Integrated mRNA, microRNA transcriptome and degradome analyses provide insights into stamen development in moso bamboo.

The flower is essential for sexual reproduction of flowering plants and has been extensively studied in model plants. Here, we used transcriptomic, small RNA and degradome analyses to characterize key miRNAs and their targets in floral organs of moso bamboo. In total, we identified 13,051 differentially expressed genes (DEGs) and 109 known miRNAs from 26 miRNA families. We aligned the miRNAs to known miRNA databases and revealed some conserved as well as novel miRNAs. Sixteen conserved miRNAs were specific highly expressed in stamens, including miRNA159 and miRNA166. In situ hybridization shows that miRNA159 plays an key role in the regulation of stamen development and expression levels of its targets PheMYB98 and PheMYB42 were low. Furthermore, Phe-MIRNA159, partially recover phenotypes of mir159ab double mutant. Overexpression of Phe-MIR159 could cause anther dehisce failure, the mature pollens could not be dispersed and further reduce fertility in Arabidopsis. Semi-thin section result shows that anther endothelial layer of Phe-MIRNA159 overexpressing lines is lack of secondary thickening, resulting in limited force for anther opening. Phe-miR159 may regulate expression of genes related to secondary thickening through negative regulation of AtMYB33, affecting the anther dehiscence. Together, this study provides insights regarding molecular networks underlying floral organs development of moso bamboo.