Studies On Regularity And Mechanism Of Transgenic Hybrid Poplar741's Insect-resistance

The larvae of Gypsy moth (Lmantriadispar L.), American white moth(Hyphcmtria cuneadrury) and Clostera anachoreta(Fabricius) were fed on transgenichybrid poplar741 with individual and group feeding methods.The clones of transgenichybrid poplar741 used in the test were PblK Pb29> Pbl2 and PblT.The normalpoplar741 was as CK.Insect-resistance regularity of transgenic hybrid poplar741 and theinfluence of insect-resistant toxin ondetoxifyication enzyme and acetylcholinesterasewere tested ,midgut was observed under microscope as well as.(1) Transgenic hybrid poplar741 had some killing effect on the larvaes of Gypsy moth,American white moth and Clostera anachoreta(Fabricius), especially on lower instarlarvaes. The killing effect of insect-resistant poplar741 on higher instar larvaes wasnot distinct, but theirdevelopment was inhibited which mainly indicated theirdevelopment period was postponed obviously, and the development speed, weightincreasing rate and the quantity of frass were all greatly decreased. Insect-resistance ofevery clone was different in which the insect-resistance of Pbll and Pb29 was best,the insect-resistance of Pbl2 was better and that of Pbl7 was badly. The mortality oflarvaes decreased with instar increasing, so that the mortality of the first instar larvaeswas higher than that of the second instar larvaes. On the other hand, the resistance oftransgenic poplar741 to the same instar larvaes feeding on transgenic poplarfromdifferent instars was various. The inhibition to the larvaes that fed on transgenicpoplar741 for longer time was more obvious than that to the larvaes that fed ontransgenic poplar741 for shorter time. The inhibtion of transgenic poplar741 to thefifth instar larvaes that started to feed on transgenic poplar741 from the first, second,third, fouth and fifth instar respectively decreased sequently. The insect-resistance oftransgenic poplar741 presented some spatiotemporal varying regularity. The resistanceof different leaves poistion and leave age was various and the insect-resistance of thefirst and the twentieth leaves was better than that of others. The resistance may persistto the next generation. The mortality of larvaes feeding on insect-resistantpoplarduring two generation was higher than that of larvaes feeding on insect-resistanthigher than that of larvaes feeding on insect-resistant poplarduring only one generation, and the inhibtion of the surviving larvaes was obvious. At the same time the mortality of larvaes that fed on insect-resistant poplarduring former generation and fed on CK during next generation was higher than that of the larvaes fed on CK during the two generation. The mortality of larvaes fed on insect-resistant poplar increased and the inhibition of insect-resistant poplar to them rised with the temperature uping.(2) The carboxzlesterase , glutathione-S-transferase and acetylcholinesterase were inhibted by insect-resistant toxin of transgenic hybrid poplar741 obviously.The activities of the three enzyme of larvaes feeding on insect-resistant poplar were lower than that of larvaes feeding on CK .The result indicated the insect-resistant toxin of insect-resistant genes made larvaesdyspepsia, nerve conduction interrupt and maldevelop ordie finally.(3) The midguts of living tested larvaes were drawed and made as paraffin sectiom.The result of observation under microscope showed: the cells of larvaes's midgut deform ,the limits between cells and caryon wasdim.There were vacuolus on cytoplasm, the quantityes and poistion of the vacuolus were abnormal.Sometimes the midgut cells of larvaes fester.