Metabolic changes in Agrobacterium tumefaciens-infected Brassica rapa

Agrobacterium has the ability to transfer its genetic material, T-DNA, into the plant genome. The unique interaction between the bacterium and its host plant has been well studied at the transcriptome, but not at the metabolic level. For a better understanding of this interaction it is necessary to investigate the metabolic changes of the host plant upon infection with Agrobacterium tumefaciens. This study investigated the metabolic response of Brassica rapa to infection with disarmed and tumor-inducing strains of A. tumefaciens using 1H nuclear magnetic resonance spectroscopy combined with multivariate data analysis. The partial least square-discriminant analysis (PLS-DA) of two varieties of B. rapa showed that there was a clear differentiation in the metabolite profiles of B. rapa leaves infected with the disarmed strain LBA4404 and with tumor-inducing octopine and nopaline strains, particularly in the flavonoid, phenylpropanoid, sugar and free amino/organic acid contents. However, individual PLS-DA of each type of infection suggests that, in general, some flavonoids and phenylpropanoids were suppressed as a consequence of these infections. The results obtained in this study indicate that the disarmed strain LBA4404 and tumor-inducing strains have different effects on the metabolite profile of B. rapa.