Novel endophytic pestalotioid species associated with Itea in Thailand

Abstract

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. Itea 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 in vitro. Eleven strains of Pestalotiopsis-like taxa were isolated from the healthy leaves, stems, and roots of Itea japonica and I. riparia from Chiang Mai Province, Thailand. Species delimitation was based on morphology, multiloci phylogeny of a concatenated ITS, tub2, and tef1-α sequence data, and nucleotide polymorphism analyses. Neopestalotiopsis iteae and Pseudopestalotiopsis iteae are proposed as new species on I. japonica and I. riparia, respectively. Neopestalotiopsis chrysea, N. haikouensis, and Pestalotiopsis jinchanghensis are described as new records on I. riparia. Owing to the conspecific relationship based on multiloci phylogeny and identically nucleotide pairwise comparison of sufficient gene regions, several species are synonymized including Neopestalotiopsis cercidicola and N. terricola as N. haikouensis, N. umbrinospora as N. chrysea, and Pestalotiopsis zhaoqingensis as P. jinchanghensis. 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 Itea endophytes in Thailand, and it reveals the intra- and interspecific relationships of pestalotioid species, which need to be further reevaluated because of ambiguous taxa.

Keywords: Neopestalotiopsis; Pestalotiopsis; Pseudopestalotiopsis; Sporocadaceae; polyphasic taxonomic approach.

Figure 1

Phylogram constructed by maximum likelihood (ML) analyses of combined ITS, tub2, and tef1-α sequence dataset of Neopestalotiopsis. Bootstrap support valued for ML and Bayesian posterior probabilities (BYPP) equal to or greater than 70% and 0.90 are shown above the nodes as ML/BYPP. The new isolates are indicated in red and the ex-type strains are in bold. The synonymized taxon is indicated in blue. The tree is rooted with Pestalotiopsis diversiseta (MFLUCC 12-0287) and P. spathulata (CBS 356.86).

Figure 2

Phylogram constructed by maximum likelihood (ML) analyses of combined ITS, tub2, and tef1-α sequence dataset of Pestalotiopsis. Bootstrap support valued for ML and Bayesian posterior probabilities (BYPP) equal to or greater than 70% and 0.90 are shown above the nodes as ML/BYPP. The new isolates are indicated in red and the ex-type strains are in bold. The synonymized taxon is indicated in blue. The tree is rooted with Neopestalotiopsis cubana (CBS 114178) and N. protearum (ZHKUCC 23-0825).

Figure 3

Phylogram constructed by maximum likelihood (ML) analyses of combined ITS, tub2, and tef1-α sequence dataset of Pseudopestalotiopsis. Bootstrap support valued for ML and Bayesian posterior probabilities (BYPP) equal to or greater than 70% and 0.90 are shown above the nodes as ML/BYPP. The new isolates are indicated in red and the ex-type strains are in bold. The synonymized taxon is indicated in blue. The tree is rooted with Pestalotiopsis linearis (MFLUCC 12-0271) and P. trachycarpicola (IFRDCC 2240).

Figure 4

Neopestalotiopsis chrysea (SDBR-CMU516). (A) Surface of colonies on PDA. (B) Reverse of colonies on PDA. (C) Conidiomata and conidia masses. (D–F) Conidiophores, conidiogenous cells and conidia. (G) Conidia. Scale bars: (B, C) 500 μm, (D–F) 5 μm, and (G) 10 μm.

Figure 5

Neopestalotiopsis haikouensis (SDBR-CMU517). (A) Surface of colonies on PDA. (B, C) Conidiomata and conidia masses. (D–F) Conidiophores, conidiogenous cells, and conidia. (G) Conidia. Scale bars: (B, C) 500 μm, (D–F) 5 μm, and (G) 10 μm.

Figure 6

Neopestalotiopsis iteae (SDBR-CMU515, ex-type). (A) Surface of colonies on PDA. (B, C) Conidiomata. (D–F) Conidiophores, conidiogenous cells, and conidia. (G) Conidia. Scale bars: (B, C) 500 μm, (D–F) 5 μm, and (G) 10 μm.

Figure 7

Pestalotiopsis jinchanghensis (SDBR-CMU518). (A) Surface of colonies on PDA. (B, C) Conidiomata and conidia masses. (D–F) Conidiogenous cells with attached conidia. (G) Conidia. Scale bars: (B, C) 500 μm and (D–G) 10 μm.

Figure 8

Pseudopestalotiopsis iteae [SDBR-CMU514, ex-type (A–I)], SDBR-CMU523 (J), and SDBR-CMU524 (K). (A) Surface of colonies on PDA. (B) Reverse of colonies on PDA. (C, D) Conidiomata and conidia masses. (E–G) Conidiophores, conidiogenous cells, and conidia. (H–K) Conidia. Scale bars: (C, D) 500 μm and (E–K) 5 μm.