Using T-RFLP to Assess the Impact on Soil Microbial Communities by Transgenic Lines of Watermelon Rootstock Resistant to Cucumber Green Mottle Mosaic Virus (CGMMV)

To establish quantitative methods for ecological risk assessment, we assessed the impacts of transgenic watermelon rootstock (Citrullus lanatus (Twinser) cv. Gongdae) that was resistant to cucumber green mottle mosaic virus. The diversity of soil bacteria and fungi was monitored from May to July of 2005. Terminal restriction fragment length polymorphism (T-RFLP) was used with 16S ribosomal RNA (rRNA) coding genes for bacterial communities and with internal transcribed spacer (ITS) regions of rRNA coding genes for fungal communities. Multivariate analysis of variance (MANOVA) on the principal component analysis (PCA) scores of T-RF profiles detected no significant difference between microbial communities with transgenic or non-transgenic watermelon. Likewise, the results of our multi-response permutation procedure (MRPP) tests on non-metric multidimensional scaling (NMS) showed no significant difference between plant types. However, both MANOVA on PCA and MRPP on NMS revealed significant changes in the microbial community during the growing season. We used loading values of PCA to rank the abundances of bacterial species and found increases of some species in June and July.