Changes In Diversity Of Phyllosphere Microorganisms In Transgenic Bt Cottons

A field planted with transgenic Bt cotton (GK-12) and non-transgenic Bt cotton (Simian No.3) grown under normal agricultural practice was monitored for changes in culturable bacterial, actinomycetic and fungal populations in 2005. A culture-independent approach was chosen to characterize microbial communities in 2006. The results are as follows:1. There was a positive correlation between the leaf surface microorganisms and cotton development. The total number of bacteria,fungi and actinomyces began to rise at seedling and reached its peak at flower stage,but decreased obviously at boll-opening stage. The numbers of phyllosphere bacteria were different between Bt cotton and non-Bt cotton at various development stages,despite the change tendencies were consistent. In 2005, the phyllosphere bacteria number of Bt cotton was was significant higher than that of non-Bt cotton at the squaring and flower-boll stages. With respect to the phyllosphere fungi population, there was significant difference at the stage of Boll-opening. The phyllosphere fungi number of Bt cotton was significant higher than that of non-Bt cotton at the squaring and flower-boll stages. As to culturable actinomyces, it was interesting to notice that total culturable actinomyces of Bt cotton were significant higher than that of non-Bt cotton at the squaring stages, but lower at the flower and boll stage.2. According to amount grade of bacterial physiological groups of phyllosphere of Bt cotton and non-Bt cotton we known that Aerobic cellulose-decomposing and Lactobacillus were dominant groups associated with Bt cotton and non-Bt cotton at stages of boll opening and flower-boll. There was significant difference in other bacterial physiological groups of phyllosphere of the two varieties.3.In the analysis of diversity changes of bacterial physiological groups, we concluded that D, HËŠand R of Bt cotton were all higher than that of non-Bt cotton at flower and boll stage, however, at boll-opening stage, diversity indexes of Bt cotton were all lower than that of non-Bt cotton.4. The best treatment of extraction for microorganism DNA on the leaves of transgenic Bt cotton was 20mg/mL SDS, 30mg/mL Lysozyme, 10mg/mL Proteinase K and 180min incubation time, which could effectively obtain greater DNA both in size and quality than other treatments.5. PCR-PAGE indicated that Bt cotton and non-Bt cotton at stages of seedling, squaring, flower and boll had significant similarity, whereas at the stage of boll-opening they had significant difference.