PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF RELEVANT Sclerotinia sclerotiorum ISOLATES

Authors

Thomas J.J. Miorini, University of Nebraska-LincolnFollow
Anthony G. Pannullo, University of Nebraska-LincolnFollow
T. Hornby, University of Nebraska-Lincoln
R. B. Higgins, University of Nebraska-Lincoln
Sydney E. Everhart, University of Nebraska-LincolnFollow
James R. Steadman, University of Nebraska-LincolnFollow

Date of this Version

3-2017

Citation

ANNUAL REPORT OF THE BEAN IMPROVEMENT COOPERATIVE, No. 60, March 2017. Published by USDA.

Comments

U.S. government work.

Abstract

Knowledge of pathogen population structure is useful to identify isolates for screening cultivars and lines for resistance. For S. sclerotiorum, causal agent of white mold in more than 400 plant species, including common bean and soybean, breeding for resistance is particularly challenging. The objective of this study was to characterize phenotypic and genotypic variation of S. sclerotiorum isolates from soybean production areas of the U.S.A. (15), Brazil (75), and Argentina (5) to compare them with 366 isolates from dry bean characterized previously (Everhart et al., 2016).

Genotyping – DNA of 95 isolates was extracted and genotyped at 11 SSR loci (Sirjusingh, and Kohn, 2001). Identified were 92 multilocus genotypes, with only four represented by more than one isolate. Our results showed these isolates had greater genotypic richness and diversity compared with the 366 isolates genotyped previously (Everhart et al., 2016). Pairwise genetic distances between isolates was estimated using Bruvo’s distance, which utilizes a stepwise model of mutation. The matrix of pairwise distances was used to construct a minimum spanning network (MSN); using the R package poppr (Fig. 1). Within the MSN was a core set of 12 MLG that were closely related (thick lines in MSN) and from six states in Brazil. These results are consistent with that expected for a soilborne organism, such as S. sclerotiorum.