Construction of Lactuca sativa Plastid Transformation Vector and High-level Expression of gfp Gene in Escherichia coli

Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragments of exogenous gene were integrated to construct lettuce plastid expression vector p Brpo AGFP,which harbored the expression cassette Prrn-gfp-aad A-Tpsb A. The results showed that the amplified flanking fragments were 1.2 and 1.1 kb in size. After sequencing,restriction digestion,ligation and transformation,lettuce plastid expression vector containing expression cassette Prrn-gfp-aad A-Tpsb A was constructed and confirmed by SDS-PAGE electrophoresis. The results of SDS-PAGE electrophoresis indicated that gfp gene was efficiently expressed under the regulation of plasmid specific promoter Prrn and terminator Tpsb A. GFP accounted for 45. 6% of total soluble proteins; inclusion bodies accounted for 47.5 % of bacterial proteins,which reached relatively high expression levels. The construction of lettuce plastid expression vector p Brpo A-GFP laid a solid foundation for establishment of subsequent lettuce plastid transformation system and genetic improvement of lettuce using various functional genes.

Cloning and Sequence Analysis of Polygalacturonase(PG) Promoter in Tomato

In this study, 1 500 bp PG gene promoter was amplified from leaves of tomato cultivar ＇ Zhongshu No. 4＇. The bioinformatic analysis of PG promoter sequences was conducted. PG promoter elements were predicted and analyzed by PLANTCARE and PLACE. The results showed that tomato PG promoter contained multiple c/s-acting regulatory elements such as typical basic elements TATA-Box and CAAT-Box, light responsive elements 3-AF1 binding site, ATl-motif, ATCT- motif, Box 4, Box I, GA-motif, GTl-motif, Spl and MRE, heat stress-responsive element HSE, ethylene-responsive element ERE, meristem-specifie regulatory element CCGTCC-box, endosperm expression-related regulatory elements GCN4_motif and Skn-l_motif, defense and stress responsiveness element TC-rich repeats, and circadian control-related element circadian, indicating that the expression of tomato PG gene is related to light, temperature, hormone, stress and other factors. This study laid the foundation for subsequent research about regulation of PG gene expression in plants.