Poster: Comparative Genomics

Abs # 918: Cloning and sequence analysis of a putative plastidic glutamine synthetase cDNA from Heteropappus meyendorfii.

Presenter:	Walters, Lisa A, walterslisaa@yahoo.com
Authors	Walters, Lisa A (A)   Twigg, Paul G (A)
Affiliations:	(A): University of Nebraska-Kearney

Glutamine synthetase (GS) is an enzyme integral to nitrogen metabolism in all plants. This enzyme performs the initial nitrogen assimilation reaction wherein ammonium is added to glutamate making glutamine. This assimilated nitrogen can then be further used in amino acid synthesis, nucleic acid synthesis, and alkaloid synthesis amongst others. In this study, we outline the isolation of a GS cDNA from Heteropappus meyendorfii (Blue Chrysanthemum). This plant is a member of the Asteraceae, and is native to Western Siberia. The "Blue Knoll" variety tested is however a common horticultural plant. Total RNA was isolated from leaves of Heteropappus. We will outline the procedure used to isolate good quality RNA from this plant. We will also outline the 3' Rapid Amplification of cDNA Ends (RACE) procedure used to clone the cDNA. In addition to good quality total RNA, using the proper oligonucleotide primers is crucial to 3' RACE. We will discuss primer design issues for the success of these RACE systems, as well. The Heteropappus GS cDNA isolated was 1058 bp in length encoding an open reading frame of 225 amino acids. Nucleic acid comparisons showed this cDNA to be most similar to plastidic GS2's of Gazania, Echinacea, Helianthus, Daucus, and Solanum. We will lastly consider the applicability of GS sequence data such of that presented in the assessment of phylogenetic relationships amongst higher plants. This project was partially supported by NIH Grant Number 1 P20 RR16469 from the BRIN Program of the National Center for Research Resources, and by the UNK Department of Biology.