Genetic variation and demographic history analysis of Pestalotiopsis, Pseudopestalotiopsis, and Neopestalotiopsis fungi associated with tea (Camellia sinensis) inferred from the internal transcribed spacer region of the nuclear ribosomal DNA

Abstract

AbstractTo elucidate the demographic history within and among the genera Pseudopestalotiopsis, Neopestalotiopsis, and Pestalotiopsis and their genetic diversity, we studied internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA (nrDNA) with no saturation effects in 172 Pestalotiopsis‐like fungal accessions isolated from Camellia sinensis planted in nine provinces in China (64 from Yunnan, 4 from Guangxi, 2 from Guizhou, 42 from Jiangxi, 3 from Sichuan, 3 from Zhejiang, 1 from Henan, 18 from Fujian, 12 from Chongqing, and 18 from other provinces) and in Japan (1), France (1), Turkey (1), and Thailand (2). Among these, 44 Pestalotiopsis‐like isolates from Yunnan in this study formed a clade in phylogenetic trees with Pestalotiopsis accessions in GenBank, despite their cultural characteristics on potato dextrose agar displaying no genus specificity. Based on estimated sequence polymorphism parameters of average pairwise differences (K), haplotype diversity (Hd), nucleotide diversity (Pi), θ (per site) from η, and recombination event rate (Rm), we identified moderate genetic variation in these three genera. Molecular evolution analysis with neutrality tests and mismatch distribution demonstrated that Pseudopestalotiopsis and Pestalotiopsis ribosomal ITS sequences evolved under a neutral model. However, the recent demographic expansion of the three genera promoted geographical isolation but showed no clear geographical structure. Pairwise genetic divergences between haplotypes and a median‐joining network revealed Yunnan or Jiangxi as a possible centre of origin, and that Pseudopestalotiopsis and Neopestalotiopsis may derive from Pestalotiopsis.