The effects of foreign genes in transgenic Thale cress (Arabidopsis thaliana

Abstract

Agrobacterium tumefaciens-mediated transformation was used to introduce foreign genes into Arabidopsis thaliana (Thale Cress). Initially a simple marker gene construct (pJIT73) was used to set up the transformation system. Once established, three further constructs were introduced to test all aspects of the system: a gene; a promoter- reporter fusion; and a transposable element, PsMT(_A) (isolated from Pisum sativum [Evans et al., 1990a] encodes a polypeptide with strong homology to class I metal-binding proteins or metallothioneins. In order to determine its function in planta, PsMT(_A) was introduced into Arabidopsis thaliana under the control of the 35S CaMV promoter. PGR analysis was used to confirm the presence of the engineered gene and its expression. Fl transgenic seedlings, grown on both copper-supplemented and control medium, accumulated copper at a higher concentration than control seedlings. This data suggests that the PsAfT^ gene encodes a copper chelating protein. The structure of specialized plant cell walls varies with their function. Hydroxyproline-rich glycoproteins (HRGPs) or extensins are frequently present in the cell walls of strengthened cell types. A rape extensin gene promoter (extA [Evans et al.,1990b1) fused to a GUS reporter was introduced into Arabidopsis, using Agrobacterium tuwefaciens-mediated transformation. extA expression in the stems of transgenic plants was localized to the phloem and the epidermal tissue (using GUS histochemical staining and an anti-GUS immuno-gold assay).Transposition of the TanB element (from Antirrhinum majus) has been studied in tobacco (Martin et ah, 1989). TanQ was introduced into Arabidopsis thaliana in a modified version of pJIT73. Transgenic plants were identified by GUS histochemical staining, immunogold labelling and PGR analysis, and the presence of the TanB element was determined by genomic blotting. However, no evidence of a TamB transposition event was conclusive.