Abstract

The impact of ultraviolet-B (UV-B) radiation on the culturable and unculturable bacterial communities were studied in field experiments using soybean plants grown under increased UV-B (UV-B+), negative control (UV-B-) and solar UV-B. Sampling of leaves exposed to UV-B was performed in different developmental stages of the plant. The data obtained demonstrate that UV-B radiation did not alter the culturable and unculturable bacterial community. In contrast, culture independent analysis revealed major differences between cultivars for the stage of development (cultivation time) of the plants. Regarding the bacterial communities of the phyllosphere, it is possible to observe a similar behavior of the analyzed groups (Bacteria, β-Proteobacteria, and Pseudomonas) on both cultivars (BRS-262 and IAC-100) according to the analyzed environmental factors (increased UV-B, negative control and solar UV-B). These results indicate that leaf surfaces are composed of epiphytic bacterial communities that have survival mechanisms of different environmental conditions, such as repair of DNA damage, pigmentation and production of exopolysaccharides (EPS).

Key words: Ultraviolet-B (UV-B), phyllosphere, pigmented bacteria, survival.