Biochemical changes of the cereal cyst nematode, Heterodera avenae, at low temperatures

Abstract

Cereal cyst nematode (Heterodera avenae) diapause is induced by high temperatures and is broken by low temperatures. In this study, metabolic responses were monitored in diapause and non-diapause H. avenae during exposure to 4°C for 10 weeks. The results showed that there was no difference in total carbohydrate content. The content of glycogen and glycerol at 0 week was relatively high but decreased with increased storage time at 4°C. The content of trehalose of the nematode at 10 weeks was significant lower than that at 5 weeks at 4°C. Protein content increased significantly after incubation for 5 and 10 weeks. Esterase and trehalase activity increased with the increasing period at 4°C and showed a significant difference between treatments for esterase activity but there was no significant difference between 5 and 10 weeks for trehalase activity. The SDS-PAGE pattern indicated that a 15.5 kDa protein was absent at 10 weeks and present at 0 and 5 weeks. Esterase isoenzyme patterns of H. avenae showed that at 10 weeks there were four bands: EST 0.21, EST 0.24, EST 0.30 and EST 0.34 (Rf values). EST 0.24 was the common band in the three treatments. Biochemical tests were conducted to correlate with hatching experiments using the same treatments. 2-DE patterns of H. avenae showed that diapause and non-diapause nematodes had 409 and 412 protein spots, respectively, and 19 protein spots were unique: 11 distinct proteins in non-diapause and eight distinct proteins in diapause. This information could be helpful in understanding the diapause mechanism of the cereal cyst nematode.