ISHS Acta Horticulturae 637: XXVI International Horticultural Congress: Advances in Vegetable Breeding
TRANSGENIC CARROTS EXPRESSING ENHANCED TOLERANCE TO HERBICIDE AND FUNGAL PATHOGEN INFECTION |
| Authors: | Z.K. Punja, W.P. Chen |
| Keywords: | antifungal proteins, disease resistance,Daucus carota L., genetic engineering, phosphinothricin, thaumatin-like protein |
| Abstract:
Transgenic carrot (Daucus carota L.) plants expressing a thaumatin-like protein (TLP) from rice with potential antifungal activity were obtained by Agrobacterium tumefaciens-mediated genetic transformation. Two genes encoding phosphinothricin (PPT) acetyltransferase (bar) and hygromycin (Hyg) phosphotransferase (htp) were used as selectable markers. Petiole and hypocotyl explants of three carrot cultivars (Danvers Half Long, Nanco and Nantes Coreless) from 3-4 week-old seedlings were used for infection. Selection was initiated after three days of co-culture, using Murashige and Skoog medium containing 1 mg/L 2,4-D, and 1 mg/L PPT or 25 mg/L hygromycin. After four weeks, selection was increased to 10 mg/L PPT and 100 mg/L Hyg. The presence of the tlp and bar transgenes was detected by polymerase chain reaction and confirmed by Southern analysis. The expression of TLP was demonstrated by Western analysis. From 45 primary transformed lines, 13 were selected for assessment of enhanced herbicide and/or disease tolerance. The transgenic lines showed varying levels of tolerance to phosphinothricin, the active ingredient in several commercially available herbicides. Four of the transgenic lines also showed significantly enhanced tolerance to the fungal pathogens Sclerotinia sclerotiorum or Botrytis cinerea when detached petioles and leaflets were inoculated under controlled environmental conditions. Two carrot lines had significantly enhanced tolerance to the herbicide as well as to both pathogens (lesion development reduced by 30-50%). The results from this study demonstrate the feasibility of introducing two potentially useful agronomic traits into carrot through genetic engineering. | |
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