| Salinization of soil is one of the major abiotic-stress that influences agricultural production and entironment. With the growing of world's population and the decreasing of field, how to develop and utilize salinized-soil becomes more and more important. To increase food production for the need of population growing and maintain sustainable development of agriculture, the most economic and efficiency strategy to improve and utilize salinized-soil is screening salt-tolerant germplasm resources, discovering and cloning the genes related to salt-tolerance, and breeding new varieties tolerant to salt-stress using biotechniques.Based on 28 accessions of wheat germplasm introduced from USA, the aim of this study is to screen elite wheat germplasm of salt-tolerance by evaluation of salt-tolerant capacity at three stages of germination, seedling and whole period of growth, assay some physiological factors related to salt-tolerance and clone the genes related to salt-tolerance.The study has got following results:1. Evaluation of salt-tolerant capacity at three stages of germination, seedling and whole period of growth in wheat germplasmAfter being identified for salt-tolerance at stages of germination and seedling, 13 accessions of wheat germplasm with lower than 20% relative salt harm rate at the germination stage and 40% or less salt harmful index at the seedling stage were screened out primarily from 28 spring wheat varieties introduced from USA. Then, the 13 candidate cultivars were planted in the soil with more than 0.37% salinity for field test. Data on agronomic traits, such as germination frequency, tillerring rate, plant height, spike length, spikes, grains per spike and TGW, were collected before and after harvesting. The results showed that the 13 candidate cultivars were divided into 3 grades according to their salt-tolerant capacity, cultivars SW10 and SW12 had higher salt-tolerant capacity than the others. The analysis of variance of field experiment demonstrated that yield both of W12 and SW10 were extreme higher than that of the Ningchun 4. Comprehensive analysis indicated that the two varieties of SW10 and SW12 appeared higher salt-tolerance and better agronomic characters, and their yields were 61% and 54% higher than that of Ningchun 4, a main commercial local variety. These two varieties with strong salt-tolerance are suggested being used directly for wheat production in salinity regions.2. Measurement of some physiological factors related to salt-tolerance in wheat cultivars SW12Using HPLC-ESI-MS technique, Glycinebetaine, proline and malondialdehyde (MDA) in leaves, which collected from wheat cultivars SW12, Ningchun 4 and Chinese Spring exposed to salt treatments with concentration ranges of NaCl s of 0, 100, 200, 300, 400 and 500 mmol/L and sampling for 1, 3, 5, 10, 20 and 30 days, respectively, were measured. The result indicated that the content of GB, Pro and MDA were accelerated to different degree with the increase of salt-stress, but the content of GB and MDA were quite different amongst the three varieties under salt-stress. The variance analysis showed that the differences of GB content were extremely significant and differences of MDA content were significant under different salt-stress amongst the three varieties. This result implies that there is a true diversity amongst the three varieties in the amount of GB and MDA. The salt-tolerance of SW12 is the strongest than that of Ningchun 4 and Chinese Spring suggesting that SW12 is a possible carrier of the salt-tolerance gene.3. Cloning of salt-tolerant gene Ta-ALDH in wheat cultivars SW12A novel full-length cDNA of Aldehyde Dehydrogenase-like gene, designated as Ta-ALDH, was isolated from SW12 exposed in 380mmol/L NaCl stress for 72 hrs by using techniques of cDNA-AFLP (cDNA amplified restriction fragment length polymorphism) and RACE (5' and 3'-rapid amplification of cDNA ends). The full-length of Ta-ALDH cDNA, coded a polypeptide with 509 has amino acid residues, consists of 1948 nucleotides (nt) with an open... |
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