Studies on the Mechanism of Biochemical Resistanceof Wheat to Wheat Midge

Sun Sitai Ni Hanxiang Ding Hongjian (Institute of Plant Protection , CAAS, Beijing 100094) Qu Zhengang Zhang Shufen (Institute of Plant Protection , Hebei AAS)

Wheat ; Sitodiplosis mosellana Gehin ; Biochemical resistance mecha- nism

The biochemical mechanisms of 37 wheat varieties /Iines resistant to wheat midge Sitodiplosis mosellana Gehin were studied by SDS-polyacrylamide gel electrophore- sis and chemical analysis methods to explore the possible factors contributing to wheat midge resistance. Principle analysis and variance analysis showed that the biochemical re- sistance of wheat to S. mosellana is multi-factoral and synthetic , of which , the induced re- sistance was the main one. Total phenolics , tannins , reduced sugar , and flavonoids were the factors of wheat resistance to wheat midge , their rather strong effects appeared at ear- ly milky stage. Total phenolics , tannins , and reduced sugar played more important parts than flavonoids , and total phenols was the most important factor of the three. Soluble car- bohydrate shows little correlation to wheat resistance. Total phenolics and reduced sugar were the substances of wheat induced resistance to wheat midge , while tannins had no re- lation to induced resistance. The components of soluble proteins in resistant wheat vari- eties changed after being infested by S. mosellana , and a new band of 39. 2 kD appeared , suggesting that it may be related to the resistance of wheat to S. mosellana.