Molecular identification and dynamics in bacterial population in the phyllosphere of insect-resistant transgenic cotton

【Objective】To study the dynamics in bacterial population and identify the main strains in the phyllosphere of insect-resistant transgenic cotton.【Method】Insect-resistant transgenic cotton 33B, SGK321 and GK12, and corresponding receptor cotton 33, Shiyuan 321 and No.3 Simian cotton were sampled at different growing stages. Dynamics and diversity among bacterial populations in the phyllosphere were analyzed with the conventional culture methods and RISA. In addition, in order to indentify the main strains, the ITS squences of main strains were cloned, sequenced and analyzed by using BLAST【.Result】At different sampling times, significant differences were found among the total number and diversity index of phyllospere bacterial population of each cotton variety, but little differences were observed between insect-resistant transgenic cotton and corresponding receptor cotton at the same time. With RISA, a clear fingerprint map was obtained. The phyllospere bacterial population structure presented complexity and rich diversity. Cluster analysis showed that the composition of phyllospere bacterial population displayed a great uneveness and randomness, suggesting that environment and climate factors affected the phyllosphere bacteria, but insect-resistant transgenic cottons did not present visible impact. According to phenotype characters, the strains isolated from cotton phyllospere were classified into 104 strains. The ITS squences of 17 main strains were idendified and submitted to GenBank (Accession number DQ447751-DQ447764). 【Conclusion】 It was suggested that little differences were found among the total number and diversity index of bacterial population between insect-resistant transgenic cotton and corresponding receptor cotton, the main bacterial strains in the phyllosphere of insect-resistant transgenic cotton were divided into 9 genus including 9 bacteria families, the predominance familis in phyllospere of all six cotton varieties were Bacillus and Pseudomonas.