Identification Of Salt Toleranceand Cloning And Bioinformatics Analysis The TtHKT1;5 Genes In Wild Emmer(Triticum Dicoccoides)

Wheat is one of the most important crop, which provides 20% of the energy consumed of the word required. Salt stress adversely affects crop yields in the world, and global warming,environmental degradation and irrigation aggravated soil salinization, have posed a serious threat to wheat production. Due to the diminishing arable land and increasing population in China, it is the most effective way to improve agriculture production of saline alkali land by developing and using saline alkali land, improving saline alkali soil and planting and cultivating salt tolerant plants. The birthplace “Fertile Crescent” of wild emmer, the tetraploid ancestor of bread wheat, where has diverse natural environment. Wild emmer growth here showed abundant genetic diversity and phenotypic diversity. So Wild emmer can be important germplasm and gene pool to improve cultivated wheat. So it is wise to select wild emmer as the research material to improve wheat salt tolerance and cultivate new excellent varieties. In this experiment we have 45 wheat materials, including 30 wild emmer, 13 durum wheat, 1xuemai, 1 Chinese spring, these all used for tolerance identification, and which selected salt resistant materials can be used for further research. Then we cloning homologous gene of TtHKT8-B1 in salt resistant varieties B5 and salt sensitive varieties A9 Then compared the difference of them. The follows as our main results:1. Under 150 mM NaCl salt treatment, indicators of seeding height and root length are more sensitive to salt stress than germination rate. The fact may result of plant mainly depended on seed nutrition rather than external nutrition during bud stage. Together all the indicators we calculated integrated salt damage membership values(D value) at all tested materials. B1, A4, B6, B7 have a lower D value, under 20%, considered as salt resistant wheat,and TDWZ15、C5 have a higher D value more than 60% considered as salt sensitive wheat in bud stage.2. Then evaluation of salt tolerance at seeding stage on tested materials, we conducted the principal component analysis, the first five components represent 89.5% of the original data. Reference the result of principal component analysis all indicators divided into two categories: the first category includes biomass, root length, root surface area, the second category includes chlorophyll content, water content, net photosynthetic efficiency,transpiration rate, stomatal conductance, CO2 concentration. Based on the two categories wedo cluster analysis, all the materials were divided into 5 categories when the euclicen was 5.Results were that: A2, B5,C1, C8,C3 were best salt resistant wheat among tested, and A3,D8,B1,B6, D5, D4, B2, A5 were better salt resistant wheat among tested, A7, D2, B3, E6, A4, A8,A6, D1,C6 were salt resistant wheat but not good as before. While C4, E6, E4, E7, A1, E3,B4, B9, B7, D9, C5, C2, D7, E8, E2, A9,B8, C7, C9, E5 were salt sensitive wheat materials.In comparison, wild emmer has a greater diversity and has a wilder range of salt resistance than cultivar.3. Next,system cluster analysis was conducted in budding and seeding data, and all the materials was divided into five categories when the Euclidean distance was 5. The first branch of C5 has a poor tolerance all in budding and seeding stage. The second branch of B1 has a good tolerance in budding while poor in seeding stage. The third branch of B5 has poor tolerance in budding while goog tolerance in seeding stage, comprehensive tolerance was better. The forth branch(A5, A8, A4, C3 and so on) have good tolerance all in budding and seeding stage. The fifth branch’s(A2, C4, A9, C2 and so on) tolerance were poor in budding and seeding stage. In summary, 50% of our wild emmer were salt tolerance in budding stage,and 55% of our materials were salt tolerance in seeding stage, 37% of our materials were salt tolerance in all stage.4. At last, we cloning homologous gene HKT8, The sequences TtHKT8-B1.1,TtHKT8-B1.2 compared with TaHKT8 sequence had 10 and 9 bases difference, respectively.The amino sequence had 6 and 5 difference. While the changes are within hydrophobic or hydrophilic amino not between them. Compared these two predicted protein, TtHKT8-B1.1has lower isoelectric point, more unstable, and hydrophobic transmembrabce domain wewe increased. All these changes may cause translocation efficiency of Na+/K+.