Sensitive and Direct Detection of Heterodera filipjevi in Soil and Wheat Roots by Species-Specific SCAR-PCR Assays.

Cereal cyst nematodes are the most important plant-parasitic nematodes on cereal crops in wheat producing areas of the world. Heterodera filipjevi was first reported in China in 2010. In this study, species-specific sequence characterized amplified region-polymerase chain reaction (SCAR-PCR) assays for detection and identification of H. filipjevi from infected wheat roots and soil were developed. The species-specific primers were designed according to the randomly amplified polymorphic DNA (RAPD) markers amplified with random primer OPK16. A 646-bp specific fragment of sequence was generated, which characterized amplified regions in H. filipjevi. The detection limitation of the PCR assay was as low as 0.125 μl second-stage juvenile (J2) lysate, 3.9 × 10-3 μl adult female lysate, and 10-3 μl cyst lysate. The method was able to detect the various stages (J2, J3, J4, and female) of H. filipjevi, and a single of nematode in 0.5 g of soil. H. filipjevi was detected by the method in two of six field samples, and one of those samples contained a mixed population of H. filipjevi and H. avenae. This study is the first to provide a definitive diagnostic assay for H. filipjevi in wheat roots and soil.