ARS | Publication request: The regulation of post-germinative transition from the cotyledon- to vegetative-leaf stages by microRNA-targeted SQUAMOSA PROMOTER-BINDING PROTEIN LIKE13 in Arabidopsis

Submitted to: Seed Science Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 27, 2010
Publication Date: June 15, 2010
Citation: Martin, R.C., Asahina, M., Liu, P., Kristof, J.R., Coppersmith, J.L., Pluskota, W.E., Bassel, G.W., Goloviznina, N.A., Nguyen, T.T., Martinez-Andujar, C., Kumar, A.M., Pupel, P., Nonogaki, H. 2010. The regulation of post-germinative transition from the cotyledon- to vegetative-leaf stages by microRNA-targeted SQUAMOSA PROMOTER-BINDING PROTEIN LIKE13 in Arabidopsis. Seed Science Research. 20:89-96.

Interpretive Summary: Germination and early seedling development are critical for successful stand establishment. A young seedling consists of mainly embryo derived tissues until the first true leaves develop. This switch to vegetative growth marks a significant transition during the early stages of plant development. Various MicroRNAs are essential for normal plant growth and development. In this paper, miR156 was shown to be important for the early transition from embryonic to vegetative growth. When the down regulation of SQUAMOSAPROMOTER-BINDING PROTEIN-LIKE13 by miR156 was interrupted, there was a delay in seedling development indicating that this down regulation is important for normal plant development.

Technical Abstract: Germination and early seedling development are critical for successful stand establishment of plants. Following germination, the cotyledons, which are derived from embryonic tissue, emerge from the seed. Arabidopsis seedlings at the post-germinative stages are supported mainly by the nutrition supply from the cotyledons until vegetative leaves emerge and initiate photosynthesis. The switch to autotrophic growth is a significant transition at the post-germinative stage. Here, we provide evidence that down-regulation of SQUAMOSA PRMOTERBINDING PROTEIN13 (SPL13) by microRNA156 (miR156) plays an important role in the regulation of the post-germinative switch from the cotyledon stage to the vegetative-leaf stage. Silent mutations created in the SPL13 sequence in the region that is complementary to the miR156 sequence caused the de-regulation of the mutant form of SPL13 (mSPL13) mRNA from miR156. Mutant seedlings over-accumulated miRNA-resistant messages and exhibited a delay in the emergence of vegetative leaves compared to wild-type seedlings. The delay was not observed in control transgenic plants expressing non-mutated SPL13, indicating that the phenotype was caused specifically by the silent mutations and de-regulation of SPL13 from miR156. Characterization of the SPL13 promoter indicated that this gene is expressed mainly in the hypocotyl and affects leaf primordium development. These results suggest that the repression of SPL13 by miR156 is essential for normal post-germinative growth in Arabidopsis.