T-DNA and the GUS Gene

Type :

Term papers

Pages :

24 pages

Format :

.doc

Published date :

05/27/2009

Category :

Science & technology

Sub category :

Medical studies

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Summary :

Introduction
Basics of a promoter
Core promoter
Types of plant promoters
Promoter isolation and characterization in plants
Binary vector (pBI-101)
Material methods
Results and discussion
Conclusion
Bibliography

Abstract

Development of an organism is strictly regulated by molecular and genetic mechanisms. The precise regulatory processes involving switching on or off of certain set of genes at a specific stage and place mediated by certain combination's of regulatory elements are fundamental to the development. Identification and isolation of plant genes and promoters are essential in plant research communities to understand the biological processes at molecular level. Identification and isolation are also beneficial in studying genetic expression in transgenic plants. So it is important to have a deep knowledge and understanding of regulatory mechanisms at gene level to select the best promoter for use in transgenic plants.

A promoter is a regulatory element that drives the expression of introduced genes in transgenic plants that are of agricultural and economic importance in a specific manner. So there is a need to identify and isolate promoters that regulates tissue specific and stage specific expression of genes in plants. Trichomes are specialized epidermal cells that provide first line of defense against insects and pests. In order to develop transgenic plants that are resistant to pests and insects attack .To isolate trichome specific promoter T-dna insertional mutagenesis has been used. In this approach a binary vector (pGKB5) containing promoter less reporter gene B-glucuronidase (uidA) adjacent to right border of T-dna is used to create mutant Arabidopsis thaliana plants.

Arabidopsis thaliana is an angiosperm, dicot plant of Brassicaceae family, which is also a model organism in plant kingdom. It is useful for making transgenic plants because of its small genome, small size, easy growth in lab in a relatively small space, development is also rapid (only 5-6 weeks from seed germination to production of a new crop of seeds) and very little repetitive dna. On screening of mutant plants there is an expression of gus gene exclusively in trichomes. Due to t-dna insertional mutagenesis, sequences upstream to gus gene acts as a promoter, which drives its expression in trichomes.