Insights into the global spread of the sugar beet cyst nematode and its relevance to host breeding

BACKGROUND The sugar beet cyst nematode ( Heterodera schachtii ) is a globally distributed plant parasite that causes significant agricultural losses. It was recently detected for the first time in Xinjiang Uygur Autonomous Region, China. However, knowledge of the population genetics of this nematode is still limited, especially concerning the origin of H. schachtii populations in China. RESULTS We genotyped H. schachtii populations from China and integrated global datasets to assess genetic diversity, population structure, and migration history. Global populations showed high genetic diversity, with the greatest variation in China, Germany, and the United States. Three genetic groups were identified: Group EA (Europe, North America, Oceania, Middle East), Group CN (China), and Group KR (Korea). Moderate differentiation was observed among most populations, with low genetic distance between Chinese and German populations. Gene flow analyses revealed frequent exchanges, especially asymmetric migration from Europe/Middle East to other regions. Demographic modeling supports that Chinese H. schachtii populations were derived from Germany, which is likely the center of origin for H. schachtii . CONCLUSION Global H. schachtii populations exhibit complex migration patterns with significant genetic structure. The evidence for German ancestry of Chinese populations and asymmetric gene flow from Europe advances our understanding of this pathogen's global spread. Our findings will facilitate the selection of resistant cultivars and development of effective pest management strategies in northwestern China.