Study On The Soil Environmental Security Of Srmv-p₁ Gene Transgenic Sugarcane

Transgenic sugarcane clones mediated with SrMV-P₁ gene were used as plant material.PCR amplification of specific primers of SrMV-P₁ was carried out to study the possible horizontal transfer of foreign SrMV-P₁ target gene from transgenic pants to the soil microorganism and grassy weed(Eleusine indica(Linn.) Gaertn).The influences of transgenic sugarcane mediated with SrMV-P₁ gene on the soil microorganism and physicochemical property were investigated by microorganism plate cultivation and soil enzyme activity and nutrient content analysis,respectively, to study the soil environmental security of SrMV-P₁ gene.SrMV-P₁ gene was detected neither in total DNA of soil microorganism nor in grassy weed(Eleusine indica(Linn.) Gaertn),which indicated that the SrMV-P₁ gene was not horizontally transferred.Total number of colony forming units(CFUs) of soil culturable microorganism was not remarkably different between transgenic sugarcane and non-transgenic one from the bury test of sugarcane leaves.However,it was significantly higher after inoculation with Sorghum mosaic virus(SrMV) in the pot test during the prometaphase of sugarcane.Total number of CFUs of bacteria and actinomycetes in rhizosphere were higher at the sugarcane's early growth stage than that at later growth stage,while the total number of CFUs of fungi in rhizosphere was the highest in the tillering stage of sugarcane.In the field,the total number of CFUs of cultural bacteria in rhizosphere was not significantly different at the different growth stages of sugarcane,and the total number of CFUs of actinomycetes in rhizosphere soil reached at the highest level in the tillering stage of sugarcane,while the total number of CFUs of fungi in rhizosphere soil was the highest in the maturing stage of sugarcane.The transgenic sugarcane had complicated influences on soil actinomycetes and fungi, while the influence on soil bacteria was mild.The result of enzyme activities detection in rhizosphere soil indicated that the transgenic sugarcane had no significant effect on the activities of alkaline phosphatase and hydrogen peroxidase in the rhizosphere soil,while it had a little influence on the activities of other soil enzyme from the bury test.Under different planting practices of sugarcane,the activities of sucrase and urease as well as hydrogen peroxidase in the pot rhizosphere soil cultivated with non-viruses inoculated sugarcane were higher than those with viruses inoculated sugarcane,alkaline phosphatase activity in the pot rhizosphere soil cultivated with non-viruses inoculated sugarcane was lower than that of pot counterpart,and the performance of acid phosphatase in the pot rhizosphere soil cultivated with non-viruses inoculated sugarcane was contrary to that of alkaline phosphatase activity.At different growing stages,the activities of sucrase and urease in the rhizosphere soil were higher in the elongation and the technical maturing stage of sugarcane,while the two kinds of phosphatase and hydrogen peroxidase activities steadily sank down as the sugarcane growing.Transgenic sugarcane had slight influences on the urease and acid phosphatase in the rhizosphere,while it had some effects on sucrase,alkaline phosphatase and hydrogen peroxidase activities.The rhizosphere pH was weakly acid in different planting practice,which in the pot cultivated with non-viruses inoculated sugarcane was higher than that in the pot cultivated with viruses inoculated sugarcane.Among different growing stages of sugarcane,the pH of pot rhizosphere cultivated with sugarcane came down then went up as the growing of sugarcane.But the pH in the field rhizosphere soil increased slightly as the growing of sugarcane.The transgenic sugarcane somewhat reduced the rhizosphere soil pH in the sugarcane's elongation and technical maturing seasons. Under bury test,the transgenic sugarcane cultivated in pot also reduced the soil pH. The conductivity in pot rhizosphere cultivated with sugarcane ranged from 1.08 ms/cm to 3.08 ms/cm,but the conductivity in the field rhizosphere was only from 0.108 ms/cm to 1.24 ms/cm.With the growing of sugarcane,the rhizosphere soil conductivity increased first then declined a little.Under bury test,the soil conductivity ranged from 0.18 ms/cm to 0.26 ms/cm.And the transgenic sugarcane as well as its residues had complicated influences on soil conductivity.The results from the analysis of soil nutrients in rhizosphere showed as fellows:1) Under bury test,the transgenic sugarcane had no significant effect on the major soil nutrients(except total N);2) Under different planting modes of sugarcane,the content of total N and available P as well as the organic matter in the pot rhizosphere cultivated with non-viruses inoculated sugarcane was equal to those of the pot soil cultivated with viruses inoculated sugarcane,the content of total P and available K in the pot rhizosphere soil cultivated with non-viruses inoculated sugarcane was higher than those of pot counterpart,the content of total K and available N in the pot rhizosphere soil cultivated with non-viruses inoculated sugarcane was lower than those of pot counterpart.3) Among different growing stage of sugarcane,the content of total N and P,available P and K as well as organic matter in the rhizosphere soil all decreased as the growing of sugarcane,while the content of total K in the rhizosphere soil came down first,then went up a little following the growth of sugarcane,and the content of available N in the rhizosphere soil was highest at the elongation stage of sugarcane.4) Transgenic sugarcane had complicated influence on the available nutrients and organic matter in the rhizosphere,but had slight influence on the contents of total N,P and K.These primary results indicated that transgenic sugarcane had some effects on enzyme activities,pH and conductivity in rhizosphere soil,and had complicated effect on available nutrients and organic matter in the rhizosphere soil,while its influence on soil total N,P and K was slight.Different planting modes or different growth stages of sugarcane may have remarkably different effect on soil properties.From above,it was suggested that the changes of micro-ecology of rhizosphere soil were unlikely caused by exogenous gene expression in transgenic sugarcane,maybe there was the non-prediction effect after environmental release of transgenic sugarcane.