Comparative Analysis And Safety Evaluation Of Seedlings Trait In The Field Of Transgenic Populus Tomentosa With AhDREB1 Gene

Soil salinization is a worldwide ecological problem and continues to endanger the ecological resoxurces necessary for human survival.It is extremely urgent to control and utilize salinized soil.The cultivation area of poplar plantation in China is the first in the world,and the cultivation of new salt-tolerant poplar varieties will be of great significance for the control of saline-alkali Iand in China.The laboratory has successfully transferred the AhDREB1 gene into the Populus tomentosa(Populus tomentosa × P.bolleana × P.tomentosa),and in 2005 conducted an intermediate test for the release of the transgenic environment.The use of multiple breeding methods to expand the scale of reproduction and to assess the ecological safety of transgenic Populus tomentosa has important practical significance for accelerating the process of identification and comlercialization of new varieties of AhDREBl gene.In this study,the transgenic Populus tomentosa self-rooted seedlings and grafted seedlings were used as materials to detect the phenotypic traits,Physiological and biochemical indexes and exogenous gene expression of transgenic self-rooted and grafted seedlings to assess whether grafting was propagated.It will affect the expression and salt tolerance of the foreign gene of transgenic Populus tomentosa.In addition,this study systematically explored the safety of transgenic Populus tomentosa by using the transgenic 12-year-old transgenic rice poplar T-46 as a material.The main research contents include the possibility of exogenous genes of transgenic Populus tomentosa through pollen escaping,the horizontal transfer of foreign genes,and the natural degradation cycle of exogenous genes in transgenic Populus tomentosa.The transgenic Populus tomentosa can be used for different soil layers.The influence of microbial population and the influence of transgenic Populus tomentosa on endophytic bacterial community diversity provide a more comprehensive theoretical basis for the safety of transgenic forestry.The main findings are as follows:(1)Comparative analysis of phenotypic traits of transgenic Populus tomentosa clones and grafted seedlings grown in field.The statistical results of self-rooted seedlings in 2017 and 2018 indicate that the annual growth rate of the height and diameter of the transgenic Populus tomentosa roots and the control is not much different when the soil salinity is normal or slightly(0.2%).Under the condition of saline-alkali stress(0.4-0.6%),the annual growth of tree height and ground diameter of transgenic Populus tomentosa was significantly higher than that of the control.The measurement results of grafted seedlings in 2018 showed that the tree height and ground diameter of the grafted poplar grafted seedlings were not significantly different from those of the control and rootstocks when the soil salinity was normal or slightly(0.2%),but in the saline-alkali The tree height and ground diameter of transgenic poplars under stress conditions were significantly higher than that of controls and rootstocks(2)Comparative analysis of physiological and biochemical indexes and exogenous gene expression of transgenic Populus tomentosa clones and grafted seedlings grown in the field.The results of physiological indexes of transgenic Populus tomentosa seedlings in different breeding modes(clonal and grafting)in 2018 showed that SOD activity,POD activity and PRO content in transgenic Populus tomentosa leaves were significant in both cloned and grafted reproduction.Compared with the control non-transgenic Populus tomentosa(receptor),control 741 poplar and rootstock poplar,the MDA content was significantly lower than the control.The results of detection of exogenous gene expression in the roots,stems and leaves of transgenic Populus tomentosa in different breeding methods(self-rooted and grafted)in 2018 showed that the expression of exogenous genes in transgenic Populus tomentosa was different between different lines and different lines.There are differences in the amount,but the difference is not obvious.The expression of exogenous genes was different in different organs of the same plant,and the expression level of exogenous genes in leaves was the highest.The expression of exogenous genes in grafting and self-propagation of Populus tomentosa was different,but the difference was irregular.(3)The system systematically evaluated the possible environmental impact of perennial transgenic Populus tomentosa.A the study of exogenous gene drift.In 2018,the pollen vigor and hybrid seed setting rate of transgenic Populus tomentosa planted in the field for 13 years were tested.The results showed that the pollen of the transgenic hybrid Populus tomentosa had almost no vigor and the hybridization rate was extremely low.In addition,in 2017 and 2018,the soil microbial gene level transfer in the field of transgenic Populus tomentosa planted in the field for 12 years and 13 years was tested by PCR.The results of two consecutive years of experiments showed that we have not detected the level of foreign genes.Transfer to the soil microbial genome.B,study on the natural degradation cycle of exogenous genes in transgenic Populus tomentosa litter.In May,July and September of 2017,the degradation cycle of exogenous genes in the transgenic Populus tomentosa litter in the natural environment was carried out.The results showed that the explants(branches,stems and leaves)of transgenic Populus tomentosa were buried.In the soil,falling on the surface,falling on the lawn,its exogenous genes can naturally degrade after 3 months.C,research on the effects of transgenic poplar planted on soil culturable microorganisms for many years.In 2017,the number of culturable microorganisms in rhizosphere soil at different depths of transgenic Populus tomentosa planted in the field for 12 years was statistically analyzed.The results showed that the transgenic poplar planted for many years had no significant effect on the number of culturable microorganisms in the rhizosphere soil.D.the effect of transgenic poplar on the diversity of endophytic communities.The results showed that there was no significant difference in the community structure of endophytic bacteria between the transgenic Populus tomentosa and the control non-transgenic Populus tomentosa,but there were significant differences in endophytic bacterial community structure.The most significant genus is Cyanobacteria,Mycobacterium,Ralstonia,Pseudomonas,and Burkholderia-Paraburkholderia.