogenetic analysis based on Maximum Parsimony (MP), Maximum Likelihood (ML) and Bayesian Inference (BI) confirmed the molecular identification of the pathogen as E. vexans strain. Further, BI analysis using BEAST mediated the estimation of the divergence time and evolutionary relationship of E. vexans within genus Exobasidium. The speciation process followed the Yule diversification model wherein the genus Exobasidium is approximated to have diverged in the Paleozoic era. The study thus sheds light on the molecular barcode-based species delimitation and evolutionary relationship of E. vexans within its genus Exobasidium.
外生菌根真菌 vexans，一种担子菌病原菌，是茶疱枯病菌的病原体。由于序列库中基因组数据的有限可用性和属内生外囊菌的隐种现象，该病原体的分子鉴定仍然具有挑战性。在这项研究中，基于核内转录间隔区 rDNA 区（ITS）的 DNA 条码被开发用于 vexans，以解决隐种背景下的分子鉴定问题。通过形态学研究和随后利用开发的 ITS 条码进行分子鉴定，确认了 vexans 菌株的分离。基于最大简约法（MP）、最大似然法（ML）和贝叶斯推断（BI）的系统发育分析证实了病原体是 vexans 菌株。此外，使用 BEAST 介导的 BI 分析估计了内生外囊菌属内 vexans 的分歧时间和进化关系。种形成过程遵循 Yule 多样化模型，其中外生菌根属被近似为在古生代分化。因此，该研究阐明了基于分子条码的 vexans 种内分类和属内生外囊菌内的进化关系。
