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Genetics Section

Johnson, Deborah Alongi [1], Thomas, Michael A. [1], Hill, Jeffrey P. [1].

Sugar transporter gene family discovery in the fern Ceratopteris richardii.

Monosaccharide transporters (MSTs) are integral membrane proteins that are present in all organisms and play a fundamental role in carbohydrate flux and metabolism. In plants, MST genes are expressed in both source and sink tissues and some are gametophyte-specific. In angiosperms, the MST gene family is large with 53 MST-like genes identified in the Arabidopsis genome. Phylogenetic analysis of these genes reveals them to cluster into seven subfamilies. Expression analyses of genes from Arabidopsis and other plant species reveal that these subfamilies probably comprise different functional classes and/or expression of transporters in different membranes. Our hypothesis is that the structure of this gene family is ancient, with ancestral members of each gene subfamily likely being present in the algal ancestor of all land plants. Our research approach is to use various bioinformatic and molecular biological methods, including BAC library screening, to identify MST genes from each of the subfamilies, if present, in the model non-seed vascular plant, Ceratopteris richardii. Discovery of the size and structure of this gene family in this model fern species will shed light on how this gene family evolved in the pteridophyte lineage and allow phylogenetic comparison to its sister clade, the seed plants. Expression studies in the free-living gametophyte and sporophyte phases of the fern life cycle will allow us to discover how this gene family evolved in the context of the evolution of alternation of generations. Thus far we have cloned and sequenced two MST genes identified through degenerate PCR, and identified two Ceratopteris ESTs with high sequence similarity to Arabidopsis MSTs. These putative MST genes fall into two of the seven subfamilies. Our work continues with the development of multiple MST probes and screening of the recently developed Ceratopteris BAC library to identify additional MST candidates.

Related Links:
Primary author's department web page
Second author's department web page
Third author's department web page

1 - Idaho State University, Department of Biological Sciences, Campus Box 8007, Pocatello, Idaho, 83209-8007, USA

BAC library
candidate genes
comparative genomics
expressed sequence tags
gene family
monosaccharide transporters
alternation of generations
fern life cycle.

Presentation Type: Poster
Session: 32-50
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:586

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