Genome-wide comprehensive analysis of miRNAs and their target genes expressed in resistant and susceptible Capsicum annuum landrace during Phytophthora capsici infection

MiRNAs regulate plants responses to fungal infection and immunity by modulating the gene expression. Despite extensive works on miRNAs role during plant-fungus interaction, work in Capsicum annuum-Phytophthora capsici pathosystem is limited. Therefore, in the current study, genome-wide known and novel miRNAs were identified in two contrasting chilli pepper landraces, i.e. GojamMecha_9086 (resistant) and Dabat_80045 (susceptible) during P. capsici infection. The small RNA deep sequencing resulted in 79 known miRNAs corresponding to 24 miRNAs families and 477 novel miRNAs along with 22,895 potential targets, including 30 defence-related genes against P. capsici infection. The expression analysis of [~]29 known & 157 novel miRNAs in resistant and 30 known and 176 novel miRNAs in susceptible landrace revealed differential accumulation pattern. RT-qPCR of a set of 8 defence related miRNAs representing 4 novel (Pz-novel-miR428-1, Pz-novel-miR160-1, Pz-novel-miR1028-1, Pz-novel-miR204-1) and 4 known (Pz-known-miR803-1, Pz-known-miR2059-1, Pz-known-miR2560-1, Pz-known-miR1872-1) revealed differential accumulation pattern in both resistant and susceptible landrace. Additionally, validation of 8 target genes of corresponding miRNAs using RA-PCR, which as good as 5 RLM-RACE, revealed an inverse relation with their corresponding miRNAs suggesting their key role during disease response. This study provides comprehensive genome-wide information about the repertoire of miRNAs and their target genes expressed in resistant and susceptible chilli pepper landrace, which can serve as a valuable resource for better understanding the post-transcriptional regulatory mechanism during C. annuum - P. capsici pathosystem.