Identification and characterization of differentially expressed novel miRNAs (21–24 nt) in a Macrophomina phaseolina resistant RIL line of jute (Corchorus capsularis L.)

Abstract

A RIL population of jute developed by crossing one resistant accession CIM 036 and a susceptible variety JRC 412 was used to identify novel defence related miRNAs activated upon challenged inoculation with stem rot pathogen Macrophomina phaseolina. About a total of 15.7 million reads were generated from the resistant line with the read length of 1 × 50 bp. Here, we identified nine mature novel microRNAs which passed Minimum Free Energy (MFE Kcal/mol) criteria. Target site and secondary structure were predicted and most of them showed ubiquitination and selective autophagy activity with high expression value. Five novel miRNAs viz. Candidate_41, Candidate_9, Candidate_66, Candidate_65 and Candidate_8 had free energy less than -25 kcal/mol. Known microRNAs viz. miR-845b and miR-166 superfamily are abundantly expressed with high expression value. The sequence of jute miR-845b superfamily is identical to that of Arabidopsis thaliana except at 18th position, but unlike in A. thaliana it targets the coding sequence for the P-loop motif in the mRNA sequences for disease resistance proteins with nucleotide binding site (NBS) and leucine-rich repeat (LRR) motifs. In-silico analysis suggested that miR-845b and miR-166 superfamily provided NBS-LRR and ROS mediated defence and subsequently expression of novel microRNAs with selective autophagy activity enabled multi-layered defence cascade against M. phaseolina in jute.