Abstract
Crenate broomrape (Orobanche crenata Forsk.) is a serious
long-standing parasitic weed problem in Algeria, mainly affecting
legumes but also vegetable crops. Unresolved questions for parasitic
weeds revolve around the extent to which these plants undergo local
adaptation, especially with respect to host specialization, which would
be expected to be a strong selective factor for obligate parasitic
plants. In the present study, the Genotyping-By-Sequencing (GBS)
approach was used to analyze genetic diversity and population structure
of 10 Algerian O. crenata populations with different geographical
origins and host species (faba bean, pea, chickpea, carrot and tomato).
In total, 8,004 high-quality single-nucleotide polymorphisms were
obtained and used across the study. Genetic diversity and relationships
of 95 individuals from 10 populations were studied using model-based
ancestry analysis, principal components analysis, discriminant analysis
of principal components, and phylogeny approaches. The genetic
differentiation (FST) between pairs of populations was
lower between adjacent populations and higher between geographically
separated ones, but no support was found for isolation by distance.
Further analyses identified four genetic clusters and revealed evidence
of structuring among populations and hosts with more evident structuring
among hosts than strictly along a geographic gradient. In the most
striking example, O. crenata growing on pea had a distinct SNP
profile from those growing on faba bean or other crops. These results
illustrate the potential of GBS to reveal the dynamics of parasitic weed
dispersal and adaptation.
Key words: Orobanche crenata , Algeria, genetic
diversity, population structure, genotyping by sequencing, GBS.