Multilocus Phylogenetic Analyses of Colletotrichum gloeosporioides Species Complex Causing Crown Rot on Strawberry in Florida

Abstract

Colletotrichum gloeosporioides is the causal agent of Colletotrichum crown rot of strawberry in the southern United States. Recent multi-gene studies defined C. gloeosporioides as a complex species comprised of 37 species. In our study, we phylogenetically characterized C. gloeosporioides isolates from strawberry and other non-cultivated plants around strawberry fields. One hundred and fifteen strawberry isolates and 38 isolates from non-cultivated hosts were sequenced for five genomic regions: internal transcribed spacer (ITS), actin (ACT), calmodulin (CAL), chitin synthase (CHS-1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Phylogenetic analysis using the maximum likelihood and Bayesian inference methods, based on partition-specific models, revealed that most of the isolates in Florida (86%) were closely related to C. siamense, whereas 14 isolates were closely related to C. theobromicola (syn. C. fragariae), four isolates were C. fructicola, and three were C. clidemiae. However, only the first three species were pathogenic to strawberry. Morphological characteristics evaluated show that mycelial growth of all species is about 5 mm/day but colony morphology varies by species and incubation conditions. In vitro mating of the isolates demonstrated that C. fructicola is homothallic whereas C. siamense and C. theobromicola isolates are heterothallic. The biological importance of these different Colletotrichum species is currently being investigated to determine whether different management strategies are needed in strawberry production fields.

Colletotrichum species pathogenic to strawberry: discovery history, global diversity, prevalence in China, and the host range of top two species

“…In northern China, Korea, and Japan of eastern Asia-Pacific region, C. fructicola is prevailing. Recently, C. siamense is increasingly prevailing in USA (Adhikari et al 2019;Oliveira et al 2022) and China (Wang et al 2022), which is in accordance with the tolerance of C. siamense to high temperature observed in several labs (Han et al 2016;Chung et al 2020;Zhang et al 2020). It is expected that the diversity and global distribution of Colletotrichum pathogens of strawberry are undergoing plentiful changes with the gradual shift of agricultural system under a global warming context.…”

“…Both two species are cosmopolitan fungi adapting to a wide range of host plants, most reported in tropical and sub-tropical regions but with significantly higher occurrences in Asia than in other continents. In vitro mating of fungal isolates demonstrated that C. fructicola is homothallic whereas C. siamense is heterothallic (Oliveira et al 2022), hinting the latter with a relatively higher capability of genetic mutations and flexibility, partially congruent with a wider host spectrum than C. fructicola.…”

“…Indeed, C. paranaense has been considered as an endemism associated with apple, peach, and nectarine from Brazil only (Talhinhas and Baroncelli 2021). Recently, in an effort to reveal the causal agent of strawberry crown rot in USA, C. clidemiae was isolated from strawberry fields together with C. siamense (86%), C. theobromicola, and C. fructicola, but C. clidemiae was suggested as the only species not pathogenic to strawberry (Oliveira et al 2022). Therefore, these two species (C. paranaense and C. clidemiae) are not included in current list of strawberry pathogens.…”

“…In Canada, three species including C. fructicola (Weir et al 2012), C. nymphaeae, and C. lineola (Jayawardena et al 2016b) were reported to be infectious to strawberry. At least six Colletotrichum species pathogenic to strawberry were revealed in USA, namely, C. simmondsii (Faedda et al 2011), the dominant C. nymphaeae (Wang et al 2019) C. siamense (Adhikari et al 2019;Eaton et al 2021;Oliveira et al 2022), the less prevailing C. fioriniae (Wang et al 2019;Eaton et al 2021), C. fructicola, and C. theobromicola (Weir et al 2012;Oliveira et al 2022). In Mexico, only Colletotrichum spp.…”

“…As the most prevailing pathogens causing strawberry anthracnose crown rot in Asia-Pacific region (Nam et al 2013;Han et al 2016;Jayawardena et al 2016a;Gan et al 2017;Hirayama et al 2018;Gupta et al 2019;Chen et al 2020;Chung et al 2020;Zhang et al 2020;Jian et al 2021;Zhong et al 2021;Oliveira et al 2022;Wang et al 2022), C. siamense and C. fructicola are actually the top two Colletotrichum species most frequently occurred worldwide (Talhinhas and Baroncelli 2021). Both two species are cosmopolitan fungi adapting to a wide range of host plants, most reported in tropical and sub-tropical regions but with significantly higher occurrences in Asia than in other continents.…”