Abstract Detail

Poster Session

Habibi, Azadeh [1], Frederick, Zachary [1], Koberstein, Staci [1], Liu, Lu [1], Nazarov, Taras [1], Salamone, Amy [1], Wheeler, David [1], Carris, Lori [1], Peever, Tobin [1].

How many species of Ascochyta cause Ascochyta blights of cultivated legumes and their wild relatives?

Ascochyta blights of cool season legumes are economically important diseases caused by host-specific Ascochyta taxa that infect both cultivated hosts and their wild relatives. Based on the results of previous phylogenetic analyses, 10 Ascochyta isolates from cultivated (faba bean, lentil, pea) and wild (common vetch, hairy vetch, spring vetch, winter vetch, cypress vetch, and grasspea) hosts were selected to represent different multilocus haplotypes within a major clade of Ascochyta infecting cool season food legumes. This sample formed the basis of a class project by graduate students enrolled in Plant Pathology 526 “Advanced Fungal Biology” at Washington State University. Phylogenetic analyses of ß-tubulin, translation elongation factor 1-alpha (EF), glyceraldehyde-3-phosphate-dehydrogenase (G3PD), chitin synthase1, and two sequence characterized amplified regions (SCAR) were conducted in order to resolve outstanding questions about branching order, timing of divergence events, and recognition of phylogenetic species. Ascochyta isolates infecting lentil (Lens culinaris) and grasspea (Lathyrus sativus) with identical EF + G3PD haplotype were selected for more intensive study and application of additional species concepts. Both isolates were host-specific, capable of infecting the host from which they were isolated. Crosses were made to test reproductive compatibility under the biological species concept. Pseudothecia developed readily, and segregation of alleles at four microsatellite loci and the MAT locus confirmed hybrid status. Segregation ratios were not statistically different from 1:1 indicating normal meiotic segregation. Mean lengths of conidia produced by the two taxa were statistically different (P<0.05) indicating morphological differentiation. Results of phylogenetic analyses and crosses resolved branching order, time of divergence, and reproductive compatibility among Ascochyta isolates infecting cool season legumes and their wild relatives.

1 - Washington State University, Department of Plant Pathology, Advanced Fungal Biology Class, Pullman, WA, 99164-6430, USA

Keywords:
Ascochyta
Didymella
host specificity
phylogeny
speciation.

Presentation Type: Offered Paper - Poster
Session: P6
Location: Lincoln Room/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 8:00 PM
Number: P6010
Abstract ID:152
Candidate for Awards:None