Inbred‐Race Recovery From a Mixed Population of the Parasitic Weed Sunflower Broomrape ( Orobanche cumana Wallr .)

ABSTRACT Sunflower broomrape ( Orobanche cumana Wallr.) is a holoparasitic weed with two distinct genetic pools in Spain: the Guadalquivir Valley (GV) and Cuenca province (CU). From a stable situation where races F (F GV and F CU ) were predominant, new races have recently emerged: G GV and G CU , presumably caused by population movements and cross‐fertilisation, and F + CU , putatively arising from a point mutation. Population NCU3 was found in a previous study to have full membership (100%) to the CU gene pool and F + CU virulence, although we hypothesised that individuals with F CU virulence could also be present. Because the original F CU race had become indistinguishable due to admixture with populations of other races, this research aimed to identify and isolate individuals of the inbred F CU race from the NCU3 population. For this purpose, 82 individual plants of the NCU3 population were self‐fertilised and genotyped using the SNP marker SNcum‐26, which consistently discriminates between the GV and CU gene pools. This confirmed that the 82 individuals belonged to the CU gene pool. Their progenies were evaluated against the differential line DEB2, which is resistant to race F CU and susceptible to race F + CU . The progenies of four individuals showed avirulence against DEB2, which was confirmed for three of them in a subsequent evaluation of their progenies. One of the progenies was selected and re‐evaluated, proving that it behaves like the F CU race. This study introduces a novel methodological approach using progeny testing on a differential line to separate two inbred races from a mixed population. While this method was developed with the specificity of the CU gene pool populations, it can also be applied in other contexts.