The Effects Of Soil Environment On Soybean Cyst Nematode(Heterodera Glycinese) Egg Hatch And Nematode Molecular Diagnosis

Soybean cyst nematode(Heterodera glycilnes Ichnohe,SCN)is one of maindiseases of soybean continuous cropping and a main barrier factor of those. Therelationship between soybean cyst nematode and soybean continuous croppingwas attented by researcher. First time using long term site-specific fieldexperiment to study soil environment effects on soybean cyst nematode ofdifferent rotation systems in black soil, the aim was to search the relationshipbetween soybean root exudates and soil leachate of different rotation systems andsoybean cyst nematode egg hatch. The resistance mechanism study aboutresistance variety Kangxian 4 which was breeded in China to soybean cystnematode was conducted. The molecular diagnosis with rDNA-ITS-RFLP and ISSR were used toidentify SCN　 population isolated from China, America, Canada, and Argentina.The study also focused on SCN　 populations China　 (Helongjiang isolates) as amodel to test the relationship between a major factors, plant root exudates, and thenematode egg hatch in the soil. The results showed soybean cyst nematode populations variety of the soil insoybean continuous cropping(S… S) 8-12 years, soybean rotation with corn andwheat(WCS) and soybeanrotation annually with wheat(or corn, SWS or SCS).Thecysts of soybean cyst nematode of the soil in S… SS for 8-12 years were more thanother rotation systems, the cysts of soybean cyst nematode of the soil in SWS andSCS were less and the cysts of soybean cyst nematode of the soil in WCS wereleast. As the years of soybean continuous cropping increase, the cysts of soybeancyst nematode in the soil had a trend to decrease. Perhaps it was the reason thatthere was suppressive soil . XIII东北农业大学农学博士学位论文 Since the 80's of 20 centuries some resistance varieties to SCN such asKangxian 1, Kangxian 2, Kangxian 3,Kangxian 4 and Kangxian 5, were breeded inChina that were released in Heilongjiang province .But now the resistancemechanism of theirs were not know yet. In order to understand resistancemechanism of resistance variety Kangxian 4 relationship between the developmentdynamic of SCN and different soybean varieties was studied. The results showedresistance mechanismof resistance variety Kangxian 4 was resistance invasion. Soil leachate extracted from different crops cultivation showed differenteffects on the nematode egg hatch. Eggs treated with soil extract from soybeancultivation had significantly higher hatch rate than the ones treated with that fromother crops such as corn, sugar beet, wheat, and flax. Soil leachate extracted fromdifferent crops pre-cultivation showed positive effect on the nematodes egg hatch,in which beet pre-cultivation showed the most. This result explained why yearlyrotation between soybean and other crops can reduce the nematode damage.However, the soil extract from multi years continues cropping of soybean showedsuppression on the nematode egg hatch. This indicated that the concentration ofthe putative factors plays a role of regulating the nematode egg hatch. The amplification of the rDNA-ITS region of SCN populations from China,America, Canada, and Argentina yielded a single PCR fragment of approximately1060bp(including primes) for each of 16 SCN populations. No PCR products wereobtained in the control lacking the DNA template. A total 25 scored fragmentswere obtained with 17 restriction enzymes and used for analysis. The AvaI,EcoRI, HinfI, AluI, HaeⅢ, ClaI, MboI, AccI and RsaI digestions each showedidentical restriction profiles for all populations .The AvaI digestions of 5 ChineseSCN populations yielded 3 restriction fragments ,but yielded 2 restrictionfragments for America, Canada, and Argentina. It was the first report of geneticdiversity of SCN of Chinese , Canada, and Argentina with rDNA-ITS-RFLP. The genetic diversity of SCN populations from China, America, Canada, andArgentina were tested by ISSR analysis .The sel...