Electronic Thesis and Dissertation Repository


Master of Science




Dr. Abdelali Hannoufa


MiR156 regulates plant biomass production through regulation of members of Squamosa-Promoter Binding Protein-Like (SPL) genes. In this study, I investigated function of miR156 in Medicago sativa (alfalfa). Alfalfa plants overexpressing alfalfa miR156 and Lotus japonicus miR156 were generated, and the miR156 cleavage targets were validated. In silico analysis showed that some alfalfa sequence reads (~ 60 bp) are similar to miR156 precursors but the hairpin secondary structure could not be produced from these sequences. Of the five predicted target SPLs genes, three (SPL6, SPL12 and SPL13) contain miR156 cleavage sites and their expression was downregulated in transgenic alfalfa overexpressing miR156. These transgenic alfalfa genotypes had reduced internode length, enhanced shoot branching, and elevated biomass. Although alfalfa miR156 had little effect on nodulation and flowering time, L. japonicus miR156 reduced nodulation and delayed flowering time (up to 50 days). Our observations imply that miR156 could be employed in improving alfalfa biomass.

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