engleski

Genetic variability among O. foetida populations collected in Morocco

Orobanche foetida Poir. parasitizes several herbaceous wild and cultivated legumes. It has been only considered an important threat, as agricultural parasite, on faba beans and common vetch in Tunisia. Very recently, O. foetida has been reported in Morocco also infecting common vetch. Better understanding of the evolution of this species is essential to determine the risks of appearance of a new race capable of parasitizing a particular crop where it was not observed before. Thus, the objectives of this study were to analyse molecular variability between and within different pathogenic populations of O. foetida collected in Morocco. Five populations of O. foetida were analysed by AFLP markers One population was collected from a cultivated host (Vicia sativa) while the rest was collected from wild plant species (three from Scorpiurus muricatus and one from wild Vicia sp. or Lotus sp.). Although an analysis of molecular variance (AMOVA) attributed most of the AFLP phenotypic diversity (86.25%) to differences among individuals within populations, significant  -values among populations suggested the existence of population structure. Nevertheless, when populations were grouped according to host status (cultivated vs. wild), among-group variation was not significant. Principal coordinate analysis based on Dice's distance matrix showed clear separation of individuals belonging to population parasitizing wild Vicia sp. or Lotus sp. from the rest. The Bayesian model-based clustering method implemented in the program STRUCTURE allowed the identification of three gene pools. The gene pool A was predominant in populations infecting Scorpiurus muricatus while the gene pool B occurred exclusively in the population collected from wild Vicia sp. or Lotus sp. The gene pool C was mostly found in population parasitizing common vetch, but was also present, to a lesser extent, in two of three population infecting Scorpiurus muricatus. Observed partitioning of diversity among and within sampled populations could indicate that O. foetida is mixed-mating or outcrossing species. Newly detected O. foetida population infecting common vetch could not be unambiguously separated form populations infecting Scorpiurus muricatus implying the existence of a recent common ancestor and/or a high gene flow among them. Thus, it would seem that the parasite genotypes able to infect a cultivated species arose from naturally occurring O. foetida populations growing on wild hosts. Moreover, the results of the Bayesian analysis of underlying population structure could suggest that the host-induced differentiation process started only recently and is currently in action.

Orobanche foetida; AFLPs; diversity; population structure; host-differentiation

nije evidentirano