Study On The Species And Pathotypes Of Three Cereal Cyst Nematode Populations From Henan Province And The Resistance Of Wheat Cultivars

The cereal cyst nematode (CCN) occurred and distributed widely in the major wheat growing regions which brought a potential menace on the wheat production in China. Henan province was the main wheat production region and its cultivated area and total output of wheat ranked first in China. In recent years, CCN has caused serious yield losses in Zhengzhou and Xuchang, Henan province. In order to provide basis for the disease control, species and pathotypes of CCN from both areas and the resistance of wheat and its relatives to CCN were identified, the disease-resistant mechanism of wheat to Heterodera avenae were preliminarily studied .The main research results presented as follows.The species of cereal cyst nematode from Zhengzhou (Xingyang population and Xushui population) and Xuchang (Xuchang population) were definited based on morphological and molecular methods. Xingyang population and Xushui population belonged to Heterodera avenae Wollenweber, 1924and Xuchang population belonged to H. filipjevi( ( Madzhidov,1981 )Stelter,1984. The mature cysts of both populations from Zhengzhou were lemon shaped, with colors from brown to dark brown, long neck, vulval cone, bifenestrate, vulval bridge. Cysts of Zhengzhou population didn′t have underbridge and their vulval cone had many bullae, yet the cysts of Xuchang population had underbridge, their vulval cone had less bullae. Second-stage juveniles of three populations were worm-shaped, with stylet of anchor-shaped basal knobs, ovoid oesophageal bulb, conical tail, hyaline tail.Amplification of the rDNA-ITS region yielded a single PCR fragment of approximately 1000bp for each of the 3 populations. Eight kinds of restriction enzymes, TaqⅠ、AluⅠ、HaeⅢ、HinfⅠ、RsaⅠ、PstⅠ、CfoⅠ、Tru9Ⅰwere used to digest production of rDNA–ITS–PCR. The result showed restriction patterns of Xingyang population and Xushui population were the same, their ITS type were type B.The restriction pattern of Xuchang population was the same as the roports before. Zhengzhou cereal cyst nematode could be separated from Xuchang cereal cyst nematode using restriction enzymes Taq I and Pst I.Cluster analysis for rDNA-ITS sequence, the populations of Xingyang and Xushui closely related to the herrings and native to the H. avenae populations from China and H.australis from Australia. The populations of Xuchang was clustered with high bootstrap supported with all H. filipjevi reported from foreign countries.The pathotypes of three populations of cereal cyst nematodes from Zhengzhou and Xuchang were identified using the International Host Differentials (IHD). According to the reactions of IHD (group A) to the nematodes, the pathotypes of both populations from Zhengzhou were the same, but they were different from ones which had been nominated and reported. The pathotype of Zhengzhou populations were similar to Hal3, which was the dominant pathotype in Australia. Accoding to nomenclature, the two populations of Zhengzhou should belong to pathotype group 3, so the pathotype of Zhengzhou populations were named as Ha43.The pathotype of Xuchang population was different from ones which had been nominated. It was different from the two populations of Zhengzhou. The resistant reaction of five barley, two oats and a wheat cultivars were different. Compared with other pathotypes in China, the pathotype of Xuchang population was the same as Fangshan population in Beijing and Xinxiang population in Henan, with little difference from Dingzhou population in Hebei, Taigu population in Shanxi and Guzhen population in Anhui. The pathogenicity of Zhengzhou populations was stronger than Xuchang population to IHD (group A).Resistance of main released wheat cultivars in Huanghuai wheat area was tested to H.avenae and H. filipjevi by inoculation in greenhouse or in diseased field. The results indicated that the reactions of 46 cultivars were not good in general for Xingyang population, most of cultivars were susceptible (moderate susceptible, susceptible or high susceptible), immune and high resistant cultivars were lacking, Taikong 6, Xinmai18, Zhongyu6 and Xinmai11 were resistant to H.avenae. Resistance of 46 cultivars was not good in general for Xuchang population, also. There was no resistant cultivars in greenhouse identification and all cultivars were moderate susceptible, susceptible or high susceptible. Six cultivars were resistant to Xuchang population in the field testing, they were Zhongyu6, Zhongyu6, Yanzhan4110, Pumai9, Yunong201 and Yunong949.The resistance of 66 wheat variety resources providing by CIMMYT and 41 relatives of wheat were tested to H. filipjevi of Xuchang population or H.avenae of Xingyang population. The results showed that 12 wheat cultivars were resistant to H. filipjevi of Xuchang population, for instance, 6R(6D), MACKELLER, CPI 133842, ect. There were abundant resistant resources in the relatives of wheat to cereal cyst nematode. Some materials in Aegilops, Agropyron, Elytrigria, Haynaldia were resistant to H.avenae and H. filipjevi, and they could be utilized in breeding for cereal cyst nematode disease resistance.Taking wheat Actin gene as a control, expression of wheat chitinase gene 4(Chi4) were analyzed in the different growing periods, in different positions of different resistant wheat cultivars after inoculating H. avenae by semi-quantitative RT-PCR. The results showed that the expression of Chi4 was up-regulated when wheat plants were infected by H. avenae, no matter the cultivar was resistant or susceptible. There was no significant difference for Upregulation of Chi4 between resistant and susceptible cultivars. The change of Chi4 activities was not the principal mechanism for the resistance of wheat to cereal cyst nematode.