The Mechanism Analysis Of Combined Cold And Salinity Stress Response And Stress-resistance MiRNA Mining Of Bermudagrass

China has various salinized land resources 550 million acres,including severe salinized land of 33.7 million acres,that are the largest arable land resources for sustainable development of irrigated agriculture.Bermudagrass[Cynodon dactylon(L.)Pers.],a typical warm-season turf grass,has the potential to improve salinized land.However,low temperature limits the growth of the grass.A number of microRNAs are exist in eukaryotic cell as central regulatory tools for gene expression and regulation system.Mining stess-related microRNAs is beneficial to illustrate plant stress tolerance mechanism.In this study,cold-tolerant bermudagrass 'WBD128' were applied with four different treatments(Control,Cold stress,Salt stress,Combined cold and salt stress)in order to investigate its physiological and molecular level response.Four small RNA libraries were constructed using the high-throughput sequencing technology.Transcriptome data of bermudagrass was also applied to discover new miRNAs and predict their targets.Moreover,in order to enhance salt tolerance,400mM salt solution were applied to bermudagrass.In the meanwhile,those bermudagrass were treated with NO donator and inhibitor to figure out the role of NO under the stress treatment.As results shows,single cold or salt stress is able to inhibit normal growth of bermudagrass by causing osmosis stress and oxdative stress in plant cell,damaging stability of cell membranes as well as disturbing normal operation of photosynthetical system ?.Combined cold and salt stress leads to severe damage to bermudagrass and further reduces its stress tolerance.NO significantly increases salt tolerance of bermudagrass.Compared to control and NO inhibitor treatment regimes.The membrane stability,photosynthesis ability and inon balance are enhanced in NO donator regime.Moreover,449 mature miRNAs are found in the four libraries,including 246 conserved miRNAs and 203 potential novel miRNAs.After analysis miRNA expression profiles under four treatments,102 miRNAs shows differentially expression.274 miRNAs'2200 targets are predicted via TargetFinder.Through GO(Gene Ontology)analysis,we found those target genes involving comprehensive regulation network in organisms,which revealing the potential regulating role of miRNAs.Our study is valuable for understanding the molecular mechanisms of cold and salt combined stress in bermudagrass.The miRNAs and its targets found in this research can be combined with molecular makers for developing bermudagrass cultivars that tolerant to cold and salt stresses,which is beneficial for improving salinized land use.