| In this study,poplar hybrid 741 poplar,Bt Cry1 Ac gene 741 poplar high resistance strain Pb29 and transgenic Bt Cry1 Ac gene poplar 107 high resistance strain Hb1 were used as test materials.They were grafted to each other in two ways.They were(1)different poplar species.In other words,the non-transgenic 741 poplar and the transgenic European and American poplar 107 Hb1 grafted to each other.When the grafting site is the annual trunk part of the plant,two grafting combinations of 741/Hb1 and Hb1/741 were formed.When the grafting site was a perennial collateral part,Two grafting combinations of741/Hb1 s and Hb1/741 s.(2)Grafting was carried out using the same species of poplar 741 and transgenic poplar Pb29 grafted to each other.Normal management for 8 years resulted in two graft combinations of Pb29/741 and 741/Pb29.By detecting the m RNA,Bt protein and insect resistance of Bt gene in different grafted plants,the transport law of Bt gene expression products in poplars was investigated.The main findings are as follows:(1)RT-PCR results showed that the m RNA of Cry1 Ac gene could be detected in Hb1 as the rootstock or scion in each grafting combination,but no 741 poplar was detected.Three-generation digital PCR results showed that the copy number of Cry1 Ac gene in the shoots and young leaves of Hb1 was much higher than that of 741 poplar(no significant difference with the negative control).It was shown that the m RNA of the transcription product of the exogenous Cry1 Ac gene cannot be transported between the rootstock and the scion.(2)The ELISA results in the combination of different anvil grafts showed that the toxic proteins can be transported between rootstocks and scions.The content of Cry1 Ac protein was highest in the phloem or leaves,and the main transport site was phloem.The content of toxin proteins in the upper phloem of the 741 shoot was lower than that in the lower part of the corresponding branches;in September,the content of toxic protein in the leaves of 741 poplar was the highest,and in the Hb1 scion leaves in July.The highest value was reached,and the rootstock leaves were the highest in August;in the graft combination where the rootstock was a perennial plant,the content of toxin protein in 741 poplars changed more distinctly in each month.(3)The Cry1 Ac toxic protein content in the same grafting combination ELISA results showed that the content of toxic protein in the phloem of the trunk of Pb29/741 was the highest,followed by the trend of decreasing first and then increasing along the trunk,and the scion of Pb29 always showed an upward trend;741/ The content of toxin protein in phloem in the Pb29 grafting combination was the highest,showing a decreasing trend overall.The content of toxic egg in other tissues was lower,and there was no obvious rule.The content of toxin protein in the phloem of Pb29/741 showed greater than that in the base of the crown,and the upper part of the shoot was larger than the lower part.The content of toxic protein in the grafted phloem of the 741/Pb29 showed that the base of the phloem was larger than the middle,and the lower part of the branch was larger than the upper part.Xylem,pith tissue and leaves do not have obvious rules.(4)The results of the insect feeding test showed that the Cry1 Ac gene grafting combination had certain toxic effects on the larvae of the Hyphantria cunea Drury and the young moth larvae.The larvae played a role in inhibiting growth and development,and the overall insect resistance was weaker than that of Hb1.The 741/Pb29 scioned leaves had a certain resistance to insects,and the overall resistance to insects was less than that of Pb29/741.(5)The photosynthetic indexes,chlorophyll fluorescence parameters and chlorophyll content of the four grafting combinations of 741/Hb1,Hb1/741,Hb1/741 s and 741/Hb1 s were determined.The transpiration rates of different grafting combinations were significantly higher than those of 741 and Hb1.Other photosynthetic parameters,chlorophyll fluorescence parameters and chlorophyll content were all different,but they did not have obvious rules. |
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