Improving Cold Tolerance Of Centipedegrass(Ermochlod Ophiuroides(Munro) Hack.) By Overexpressing SAMDC

Centipedegrass(Eremochloa ophiuroides(Munro) Hack.) is one of the three major warm-season turfgrass species of the world, and the only grass species that can be used as turfgrass in the Eremochloagenus,but lack of cold-stress tolerance. SAMDC is a key enzyme for transform Put into Spd or Spm.By overexpressing SAMDC, the contents of Spd and Spm in plants can be up-regulated.This research focuses on improving cold tolerance of the centipedegrass by overexepressing SAMDC, and study the mechanism behind. The main results were shown as following:The contents of Put between WT and SAMDC–overespressing centipedegrass are nearly the same;though the SAMDC–overespressing centipedegrass’ Spd and Spm contents are greatly higher than the in WT’s.The result indicates that the contents of Spd and Spm can be improved by overespressing SAMDC.By putting transgenic and WT centipedegrass in the same chilling condition, after the chilling treatment, we nocited that the activities of SOD and CAT of the transgenic centipedegrassare higher than the WT’s, stomatal conductanceand Fv/Fm, lower MDA content, H2O2 content, and relative conductivity.These results indicated that the transgenic centipedgrass has stronger chilling tolerance than the WT.By putting transgenic and WT centipedegrass into the same cold acclimation,and then measured the TL50, proline and soluble sugar content of the transgenic plants and wild-type control before and after cold acclimation. The results indicated that in normal codition,SAMDC-overexpressing centipedegrass has stronger freezing tolerance than the normal control; and after a short cold acclimation, the difference becomes even greater.In order to study cold-toleracing-mechanism induced by SAMDCin centipedegrass, we measured the activity of PAO、NR、SOD and CAT, H2O2 and NO contents of transgenic and WT centipedegrass, and fighur out their relationships in the cold-tolerancing mechanism. The results indicated that by overexpressing SAMDC, the content of Spd and Spm got improved, which induced the activity of PAO, and then improved the content of H2O2.On one hand, H2O2 upregulated the activity of SOD and CAT; on the other hand, H2O2 improved the content of NO by upregulating the activity of NR, and NOinduced theactivity of CAT, and then improved the chilling tolerance of centipedegrass.Spd and Spm induced the production of proline and soluble sugar, then improved the freezing tolerance.