Transgenic chrysanthemum plants expressing a harpinXoo gene demonstrate induced resistance to alternaria leaf spot and accelerated development

In order to improve resistance to pathogens in chrysanthemum, we generated transgenic chrysanthemum plants heterogeneously expressing hpaGXoo gene from Xanthomonas oryzae pv. oryzae via leaf-disc mediated Agrobacterium tumefaciens (EHA105) transformation. Polymerase chain reaction (PCR), Southern blot, and Reverse transcription PCR (RT-PCR) analysis showed that the hpaGXoo gene was successfully integrated into the chrysanthemum genome and expressed in transgenic lines. An inoculation assay indicated that the presence of the transgene was associated with an improved level of resistance to alternaria leaf spot. The transgenic introduction of pathogen elicitor-encoding genes has a considerable potential for improving the disease resistance of ornamental plants. Furthermore, transgenic chrysanthemums flowered significantly earlier than the wild-type plants did, suggesting that the hpaGXoo gene probably accelerated chrysanthemum development.