Host range studies with an Australian isolate of Ascochyta rabiei

Khan, M. S. A.; Ramsey, M. D.; Scott, Eileen S.

doi:10.1071/ap99028

Cited by 17 publications

(12 citation statements)

References 7 publications

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“…Experimental inoculations of various legume hosts with Ascochyta spp. has confirmed host specificity and supports this hypothesis (Gossen et al 1986, Kaiser et al 1997, Khan et al 1999, Hernandez-Bello et al 2006. Isolates sampled from Pisum, Vicia and Lens fell into two well supported major clades that we have labeled the ''A.…”

Section: Discussionsupporting

confidence: 71%

Evolutionary relationships among Ascochyta species infecting wild and cultivated hosts in the legume tribes Cicereae and Vicieae

Peever¹,

Barve²,

Stone

et al. 2007

Mycologia

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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. & 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. & 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.

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Section: Discussionsupporting

confidence: 71%

Evolutionary relationships among Ascochyta species infecting wild and cultivated hosts in the legume tribes Cicereae and Vicieae

Peever¹,

Barve²,

Stone

et al. 2007

Mycologia

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“…Ascochyta fabae, A. pisi, A. rabiei, A. lentis and A. viciae-villosae caused disease when inoculated onto faba bean, pea, chickpea, lentil and hairy vetch, respectively (Hernandez-Bello et al 2006). The results of Hernandez-Bello et al (2006) agree with previous inoculation studies where A. rabiei failed to cause disease on lentil, pea and vetch (Kaiser 1973;Tripathi et al 1987;Kaiser 1991;Khan et al 1999) and A. fabae and A. lentis could only cause disease on their respective hosts (Kaiser et al 1997). The phylogenetic analyses demonstrated that A. rabiei, A. pisi, A. lentis, A. fabae, and A. viciae-villosae are each monophyletic (Fig.…”

Section: Species Of Ascochytasupporting

confidence: 90%

“…Artificial inoculations in the greenhouse and in growth chambers have demonstrated that legumeassociated Ascochyta fungi are host-specific (Kaiser 1973;Tripathi et al 1987;Kaiser 1991;Kaiser et al 1997;Khan et al 1999;Hernandez-Bello et al 2006). Ascochyta fabae, A. pisi, A. rabiei, A. lentis and A. viciae-villosae caused disease when inoculated onto faba bean, pea, chickpea, lentil and hairy vetch, respectively (Hernandez-Bello et al 2006).…”

Section: Species Of Ascochytamentioning

confidence: 97%

Role of host specificity in the speciation of Ascochyta pathogens of cool season food legumes

Peever

2007

Eur J Plant Pathol

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Ascochyta/legume interactions are attractive systems for addressing evolutionary questions about the role of host specificity in fungal speciation because many wild and cultivated cool season food legumes are infected by Ascochyta spp. and most of these fungi have described teleomorphs (Didymella spp.) that can be induced in the laboratory. Recent multilocus phylogenetic analyses of a worldwide sample of Ascochyta fungi causing ascochyta blights of chickpea (Cicer arietinum), faba bean (Vicia faba), lentil (Lens culinaris), and pea (Pisum sativum) have revealed that fungi causing disease on each host formed a monophyletic group. Host inoculations of these fungi demonstrated that they were host-specific, causing disease only on the host species from which they were isolated. In contrast to the strict association between monophyletic group and host observed for pathogens of cultivated legumes, Ascochyta fungi causing disease on wild bigflower vetch (Vicia grandiflora) were polyphyletic. Genetic crosses between several pairs of closely related, host-specific, and phylogenetically distinct Ascochyta fungi were fully sexually compatible. Progeny from these crosses had normal cultural morphology and segregation of molecular markers indicating a lack of intrinsic, post-zygotic mating barriers between the parental taxa. However, when progeny from a cross between a faba bean-adapted isolate (A. fabae) and a pea-adapted isolate (A. pisi) were assessed for their pathogenicity to the parental hosts, almost all progeny were non-pathogenic to either faba bean or pea. These results suggest that although these fungi have retained the ability to mate and produce progeny with normal saprophytic fitness, progeny are severely compromised in parasitic fitness. The host specificity of these fungi, coupled with the inability of hybrid progeny to colonize and reproduce on a host, may constitute strong extrinsic, pre-zygotic and postzygotic mating barriers in these fungi and promote the genetic isolation and speciation of host-specific taxa. A phylogeny of the host plants is also being developed, and with more extensive sampling of pathogens and hosts from sympatric populations in the centre of origin, the hypothesis of cospeciation of pathogens and hosts will be tested. The objectives of this review are: (1) to summarize recent phylogenetic, host specificity and speciation studies of Ascochyta fungi, and (2) to suggest how current and future research using these pathosystems may lead to a better understanding of the role of host specificity in the speciation of plant-pathogenic fungi and the cospeciation of pathogens and their hosts.

