Functional study of miR156-SPL (SQUAMOSA PROMOTER BINDING PROTEIN-LIKE) regulatory module involved in high temperature-induced flowering mechanism in Oncidium Gower Ramsey

• Main Authors: Yu-Chen Tsang, 臧友真
• Other Authors: Kai-Wun Yeh
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/98045481239709997638

碩士 === 國立臺灣大學 === 植物科學研究所 === 101 === Previous studies have shown that high temperature-induced flowering is regulated by Oncidium cytosolic ascorbate peroxidase 1 (OgcytAPX1) through mediating the redox state of ascorbate (AsA) in Oncidium Gower Ramsey. Ecotopically overexpressing OgcytAPX1 in Arabidopsis can induce the expression of miRNA156-targeted SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 3 (SPL3) under high-temperature treatment. The miR156-SPL regulatory module has been known to regulate flowering in Arabidopsis, but its specific regulatory role on flowering is unclear. In order to dissect the function of miR156-SPL regulatory module on high temperature-induced flowering in Oncidium. We found three possible miR156-target SPL genes in Oncidium (OgSPLs). The study on expression profiling of Oncidium pseudobulbs at different growth stages indicated that miR156 steadily decreased, and OgSPLs increased as the Oncidium matures. Higher growth temperature increased OgSPLs transcription levels in both pseudobulbs and inflorescence buds, but the effect diminished after AsA application. However, the influence on miR156 under these treatments was not significant, suggesting that OgSPLs was independent of miR156 in high temperature-induced flowering mechanism. Meanwhile, ecotopically overexpressing OgSPLs in Arabidopsis mutant apx1 restored the delayed flowering phenotype compared to WT, suggesting that flowering regulation of OgSPLs was located at the downstream of OgcytAPX1. In conclusion, these results indicate that miR156 regulates phase transition through OgSPLs; however, OgSPLs act independently of age-mediated miR156 as one of the AsA redox downstream signal on the high temperature-induced flowering processes in the adult Oncidium.