Investigation Of Cereal Cyst Nematode On Wheat In Jiangsu Province And The Sequence Analysis Of RDNA-Its Region From Jiangsu Populations

Cereal cyst nematode (CCN), Heterodera avenae Wollenweber 1924, is a plant parasitic nematode which threat the production of wheat. It was first discovered at Tianmen county of Hubei Province in 1989. During the following 20 years, the cereal cyst nematode has been reported continuously in Hebei, Henan, Beijing, Shannxi, Shan'xi, Inner Mongolia, Qinghai, Gansu, Shandong and Anhui, which has caused serious economic loss to the production of wheat. However, the occurrence of CCN in Jiangsu Province is still unknown.During May of 2009, the investigation of cereal cyst nematode (CCN) was carried out on wheat fields from 22 counties of 5 districts(Xuzhou, Liangyungang, Suqian, Yancheng and Huanan) in Jiangsu province, China. Total 76 samples with roots and soils were collected. The results of the nematode extraction and identification demonstrated that H. avenae was distributed in Xuzhou, Liangyungang, Suqian and Yancheng districts. The incidence rate was 35%. The occurrence of CCN was varied in different district and CCN was wide distributed in Xuzhou district where 67% samples were detected with CCN. The CCN incidence rates in wheat growing areas of Peixian, Fengxian, Pizhou and Suining counties from Xuzhou district were higher than 90%. The Xuzhou district was heavily infested by CCN and the average cyst number per 100 mL soil of all CCN samples was 54. The Yancheng distict was the second one with average 37 cysts for CCN samples. The Liangyuangang and Suqian district were slightly infested by CCN. Moreover, the population density was varied in different districts and different sampling sites from the same district. The number of eggs per cyst was also significantly different in different sampling places. The cyst densities of the fields from Huashan town (Fengxian), Hekou town (Peixian) and Surburb of Fengxian were higher than the other investigated fields, with average 161,159 and 112 cysts/100ml soil and 187,190 and 174 eggs/cyst, respectively. The ITS region of ribosomal DNA was amplified from 15 CCN populations from Jiangsu Province. The ITS-RFLP patterns revealed that all populations were showed with the same fragments after digestion with 8 restriction enzymes. The Jiangsu populations not only obtained the same patterns as the " B" type (Indian populations) by AluⅠand RsaⅠdigestions, but also the "C" type by HinfⅠand Tru9Ⅰdigestions which were specialized for Chinese populations. The phylogeny trees were constructed by Neighbor-Joining (MEGA 4.0) based on ITS sequences and revealed that all of Jiangsu populations were grouped with the species from H. avenae complex, which was one of the branches of the H. avenae group. Most of the Jiangsu populations were genetically closed to the Russian and German populations of H. pratensis. The comparisons of ITS sequences from Jiangsu populations with other CCN populations from China and abroad revealed the rich genetic diversities were existed in CCN populations from Jiangsu and other provinces in China.