Circular RNA (RNA حلقوی) و نقش آن‌ در مقاومت به بیماری‌های گیاهی

Circular RNA is one of the types of RNA, in the form of a continuous closed loop due to the covalent bond between its two ends. Circular RNA is resistant to many exonuclease enzymes due to the absence of terminal structures at its 3' and 5' ends. circular RNAs have been observed in archaea and various eukaryotic organisms. Circular RNAs are divided into exonic, intronic, exonic-intronic, intergenic and antisense types according to their genetic or non-genetic origin. Depending on the location of circular RNAs in different parts of the cell, they have different functions. Functions of circular RNA including regulation of transcription, binding with miRNA and protein and thus inhibiting their activity and generally regulating gene expression. Circular RNA plays a role in plant biological processes such as growth and response to biotic and abiotic stresses by regulating gene expression. In the cotton plant infected with Verticillium, the origin of the genetic that produces many circular RNAs is the plant's own resistance genes, including the genes of the NBS-LRR family, which indicates the role of circular RNAs in creating resistance to the pathogen in the plant. Circular RNA in conidia and mycelium of rice blast fungus (Magnaporthe oryzae) have different genetic origin. In mycelium, they originate from genes related to basic processes in growth, and in conidia originate from genes related to the storage of materials needed in infection, which shows the role of circular RNAs in mycelium growth and infection. Also, in the Kiwi plant infected with Pseudomonas, the genetic origin of many circular RNAs are genes related to photosynthesis and the plant's immune response, which during infection has a decreasing and increasing effect on them, respectively. In the nematode Caenorhabditis elegans, circular RNA accumulation increases significantly from the fourth larval stage onwards. Studies show that the very high resistance of circular RNA in the post-mitotic cells of the nematode is the cause of this significant accumulation. The genetic origin of circular RNA in the nematode is the genes related to its lifespan, so the employment of mutation in this circular RNA can be used in disease control in the future. The future approach regarding circular RNA is to use them in the control of diseases and also to use them as biomarkers in the diagnosis of diseases.