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Title: DEVELOPING PHYTOPHTHORA PALMIVORA RESISTANCE IN CARICA PAPAYA L. BY OVEREXPRESSION OF THE NPR1 GENE

Author
item AGBAYANI, RICELLE - HARC
item NISHIJIMA, WAYNE - UNIVERSITY OF HAWAII
item QUI, XIAOHIU - HARC
item Albert, Henrik
item Moore, Paul
item ZHU, Y. JUDY - HARC

Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/18/2005
Publication Date: 7/7/2005
Citation: Agbayani, R., Nishijima, W.T., Qui, X., Albert, H.H., Moore, P.H., Zhu, Y. Developing phytophthora palmivora resistance in Carica Papaya L. by overexpression of the NPR1 gene. Proceedings XIII Int. Congress Molecular Plant-Microbe Interactions Cancun, Mexico July 17-22, 2005.

Interpretive Summary:

Technical Abstract: NPR1 is the key regulatory gene controlling the onset of the SAR signaling pathway in Arabidopsis. Overexpression of the Arabidopsis NPR1 gene (AtNPR1) gave Arabidopsis plants enhanced resistance to the pathogens Pseudomonas syringae and Peronospora parasitica without any obvious detrimental effectsa. Thus, NPR1 could be the basis of an ideal approach for engineering broad-spectrum disease resistance. The goal of this study is to increase the resistance of papaya to Phytophthora palmivora, the causal agent of papaya root-rot, by expressing AtNPR1 in transgenic plants. In subsequent research we will compare results of AtNPR1 with overexpression of the endogenous NPR1 gene of papaya (CpNPR1). Transformations using constructs containing either AtNPR1 or CpNPR1 were carried out using gene gun bombardment. The constitutive CaMV35S promoter was used to drive expression of the NPR1 genes and the NPTII gene that was used as a selectable marker. Following selection on kanamycin, the polymerase chain reaction was carried out to indicate the presence of the transgene. Transgenic AtNPR1 plants were challenged with P. palmivora to evaluate resistance. Since NPR1 regulates the expression of PR genes after pathogen induction, changes in the level of PR1 gene expression were measured using Reverse Transcriptase Polymerase Chain Reaction. Bioassays done 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 has been improved. aCao, H. et.al. (1998) Proc Natl Acad Sci USA 95, 6531-6536 bUniv. of Wyoming, Laramie, WY 82071 USA