Identification and characterization of microRNAs in maize endosperm response to exogenous sucrose using small RNA sequencing

Sucrose acts as a signaling molecule for genes critical to starch biosynthesis in maize endosperm. Previously, we showed that sucrose could regulate starch biosynthesis in maize via transcription factors. To better understand the complex regulation of starch biosynthesis, the 10 days after pollination endosperm from Zea mays L. B73 inbred line was collected and treated with sucrose for small RNA sequencing. The sequencing results revealed that 24 known miRNAs and 190 novel miRNAs were significantly differentially expressed in response to sucrose. In addition, most of target mRNAs were characterized as transcription factors, mainly including, MYB, ARF, NAC, AP2/ERF, WRKY, and GRAS, which play important roles in starch biosynthesis and seed development in maize endosperm. The expression profiles of miR398a/b and miR159b/j/k followed opposite expression trends to their target genes when analyzed by qPCR. In conclusion, these results show that sucrose regulates the expression of starch synthetic genes through miRNAs.