Mycologia (2007) 99, 59-77

T.L. Peever, M.P. Barve, L.J. Stone and W.J. Kaiser (2007)
Evolutionary relationships among Ascochyta species infecting wild and cultivated hosts in the legume tribes Cicereae and Vicieae
Mycologia 99 (1), 59-77
Abstract: Evolutionary relationships were inferred among a worldwide sample of Ascochyta fungi from wild and cultivated legume hosts based on phylogenetic analyses of DNA sequences from the ribosomal internal transcribed spacer regions (ITS), as well as portions of three protein-coding genes: glyceraldehyde-3-phosphate-dehydrogenase (G3PD), translation elongation factor 1-alpha (EF) and chitin synthase 1 (CHS). All legume-associated Ascochyta species had nearly identical ITS sequences and clustered with other Ascochyta, Phoma and Didymella species from legume and nonlegume hosts. Ascochyta pinodes (teleomorph: Mycosphaerella pinodes [Berk. and Blox.] Vestergen) clustered with Didymella species and not with well characterized Mycosphaerella species from other hosts and we propose that the name Didymella pinodes (Berk. and Blox.) Petrak (anamorph: Ascochyta pinodes L.K. Jones) be used to describe this fungus. Analysis of G3PD revealed two major clades among legume-associated Ascochyta fungi with members of both clades infecting pea ("Ascochyta complex"). Analysis of the combined CHS, EF and G3PD datasets revealed that isolates from cultivated pea (P. sativum), lentil (Lens culinaris), faba bean (Vicia faba) and chickpea (Cicer arietinum) from diverse geographic locations each had identical or similar sequences at all loci. Isolates from these hosts clustered in well supported clades specific for each host, suggesting a co-evolutionary history between pathogen and cultivated host. A. pisi, A. lentis, A. fabae and A. rabiei represent phylogenetic species infecting pea, lentil, faba bean and chickpea, respectively. Ascochyta spp. from wild relatives of pea and chickpea clustered with isolates from related cultivated hosts. Isolates sampled from big-flower vetch (Vicia grandiflora) were polyphyletic suggesting that either this host is colonized by phylogenetically distinct lineages of Ascochyta or that the hosts are polyphyletic and infected by distinct evolutionary lineages of the pathogen. Phylogenetic species identified among legume-associated Ascochyta spp. were fully concordant with previously described morphological and biological species.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website

Research topic(s) for pests/diseases/weeds:
identification/taxonomy

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Ascochyta lentis	Lentil (Lens culinaris)
	Didymella pinodes
	Ascochyta fabae	Broad/faba bean (Vicia faba)
	Ascochyta pisi	Pea (Pisum sativum)
	Ascochyta rabiei	Chickpea (Cicer arietinum)