9% 1.76 Site 3 44 15.0 65.9% 1.93 Site 4 33 13.8 58.2% 1.39 aFor months, data summarized over all sites; for sites, data summarized over all months. Temporal variations of leaf endophytic bacteria were also observed in T-RFLP patterns, which reveal the development of different T-RFs during the growing season. We labeled three A. viridis plants

at each site in order to track the dynamics of the leaf endophytic bacterial community of the same host plants. Figure 1(a) shows the comparison of T-RFLP patterns of one A. viridis individual from May to July. On May 14, the dominant T-RF in this bacterial community was the T-RF 85 bp. On June 16, an increase of the relative abundance of the T-RF 529 bp led this T-RF to share dominance of this bacterial community with the T-RF 85 bp. On July 14th, the dominance of the T-RF 85 bp had been replaced by the T-RF 75 bp, which check details had a significant increase in relative abundance from May to July. The observations indicate that the leaf endophytic bacterial community changed with the season. Figure 1 Comparisons of T-RFLP profiles of endophytic bacterial communities. Relative fluorescence intensity (normalized to the most intense peak) is plotted against length of the T-RF. T-RFLP profiles represented the bacterial species compositions, indicating the influences from multiple factors: (a) T-RFLP profiles see more from one tagged A. viridis individual, samples of which were collected

respectively on May 14th, June 16th and July 14th, 2010. (b) T-RFLP profiles from two A. viridis individuals respectively from Site 2 and Site 3, both collected on July 14th, 2010. (c) Selected T-RFLP profiles from 3 individuals respectively from A. viridis, A. psilostachya and P. virgatum. For the dominant T-RFs from these C59 concentration three plant species, see Additional file 1: Table S2. A. viridis T-RFLP pattern variation contributed by sampling sites and dates Unlike the samples from different months, the samples from different sites did not show significant variation when the data were analyzed for the presence or absence of individual

T-RFs (Table 1) even though samples from site 4 appeared to have a lower diversity of leaf endophytic bacteria than others. Although the general level of diversity of leaf endophytic bacteria did not show variation among sites when presence/absence data were considered, the T-RFLP profiles of samples from different sites suggested that the compositions and the relative abundances of individual T-RFs varied with the site/location of host plants, revealing a possible connection of leaf endophytic bacterial species with host locations. Figure 1(b) shows the T-RFLP patterns of two A. viridis plants both collected on July 14, 2010, but from different sites. In the sample from site 2, the T-RF 75 bp was more prominent than the T-RF 85 bp; while in the sample from site 3, the T-RF 85 bp was more prominent. Other dominant T-RFs, including the T-RF 364 bp and the T-RF 529 bp, also show differences in relative abundance.