Effects Of Salt Stress On Tall Fescue Seedgermination Seedling Physiological And Biochemical Index And Indentification Of Salt Stress On MiRNA

The exploitation and utilization of saline soil resources has great potential inChina, and salt tolerance of high quality herbages growing is an effective way tomodify and utilize the saline land. Tall fescue has stronger salt tolerance and it is ahigh quality forage can be generalized in the area of the saline soil.Therefore, it isvery important to in-depth understand the mechanism of salt tolerance andidentification of miRNA for the development and utilization of the saline soil,so as tolay the theoretical foundation for the new of further developing efficient,stressresistance and high-quality of Tall fescue.1.In this study，4varieties of tall fescue such us phoenix, Jaguar3, Arid3,Athena were employed to analyze as experiment materials.Using6NaCl and Na2CO3concentration gradients that was0(CK),20,40,60,80L,100mmol/L. Firstly,thedetermination of4varieties of tall fescue in seed germination stage for the germinationrate, germination potential and other index were conducted; then selected which hasthe best salt tolerance during germination stage was to be seeding cultivated, thedetermination of seedling stage in protein concentration, the proline contents andother physiological and biochemical indicators, observing a series of physiological andbiochemical reaction under salt stress treatment，and comprehensively evaluated thesalt tolerance.The results showed that：（1）Under NaCl stress, NaCl concentration is lower than20mmol/L, thegermination rate and relative germination rate of tall fescue increased firstly and thendecreased, this indicated that low concentration of NaCl can promote the germinationof seeds, but with the increase of NaCl concentration(higher than40mmol/L), thegermination rate, relative germination rate,germination potential and relative germination was significantly decreased, this indicated that the higher concentration ofNaCl can inhibit seed germination.4varieties of tall fescue in seed germinationstage,their salt tolerance was: Phoenix>Arid3> Athena>Jaguar3.（2）Under NaCl stress,the effect on the germination rate, relative germinationrate, germination potential, relative germination potential and relative salt damage rateof the four kinds of tall fescue seed was extremely significant. Tall fescue seedgermination potential was extremely significantly affected by the tall fescue seedvariety, and germination potential was significantly affected, but the other three indexwere not significantly affected.There was significant and extremely significantinteraction between NaCl concentration and tall fescue varieties.（3）Under Na2CO3stress, With the Na2CO3concentration increasing, thegermination rate, relative germination rate, germination potential and relativegermination potential decreased, but the relative salt damage rate rised,this indicatedthat the concentration of Na2CO3can inhibit seed germination. their salt tolerance was:Arid3>Jaguar3>Phoenix> Athena.（4） Under Na2CO3stress, the effect on the germination rate, relativegermination rate, germination potential and relative germination potential of the fourkinds of tall fescue seed was extremely significant. Tall fescue seed germinationpotential was extremely significantly affected by the tall fescue seed variety, and thegermination rate was significantly affected. but the other three index were notsignificantly affected. There was significant interaction between Na2CO3concentrationand tall fescue varieties except germination potential.（5） Low concentration of NaCl （lower than20mmol/L） onthe phoenix seedling growth was not obviously. With the increasing of NaClconcentration, the effect was significant the on physiological characteristics of phoenixseedling. The protein contents of the phoenix seedlings decreased, Pro contents, MDAcontents, CAT activities and SOD activities increased, the activity of POD increasedfirstly and then decreased. The effect of Na2CO3concentration on Arid3seedlingsprotein content was not significant，but the effect of Pro, POD, CAT, MDA, SOD wasextremely significant.2. miRNA is a kind of single stranded non-coding, endogenous, small RNA thatrange in length from roughly22nucleotides.Studies confirmed that miRNA playimportant roles for stress responses as well as growth and development in plants. In this research, by using the method of computational homology search,8conservedmiRNAs were detected in the Expressed Sequence Tags (EST) Tall fescue databases.Using online software RNAhybrid, we further predicted the target genes of these8miRNAs and got20potential targets genes by searching the mRNA database.