Oligonucleotide fingerprinting detects genetic diversity among Ascochyta rabiei isolates from a single chickpea field in Tunisia

Abstract

Fifty isolates of Ascochyta rabiei (Pass.) Labr. were hierarchically sampled from four well-separated locations of a single chickpea field in Beja (Tunisia), and single-spored. DNA was isolated from in-vitro-grown mycelia, digested with HinfI or RsaI, and hybridized to a set of synthetic oligonucleotides complementary to simple repetitive sequences. According to the fingerprint patterns derived from the probes (CA)8, (CAA)5, (CAT)5 and (GATA)4, 12 different fungal haplotypes were found at various frequencies within the investigated field. Seven haplotypes were confined to one location only, four occurred at two, one at three, and none at all four locations. Most of the genetic variability originated from diversity within, rather than between, locations. In some cases, more than one haplotype was isolated from the same lesion of a single host plant. Genetic distances between isolates, as calculated from band-sharing data, varied between 0.05 and 0.22. Relatedness between the different haplotypes was evaluated by cluster analysis using UPGMA.

Genetic diversity and population structure of Ascochyta rabiei from the western Iranian Ilam and Kermanshah provinces using MAT and SSR markers

“…This compares to Tunisia where 123 A. rabiei isolates representative of five regions were analyzed to estimate genetic diversity and where a high level of genetic differentiation was detected among subpopulations (Gst=0.33; Rhaiem et al 2007). In contrast, on a smaller scale in Tunisia, Morjane et al (1994) examined the genetic variation among 50 isolates sampled from one single chickpea field. Most of the genetic variability was attributable to diversity within locations rather than between locations.…”

“…Molecular markers have been widely deployed to detect and identify A. rabiei isolates and to examine genetic diversity, genetic structure, and virulence in populations of this fungus (Morjane et al 1994;Peever et al 2004;Phan et al 2003;Santra et al 2001;Udupa et al 1998). Significant genetic variation was shown in populations of A. rabiei in Italy (Fischer et al 1995), Tunisia Morjane et al 1994), Syria and Lebanon (Udupa et al 1998), Spain (NavasCortés et al 1998), Pakistan (Jamil et al 2000) and India (Santra et al 2001). In some regions of the world where chickpea has only recently been introduced, for example Australia and California, only modest genetic diversity and a single mating type has been reported (Kaiser 1997;Phan et al 2003).…”

Genetic diversity of Microdochium nivale isolates from turfgrass

“…Genotypic diversity in local populations may arise from different factors, depending on source and type of inoculum, migration, sexual recombination, genetic drift and selection (Huff et al, 1994 ;Morjane et al, 1994 ;Peever & Milgroom, 1994). Forces such as the founder effect and random genetic drift followed by selection may act to reduce genetic diversity (Kohn et al, 1988 ;McDonald et al, 1989 ;Milgroom, Lipari & Powell, 1992), while immigration of propagules from outside areas, or the presence of a sexual state would increase genetic diversity (Morjane et al, 1994).…”

“…Forces such as the founder effect and random genetic drift followed by selection may act to reduce genetic diversity (Kohn et al, 1988 ;McDonald et al, 1989 ;Milgroom, Lipari & Powell, 1992), while immigration of propagules from outside areas, or the presence of a sexual state would increase genetic diversity (Morjane et al, 1994). Selection over time might either amplify or reduce the presence of certain genotypes (Morjane et al, 1994).…”

Chickpea Improvement: Role of Wild Species and Genetic Markers

“…Oligonucleotide fingerprinting has been used to distinguish isolates of Ascochyta rabiei collected from a single field (Morjane et al, 1994). Based on the fingerprint patterns derived from probes (CA) 8 , (CAA) 5 , (CAT) 5 and (GATA) 4 , a total of twelve different fungal haplotypes were observed at various frequencies within a single field.…”