Distribution and diversity of cyst nematode (Nematoda: Heteroderidae) populations in the Republic of Azerbaijan, and their molecular characterization using ITS-rDNA analysis

Abstract

Cereal cyst nematodes (Heterodera spp.) are a significant threat to global cereal production systems and choosing the correct management strategy requires knowledge and identification of various species. We conducted a survey across the main cereal-growing regions of the Republic of Azerbaijan in 2017. Cyst-forming nematodes were detected in 34 samples (44.7%), of which 28 were identified as H. filipjevi or H. avenae using internal transcribed spacer (ITS)-rDNA sequencing. Six populations were unidentifiable to species level and were recorded as belonging to the H. avenae group. H. filipjevi was the dominant species, found in 19 samples (25%) from the provinces of Qobustan, İsmailli, Oguz, Sheki, Barda, and Kurdamir. H. avenae was detected in 9 samples (11.8%) across the provinces of İsmailli, Oguz, and Sheki. ITS-rDNA phylogenetic analyses showed that populations of H. filipjevi clustered in one group with two subgroups, all supported by high bootstrap values. Populations of H. avenae also clustered in one group with two subgroups. Genetic dissimilarities were higher within populations of H. filipjevi when compared to populations of H. avenae. The density of many of these cyst populations approached or exceeded the maximum threshold level for economic losses. This is the first report on H. filipjevi and H. avenae in Azerbaijan. The knowledge of cereal cyst nematode presence is extremely important for Azerbaijan’s agricultural industry when assessing the occurrence and distribution of soilborne diseases. Management measures to control cereal cyst nematodes should be directed towards breeding for resistant germplasm, crop rotation, and implementing other management practices.