Genetic diversity of Orobanche cumana populations from Spain assessed using SSR markers

Abstract

SummaryOrobanche cumana (sunflower broomrape) is found in Spain as an allochthonous species parasitising exclusively sunflower. For many years, it was distributed in the Guadalquivir Valley and Cuenca province, but in recent years, it has spread to new areas. The objective of this research was to study genetic diversity of O. cumana populations from Spain using robust co‐dominant molecular markers. Cluster analysis on a set of 50 populations using 15 microsatellite markers revealed the existence of two distant gene pools, one in Cuenca province and another one in the Guadalquivir Valley. Within each gene pool, both inter‐ and intrapopulation variability were extremely low. This population structure probably reflects a founder effect, with the two genetically distant gene pools deriving from separate introduction events. Different races occurred within the same gene pool, suggesting that current races might have evolved through mutation from a common genetic background. Most of the populations from new areas were identical to the populations from the Guadalquivir Valley. Only a few populations showed larger intrapopulation variation. In these cases, our results suggested the co‐existence of both gene pools within the same population, as well as the occurrence of genetic recombination between them. Genetic recombination between distant gene pools is an important mechanism for creating new variation, which might also have an effect on race evolution. These results will contribute to the establishment of improved crop breeding and management strategies for O. cumana control.