Prediction of miRNA and Identification of their Relationship Network Related to Late Blight Disease of Potato

Late blight is a serious disease in potato caused by Phytophthora infestans. To date only few miRNA have been discovered which are related to late blight disease of potato during host pathogen interaction. Recent studies showed that miRNA, an important gene expression regulator, plays a very important role in host-pathogen interaction by silencing genes either by destructing or blocking of translation of mRNA.

Homology search was performed between non-redundant mature miRNA sequences from miRBase database and Solanum tuberosum EST sequences from NCBI database. Screening of the potential miRNA was done after secondary structure prediction. The target related to late blight disease of respective miRNA was functionally annotated. To identify the relationship between the predicted and mature miRNAs, multiple sequence alignment and evolutionary relationships were established.

34 Candidate miRNA related to late blight disease of potato were identified which were associated to five target genes. These miRNAs were linked with Avr3a, INF1, INF2b genes which are elicitin like protein and triggers a hypersensitive response to host cell. Mapping of target sequences showed similarity with Solanum lycopersicum NRC1 gene of chr.1, which are reported as a casual protein required for Pto-mediated cell death and resistance in N. benthamiana. NRC1 are considered as a RX-CC_like domain-containing protein which shows similarity with coiledcoil domain of the potato virus X resistance protein (RX) in Solanum tuberosum. RX recognizes pathogen effector proteins and triggers a response that may be as severe as localized cell death thereby providing resistance against potato virus X.