Novel endophytic pestalotioid species associated with Itea in Thailand

Endophytic fungi are a well-known fascinating host-associated fungal group that can enhance plant growth and fitness by producing various bioactive secondary metabolites. They are an excellent source of industrial enzymes for potential secondary metabolite synthesis, which is useful in green agriculture, biotechnology, and pharmaceuticals. <i>Itea</i> is a valuable plant genus since it naturally contains rare sugar; however, endophytic fungi associated in this host have not yet been documented. In the present study, 11 strains of endophytic fungi were isolated and primarily identified as pestalotioid taxa based on morphological characteristics exhibited <i>in vitro</i>. Eleven strains of <i>Pestalotiopsis-</i>like taxa were isolated from the healthy leaves, stems, and roots of <i>Itea japonica</i> and <i>I. riparia</i> from Chiang Mai Province, Thailand. Species delimitation was based on morphology, multiloci phylogeny of a concatenated ITS, <i>tub2</i>, and <i>tef1-α</i> sequence data, and nucleotide polymorphism analyses. <i>Neopestalotiopsis iteae</i> and <i>Pseudopestalotiopsis iteae</i> are proposed as new species on <i>I. japonica</i> and <i>I. riparia</i>, respectively. <i>Neopestalotiopsis chrysea</i>, <i>N. haikouensis</i>, and <i>Pestalotiopsis jinchanghensis</i> are described as new records on <i>I. riparia</i>. Owing to the conspecific relationship based on multiloci phylogeny and identically nucleotide pairwise comparison of sufficient gene regions, several species are synonymized including <i>Neopestalotiopsis cercidicola</i> and <i>N. terricola</i> as <i>N. haikouensis</i>, <i>N. umbrinospora</i> as <i>N. chrysea</i>, and <i>Pestalotiopsis zhaoqingensis</i> as <i>P. jinchanghensis</i>. The updated phylogenetic trees, nucleotide comparisons, and morphological descriptions are herein provided and discussed for the taxonomic placements of these new species and records. This study is the first to investigate <i>Itea</i> endophytes in Thailand, and it reveals the intra- and interspecific relationships of pestalotioid species, which need to be further reevaluated because of ambiguous taxa.