|Reyes, Jose Luis|
Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2010
Publication Date: 6/11/2010
Publication URL: http://hdl.handle.net/10113/46892
Citation: Valdes-Lopez, O., Yang, S.H., Aparicio-Fabre, R., Graham, P.H., Reyes, J., Vance, C.P., Hernandez, G. 2010. MicroRNA Expression Profile in Common Bean (Phaseolus vulgaris) under Nutrient Deficiency Stresses and Manganese Toxicity. New Phytologist. 187(3):805-818. Interpretive Summary: Phosphorus (P) is a critical nutrient for crop growth quantity and quality. Agriculture faces two issues with P fertilizer. Application of too much P fertilizer results in water pollution while insufficient P fertilizer results in poor crop growth. A major goal in agriculture is to improve P acquisition and use by crop plants. Small molecules called miRNA have been proposed to be involved in plant acclimation to abiotic stress. In this study we grew common bean plants that were subjected to several abiotic stresses including: phosphorus deficiency, nitrogen deficiency, iron deficiency, manganese toxicity, or acidic conditions and measured the expression of 68 miRNAs in leaves, roots, and nodules. We found that some miRNAs were expressed in all abiotic stress conditions, while others were expressed under specific stress conditions. In addition, we found that roots, nodules, and leaves had a suite of miRNAs specific to each organ. The manipulation of selected miRNAs through biotechnology approaches has been shown previously to improve tolerance to abiotic stress. This research is useful because the identification of miRNAs in common bean grown under abiotic stress will provide new avenues to pursue in developing stress-tolerant plants.
Technical Abstract: MicroRNAs (miRNAs) play a pivotal role in post-transcriptional regulation of gene expression in plants. The information on miRNAs in legumes is scarce. This work analyzes miRNAs in the agronomically important legume common bean (Phaseolus vulgaris. A hybridization approach of miRNAs-macroarrays printed with oligonucleotides complementary to 68 known miRNAs was used to detect miRNAs in leaves, roots, or nodules from control or nutrient-stressed (phosphorus, nitrogen, or iron deficiency; acidic pH; and manganese toxicity) common bean plants. Thirty-three miRNAs were expressed in control plants; five miRNAs were only expressed in stress treatments. The miRNA expression ratios (stress treatment/control) were analyzed by principal component and hierarchical cluster analyses. A group of miRNAs responded to almost all the stresses and organs while other miRNAs responded specifically in stressed leaves, roots (mostly down-regulated), or nodules (mostly up-regulated). MiRNA-blot expression analysis confirmed the macroarrays results. Novel miRNA target genes were proposed for common bean, and the expression of selected targets was evaluated by qRT-PCR. In addition to the detection of previously reported stress-responsive miRNAs, we discovered novel common bean stress-responsive miRNAs, i.e., for manganese toxicity. Our data provide the foundation to evaluate the individual roles of miRNAs in common bean.