Xylem Occlusion Incited by Endophytic Bacteria Leading to Reduction of Vase Life in Cut Rose Variety Taj Mahal

摘要

The present study was undertaken with an aim to understand the mechanism of xylem occlusion by endophytic bacteria and its effect on vase life of cut rose var. Taj Mahal. The cut roses exhibit characteristic symptoms such as bent neck and wilting of petals in xylem occluded condition owing to water stress. Three prominent endophytic bacteria were isolated from the stem ends of cut rose. The isolates were identified as Bacillus subtilis, Agrobacterium tumefaciens and Ochrobactrum sp based on the molecular characterization by sequencing 16S rRNA gene. At the cut ends, the endophytic bacteria caused occlusion and arrested water movement. It was evidenced using Field emission Scanning electron microscopy (FE-SEM) which confirmed the occlusion of inter-vessel pits inside the xylem vessels induced by spatial distribution of endophytic bacteria leading to short vase life. As per the morphological observations, the vase life of cut roses treated with gentamicin sulphate 500ppm as positive control was foundto be 7 days at room temperature (without pulsing) compared to control cut roses (3 days) in deionised water and bacterial treated cut roses (2 days). Hence, the reduced vase life of cut roses could be correlated with the multiplication and physical plugging of inherent endophytic bacteria affecting the post-harvest life of cut roses.