In order to evaluate the effect of transgenic maize on epiphytes, the transgenic Bt maize Mon810 and its parental non-transgenic maize were grown in field to study the quantitative changes of culturable microorganisms and the diversity of bacterial functional groups at different growth stages in 2010 and 2011.Although there were differences in the colony-forming unites of culturable bacteria, actinomycetes and fungi of phyllosphere between Bt maize and non-Bt maize in different growing periods and different years, the trend of annual differences was basically consistent at the same growth period: the quantity of microbes in seedling stage is fewest and reaches the peak in the late of growing period.Compared with the controls, transgenic Bt maize seemed to stimulate the reproduction of phyllosphere fungi.However, no significant effect on the populations of actinomycete was observed.Significant differences were detected for bacteria at jointing stage, trumpet stage, silking stage and milking stage.In 2010, the Shannon-Wiener index, Simpson index and evenness index of bacteria physiological groups were higher at seedling, jointing and full-ripe stage, but lower at trumpet stage, tasseling stage, silking stage and milk stage.In 2011, the population characteristic parameters of the microorganisms of Bt-corn are more than the ones of non-Bt corn in the whole growing period except trumpet stage.It may be concluded there was some difference in terms of impacts between transgenic maize and non-transgenic maize, while the main impacts on microbial community composition were likely due to different years and different growth periods.

With the transgenic insect-resistant corn Mon810 and its non-transgenic parent as materials,the enzyme-linked immunosorbent assay(ELISA) method was used to detect the expression and quantitate the exudation of Bt protein in corn leaves.The results showed that Bt protein could be detected in tissue and on surface of leaves.The Bt content in tissues showed a rising trend from seedling stage to silking stage with the advances of vegetable growth,and reached the peak at the silking stage and then declined gradually.The variation of Bt exudation on leaf surface had no obvious regularity.

Traditional isolation and culture method for microorganisms had been found to have limitations in reflecting the whole genome information of phyllospheric microorganisms and have been gradually replaced by molecular ecology methods.The high-quality,large-fragment and unbiased DNA is the important basis for studying phyllospheric microorganisms at molecular level.In this paper,four methods,improved Sambrook method,CTAB method,improved chemical method and Kit method,were adopted respectively to extract the total DNA of microorganisms from maize leaves in early,middle and late growth periods and then the size and output of DNA fragments were evaluated synthetically.The 16S rDNA were amplified by primers 357/518 and 984/1387,meanwhile,the primers NS1/fungi,ITS1-F/ITS2,NS1/AM1,EF4/fung5 and SSU-0817/SSU-1196 were used for the amplification of 18S rDNA.The results showed that all of the four methods could get appropriate fragments for PCR,but the output and purity of DNA were different between different methods and the best was Kit method.Except the improved chemical method,the other methods could get products of PCR.The primers 984/1387 and ITS1-F/ITS2 were the best for amplifying 16S rDNA and 18S rDNA respectively.

There are two types of starch, amylose and amylopectin of flour. Amylose content (AC) is significantly negatively correlated with noodle quality. The waxy gene (Wx) encodes the granule-bound starch synthase (GBSS, EC 3.4.1.11), or Wx protein, is responsible for the synthesis of amylose in wheat. Common wheat is allohexaploid, it has three different Wx proteins: Wx-A1, Wx-B1, and Wx-D1. Consequently, amylose content and pasting properties of starch were influenced by the lack of the Wx-B1 protein, followed by that of Wx-D1, and Wx-A1. Using STS (sequence-tagged sites) primers, the sequences were amplified near the 4th intron region, and fragments amplified were digested by BamHI in 35 wheat cultivars. The results indicate that some fragments can be digested and the other cannot. The fragments digested showed two length polymorphism, and the length is negatively correlated with amylose content. The fragment in many cultivars with amylose content above 20% can be digested by BamHI, while those with amylose content below 20% cannot. All these indices demonstrate that there is variation exists in amplified region of Wx-B1 gene. This can be useful in breeding program to select wheat cultivars with different amylose content, and improve wheat quality.