Analysis of expression regulation of AP2 gene by pre-miR172 and miR172 in rape

Abstract

The appropriate flowering time is of great significance for crop yield. In the cropping pattern of “rice-rice-oil” in southern region, researching on the flowering period of Brassica napus can provide a theoretical basis for the breeding of early maturing rape varieties. The AP2 family transcription factors in rape are widely involved in the growth and development and play an important role during flower development. However, there are few studies exploring the regulation of AP2 at the microRNA level. In order to investigate the regulatory functions of the miR172 precursor (pre-miR72) and mature body (miR172) on AP2 gene in rape, the regulatory elements of miR172 and AP2 promoters were predicted based on bioinformatics, then the evolutionary relationship of six rape AP2 genes and the targeting relationship between miR172 and AP2 were analyzed, and the expression patterns of AP2, miR172 and pre-miR172 in different tissues of early and late maturing rape were detected by qRT-PCR. Finally, the correlation between miR172 abundance and AP2 expression level was studied, as well as the correlation between pre-miR172 and miR172. The results were as follows: (1) Both miR172 and AP2 promoter regions had cis-elements that regulated flower development. (2) The six AP2sequences holded the strong purification selection, and they were the target genes of miR172 based on their binding sites for miR172. (3) miR172 family could promote the flowering of early maturing rape by increasing AP2 expression levels, except for miR172d. In late maturing rape, miR172a and miR172c performed weakly in flowering, while miR172b and miR172d worked together to reduce the expression level of AP2 to inhibit flowering. (4) The pre-miR172 family had a promoting effect on the expression level of miR172 family in early maturing rape; in late maturing rape, pre-miR172a and pre-miR172b exerted positive regulation on the formation of their mature bodies, while pre-miR172c and pre-miR172d exerted the opposite effects. After overexpression of pre-miR172, the expression patterns of miR172 and AP2 remained consistent with the above results, confirming the regulatory function of pre-miR172 on miR172 and AP2. The results of this study enrich the functional regulation pathway of rape AP2 gene, and provide new ideas for the study of gene regulatory function.

Keywords

• rape
• ap2
• mir172
• pre-mir172
• expression pattern