Mating type idiomorphs and genetic diversity of venturia carpophila, cause of peach scab

Authors: Bock, Clive; YOUNG, CAROLYN - Noble Research Institute; Zhang, Minling; Chen, Chunxian; BRANNEN, PHILLIP - University Of Georgia; ADASKAVEG, JAMES - University Of California; CHARLTON, NIKKI - Noble Research Institute

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2020
Publication Date: 2/8/2021
Citation: Bock, C.H., Young, C.A., Zhang, M., Chen, C., Brannen, P.M., Adaskaveg, J.A., Charlton, N.D. 2021. Mating type idiomorphs and genetic diversity of venturia carpophila, cause of peach scab. Phytopathology. 111(2):408-424. https://doi.org/10.1094/PHYTO-12-19-0485-R.
DOI: https://doi.org/10.1094/PHYTO-12-19-0485-R

Interpretive Summary: Scab is a major disease affecting peach in the southeastern U.S.A. and causes economic losses. We identified the mating type genes of the causal pathogen, Venturia carpophila, and explored whether they were in equilibrium. Preliminary studies of the population genetic diversity using previously developed microsatellite markers were performed. The mating type genes MAT1-1-1 and MAT1-2-1 were PCR amplified. The structures of the mating type loci were consistent with those of other Venturia species (V. effusa and V. inaequalis). Primers designed to each of the mating type genes and a reference gene TUB2 were used in a multiplex PCR reaction to screen populations of V. carpophila from various locations in the eastern U.S.A. The mating type loci were in equilibrium. The genetic analysis of these isolates showed them to be a genetically diverse group. Among the 81 isolates, there were 69 unique genotypes. The ability to identify mating types of V. carpophila provides a basis for understanding reproductive methods of the pathogen in different peach production areas and can be a basis for further studies of genetics of the peach scab pathogen.

Technical Abstract: Scab is a major disease affecting peach in the southeastern U.S.A., causing significant economic losses. We identified the mating type idiomorphs of the causal pathogen, Venturia carpophila, and explored whether they were in equilibrium. Preliminary studies of the population genetic diversity using previously developed microsatellite markers were performed. The mating type gene MAT1-1-1 was identified in isolate JB3-5 in an available genome sequence, and the MAT1-2-1 gene was PCR amplified from isolate PS1-1. The structures of the mating type loci were consistent with those of other Venturia species (V. effusa and V. inaequalis): the mating type gene is positioned between APN2 encoding a DNA lyase and a gene encoding a Pleckstrin homology domain. Primers designed to each of the mating type genes and a reference gene TUB2 were used as a multiplex PCR reaction to screen populations of V. carpophila from various locations in the eastern U.S.A. The mating type loci were in equilibrium. The genetic analysis of these isolates showed them to be a genetically diverse group. Among the 81 isolates, there were 69 multilocus genotypes. A discriminant analysis of principal components indicated limited differentiation with overlap among populations. However, population isolate numbers were small, so these results are considered preliminary. The ability to identify mating types of V. carpophila provides a basis for understanding reproductive methods of the pathogen in different peach production areas and can be a basis for further studies of genetics of the peach scab pathogen.