| Soybean Cyst Nematode (abbreviation:SCN) is one of the most serious diseases in soybean which was infected by Heterodera glycines Ichinohe(Wang Jinling,1982). Because of it's characters of the wide distribution, heavily damaged, wide range of host, many transmitted ways and the dormant cyst which could survive long time, it was a soil-borne diseases that was extremely difficult to control. The incubation characteristics of SCN were studied in this paper, such as the adaptation to temperature and other conditions, we also discussed the methods of breaking dormancy. At the same time, we hoped the molecular mechanisms of SCN's dormancy and hatching could be revealed from the perspective of physiological and biochemical point of view and the main results were summarized as follow:1. Through tested the total hatching number of J2 from eggs collected from 12 months and form rhizospheres of different corn cultivars and soybean cultivars with different resistance to SCN, the results showed that the total number of hatching J2 was fluctuated with the season. In spring(from Mar. to May), the total number of hatching J2 from cyst was largest, followed by summer(from June to Agu.in July the number disincrease Slightly);in fall, the total number of hatching J2 from cyst was the least. Cyst collected from Maize rhizosphere had higher hatching rate than soybean, while there was no obvious links in the number of hatching J2 between resistant and susceptible soybean cultivars2. By measuring the temperature, light and humidity on the the eggs collected for one year, the optimum temperatures of hatching were different for the eggs collected from different months, the range of the optimum temperatures on eggs hatching was between 24 to 30℃and eggs collectd form fall needed the highest optimum temperatures,28 to 30℃. Long illumination were help to increase the total number of hatching J2 from cyst on the eggs collected from 12 months. In vitro,15% soil water content was proper to eggs hatching of J23. Four inorganic acid,5 kinds of organic acid, an alkaline salt and two alkaline were tested on hatching of different periods eggs under different pH values. The results indicated that five organic acids showed inhibited effects on four periods'Cyst eggs hatching under the testing condition; sulfuric acid played a promoting role on four periods eggs' hatching in the condition of pH5.0. Sodium carbonate, sodium hydroxide and potassium hydroxide promoted the hatching of J2 on all kinds of eggs.4. The effects of corn and soybean cultivars were tested on SCN cyst hatching eggs. Shenyu 18 maize varieties for maize varieties in SCN cyst on the role of egg incubation for most species, it was the most suitable crop rotation with soybean varieties. Soybean varieties with different resistance demonstrated a low rate of resistant varieties incubation, hatching rates showed susceptible.5. By testing the effect of low temperature, hydrogen peroxide, surface disinfectants and metal ions on dormant egg hatching, the dormancy would be broken by treated the dormant eggs exposing in 4℃for 10 days and in 0.02% hydrogen peroxide stored at 4℃for 15mins. The ions, only the presence of zinc sulfate could increase the number of cyst nematode hatched within the testing condition..6. The dynamic regulation of metabolites was determined by assaying the physiological and biochemical substances content of dormant SCN. The results showed that trehalose was accumulated during the dormancy period, and total sugar, glycogen and soluble protein participated in metabolism of SCN, providing energy for dormant SCN. Glycerol content was closely related to cold tolerance of SCN. The activity of trehalase, Gpase,PFK,PK,FBP and NAD-SDH during SCN dormant period were assayed, the results showed that the activity of trehalase and Gpase activity significantly increased when SCN enter into dormant stage. But the activity of PFK,PK,FBP and NAD-SDH in dormant SCN were obviously lower than active SCN.7. The hatching related gene was firstly ampliflied and cloned from SCN. The lengh of fragment was 800bp. Through compared with the genbank, this fragment was the partial cDNA fragment of Hg-MMP... |
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