|Valdes-Lopez, Oswaldo -|
|Naya, Loreto -|
|Hernandez, Georgina -|
Submitted to: Joint Meeting of the American Society of Plant Biologists and the Canadian Society of Plant Physiologists
Publication Type: Abstract Only
Publication Acceptance Date: May 5, 2010
Publication Date: July 31, 2010
Citation: Yang, S.H., Valdes-Lopez, O., Naya, L., Gronwald, J.W., Samac, D.A., Hernandez, G., Vance, C.P. 2010. microRNAs and microRNA targets involved in alfalfa stem development [abstract]. Plant Biology 2010: Joint Meeting of the American Society of Plant Biologists and the Canadian Society of Plant Physiologists, July 31 - August 4, 2010, Montreal, Canada. Abstract No. PO8083. Technical Abstract: To examine the possible involvement of microRNAs (miRNAs) in alfalfa stem development, we hybridized 32P-labeled total miRNA purified from elongating and post-elongation stem internodes (ES and PES, respectively) of alfalfa clone 252 to a miRNA-macroarray that contained a total of 70 reference anti-miRNA oligonucleotides from Arabidopsis, soybean, and common bean (Phaseolus vulgaris). After three independent hybridizations, the signal for each miRNA was normalized using the miRNA482* signal as a control (normalization = signal/control). Using a t-test with p-value cut-off of 0.05, we identified four miRNAs up-regulated and one down-regulated in PES compared to ES. We also identified six miRNAs detected only in PES, and two of them were involved in the auxin signaling pathway. We validated miRNA-macroarray data using miRNA blot analysis and/or miRNA qRT-PCR. To predict the global expression pattern of miRNAs and miRNA target genes during alfalfa stem development, the 266 putative Medicago miRNAs currently available in Medicago-MIRATdb were used to search putative targets among Medicago GeneChip probe set consensus sequences using the psRNATarget algorithm. A total of 1,318 putative miRNA target probe sets were identified. Fisher's exact test with Bonferroni correction identified over-representation of genes involved in photosynthesis, amino acid metabolism, stress response, and transcription factors among putative miRNA targets. The expression pattern of putative miRNA target genes in the GeneChip data for stems of alfalfa clonal lines 252 and 1283 suggested that transcript levels of key regulatory genes, including transcription factors and signaling genes involved in stem development in alfalfa, are regulated by miRNAs.