The role of small RNA molecules in plant response to pathogen infection

Rastline imajo razvite raznolike in kompleksne mehanizme za regulacijo izražanja genov. Nedavno je bil odkrit nov mehanizem, imenovan RNK interferenca (RNKi). Osrednjo vlogo v RNKi imajo male nekodirajoče RNK (sRNK) dolge od 21-24 nukleotidov, ki z vezavo na komplementarna mesta v transkriptih preprečijo njihovo prevajanje v proteine. Ker sRNK definira izvor, strukturne lastnosti prekurzorjev ter sekvenčne lastnosti, jih delimo v več različnih razredov. mikroRNK (miRNK) ter sekundarne male interferenčne RNK (siRNK), med katere prištevamo tasiRNK in phasiRNK imajo pomembno vlogo v regulaciji izražanja genov v številnih bioloških procesih ter odzivu rastlin na biotske ali abiotske dejavnike stresa. Kljub številnim ohranjenim sRNK med rastlinskimi vrstami ter karakterizaciji njihovega delovanja, do danes še ni celovitega razumevanja njihove vloge v obrambnem odzivu rastlin pred fitopatogeni. Ta pregled povzema trenutno razumevanje patogeneze verticilijske uvelosti, obrambnega mehanizma rastlin pred fitopatogeni in biogeneze ter vloge miRNK, tasiRNK ter phasiRNK v obrambnem odzivu rastlin pred glivnimi patogeni. Nadaljnje raziskave rastlinskih sRNK in njihovo izražanje v odzivu rastlin na različne fitopatogene organizme so potrebne za jasno določitev njihove vloge. Novi pristopi sekvenciranja ter bioinformacijske analize in napovedovanja vloge miRNK tarč v času okužb nam lahko pri nemodelnih organizmih omogočijo razvoj novih načinov varstva rastlin.Plants have evolved diverse and complex mechanisms to regulate gene expression. Recently, a new mechanism called RNA interference (RNAi) has been discovered. At the core of RNAi are small non-coding RNAs (sRNAs), 21-24 nucleotides in length, that prevent the translation of transcripts into proteins by binding to complementary sites in transcripts. Because sRNAs are determined by origin, precursor structural properties, and sequence characteristics, they are classified into several classes like microRNAs (miRNAs) and secondary small interfering RNAs (siRNAs), which include tasiRNAs and phasiRNAs. They play important roles in regulating gene expression in a wide range of biological processes and in plant responses to biotic or abiotic stresses. Despite the numerous conserved sRNAs among plant species and the characterization of their function, there is still no comprehensive understanding of their role in plant defense responses against phytopathogens. This review summarizes the current understanding of Verticillium wilt pathogenesis, plant defense mechanisms against phytopathogens, and the biogenesis and roles of miRNAs, tasiRNAs, and phasiRNAs in plant defense responses against fungal pathogens. Further studies on plant sRNAs and their expression in response to various phytopathogens are needed to clearly define their roles. New sequencing approaches, bioinformatic analysis, and prediction of the role of miRNA targets during infection may allow us to develop new forms of plant protection in non-model organisms