Re-identification of Colletotrichum acutatum Species Complex in Korea and Their Host Plants

Abstract

<i>Colletotrichum acutatum</i> species complex is one of the most important groups in the genus <i>Colletotrichum</i> with a high species diversity and a wide range of host plants. <i>C. acutatum</i> and related species have been collected from different plants and locations in Korea and deposited into the Korean Agricultural Culture Collection (KACC), National Institute of Agricultural Sciences since the 1990s. These fungal isolates were previously identified based mainly on morphological characteristics, and a limitation of molecular data was provided. To confirm the identification of species, 64 <i>C. acutatum</i> species complex isolates in KACC were used in this study for DNA sequence analyses of six loci: nuclear ribosomal internal transcribed spacers (ITS), betatubulin 2 (TUB2), histone-3 (HIS3), glyceraldehyde3-phosphate dehydrogenase (GAPDH), chitin synthase 1 (CHS-1), and actin (ACT). The molecular analysis revealed that they were identified in six different species of <i>C. fioriniae</i> (24 isolates), <i>C. nymphaeae</i> (21 isolates), <i>C. scovillei</i> (12 isolates), <i>C. chrysanthemi</i> (three isolates), <i>C. lupini</i> (two isolates), and <i>C. godetiae</i> (one isolate), and a novel species candidate. We compared the hosts of KACC isolates with “The List of Plant Diseases in Korea”, previous reports in Korea and global reports and found that 23 combinations between hosts and pathogens could be newly reported in Korea after pathogenicity tests, and 12 of these have not been recorded in the world.

Re-identification of Colletotrichum gloeosporioides Species Complex Isolates in Korea and Their Host Plants

“…Later, causal agents of apple bitter rot disease in the country were authentically identified as C. siamense , C. fructicola , C. nymphaeae , C. fioriniae , C. gloeosporioides , and C. aenigma based on multi-locus sequence analyses ( Cheon et al, 2016 ; Kim et al, 2020 ; Lee et al, 2021 ; Oo et al, 2018 ). The Colletotrichum isolates from apple in this work and in our earlier study ( Thao et al, 2023 ) have been collected since 1997 from many different geographic locations in Korea, and the most prevalent species on apple were C. siamense (10 isolates), followed by C. fructicola (seven), C. nymphaeae (five) and C. fioriniae (four), while only one isolate of C. gloeosporioides sensu stricto was from apple and no C. acutatum sensu stricto isolates were found in KACC. Additionally, a fungal species C. temperatum , originally described by Doyle et al (2013) on Vaccinium macrocarpon , was first detected on apple in this study.…”

“…However, only one strain of C. fructicola in the C. gloeosporioides species complex from chili pepper is stored in KACC. While 16 strains of the C. acutatum species complex from chili pepper are preserved in KACC ( Thao et al, 2023 ). It suggests that C. gloeosporioides s.c. is not a main causal fungus on chili pepper anthracnose in Korea.…”

“…Each polymerase chain reaction (PCR) was performed in a volume of 25 μl containing 12.5 μl PCR Master Mix (2×), 8.5 μl nuclease-free water, 1 μl (4.5 pMol) of each primer, and 2 μl DNA template (100 ng/μl). PCR conditions of six loci were set up as described by Thao et al (2023) . PCR amplifications were carried out using a MJ Research PTC-200 Thermal Cycler (MJ Research, Ramsey, MN, USA).…”