Physiological Effects Of Phosphorus Deficiency Stress On Chromosome Substitution Of Wheat Seedlings And Research Of Chromosome Localization

Wheat (Triticum aestivum L.) is China’s second-largest food crop. Improving thephosphorus efficiency of wheat has very important significance. Wheat chromosomesubstitution lines, which have21members, each member of the recipient (backgroundspecies) with only a pair of chromosomes, are good material to study the genetic effect ofindividual chromosomes. Phosphorus is one of the essential elements in the wheatgrowth and plays a significant role in its growth and development, physiology, yield andquality. It is very important to exploit and utilize wheat substitution lines in lowphosphorus resistance breeding. The seedlings of Chinese Spring (CS)-Synthetic6xsubstitution lines and parents were used to study the effect on physiological andbiochemical indexes and to determine the main effect chromosomes controllingcorrelated indexes as well as to evaluate the low-phosphorus stress resistance propertiesby measuring indexes under low-phosphorus stress and control treatments. The mainresults were as follows：1. The results showed that low-phosphorus stress resulted in accumulation ofspecific leaf weigh and reduction of chlorophyll content, corticoid content, netphotosynthetic rate, transpiration rate.Under low-phosphorus stress, the genes promoting specific leaf weigh might belocated on5A,7A,5B and7B chromosome of Synthetic6x,the genes promotingchlorophyll content and corticoid content might be located on5B and6D chromosome;the genes of regulating high photosynthesis may be located on4A,6A,1B,5B,2D,3D,4Dand5D chromosomes, the genes of regulating high transpiration rate may be located on4A,6A,4B and5B chromosome.2. The results showed that low-phosphorus stress resulted in accumulation ofroot-shoot ratio, APase activity, RNase activity, SOD activity, POD activity, plant hormones (IAA, GA, ZR and ABA) content and reduction of root total length, total rootsurface area, root average, root activity, MDA content, protein content.Under low-phosphorus stress, the genes promoting root-shoot ratio might be locatedon4A,4B,6B,1D,2D and7D chromosome; the genes promoting APase activity might belocated on4A,1D and4D chromosome; the genes promoting RNase activity might belocated on2A,6B and4D chromosome; the genes promoting SOD activity might belocated on3A,4A,5A and7A chromosome, the genes promoting POD activity might belocated on5A,1D and2D chromosome the genes promoting IAA content might belocated on2A and4D chromosome; the genes promoting GA content might be located on1D、2D、3D、4D and5D chromosome; the genes promoting ZR content might be locatedon3A、4A、5A、6A and7A chromosome; the genes promoting ABA content might belocated on2A and7B chromosome; the genes promoting root total length content mightbe located on3A,4A,6A and4B chromosome; the genes promoting total root surface areacontent might be located on4A,4B and4D chromosome; the genes promoting rootaverage content might be located on4A,3B,6B and4D chromosome; the genespromoting root activity content might be located on1A,2A,3A,5A,7B,2D,3D,5D and7Dchromosome; the genes inhibiting MDA content might be located on1A,2A,4B,6B and7D chromosome and the genes promoting soluble protein content might be located on4Aand7A chromosome of Synthetic6x.3. The low-phosphorus stress comprehensive resistance of physiological andbiochemical indexes of Chinese Spring (CS)-Synthetic6x substitution lines as well asparents was evaluated by principal components analysis. The results showed that the20single indexes could be classified into8independent comprehensive components. Thecluster analysis was used to divide21substitution lines and their parents into three typesof tolerance to low phosphorus.5B substitution lines and Synthetic6x belonged to thehigher tolerance types to low phosphorus stress;1A,4A,5A,6A,7A,3B,4B,6B,1D,4D and7D substitution lines belonged to middle tolerance types to low-phosphorus stress;2A,3A,1B,2B,7B,2D,3D,5D,6D and Chinese Spring belonged to poor tolerance types tolow-phosphorus stress.