Spatiotemporal Pattern Of OsmiR393 And Target Genes And Their Functions In Auxin Response Pathway

miR393 is a member of five most conserved miRNA families. miR393/target regulatory module plays crucial roles in plant growth and development, auxin signaling pathways and stress response. In this article, we focus on the spatiotemporal expression pattern and regulation mechanism of miR393/target regulatory module. Besides, we use miR393 transgenic lines to study the relationship between miR393 and important gene families of auxin signaling pathway. Our main results are presented as follows:1. Analysis of the spatiotemporal expression pattern of OsmiR393 and target geneGUS staining of epoxy resin semi-thin sections of pMIR.393:GUS, pTIR1:GUS and pDR5:GUS reporter lines illustrated that MIR393 was highly expressed in stele tissues, pericycle and endodermis, while TIR1 expressed in the tissues between lateral root tip and base. Besides, TIR1 expressed in stele tissues of primary root tip, but MIR393 did not express there.Auxin response genes expressed strongly in stele tissues, pericycle, endodermis, tip of lateral root and stele tissues of primary root. This showed that miR393/target regulatory module exists within the area that auxin response genes expressed strongly, suggesting a close relationship with auxin response.2. Expression patterns of gene families related with auxin signaling pathwayTo clarify the relationship between miR393 and auxin response, qRT-PCR was used to analysis the expression pattern of auxin synthesis, conjugation, transport, perspective and response genes in in wild type rice. Our results were as follows:1) that auxin synthesis YUC family mainly expressed in coleoptile, leaf and root. YUC2 was the highest in coleoptile and YUC6 was the highest in leaf and root.2) Auxin transport family LAX expressed strongly in coleoptile, leaf and root, and LAX5 was the highest.3) Auxin conjugation GH3 family expressed strongly in coleoptile and GH-12 was the highest.4) IAA family expressed stronglyin coleoptile and root.and IAA11, IAA12, IAA14, IAA16 and IAA31 expressed strongly in coleoptile, IAA23 expressed strongly in root.5) ARF expressed stronglyin coleoptile and root, and ARF6, ARF 10, ARF 16 and ARF21 expressed strongly in coleoptile; ARF7A was the highest in root. These results illustrated that auxin synthesis, conjugation, transport, perspective and response genes expressed mainly in coleoptile and root.3. OsmiR393 affects the expression level of gene families related with auxin signaling pathwayqRT-PCR was used to analysis the expression level of auxin synthesis, conjugation, transport, perspective and auxin response genes in 35S:miR393 and 35S: MIM393 rice lines. And we found that MIR393 promoted auxin synthesis in coleoptiles. The results were as follows:YUC1, YUC2, YUC3 and YUC4 were up-regulated in coleoptiles of 35S:miR393 lines; LAX1, LAX2 and LAX3 were down-regulated; while GH3-5 and GH-12 were up-regulated.Taken together, our results illustrated the spatiotemporal expression pattern of OsmiR393 and target gene. Furthermore, OsmiR393 could affect the expression level of auxin synthesis, conjugation and transport genes.