POPULATION STRUCTURE, GENETIC DIVERSITY AND EVIDENCE FOR RECOMBINATION IN POPULATIONS OF THE MAIZE ANTHRACNOSE FUNGUS, COLLETOTRICHUM GRAMINICOLA

RICCARDO BARONCELLI; WAGNER BETTIOL; ALBERT TENUTA; JOSE LUIS VICENTE VILLARDÓN; MICHAEL THON; IVICA BUHINICEK; VERONIQUE ORTEGA; GARY MUNKVOLD; FRANCISCO BORJA CUEVAS-FERNÁNDEZ; JOSÉ SEBASTIAN DAMBOLENA; JOANNE CROUCH; SERENELLA SUKNO

Roma

Congreso; ECFG15, 15th European Conference on Fungal Genetics; 2020

Sapienza University of Rome

Colletotrichum graminicola, causal agent of maize anthracnose, is an important maizedisease worldwide. Colletotrichum is traditionally recognized as an asexual genus.Only the asexual state has been observed in the field and it is thought to reproduceclonally, although the sexual cycle has been reported in laboratory conditions. A betterunderstanding the genetic structure and gene flow among populations is vital to thedevelopment of effective maize anthracnose control strategies. We sequenced 95strains of C. graminicola using Restriction site associated DNA markers (RAD-Seq) andan additional 20 isolates using whole genome resequencing. The isolates were obtainedfrom infected plants found in maize fields in Europe, Canada, USA, Brazil and Argentinawith additional isolates coming from international culture collections. Genetic clustering,principal components analysis, phylogenetic analysis and a minimum spanning networkall support the existence of at least three main populations associated with the continentsof North America, South America and Europe. Our results also indicate a European originof the isolates from Argentina. We found that there is little clonality among the isolatesand of the few clones that were identified, most occurred in European fields. The phitest implemented in the program splitstree found statistically significant evidence forrecombination in each population. Additionally, a linkage decay plot shows that loci thatare physically close to one another are often unlinked, as expected if recombinationis frequent. These results support the hypothesis that recombination is common in C.graminicola, much more so than previously thought.