Expression analysis of MicroRNAs and their target genes in Cucumis metuliferus infected by the root-knot nematode Meloidogyne incognita

Abstract MicroRNAs (miRNAs) are types of transcriptional and post-transcriptional modulators of gene expression that play crucial roles in response to diverse stresses. Although significant progress on the miRNA-mediated gene regulation has been made recently in plant-nematode interactions, none has been reported on root-knot nematode (RKN, Meloidogyne spp.) infection in Cucumis metuliferus, which is a relative of cucumber with resistance to M. incognita. To gain insights into the regulatory roles of miRNAs for resistance to RKN in C. metuliferus, it is necessary to create expression profiles for miRNAs and their targets. In this study, ten miRNAs were identified from our miRNAs sequencing data of C. metuliferus for expression analysis through quantitative reverse transcription-PCR (qRT-PCR). The results showed that RKN infection had a significant effect on both miRNAs expression and their corresponding targets in either resistant or susceptible plants but with differential expression. Moreover, four out of ten selected miRNA-target pairs, miR156-SBP, miR390-ARF3, ath-miR159a-MYB104 and aly-miR827-3p-PTI, exhibited inverse expression patterns between miRNAs and their targets, which laid a foundation for investigating resistance mechanisms induced in C. metuliferus by M. incognita infection. Additionally, the possible roles of these miRNAs have been discussed during C. metuliferus-RKN interactions.