Copper stress induces the differential expression of microRNAs in non-heading Chinese cabbage

Abstract

To gain a deep understanding of the regulatory mechanism of Cu-responsive microRNAs (miRNAs) in non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino), the transcription of 10 annotated stress-inducible miRNAs and their target genes were investigated in two cultivars Suzhouqing and Wutacai exposed to excess of copper. Results show that these miRNAs were negatively correlated with their target genes under the Cu stress and showed different transcriptions in different tissues and cultivars. The transcriptions of bra-miR1530a and bra-miR1533v were highest in petioles and lowest in roots. Bra-miR1533ah, bra-miR1533m, bra-miR1533t, bra-miR414a, and bra-miR398b had the highest and lowest transcriptions in leaves and roots, respectively. In contrast, the transcription of bra-miR172f was highest in roots and lowest in leaves. Bra-miR1533aj and bra-miR1533d had similar transcriptions in petioles and leaves. The promoter analysis further revealed that seven miRNAs contained the Cu-response element (CuRE). In addition, miRNAs with more CuREs in the 5'-flanking sequences showed a lower expression following the Cu treatment. It imply that CuREs likely played a role in increasing the response to Cu in non-heading Chinese cabbage.

Keywords

• brassica campestris
• cis-responsive element; cu-response element