Occurrence, Etiology And Resistant Evaluation Of Heterodera Avenae On Oat In Gansu Province

Cereal cyst nematode(CCN, Heterodera spp.) is a kind of worldwide important pathogenic nematodes which damages grain production. In order to define occurrence、distribution、infection dynamics and type of cereal cyst nematode in main oat areas of Gansu province. this tests investigate incidence rates of cereal cyst nematodes, identificate nematode species, study nematodes infection dynamics and resistant evaluation of ereal cyst nematodes in Gansu province. The results were as following:1. The tests Investigated 20 villages and towns and collecte a total of 211 soil samples. After flotation separation,cysts can finded in 145 soil samples which accounted for 68.7% of the total sample number. In Gannan, the incidence of cyst nematodes was 87.5%, in the 80 soil samples with 3.7cysts/100 g soil samples.In Tongwei, the incidence of cyst nematodes was 78.6%, in the 42 soil samples with 5.5cysts·100 g soil samples. In Linxia, the incidence of cyst nematodes was 77.8%, in the 9 soil samples with 2.4cysts·100 g soil samples. In Tianzhu, the incidence of cyst nematodes was 44%, in the 80 soil samples with 4.3cysts·100 g soil samples. Take Gannan as an example, 2501~2800m altitude area have highest incidence of cysts,it can reach100%, 3101-3500 m altitude area have lowest incidence of cysts, it can reach 58.3%.2. Morphological characteristic of Tianzhu、Gannan and Linxia show that the cysts were shallow brown and large lemon-shaped, the vulva cones were double Fenestra area. There was obvious bullaeno without under-bridge in vulva.However,There was obvious under-bridge in vulva and the vulva cones were double half Fenestra area in Tongwei. The phylogenetic tree revealed that the Tianzhu、Gannan and Linxia populations were grouped with domestic and abroad populations of H. avenae into a branch.Tongwei populations were grouped with domestic and abroad populations of H.glycines. So the nematodes collected from oats in the Tianzhu、Gannan and Linxia were identifized as H. avenae and Tongwei populations were identifized as H.glycines.3. 9 restriction enzymes enzyme 15 representative cereal cyst nematodes community of r DNA-ITS area from Gannan and Linxia,which produced 23 clear enzyme fragment. the measurement of all groups have the same enzyme. HinfⅠ digested PCR amplified ITS products of 15 populations obtained 2 same fragments(860、180 bp),MseⅠdigested PCR amplified ITS products of 15 populations obtained 4 same fragments(540、300 bp、180 bp、10bp).cereal cyst nematodes community of Tianzhu、Gannan and Linxia are divided into group "C" type in China by their enzyme map.4. Hatching dynamic and law of infection are observed in natural illness oat fields, which showed that: after two weeks of sowing seeds, the second-stage juveniles began to invade the root of oat. The tillering stage(May 4) of oat was the peak of the second-stage juveniles. In the jointing stage(May 11), the three-stage juveniles can be finded, the heading stage(June 8)was the peak of the three-stage juveniles. At the beginning of heading stage, the four-stage juveniles can be finded, the oat flowering stage(June 15)was the peak of the four-stage juveniles. Filling stage(June 29), the white female appear in oat root, grain filling stage, new wheat cyst appeared in soil. In Gansu Province, one of the first generation of oat cyst nematode disease.5. The evaluation test of host resistance with artificial inoculation showed that: 16 main oat varieties under tested of Gansu Province,the vast majority of disease resistance. White females number in roots of Longyan No.3 oat varietie are 2.4 which Show high resistance to disease and have better growth. Include Qinyin No.2,Yellow oats and Baiyan No.2 showed moderate resistance,which plus 12 oat varieties. Their roots formed White females number between 5.1~10.0. Baiyan No.9, Longyan No.2, Qinyin No.1 showed moderately susceptible, Their roots formed White females number between 10.1~20.1.