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“…Previous studies on the host range of the Ascochyta blight pathogen only demonstrated that other plant species could be alternative hosts of D. rabiei (Kaiser 1973(Kaiser , 1990Nene and Reddy 1987;Khan et al 1999). However, information is lacking on whether the teleomorph of A. rabiei develops on the debris of these asymptomatic hosts.…”

Section: Discussionmentioning

confidence: 94%

“…However, other investigators have demonstrated that the pathogen is capable of infecting different plant species, although without disease symptoms. Kaiser (1973), Nene and Reddy (1987), and Khan et al (1999) were able to infect several leguminous and non-leguminous plant species. Kaiser (1990) reported that D. rabiei was isolated from 13 asymptomatic plant species collected from blighted chickpea fields or from plantings where debris from diseased chickpeas remained on the soil surface overwinter in the Palouse region of eastern Washington (WA) and northern Idaho (ID), USA.…”

Section: Introductionmentioning

confidence: 97%

Alternative hosts and plant tissues for the survival, sporulation and spread of the Ascochyta blight pathogen of chickpea

Trapero

Kaiser²

2009

Eur J Plant Pathol

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Various crop and weed species were infected naturally by Didymella rabiei (anamorph: Ascochyta rabiei) in blight-affected chickpea fields in the Palouse region of eastern Washington and northern Idaho, USA. The fungus was isolated from asymptomatic plants of 16 species commonly found in commercial crops in this region. Isolates of the pathogen from crop and weed species were pathogenic to chickpea and indistinguishable in cultural and morphological characteristics from isolates of D. rabiei from chickpea. Both mating types of D. rabiei were isolated from eight naturally infected plant species. Chickpeas were infected by D. rabiei when plants emerged through infested debris of seven crop and weed species. The teleomorph developed on overwintered tissues of seven plant species infected naturally by D. rabiei in a blight screening nursery and on debris of wheat, white sweet clover and pea inoculated with ascospores of D. rabiei or conidia of two compatible isolates of the pathogen. Didymella rabiei naturally infected 31 accessions of 12Cicer spp. and the teleomorph developed on the overwintered debris of all accessions, including those of three highly resistant perennial species. The fungus developed on the stem and leaf pieces of ten plant species common to southern Spain inoculated with conidia of two compatible isolates of D. rabiei, and formed pseudothecia with asci and viable ascospores on six of ten species and pycnidia with conidia on all plant species.

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Host range studies with an Australian isolate of Ascochyta rabiei

Cited by 17 publications

References 7 publications

Evolutionary relationships among Ascochyta species infecting wild and cultivated hosts in the legume tribes Cicereae and Vicieae

Evolutionary relationships among Ascochyta species infecting wild and cultivated hosts in the legume tribes Cicereae and Vicieae

Role of host specificity in the speciation of Ascochyta pathogens of cool season food legumes

Alternative hosts and plant tissues for the survival, sporulation and spread of the Ascochyta blight pathogen of chickpea

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