Genetic variation of bread wheat accessions in response to the cereal cyst nematode, Heterodera filipjevi

Bread wheat, Triticum aestivum, produces large edible grains and is consumed by 75% of the world's populations. Cereal cyst nematodes have a global distribution and cause significant economic yield losses in many countries. Therefore, there is an urgent need to identify new resistance sources. In this study, the genetic diversity of 43 wheat accessions in response to cereal cyst nematode, Heterodera filipjevi Isfahan pathotype, was assessed using a simple sequence repeat (SSR) marker. Seven primers were used, out of which five primers showed polymorphisms. Alleles per primer varied from one to three per locus (mean 2.85). The highest and lowest polymorphic information content of 0.81 and 0.44 (mean 0.66) were related to Xgwm 3012DL and Xgwm147, respectively. Genetic similarity was 29-88% between accessions. SSR analysis divided the accessions into five main groups. Resistant cultivars 'Bam' and 'Behrang' possessed both Cre1 and Cre8 resistant genes. The Cre3 and Cat genes were partially sequenced in five cultivars of different responses to H. filipjevi. The nucleotide sequences were compared to Cre3 and Cat homologues, indicating 93-100% and 86-92% homology, respectively. The MEGA program showed highest similarity of Cre3 and Cat genes amplified with the resistance gene analogues (RGA14) in the wheat and Cat3-Al gene in 'Carnamah'. This research showed that SRR markers could efficiently verify genetic diversity between wheat accessions, and the known resistance genes (Cre genes) against the cereal cyst nematodes could not control the H. filipjevi Isfahan pathotype populations, except the Cre1 gene.