Study On Chromosomal Effect Of Low-phosphorus Stress Resistance Properties In Wheat Substitution Lines

Wheat chromosome substitution lines have 21 members,each member of the recipient (background species) with only a pair of chromosomes and are good material to study the genetic effect of individual chromosomes. Phosphorus is one of the essential elements in the wheat growth and plays a significant role in its growth and development, physiology, yield and quality. It is very important to exploit and utilize wheat substitution lines in low phosphorus resistance breeding. Chinese Spring (CS)-Synthetic 6x substitution lines and parents were used to study the effect on physiological and biochemical indexes and to determine the main effect chromosomes controlling correlated indexes as well as to evaluate the low-phosphorus stress resistance properties by measuring indexes under low-phosphorus stress and control treatments.The main results were as follows:1. 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 low-phosphorus stress resulted in reduction of chlorophyll content,corticoid content,net photosynthetic rate, transpiration rate, stomata conductance, Fm, Fv/Fm, soluble sugar content , protein content and accumulation of intercellular carbon dioxide concentration,Fo,SOD activity,POD activity,MDA content.Under low-phosphorus stress,The genes promoting chlorophyll content might be located on 2A,1B,7B chromosome of Synthetic 6x,and that the genes promoting corticoid content might be located on 2A,3A,7B,6Dchromosome;the genes of regulating high photosynthesis may be located on 3A,5A,2B and 2D chromosomes, the genes of regulating high transpiration rate may be located on 5B and 7B chromosome, the genes of regulating high stomata conductance may be located on 5A,5B,6B and 7D chromosome,the genes of inhabiting intercellular carbon dioxide concentration may be located on 6A,5D,6D and 7D chromosomes; The genes of regulating Fo may be located on 3D chromosome, the genes of regulating Fm may be located on 3B chromosome, the genes of regulating Fv/Fm may be located on 3B and 7D;The genes of promoting soluble sugar content may be located on 2A,3A,5B and 7D chromosomes,the genes promoting soluble protein content might be located on 3A chromosome;The genes promoting SOD activity might be located on 2A,3B,2D and 7D chromosome,the genes promoting POD activity might be located on 2A,5A,6A,7B and 7D chromosome,and the genes inhibiting MDA content might be located on 5A,2D,5D and 7D chromosome of Synthetic 6x.2. The agricultural traits of Chinese Spring (CS)-Synthetic 6x substitution lines as well as parents under the control and low-phosphorus 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 5A,6A,2B and 7D chromosomes;1A chromosomes may associate with spikelet length;3A,5A,6Aand 7A chromosomes may associate with controlling internodes length;6A,7A,1B,2B,3B,4B,5B,6B and 7D chromosomes may associate with controlling grain weight per spike;2A,5A,6A,3B,5B,6B,7B,5Dand 7D chromosomes may associate with controlling 1000-grain weight;6A,7A,1B,3B,2D and 7D chromosomes may associate with controlling kernel number per spike.3. The low-phosphorus stress comprehensive resistance 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 20 single indexes could be classified into 8 independent comprehensive components. The cluster analysis was used to divide 20 substitution lines and parents into three kinds of drought resistance type. That was that: 7B substitution line and Synthetic 6x belonged to higher low-phosphorus stress resistance properties type;1A,1B,3B,5B,6B,2D,5D,7D substitution lines belonged to middle low-phosphorus stress resistance properties type;2A,3A,4A,5A,6A,7A,2B,4B,1D,3D,4D,6Dsubstitution lines and Chinese Spring belonged to poor low-phosphorus stress resistance properties type.