Date of Award

12-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Plant and Environmental Science

Advisor

Schnabel, Guido

Committee Member

Riley , Melissa B

Committee Member

Scott , Simon W

Committee Member

Tzeng , Jeremy

Abstract

The Gastrodia antifungal protein (GAFP-1) is a mannose-binding lectin originating from the Asiatic orchid Gastrodia elata. It has potential for conferring resistance to fungal and non-fungal pathogens in other plants which is currently being investigated. The goals of this research project were to determine (i) the potential movement of GAFP-1 protein from transgenic rootstocks into the non-transgenic scion of chimeric-grafted trees (ii) the levels of GAFP-1 protein in lines of the cultivar Bluebyrd expressing the gene gafp-1 under the control of the polyubiquitin promoter bul409, and (iii) the susceptibility of selected lines to the root pathogens Phytophthora cinnamomi Rands and Meloidogyne incognita Kofoid & White in greenhouse experiments.
Wild-type (WT) plum (Prunus domestica cultivar Stanley) tissue was budded onto transgenic plum lines Stanley 4J and 4I to create chimeric-grafted trees. Tissues from chimeric-grafted trees were analyzed for protein (leaf, soft shoot (non-woody shoot), and root) by immunodetection. The GAFP-1 lectin was identified within the roots, but not in the soft shoot or leaf tissues of the grafted, WT scions. These results suggest that GAFP protein is not moving into the WT scion tissues of chimeric-grafted plum trees, a feature that would likely appeal to consumers who are concerned about GMO in their food.
Only 9 out of 17 `Bluebyrd' plum lines containing the gafp-1 gene produced GAFP-1 protein and only 1 of these 9 lines exhibited increased tolerance to Phytophthora root rot (PRR) caused by P. cinnamomi. This same line (BB-1) was also significantly more tolerant to infection by the root-knot nematode (RKN) Meloidogyne incognita. BB-1 was superior in resistance to PRR and equal in resistance to RKN compared to the previously characterized `Stanley' 4J line, which expresses the gafp-1 gene under the control of the CaMV35S promoter. The levels of GAFP-1 synthesized in BB-1 were not elevated at 30 days after inoculation by M. incognita and at 5 days after inoculation by P. cinnamomi, suggesting that bul409 is not an inducible promoter. This study confirms the potential usefulness of incorporating the gafp-1 gene in creating disease resistant rootstocks for stone fruit cultivars and suggests that the gafp-1 gene provides comparable resistance to PRR and RKN irrespective of the promoter (bul409 or CaMV35S) being utilized for controlling gene expression.

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Biology Commons

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