Rhizonin A from Burkholderia sp. KCTC11096 and its growth promoting role in lettuce seed germination

We isolated and identified a gibberellin-producing Burkholderia sp. KCTC 11096 from agricultural field soils. The culture filtrate of plant growth promoting rhizobacteria (PGPR) significantly increased the germination and growth of lettuce and Chinese cabbage seeds. The ethyl acetate extract of the PGPR culture showed significantly higher rate of lettuce seed germination and growth as compared to the distilled water treated control. The ethyl acetate fraction of the Burkholderia sp. was subjected to bioassay-guided isolation and we obtained for the first time from a Burkholderia sp. the plant growth promoting compound rhizonin A (1), which was characterized through NMR and MS techniques. Application of various concentrations of 1 significantly promoted the lettuce seed germination as compared to control.