Physiological And Chromosomal Effects Of Salt Stress On Chromosome Substitution Of Wheat Seedlings

Soil salinization is one of the most important facts influencing global agriculture and crop production. As we know wheat is an important crop in the world, which is moderately salt-tolerant and the yield of wheat is positively significant correlated with the salt content. In order to fulfill the need of world’s growing population for food, it becomes the research focus of domestic and foreign experts to study the effect of wheat salt tolerance and to breed high-resisted species. The wheat substitution lines are the precious germplasm resources of genetic research. China Spring(CS)-Synthetic 6x chromosome substitution lines are generated by the 21 chromosome of donor varieties Synthetic 6x into the recipient variety Chinese Spring.There are great genetic differences between male Synthetic 6x,and female Chinese Spring because of male Synthetic 6x containing wealthy resistance gene and rich genetic diversity. In order to study the effect and chromosomal control of salt stress in wheat seedlings, wheat substitution lines between Chinese Spring and Synthetic 6x were cultured in Hoagland’s solution. Two treatments including control group(0 mmol.L-1 Na Cl) and salt treatment group(150 mmol.L-1 Na Cl) were carried out at two-leaf stage of seeding. Physiological and biochemical indexes were measured under controlled condition and salt treatment of seedlings at four-leaf stage. It would provide a theoretical basis for the breeding and genetic improvement of salt-tolerant genotypes. The results were as following:1. The results showed that salt stess result in accumulation of soluble protein content and soluble sugar content,proline content, Na+, K+ content, SOD,POD activities and reduction of specific leaf weigh, chlorophyll content,carotenoid content,Photosynthetic rate, transpiration rate, MDA content.The genes increasimg soluble protein content might be exist on 1A,2A,4A,6A chromosomes and the genes promoting soluble sugar content might be located on 6A,7A, 7D chromosome as well as the genes promoting proline content might be located on7 A, 6D chromosome of Synthetic 6x Under salt stress. The genes inhibiting Na+ content might be located on 1A,2A,3B,7B,1D,4D and 7D chromosome and the genes increasing K+ content might be exist on 4A, 7A chromosome, the genes increased SOD activity and POD activity might be located on 1B,5B,6B and 5D chromosome and 4A,5A,6B and 7D chromosome, the genes increased specific leaf weigh might be located on 2D chromosome, the genes increased the rate of chlorophyll content and carotenoid content might be located on 1A,5A,7A,2B,3B,5B,6B,6D chromosome and1 A,4A,7A,5B chromosome of Synthetic 6x respectively, the rate of photosynthetic rate and transpiration rate might be located on 7D chromosome and 7A,3B,5B and 3D chromosome respectively, the genes inhibiting MDA content might be exist in 2A,6A,6B and 1D chromosome.2. The results indicated that salt stess result in accumulation of root shoot ratio, root average diameter and reduction of total root lengt, root surface area, root volumein, root activity.Under salt stress, the genes increased root shoot ratio activity might be located on 3A,6D,the genes promoting root average diameter might be located on 2A,5A chromosome, the genes promoting total root length might be located on 7D and 4A chromosome, the genes promoting root surface area might be located on 6D chromosome, the genes promoting total root length might be located on 2A,5A chromosome,the genes promoting root volume might be located on 3B chromosome the genes promoting root activity might be located on 6B chromosome.3.The salt stress comprehensive resistance of physiological and biochemical indexs of CS-Synthetic 6x substitution lines as well as parents was evaluated by principal components analysis. The results showed that the 19 single indexes could be classified into 7 independent comprehensive components. The cluster analysis was used to divide 21 subsititution lines and their parents into three types of tolerance to salt stress. 6A,7A,2B, 6B,1D,4D,5D,7D belonged to the higher salt tolerance types to salt stress, 1A,3B,5B, 2D,3D belonged to the middle salt tolerance types to salt stress, 2A,3A,4A,5A,1B,4B,7B, 6D, CS, Synthetic 6x belonged to the poor salt tolerance types to salt stress.