Expression Analysis of DgD14, DgBRC1 and DgLsL in the Process of Chrysanthemum Lateral Bud Formation

The growth of lateral bud can greatly affect the development of apical bud and reduce the quality of single-flower cut chrysanthemum. However, the wide use of artificial bud removal in production leads to the increase on production cost. Therefore, it is important to study the lateral bud development mechanism in chrysanthemum for plant type regulation and genetic improvement. Auxin (IAA), cytokinins (CKs) and strigolactones (SLs) have direct or indirect effects on the formation of lateral buds. D14, BRC1 and LsL are key factors regulating the signal pathways of hormones, but their regulation mechanisms on the development of lateral buds in chrysanthemum are still unclear. In this study, single-flower cut chrysanthemum ‘Jinba’ and spray cut chrysanthemum ‘Fenyan’ were used as experimental materials. Quantitative real-time PCR was used to observe the effects of apical bud removal and exogenous hormones on the growth of lateral buds and the expression levels of DgD14, DgBRC1 and DgLsL, so as to clarify the expression characteristics of three genes in the process of lateral bud formation. The results showed that GA was effective in promoting the growth of lateral buds, whereas IAA and ABA had little effects on lateral bud growth or even inhibited. Removing apical dominance can significantly affect the expression levels of three genes, which regulated the formation and elongation of lateral buds. Additionally, the three genes showed different responses to different hormone treatments. DgD14 had a significant response to GA, but a gentle response to ABA. The expression levels of DgBRC1 varied in different trends, and it responded to IAA in a more dramatic way. The levels of DgLsL reached the peaks quickly before decreased in most experimental groups, and its response to GA was extraordinary severe.