Comprehensive Evaluation Of Salt Tolerance Of Elytrigia Desv At Seedling Stage And Cloning Of A Vacuolar Na～+/H～+ Antiporter Gene In Elytrigia Intermedia

Salt tolerance is one of the most important factors that affect productivity of crops in the world. To cope with salt stress, plants have developed a variety of adaptation mechanisms. Screening identification indexes and comprehensive evaluation were the premise of the breeding of Salt Tolerance. Elytrigia Desv. is quality forage and wild species of wheat, It is very important in genetic improvement of wheat.12 indexes were monitored under salt stress at seeding stage. Screening identification indexes and comprehensive evaluation were studied by principal component analysis and subordinative function.A vacuolar Na~+/H~+ antiporter gene TiNHX1 was islated from Elytrigia intermedia. The main results of this study are as following:(1) The survival rate decreased with the increasing of NaCl stress and were 100% under 0.0%,0.4%,0.5% NaCl stress. The survival rate were 63% to 100%, 27% to 93%, 67% to 96.7% under 0.6%,0.8%,1.0% NaCl stress respectively. The D value of comprehensive evaluation was highly correlated with survival rate's saline tolerance coefficients.The correlation coefficient was 0.9370.(2) 5 indexes were monitored under salt stress at seeding stage for 21 wild Elytrigia Desv. accessions.Comprehensive evaluation was made by principal component analysis and subordinative function.Three group were divided by D value.Salt-tolerant group: ZXY03P-388,ZXY03P-349,ZXY03P-433;Sensitive group: ZXY03P-271, ZXY03P-289,ZXY04P-157; Intermediate group:the remaining materials.(3) 6 indexes were screened for salt tolerance comprehensive evaluation.There are Survival rate,K~+/Na~+ Proline,Malondialdehyde,Growth stress index,Relative growth rate.The VP value was significant related with the D value(P<0.01).(4) The pro and soluble sugar content increased with the NaCl stress;with the increasing of NaCl stressthe Na~+ content and injury rate increased significantly;The K~+ content ,chorophyll content , transpiration rate and net photosynthetic rate decreased sharply; The MDA content increased with the NaCl stress and reached the peak under medium stress and then decreased under serious stress.(5) TiNHX1, homologous with the TaNHX1 gene encoding a vacuole Na~+/H~+ antiporter was cloned from Elytrigia intermedia by RT-PCR, with primers designed according to the sequence of TaNHX1. The largest open reading frame of TiNHX1 gene has 1641bp in length and encoded a protein of 546 amino acid residues. The estimated molecular weight and isoelectric points of the putative protein was 59.8kDa and 8.0, respectively. Components of amino acids encoded by TiNHX1 contained 38 basic amino acids, 36 acidic amino acid, 256 hydrophobic amino acids and 129 polar amino acids. The predicted secondary structure composition for the protein has about 44% alpha helixes, 21% extended strand, 4% beta turn and 29% random coil. Hydrophobic analysis indicated that the TiNHX1 contained 10 potential transmembrane segments. Blast result and the phylogenetic analysis showed that TiNHX1, AtNHX1, OsNHX1, GmNHX1, TaNHX1 sharea cluster.