Genome-wide Identification And Expression Analysis Of Heat-responsive MicroRNAs In Creeping Bentgrass

Creeping bentgrass (Agrostis stolonifera) is a kind of perennial herb, and an important urban virescenc and landscaping material widely distributed in tropical, subtropical and temperate regions. Heat stress is one of the adversity factors limiting the growth of creeping bentgrass. MicroRNAs (miRNAs) are a class of non-coding, single stranded small RNA, which is playing an important role in a variety of physiological mechanisms including response to adeversity like drought, cold and salt stress through negative regulations such as translation inhibition or degradation of its target genes.Heat resistant creeping bentgrass PennA 4 was used as material, and the high-throughput sequencing of heat-treated group (HS) and control (C) small RNA libraries and bioinformation analysis identified 192 conserved mature miRNA sequences, including 84 heat-responsive miRNA sequences. Some miRNAs’ relative quantitative expression were up to nearly seven times. At the same time,10 new miRNA sequences were obtained by stem loop structure prediction analysis, and 4 of them were heat responsive miRNA. Gene expression analysis of randomly selected 15 heat-responsive miRNAs was conducted by real-time quantitative PCR and the result showed four kind of fluctuant expression patterns during heat treatment. Gene ontology (GO) pathway analyses of predicted target genes of heat related miRNAs indicated that they are involved in 3 main branches of biological process, cellular components and molecular function and 41 subordinate branches. Part of these branches are obviously different from GO analysis of rice heat-responsive miRNA. For example, target genes related to terms like single-organism process, regulations of in the process and organelle did not appear in the rice, while target genes related to terms like biosynthetic process, nuclecobase-containing compound, cellular component, nucelus, molecular funtion related gene did not appear in creeping bentgrass. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that most target genes functioned in plant hormone signal transduction, plant-pathogen interaction and polyether lipid metabolism.This study preliminarily explored the molecular mechanism of miRNAs under heat stress and provided a theoretical framework and heat-responsive miRNA data bases in creeping bentgrass for future research.