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Transgenic Plant and Fungal Expression to Assay in vitro and in planta Activity of Sus scrofa beta-Defensin 1 and Nicotiana tabacum Defensin 1

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dc.contributor.advisor Erickson, Larry
dc.contributor.advisor Goodwin, Paul Atnaseo, Chuthamat 2011-12-14T20:50:23Z 2011-12-14T20:50:23Z 2011-12 2011-12-01 2011-12-14
dc.description.abstract To explore the use of defensins for transgenic plant disease resistance, expression by agroinfiltration of plants, stable transformation of plants and stable transformation of yeast were tested for porcine β-defensin 1 (pbd-1) and Nicotiana tabacum defensin 1 (Ntdef1). Attempts to screen constructs by agroinfiltration of Nicotiana benthamiana leaves revealed that agroinfiltration alone induced localized resistance against Colletotrichum destructivum. A comparison of Agrobacterium tumefaciens strains showed that the induced resistance required the transfer of type IV effectors into plant cells and was independent of salicylic acid or ethylene signaling. Stable expression of pbd-1 in N. tabacum and Pichia pastoris showed that PBD-1 purified from P. pastoris had varying degrees of antimicrobial activity against a broad range of microbes, including P. syringae pv. tabaci, C. destructivum and C. orbiculare, but in transgenic N. tabacum, the protein could not be detected and resistance increased only slightly to P. syringae pv. tabaci but not to C. destructivum or C. orbiculare. Stable expression of Ntdef1 in P. pastoris yielded a protein with no or little antimicrobial activity, and stable expression in N. tabacum did not result in detectable Ntdef1 or increased resistance to those pathogens. Although PBD-1 had strong antimicrobial activity against plant pathogens, plant disease resistance likely did not increase because of the low level of the protein in the plants, whereas resistance did not increase with Ntdef1 likely because of low antimicrobial activity and low levels of the protein in the plant. This research demonstrates that agroinfiltration is not appropriate for testing genes for antimicrobial activity in planta, while the P. pastoris expression system is useful for producing protein for in vitro tests of a gene prior to its transfer to plants. en_US
dc.language.iso en en_US
dc.subject Agroinfiltration en_US
dc.subject Antimicrobial peptide en_US
dc.subject Defensin en_US
dc.subject Plant-microbe interaction en_US
dc.subject Agrobacterium tumefaciens en_US
dc.subject Plant pathology en_US
dc.title Transgenic Plant and Fungal Expression to Assay in vitro and in planta Activity of Sus scrofa beta-Defensin 1 and Nicotiana tabacum Defensin 1 en_US
dc.type Thesis en_US Plant Agriculture en_US Doctor of Philosophy en_US Department of Plant Agriculture en_US
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