Endophytic Fungal Diversity in Cirsium kawakamii from Taiwan

Abstract

The endophytic fungal diversity of Cirsium kawakamii, a herb indigenous to Taiwan, was analyzed in this study. In addition, some fungal isolates were evaluated for the risk they pose as plant pathogens. In total, 1836 endophytic fungi were isolated from C. kawakamii from Hehuanjian, Puli Township, and Tatachia. They were classified into 2 phyla, 8 classes, 40 families, and 68 genera. Colletotrichum, Fusarium, Phomopsis, and Xylaria, (Ascomycota, Sordariomycetes) were the dominant genera. The genus accumulation curve (based on the bootstrap estimator) was non-asymptotic, with estimated richness significantly exceeding the richness captured by our sampling to date. Considering the collection time, the data indicated significant differences in the proportions of the C. kawakamii endophyte genus from Hehuanjan, Puli Township (across two seasons), and Tatachia. The Shannon and Gini-Simpson indices revealed variations in diversity, with C. kawakamii endophytes (Puli Township in winter) significantly reducing alpha diversity compared with other seasons and locations. Meanwhile, the Gini-Simpson index suggested that there were no significant differences in richness among the four sampling sites. The PCA results unveiled distinct community structures across different locations and seasons, explaining 46.73% of the total variation in fungal community composition significantly affected diversity and richness. In addition, a considerable number of Fusarium isolates exhibited harmful properties towards wheat, potatoes, and apples. It is postulated that these fungi belong to the Fusarium tricinctum species complex (FTSC).

Keywords: Cirsium kawakamii; Fusarium tricinctum species complex (FTSC); endophytic fungal diversity; pathogen.

Figure 1

Cirsium kawakamii collection sites and number of endophytic fungal isolates identified.

Figure 2

(A–C) Relative abundance of endophytic fungi in Cirsium kawakamii at class, family, and genus levels in different sampling areas. The number at the top of the histogram indicates the number of identified fungi isolates in this analysis. In the taxonomy boxes, (A) = Ascomycota and (B) = Basidiomycota. (D) Genus accumulation curve and endophytic fungal composition in Cirsium kawakamii from three regions in Taiwan.

Figure 3

Relative abundance of endophytic fungi of Cirsium kawakamii at genus level in different sampling areas (including two seasons in Puli Township; (S) = summer, and (W) = winter). The number at the top of the histogram indicates the number of identified fungi isolates in this analysis. In the taxonomy boxes, (A) = Ascomycota and (B) = Basidiomycota.

Figure 4

Alpha diversity of Cirsium kawakamii endophytic fungal communities: Shannon diversity index (A), Chao1 richness (B), and Gini–Simpson diversity index (C). Letters indicate significant differences in different sampling areas (including two seasons in Puli Township; (S) = summer and (W) = winter) at p < 0.05 according to Tukey’s HSD.

Figure 5

Bray–Curtis cluster tree (A) and principal component analysis (PCA) (B) showing results of beta diversity analysis of endophytic fungal isolates from Cirsium kawakamii in three sampling area samples (including two seasons in Puli Township; (S) = summer and (W) = winter).