Population Genetics and Virulence Patterns of Sunflower Broomrape Populations From Serbia

ABSTRACT Sunflower broomrape ( Orobanche cumana Wallr.) is one of the most damaging biotic constraints to sunflower production worldwide. Serbia is a major sunflower‐producing country in southeastern Europe, where broomrape has shown a continuous increase in virulence during the last decades. This study aimed to characterise the genetic diversity, population structure and virulence of O. cumana populations recently collected from different regions of Serbia. Thirteen populations were analysed using 192 SNP markers and compared with 29 reference populations from nearby countries, including Hungary, Bulgaria, Romania, Russia, Turkey and Ukraine. In total, 905 individual broomrape plants were genotyped. Principal coordinates and STRUCTURE analyses revealed two distinct genetic groups among the Serbian populations. The first gene pool (G1) included eight populations from the North Bačka county, genetically close to Hungary, with very low intrapopulation variability (Shannon's index < 0.14) and phenotypically classified as Race F. The second gene pool (G2) comprised five populations from South Banat county, characterised by higher intrapopulation variability (Shannon's index up to 0.33) and higher virulence (Race G). These results indicate the coexistence of two genetically and geographically distinct gene pools of sunflower broomrape in Serbia, likely reflecting different introduction events and evolutionary histories. The low diversity within G1 suggests a founder effect, while the genetic heterogeneity of G2 points to a possible origin or admixture with populations from neighbouring eastern countries. The combined virulence and genetic evidence provide valuable insight into the evolutionary dynamics of O. cumana in Serbia and highlight the importance of regional monitoring for breeding programs seeking durable resistance in sunflower.