Regeneration of dalapon tolerant nicotiana tabacum by expressing dehalogenase E gene through agrobacterium tumefaciens mediated transformation
Date
2013
Authors
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Publisher
Universiti Teknologi Malaysia
Abstract
A dehE gene from Rhizobium sp. encodes a dehalogenase capable of degrading 2,2-dichloropropionic acid, the active ingredient of the herbicide Dalapon. The gene encoding gus in the plant transformation vector, pCAMBIA1301, was replaced with dehE under the control of the 35S promoter from cauliflower mosaic virus. Transgenic Nicotiana tabacum plants were then produced that carried the modified pCAMBIA1301, and these transgenic plants were tolerant to Dalapon. Leaf discs of 7-week-old tobacco plants grown under in vitro conditions were inoculated with Agrobacterium tumefaciens strain LBA4404 that carries dehE. After transformation, the plants were subcultured in Murashige and Skoog medium supplemented with 50 µg/ml kanamycin, 25 µg/ml hygromycin, and 500 µg/ml cefotaxime for at least 6 weeks. The presence of dehE in N. tabacum was confirmed by PCR, and dehE expression was ascertained by real-time PCR. The confirmed real-time PCR results the transgenic tobacco plantlets were transferred to soil for further growth. The tolerance of genetically transformed N. tabacum plants to Dalapon was assessed under in vitro and plant growth chamber conditions. After 7 days of growth, the transgenic plants were treated with different concentrations of Dalapon ranging from 20 to 200 mg/l using a leaf-painting bioassay method. The transformed N. tabacum showed tolerance to Dalapon up 200 mg/l, whereas the N. tabacum TAPM 26 (control) could tolerate Dalapon only up to 60 mg/l. This experiment suggests that dehE can be expressed in N. tabacum and that transgenic plants are tolerant to Dalapon
Description
Thesis (Ph.D (Bioscience))
Keywords
Biosciences and medical engineering