Assessments Of Salt Tolerance Of Wheat And Its Related Varieties

Seeds of 290 different wheat and its related varieties from 7 countries were used for germination to investigate their salt tolerance. Six indexes such as length of root, shoot, sheath, the number of root, shoot days were measures and analyzed. Four varieties such as jingzhou rye, two-rowed barley, china spring and durun wheat that differ in their ability to salt stress were used to study on the physiological and biochemical changes. Semi-quantative RT-PCR technique was used to detect the results of SOD gene (AF092524). The main results were as follows:1. Determining the concentration of salt stressYumai 18 wheat and big kernel wheat varieties germinated when subjected to salt stress with different concentration, such as 0,30,50,70,90,110,130,150,170,190,210,350mmol/L NaCl. The result demonstrated that 150mmol/L NaCl solution was used to assess the salt tolerance of wheat varieties.2. The evaluation of wheat and varitties salt toletant290 wheat varieties from 7 countries, Chile, Australia, Mexico, Holand, Russia, Ukraine and China, were used to evaluate the salt tolerance using fuzzy cluster analysis. Three clusters were identified. 24 varieties have an high salt tolerance (D≥5.5) involve in 9 varieties from Australi, 6 varieties from Mexico, 6 varieties from China, 2 varieties from Russia, 1 varieties from Chile and 1 varieties from Holand. The third cluster (D≤4.0) involve 13 varieties having weak ability of salt tolerant including 5 varieties from Mexico, 3 varieties from Chile, 2 varieties from Holand, 2 varieties from China and 1 varieties from Ukraine. There other 253 varieties were second cluster (5.5≥D≥4.0) and the salt tolerance between the two clusters.3. The physiological and biochemical change of wheat varieties under salt stress(1) Effects of salt stress onα-amulase activity on seed germinationThis paper study the change ofα-amulase activity under salt stress with different concentrations 100 and 250mmol/L NaCl solution. The result demonstrated that with the germination prolongation theα-amulase activity among different salt-stressed wheat varieties all increased first and then decreased and last increased. And theα-amulase activity was maximum at 96 hour. Salt stress reducedα-amulase activity at both salinity levels, however, the effect was greater at higher NaCl concentration.Theα-amulase activity of salt-resistant varieties jingzhou rye and two-rowed barley were less affected by NaCl than salt-sensitive varieties china spring and durun wheat.(2) Effects of salt stress on proline content on seed germination The proline content were carry out in this paper under salt stress with 100 and 250mmol/L NaCl solution and the result were that proline content increased with the prolongation of time and increase of NaCl sodium. The proline content of 4 varieties were little when no NaCl, but the more salt concentration, the more proline content. The proline content of salt-sensitive varieties china spring and durun wheat were less affected by NaCl than salt-resistant varieties jingzhou rye and two-rowed barley.(3) Effects of salt stress on MDA content on seed germinationThis paper study the change MDA content under salt stress with 100 and 250mmol/L NaCl solution. The result demonstrated that the MDA content of 4 varieties increased with prolongation of time. The MDA content of salt-resistant varieties jingzhou rye and two-rowed barley were more than salt-sensitive varieties china spring and durun wheat at 6-12 hour. But the MDA content of salt-sensitive varieties china spring and durun wheat increased apparently after 12 hour and were more than salt-resistant varieties jingzhou rye and two-rowed barley. The MDA content in wheat seeding was increased with the increasing of NaCl concentration. But there were differenct tendency between varieties salt stress.(4) Effects of salt stress on SOD, POD and CAT activities on seed germinationThis paper research the change of SOD, POD and CAT activities under salt stress with different concentrations 100 and 250mmol/L NaCl solution.Antioxidant enzyme had different response to salt stress. The SOD activity was increased first and then droped with the prolongation of time. The activities of SOD increased at 6-24 hour and decreased at 24-72 hour. With the increase of salt concentration, activities of SOD, POD and CAT enhanced and salt-resistant varieties had higher activities than salt-sensitive china spring and durun wheat varieties.4. RT-PCR analysisSearched the SOD gene AF09524 using NCBI web and designed the primer using Primer 5.0. Then test the cDNA of 2 varieties at 6h,12h, 24h, 48h, 72h.The result show that the expression of AF09524 were low at 6 and 12h, and enhanced at 24 and 48h,and then declined.