Identification and molecular characterization of miRNAs and their target genes associated with seed development through small RNA sequencing in chickpea.

Multiple studies have attempted to dissect the molecular mechanism underlying seed development in chickpea (Cicer arietinum L.). These studies highlight the need to focus on the role of miRNAs in regulating storage protein accumulation in seeds. Therefore, a total of 8,856,691 short-read sequences were generated from a small RNA library of developing chickpea seeds and were analyzed using miRDeep-P to identify 74 known and 26 novel miRNA sequences. Known miRNAs were classified into 22 miRNA families with miRNA156 family being most abundant. Of the 26 putative novel miRNAs identified, only 22 could be experimentally validated using stem loop end point PCR. Differential expression analyses led to the identification of known as well as novel miRNAs that could regulate various stages of chickpea seed development. In silico target prediction revealed several important target genes and transcription factors like SPL, mediator of RNA Polymerase II transcription subunit 12, aspartic proteinase and NACs, which were further validated by real-time PCR analysis. A comparative expression analysis in chickpea genotypes with contrasting seed protein content revealed one known (Car-miR156h) and two novel miRNA (Car-novmiR7 and Car-novmiR23) candidates to be highly expressed in the LPC (low protein content) chickpea genotypes, targets of which are known to regulate seed storage protein accumulation. Therefore, this study provides a useful resource in the form of miRNA and their targets which can be further utilized to understand and manipulate various regulatory mechanisms involved in seed development with the overall aim of improving yield and nutrition attributes in chickpea.