Analysis Of Regulation Mechanism That SOS Pathway Genes Responding To Salt Stress In Tall Fescue

Tall fescue(Festuca arundinacea Schreb.)is used at home and abroad widely with its high-quality,long green,strong adaptability and other characteristics,but it growths slowly and poor salt resistance.The conventional breeding methods are not only long-time,but also difficult to improve the properties.With the development of modern molecular biology,genetic engineering breeding has become the main way of turfgrass breeding.On the basis of regeneration system hading been established of lawn grass,this dissertation used embryogenic calli as receptors,salt tolerance-related SOS pathway genes SOS1,SOS2-SOS3 and SOS1-SOS2-SOS3 from Arabidopisis thaliana were incorporated into genome of Arid3 by Agrobacterium-mediated transformation and obtained transgenic plants with increased salt tolerances.The main results are as follows:(1)Whole genome DNA were extracted from transgenic tall fescue,PCR detection?southern blotting and RT-PCR were determined and analyzed,which showed that PCR positive rate of SOS1 was 24.2%;PCR positive rate of SOS2-SOS3 was 67.1%and PCR positive rate of SOS1-SOS2-SOS3 was 34.3%.High positive rate of PCR may be because of the resistance screening,most non-transgenic plants were dead,Southern blotting and RT-PCR test results showed that the exogenous gene has integrated into the genome of transgenic plants.(2)The transgenic plants and control plants were treated by different concentrations(OmM?150 mM?250 mM and 350 mM)of NaCL.The results are as follow:? obvious phenotypic differences were observed between wild type and transgenic plants.Wild type plants showed growth retardation,whereas the transgenic plants displayed normal growth.? The result of physiological and biochemical indexes showed that under salt stress,the superoxide dismutase(SOD),peroxidase(POD),hydrogen peroxidase(CAT)activities of transgenic plants were significantly higher than the control plants,but the content of malondialdehyde(MDA)and proline(Pro)were lower than control.? The wild-type plants and transgenic plants were treated for 21 days by 0 mM and 350mM NaCL,thereas meansured the content of K+ and Na +.The results showed that without NaCL the Na+content between transgenic and wild-type plants are similar.After treated with 350mM NaCL,the Na+content in the leaf of transgenic and wild-type plants were increased,but the wild-type plants increased more.Under the OmM NaCL treatment,K+ content in the leaves of wild-type plants significantly higher than that in the transgenic plants,but with the increasing of NaCL concentration,the transgenic plants,under 350mM NaCL treatment,K+ content increased,although the K+ content of wild-type plants reduced significantly.? Tested the plant height and chlorophyll content of three kinds of transgenic plants and wild-type plants with salt stress on the condition of greenhouse.The results showed that under 0 mM NaCL treatment,the plant height of all plants had increased,the change of chlorophyll content also were not significant.At the same time,under the treatment with 350 mM NaCL,the plant height of transgenic and non-transgenic plants were on the deCLine,the chlorophyll content also reduced.but the chlorophyll content of transgenic plants inCLuding SOS1-SOS2-SOS3 appeared a rising trend.On the whole,these results above demonstrated that the salt tolerance of transgenic plants was enhanced.