What is going on with the flower bud differentiation and metabolites control of scape elongation on Clivia miniata Regel?

Abstract

Clivia miniata Regel, a globally renowned ornamental plant, is used in China to celebrate Lunar New Year (the Chinese Spring Festival). However, its anthesis in greenhouses often misses the timing of this festival. Understanding the mechanism of flower bud differentiation and scape elongation is critical for the accurate and stable regulation of anthesis. Currently, little is known about the molecular mechanism of anthesis regulation in C. miniata. In this study, a hypothetical model for its growth and the flowering mechanism was verified by systematic observation over a whole year. Once ripe-to-flower a C. miniata plant followed an autonomous, sympodial, and modular growth system in which the stem apical meristem produced four leaves before terminating in an inflorescence. Paraffin section observation revealed six stages of flower bud differentiation. Moreover, a metabolomic profile of a young leaf adjacent to the scape, at each of four stages of scape development, enabled us to identify metabolites involved in various pathways that correlated with regulation of anthesis. A total of 510 metabolites were identified as present across the different development stages of scapes. Of them, 159 metabolites were differentially expressed, and were enriched in the pathways of amino acid, sugar, glycerophospholipid, and glutathione. Amino acids, sugars, glycerophospholipids, and hormones were suggested to participate in development to anthesis by regulating the molecular network involved in scape elongation. The rate of scape appearance was highest (100 %) following spray application of 50 mg/L GA3. While all treatments could advance anthesis, a spray treatment at 200 mg/L GA3 advanced anthesis by 42 days.