Role of miRNAs in biotic stress reactions in plants

Abstract

Biotic stress caused by viruses, bacteria, fungi, insect pests and nematode parasites is affecting the yield and quality of crop plants worldwide. Farmers use the agrochemicals extensively for the control of pathogens and pests, and this has led to the resistance by these biotic factors against agrochemicals. Therefore, the development of crop plants resistant to pathogens and pests with increased yields using novel alternative approaches has become the area of focus to meet the needs of growing population. In response to biotic stress, plants express the regulating genes such as miRNAs, which control the expression of defense responsive genes. The miRNAs expression is either induced or over-expressed after biotic stress, targeting the inhibitors of biotic stress responsive resistant genes and leading to their over-expression. The miRNAs, which negatively regulate the resistant genes are down-regulated upon biotic stress. The pathogens or pests also express miRNAs, which interferes with the expression of host plant’s genes that are involved in defense. Whereas, in resistant plants the miRNAs that positively regulate the resistant genes are over-expressed in response to biotic stress. Therefore, the miRNAs can be exploited for the control of pathogens and pests for crop improvement. In this review, we have updated the literature pertaining to the involvement of miRNAs in biotic stress responses and miRNA interference for crop improvement.