Infection、Hatching Characteristics And Physiological Mechanism In Cyst Browning Of Cereal Cyst Nematode

Cereal cyst nematode （Heterodera avenae, CCN） has been found in at least11provinces including Shandong winter wheat region in China. In order to learn information about the developmental process and dynamics of CCN （H. avenae） in wheat root and soil, wheat （variety Jimai22and Tainong18） were planted and investigated with interval times during the wheat growing season in2010and2011. The root systems were collected with mesh bag and nematodes in the root were stained using a NaC1O-acid fuchsin technique. Nematode numbers in rhizosphere soil and wheat root, including second stage juvenile （J2）、third stage juvenile （J3）、fourth stage juvenile （J4） and white cyst were counted under the stereo microscope. In nematode hatching experiment, with5cation solutions treatment the diapause eggs, the hatched J2were recorded. In order to evaluate biological character change during browning of the white cyst, difference of metabolic substance from white and brown cysts were measured in this study.1. Development and dynamics of cereal cyst nematode during wheat growing seasonCCN （H. avenae） could invade the roots of2tested winter cultivars and complete its development under Shandong province climatic condition. J2was not detected in the root of2tested varieties before wheat wintering period. Few J2s can invade root in the middle period of wintering. With the increase of soil temperature, density of J2in the root significantly increased in wheat turn-green stage （GS）. J3and J4were detected in flowering stage （BS）. There was only one generation per year in Shandong and the nematode completed its life cycle in mature stage of wheat. There was no significant difference in the number of nematodes per g fresh root between2tested varieties. Meanwhile, Pratylenchus spp. was also detected in wheat root and rhizosphere soil. The cooperative damage of Pratylenchus spp. with H. avenae on the winter wheat should be attention.2. The effect of different ion solutions on hatching of CCNBased on our previous the research findings, it is found that the eggs in new brown cyst are in diapause, and J2can not be hatched out from eggs under suitable condition. While the eggs were treated with Fe³⁺ solution diapause of eggs could be broken and J2hatched out. The results showed that when the concentration of Fe³⁺ solution is9mmol/L, eggs had the maximum accumulate hatching rate （p<0.05）, however, the other tested ion solutions had no significant effect on hatching.3. Comparison of metabolic substance between white and brown cystsThe total carbohydrate, glycogen, protein content and esterase activity in brown cyst were lower than that of white cyst, while content of glycerol and trehalase activity in brown cyst was higher. It was showed that in the process of CCN diapause, eggs will accumulate more glycerol and trehalose, and active mutual transformation between trehalose and glycogen existed in brown cyst. SDS-PAGE pattern showed that the color of low molecular weight protein bands was deeper in brown cysts than those of white cysts, while the color of high molecular weight protein bands was deeper in white cysts. Molecular weight158.5,95.0,78.1,72.4and69.1KDa proteins were existed in white cysts electrophoresis patterns, and21.2KDa proteins in brown cysts. There was only one band （EST0.20） in esterase isoenzyme pattern in white and brown cyst, while the color of esterase band was deeper in white cysts than that of brown cysts. Content of esterase and esterase activity in white cyst were higher than that in brown cyst. Therefore, we deduced that lower activity of esterase isoenzyme and more abundant low molecular weight proteins may inhibit some metabolic activities in brown cyst, which is necessary for the summer diapause of cereal cyst nematode.