Study On Chromosomal Effect Of Morphological, Physiological And Biochemical Responses In Wheat Under Drought Stress

Wheat substitution lines are the valuable resources of genetic research and breeding. It is very important to exploit and utilize wheat substitution lines in drought resistance breeding. Chinese Spring (CS)-Synthetic 6x substitution lines and parents were used to study the effect on morphological characters, physiological and biochemical indexes and to determine the main effect chromosomes controlling spikelet progress and correlated indexes by observing morphological structure and measuring indexes under drought stress. The main results were as follows:1. A series of spikelet differentiation progress of Chinese Spring (CS)-Synthetic 6x substitution lines and parents under different water treatments were observed to determine the main chromosomes controlling spikelet differentiation progress. The result indicated that the genes inhibiting spikelet differentiation may be located on 2B and 7D chromosomes and that of drought tolerance may be located on 2D chromosome.2. The physiological and biochemical indexes of Chinese Spring (CS)-Synthetic 6x substitution lines and parents were measured to study the effect on correlated characters. The results showed that drought stress resulted in reduction of relative water content, protein content, chlorophyll content, corticoid content, net photosynthetic rate, transpiration rate, Fm, Fv/Fm, Fv/Fo and accumulation of proline content, SOD activity, POD activity, MDA content, water use efficiency.Under drought stress, the chromosomes 1D, 2D, 2B, 3A, 3D, 4A, 4B, 6A, 6B, 7D and 7A of Synthetic 6x were associated with membrane stability; the genes regulating RWC and RWL may be located on 1A, 2D, 3D and 3A, 3B, 4B, 5B, 6B, 1D, 2D, 4D chromosomes respectively; 1D, 5D chromosomes may associate with the proline accumulation and the 4A, 4B, 2D, 6D chromosome may associate with the protein reduction; the genes regulating SOD and POD activity may be located on 2B, 7D and 1 A, 2A, 2D chromosomes respectively, the genes of inhabiting MDA content may be located on 7A, 1D, 7D chromosomes; the genes regulating chlorophyll and corticoid content may be located on 3A, 4D and 2A,4D chromosomes, respectively; the genes of regulating high photosynthesis may be located on 3 A and 4D chromosomes, the genes of regulating high transpiration rate may be located on 7B chromosome, the genes of regulating high water use efficiency may be located on 3A and 4D chromosomes; the genes of regulating Fo may be located on 3A chromosome, the genes of regulating Fm may be located on 4D chromosome, the genes of regulating Fv/Fm and Fv/Fo may be located on 3A and 7A chromosomes.3. The agricultural traits of Chinese Spring (CS) - Synthetic 6x substitution lines as well as parents under the control and drought conditions were measured. The results indicated that drought stress resulted in reduction of plant height, spikelet length and so on.The results also indicated the genes of controlling plant height may be located on 1A, 5A, 6A, 1D, 2D, 3D, 4D, 6D and 7D chromosomes; 1A, 4A, 6A, 7A, 1B, 2B, 4B, 6B, 7B, 2D, 3D, 5D, 6D and 7D chromosomes may associate with spikelet length; 1 A,3A, 6A, 7A, 2B and 2D chromosomes may associate with controlling internode length; 1 A, 5A, 2B, 2D and 5D chromosomes may associate with controlling grain weight per spike; 1 A, 5A, 2B, 3B, 2D 3D and 6D chromosomes may associate with controlling 1000-grain weight; 5A, 7A, 7B, 2D, 3D, 5D and 7D chromosomes may associate with controlling kernel number per spike4. The drought comprehensive resistance of DRC of physiological, biochemical indexes and agricultural traits of Chinese Spring (CS) - Synthetic 6x substitution lines as well as parents was evaluated by principal components analysis. The results showed that the 21 single indexes could be classified into 7 independent comprehensive components. The cluster analysis was used to divide 21 substitution lines and parents into three kinds of drought resistance type. That was that: 2D substitution line and Synthetic 6x belonged to high drought resistance type; 1A, 3A, 4A, 6A, 7A, 2B, 4B, 6B, 1D, 3D, 4D, 7D substitution lines belonged to middle drought resistance type; 2A, 5A, 1B, 3B, 5B, 7B, 5D, 6D substitution lines and Chinese Spring belonged to poor drought resistance type.5 The differences of cell ultra-structure of flags leaves in two wheat substitution lines and parents under drought stress were investigated. The results showed the ultra-structure of flags leaves of 2D substitution line and Synthetic 6x with strong drought resistant were less affected than 5D substitution line and Chinese Spring with weak drought resistant under drought stress.