ARS | Publication request: Genetic diversity of Sclerotinia trifoliorum infecting chickpea based on mycelial compatibility grouping, rDNA introns and multi-locus haplotypes

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2009
Publication Date: July 17, 2009
Citation: Njambere, E., Vandemark, G.J., Chen, W. 2009. Genetic diversity of Sclerotinia trifoliorum infecting chickpea based on mycelial compatibility grouping, rDNA introns and multi-locus haplotypes. Phytopathology. 99:S94

Technical Abstract: Sclerotinia trifoliorum is recently reported as a new pathogen of chickpea in North America. The diversity and genetic structure of this heterothallic fungus is poorly understood. This study was designed to investigate the genetic structure and diversity of the pathogen. A collection of 133 isolates of S. trifoliorum was obtained from 9 locations from chickpea fields in Central and Sacramento valleys of California, plus three isolates from alfalfa. Three techniques were used to measure genetic diversity: mycelial compatibility grouping (MCG), ribosomal DNA (rDNA) introns, and multi-locus haplotypes of microsatellite loci and sequence related amplified polymorphism (SRAP) markers. Very diverse MCGs were found among the populations. The 136 isolates were assigned to 80 MCGs. Variation in the rDNA introns divided the isolates into 4 rDNA haplotypes. Combination of 51 SRAP loci and one microsatellite locus divided the isolates into 69 haplotypes. A strong correlation between MCGs and rDNA haplotypes was found. However no discernible patterns were observed between MCGs and multi-locus haplotypes. This study provides evidence for both clonality and recombination in S. trifoliorum. Disease management strategies should not only identify suitable rotation crops, but also consider the high levels of genetic heterogeneity in order to effectively control the disease.