First Report of Colletotrichum aenigma Causing Anthracnose of Grape (Vitis vinifera) in Korea

Abstract

Grape (cv. Kyoho) is one of the most popular dessert fruits in South Korea. Anthracnose caused by Colletotrichum species is a common and very destructive disease of grape in the country. In 2019, severe outbreaks of anthracnose was observed in different grape orchards in Gimcheon (36º09´N, 128º00´ E), South Korea. The disease incidence on fruit was up to 50% in the orchards with most severe outbreaks and infected fruit displayed typical anthracnose symptoms including sunken necrotic lesions with orange-like conidial mass. For isolation of putative causal agents, nine diseased fruits were collected from three commercial orchards. A total of nineisolates were made from nine of the infected fruit by spreading spore masses (1x106 conidia mL-1) from each fruit on water agar and collecting single germinated spores after incubation at 25 ºC overnigh. The single germinated spores were transferred on to fresh potato dextrose agar (PDA) (Difco, Becton Dickinson) and incubated at 25ºC in the dark. Seven day old colonies were cottony white on the upper side and gray at the center on the reverse side. Conidia were cylindrical with round ends and measured 13.9 – 20.1 × 5.4 – 8.1 μm (mean = 16.5 × 6.6 μm, n = 30). Appressoria were brownish, sub-cylindrical with a few lobes and 10.3 –16.7 × 6.6 – 10.9 μm (mean = 13.1 × 8.1 μm, n = 30). The morphological characteristics of the solates resembled those of Colletotrichum species within the C. gloeosporioides complex (Weir et al. 2012). DNA was amplified using the following primer pairs: ITS1/ITS4, GDF / GDR, ACT-512F / ACT-783R, Bt2a/ Bt2b, and CHS79-F/CHS-354R (Weir et al. 2012). Accession numbers, LC586811 to LC586825 were obtained after depositing all the resulting sequences in GenBank. A 50% majority rules phylogenetic tree (Bayesian phylogenic analysis) was constructed based on concatenated sequences of ITS, GAPDH, ACT, TUB, and CHS using MrBayes 3.2.10. The present isolates formed a single clade with the reference isolates of C. aenigma (isolate ICMP 18608 and ICMP 18686). For a pathogenicity test, healthy grapefruits were collected from an orchards, surface sterilized by dipping in 1% sodium hypochlorite, rinsed with sterilized water and dried by blotting. A conidial suspension (1×106 conidia mL-1) in sterilized water were prepared from one week old colonies of isolates GRAP10 and GRAP12. A small wound was made on sterilized detached fruit by punching with a sterile pin. A drop of the conidial suspension was placed on the wound, while the control fruit received a drop of sterile water. Similarly, unwounded fruit were also inoculated with a single droplet of conidial suspension. For each isolate and method (wounded and unwounded), ten fruit were inoculated, and ten non-inoculated fruit were used as control. All the treated fruit were kept in a plastic box containing moist tissue and incubated at 25º C in the dark. Typical anthracnose lesions appeared on all inoculated wounded fruit while non-inoculated and inoculated unwounded fruits remained asymptotic. Koch postulates were fulfilled by re-isolating and re-identifying the causal agent from inoculated fruit. Colletotrichum aenigma has been reported as the causal agent of anthracnose on Juglans regia, Camellia sinensis and Actinidia arguta in China (Weir et al. 2012; Wang et al. 2016; Wang et al. 2018). Previous studies reported four Colletotrichum species (C. acutatum, C. gloeosporioides, C. fructicola, and C. viniferum) to cause this disease on grapes in South Korea (Oo and Oh 2017; Lim et al. 2020). To the best of our knowledge, this is the first report on grape anthracnose caused by C. aenigma in South Korea. This finding may help to take effective control measures of this disease.

Pest categorisation of Colletotrichum aenigma, C. alienum, C. perseae, C. siamense and C. theobromicola

“…(2017), Vieira et al (2014), Weir et al. (2012)Malaysia •Jalan Asam Jaws (Universiti Putra Malaysia) •Serdang (Selangor) PresentZakaria (2021)Republic of Korea •Bonghwa •Gimcheon •Gosung (Kangwon) •Gunwi (Gyeongbuk) PresentChoi et al (2017), Kim et al (2021), Lee et al. (2021)Thailand •Nakhon Pathom •Pathum Thani •Samut Sakhon PresentMeetum et al (2015)…”

Modeling the Effects of the Environment and the Host Plant on the Ripe Rot of Grapes, Caused by the Colletotrichum Species

“…Relationship between wetness duration (hours) and rescaled infection severity by Colletotrichum acutatum (data of Greer et al [10]) and by C. gloeosporioides (data of Yun and Park [9]). Dots show the average data from the mentioned papers, and whiskers are standard errors; the curve shows the fit of these data by Equation ( 5) in the main text, with R 2 = 0.95.…”

“…Ripe rot was first reported in the USA [3] and is currently present wherever host species (V. labrusca, V. vinifera, and V. rotundifolia [4]) are grown. The disease is caused by Colletotrichum species belonging to the complex C. gloeosporioides and C. acutatum [2,[5][6][7][8][9][10][11][12][13][14][15][16].…”

Colletotrichum aenigma Associated with Apple Bitter Rot on Newly Bred cv. RubyS Apple

“…The sequences of allied species were retrieved from NCBI GenBank (Table 1) and a phylogenetic tree was constructed using the maximum-likelihood method as implemented in MEGA7 software (Kumar et al, 2016). Strain KNUF-20GWA4 clustered together with C. aenigma IY1059, C. aenigma GRAP12, and C. aenigma GRAP07 isolated in Korea (Choi et al, 2017;Kim et al, 2021) and two other strains of C. aenigma ICMP 18608 and ICMP 18686 in a monophy- letic clade with a high bootstrap value, strongly supporting their affiliation to the same species (Fig. 2).…”

“…C. aenigma has been reported as a pathogen associated with anthracnose on several hosts, including grape and Sedum kamtschaticum (Orange stonecrop) in Korea (Choi et al, 2017;Kim et al, 2021); grapevine, Asian pear, and walnut in China (Fu et al, 2019;Wang et al, 2021;Yan et al 2015); avocado in Israel (Sharma et al, 2017); Synsepalum dulcificum (miracle fruit) in Japan (Truong et al, 2018); and Hylocereus undatus (dragon fruit) in Thailand (Meetum et al, 2015). However, this fungal pathogen has not been reported as the causal agent of bitter rot on apple fruits.…”