IMPROVING ALFALFA AND OTHER FORAGE CROPS FOR BIOENERGY, LIVESTOCK PRODUCTION, AND ENVIRONMENTAL PROTECTION
Location: Plant Science Research
Title: Understanding the Regulation of Cell Wall Composition in Alfalfa
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 9, 2010
Publication Date: January 9, 2010
Citation: O'Rourke, J.A., Tesfaye, M., Yang, S.H., Lamb, J.F., Jung, H.G., Vance, C.P., Samac, D.A. 2010. Understanding the Regulation of Cell Wall Composition in Alfalfa [abstract]. Plant and Animal Genome XVIII Conference, January 9-13, 2010, San Diego, California. Available: http://www.intl-pag.org/18/abstracts/P07c_PAGXVIII_799.html.
Alfalfa (Medicago sativa L.) is the most important forage crop in the U.S. and has excellent potential to be a sustainable cellulosic feedstock for ethanol production. As the alfalfa stem matures, the xylem tissues become rich in cellulose, xylan, and lignin. The ideal alfalfa plant would have stems with high cellulose and low lignin concentrations. The objective of this study is to identify regulatory genes involved in determining the composition of the alfalfa stem cell wall. A microarray comparison of two alfalfa clones, 252 (high cellulose, high lignin) and 1283 (low cellulose, low lignin), identified 2,137 differentially expressed transcripts between elongating and post-elongating stems. Using these transcripts and the Medicago truncatula 2.0 genome assembly, we identified the predicted genes corresponding to the transcripts on the array. We then identified a 1,000 bp region immediately upstream of the start codon. Using these 2,137 upstream sequences as the input to the Multiple EM for Motif Elicitation (MEME) program, we identified six unique motifs. A comparison to the TRANSFAC(R) database confirmed two of the six were novel sequence motifs, most likely newly identified TFBS. A genome-wide comparison identified one of the two novel motifs in the promoter region of 50 genes and the other novel motif in the promoter region of 23 genes out of the approximately 48,000 unique upstream sequences in the Medicago truncatula 3.0 genome. To identify the transcription factors that bind to these putative TFBS, we synthesized tandem repeats of the motifs for use in a yeast one hybrid experiment.