Search

The genus Ornithogalum includes several ornamental species that suffer substantial losses from bacterial soft rot caused by Pectobacteria. The absence of effective control measures for use against soft rot bacteria led to the initiation of a project in which a small antimicrobial peptide from an Asian horseshoe crab, tachyplesin ( tpn I), was introduced into two commercial cultivars: O. dubium and O. thyrsoides . Disease severity and bacterial colonization were examined in transgenic lines expressing this peptide. Disease resistance was evaluated in six lines of each species by measuring bacterial proliferation in the plant tissue. Three transgenic lines of each species were subjected to further analysis in which the expression level of the transgene was evaluated using RT-PCR and qRT-PCR. The development of disease symptoms and bacterial colonization of the plant tissue were also examined using GFP-expressing strain of P. carotovorum subsp. brasiliense Pcb 3. Confocal-microscopy imaging revealed significantly reduced quantities of bacterial cells in the transgenic plant lines that had been challenged with the bacterium. The results clearly demonstrate that tpn I expression reduces bacterial proliferation, colonization and disease symptom (reduced by 95–100%) in the transgenic plant tissues. The quantity of tpn I transcripts, as measured by qRT-PCR, was negatively correlated with the protection afforded to the plants, as measured by the reduced severity of disease symptoms in the tissue. [ABSTRACT FROM AUTHOR]