Effects of Rhinoncus sibiricus feeding on biochemical substances in different resistant cultivars of buckwheat
To investigate the responses of insect-resistant and insect-susceptible buckwheat cultivars to the feeding of Rhinoncus sibiricus,the contents of nutrients(soluble protein and soluble sugar),secondary metabolites(tannins,total phenols and flavonoids),and the activities of defense enzymes(CAT,PAL)and protease inhibitors(TI,CI)in leaves of two insect-resistant buckwheat cultivars('Meng 0207'and'Jinku 6')and two insect-susceptible buckwheat cultivars('Meng 0208'and'Jinku 2')with different damage degrees(mild damage,moderate damage and severe damage)were measured 48 h after damage.In addition,the activities of major detoxifying enzymes(CarE,GSTs,P450)in Rhinoncus sibiricus were tested too.The results showed that the contents of soluble protein,soluble sugar,tannin,total phenol and flavonoids in buckwheat leaves,as well as the activities of PAL,CAT,TI,and CI were increased by feeding on R.sibiricus.Among the four buckwheat cultivars tested,the increase of contents of soluble protein and soluble sugar in the insect-resistant cultivars is relatively more than that of the susceptible cultivars,and the tannin content,PAL,TI and CI activities of the susceptible cultivars increased relatively more than that of the insect-resistant cultivars.The TI and CI activities of insect-resistant cultivars were significantly higher than those of susceptible cultivars under different feeding levels.The activities of carboxylesterase(CarE)and glutathione SS-transferase(GSTs)of R.sibiricus fed on insect-resistant buckwheat were significantly higher than those in the individuals fed on the insect-susceptible cultivars.The results showed that the feeding of R.sibiricus on both insect-resistant and insect-susceptible cultivars could change the content of substance related to resistant in both,resistant and susceptible cultivars,but demonstrated different effects.