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Title: CHARACTERIZATION AND IMPROVEMENT OF DISEASE RESPONSE TO PHYTOPHTHORA PALMIVORA IN PAPAYA

Author
item AGBAYANI, R - UNIV HAWAII
item NISHIJIMA, W - UNIV HAWAII
item Moore, Paul
item ZHU, Y - HARC

Submitted to: CTAHR Student Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 3/3/2006
Publication Date: 4/7/2006
Citation: Agbayani, R., Nishijima, W.T., Moore, P.H., Zhu, Y.J. 2006. Characterization and Improvement of Disease Response to Phytophthora Palmivora in Papaya. 18th Annual CTAHR Student Research Symposium [abstract]. Paper No. 104-63.

Interpretive Summary:

Technical Abstract: Plant recognition of invading pathogens and subsequent activation of defense responses are controlled by resistance genes. NPR1 is the key regulatory gene controlling the onset of the systemic acquired resistance signaling pathway. NPR1 genes have been isolated from several plants including arabidopsis (AtNPR1) and papaya (CpNPR1). The goals of this study are to increase the resistance of papaya to P. palmivora, the cause of fruit and root-rot disease, by expressing AtNPR1 or overexpressing CpNPR1 in transgenic plants and to study plant-pathogen interactions by using a peptide elicitor. The peptide elicitor gene of defense responses, Pep-13 from P. palmivora, was cloned into an Agroinfiltration vector so that the Agrobacterium expression system could be used to study plant-pathogen interactions. Transformations were conducted using gene gun bombardment. The constitutive CaMV35S promoter was used to drive expression of the NPR1 genes. Following selection on G418, polymerase chain reaction (PCR) was carried out to indicate the presence of the selectable marker gene, NPTII. Bioassays with leaf discs from transgenic plants containing the AtNPR1 gene showed smaller necrotic lesions compared to those on wild-type plants indicating that resistance in papaya had been improved. Quantitative RT-PCR showed that NPR1 expression was slightly elevated. NPR1 expression was up-regulated in CpNPR1 transgenic plants inoculated with P. palmivora and in Pep-13 treated plants. Overall, our results indicated that Phytophthora elicitor induced host resistance genes and transgenic-expressed NPR1 improved papaya resistance to P. palmivora.