cla-miR164-NO APICAL MERISTEM (ClNAM) regulates the inflorescence architecture development of Chrysanthemum lavandulifolium

Abstract

Chrysanthemum × morifolium has great ornamental and economic value on account of its exquisite capitulum. However, previous studies have mainly focused on the corolla morphology of the capitulum. Such an approach cannot explain the variable inflorescence architecture of the chrysanthemum. Previous research from our group has shown that NO APICAL MERISTEM (ClNAM) is likely to function as a hub gene in capitulum architecture in the early development stage. In the present study, ClNAM was used to investigate the function of these boundary genes in the capitulum architecture of Chrysanthemum lavandulifolium, a closely related species of C. × morifolium in the genus. Modification of ClNAM in C. lavandulifolium resulted in an advanced initiation of the floral primordium at the capitulum. As a result, the receptacle morphology was altered and the number of florets decreased. The ray floret corolla was shortened, but the disc floret was elongated. The number of capitula increased significantly, arranged in more densely compounded corymbose synflorescences. The yeast and luciferase reporter system revealed that ClAP1, ClRCD2, and ClLBD18 target and activate ClNAM. Subsequently, ClNAM targets and activates ClCUC2a/c, which regulates the initiation of floral and inflorescence in C. lavandulifolium. ClNAM was also targeted and cleaved by cla-miR164 in this process. In conclusion, this study established a boundary gene regulatory network with cla-miR164-ClNAM as the hub. This network not only influences the architecture of capitulum, but also affects compound corymbose synflorescences of the C. lavandulifolium. These results provide new insights into the mechanisms regulating inflorescence architecture in chrysanthemum.

Acknowledgments

This work was supported by National Natural Science Foundation of China (No.32371948, No. 31530064, and No. 31471907).

Author contributions

S.D, J.L, and X.W. conceived the study. J.L and X.W completed the main work. Q.Z. and Y.P. analysed the data. Y.T., J.W., B.L., and Y.D. contributed to planting material and phenotype data observation. J.L. completed the first draft. S.D. and X.W. revised the manuscript. All authors read and approved the final manuscript.

Date availability

Raw sequence data were submitted to the Sequence Read Archive (SRA) database of the National Center for Biotechnology Information (NCBI) (accession number: PRJNA956717).

Conflict of interest statement:

The authors declare no competing interests.

Supplementary data

Supplementary data is available at Horticulture Research online.

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