Two Newly Identified Colletotrichum Species Associated with Mango Anthracnose in Central Thailand

Abstract

Anthracnose caused by Colletotrichum spp. is one of the major problems in mango production worldwide, including Thailand. All mango cultivars are susceptible, but Nam Dok Mai See Thong (NDMST) is the most vulnerable. Through a single spore isolation method, a total of 37 isolates of Colletotrichum spp. were obtained from NDMST showing anthracnose symptoms. Identification was performed using a combination of morphology characteristics, Koch’s postulates, and phylogenetic analysis. The pathogenicity assay and Koch’s postulates on leaves and fruit confirmed that all Colletotrichum spp. tested were causal agents of mango anthracnose. Multilocus analysis using DNA sequences of internal transcribed spacer (ITS) regions, β-tubulin (TUB2), actin (ACT), and chitin synthase (CHS-1) was performed for molecular identification. Two concatenated phylogenetic trees were constructed using either two-loci of ITS and TUB2, or four-loci of ITS, TUB2, ACT, and CHS-1. Both phylogenetic trees were indistinguishable and showed that these 37 isolates belong to C. acutatum, C. asianum, C. gloeosporioides, and C. siamense. Our results indicated that using at least two loci of ITS and TUB2, were sufficient to infer Colletotrichum species complexes. Of 37 isolates, C. gloeosporioides was the most dominant species (19 isolates), followed by C. asianum (10 isolates), C. acutatum (5 isolates), and C. siamense (3 isolates). In Thailand, C. gloeosporioides and C. acutatum have been reported to cause anthracnose in mango, however, this is the first report of C. asianum and C. siamense associated with mango anthracnose in central Thailand.

Comprehensive Investigation of Die-Back Disease Caused by Fusarium in Durian

“…Similar to other studies, the MLSA demonstrated better resolution at the species level compared to individual gene analyses. For instance, a study by Rattanakreetakul et al [23] compared two phylogenetic trees for Colletotrichum species. The MLSA approach, which used four loci (ITS, TUB2, ACT, and CHS-1), provided more accurate identification, distinguishing them into C. acutatum, C. gloeosporioides, C. asianum, and C. siamense, compared to using only two loci (ITS and TUB2).…”

“…For molecular identification of fungal isolates, the total genomic DNA was extracted from fresh mycelial on spezieller nährstoffarmer broth (SNB) for 5 days following the protocol described by Zimand et al [44] and Rattanakreetakul et al [23]. The extracted DNA samples were then stored at −20 • C for further analysis.…”