Study On The Feasibility Of Constructing Genetic Population Using Summer Planting And The Effect Of 1BL/1RS Translocation On The Inheritance Of HMW-GS

Since the 1970s, in high elevation and latitude localities of Northern of China to fully utilize the ample rainfall in summer and autumn, and to spend the slack farming season for rotation of crop in Yunnan-Kweichow Plateau, and to avoid the disadvantage of the low temperature to spring wheat planted in winter in Southern of China, wheat were usually planted in summer high temperature, which were named summer planting wheat. There was report that wheat was planted in summer successfully in Chengdu Plain of Sichuan Province, realizing the doubling reproduction during single normal wheat growth season.The wheat (Triticum aestivurn L) 1BL. 1RS translocation, which including the rye chromosomal arm 1RS and wheat chromosomal arm 1BL, is the most widespread alien chromatin in wheat breeding programmes worldwide. Because it carries resistance genes against leaf rust (Lr26), stem rust (Sr31), strip rust (Yr9) and powdery mildew (Pm8). As well as the advantages of increasing yield and improving adaptation in specific genetic backgrounds of wheat. Moreover, the rye 1RS arm is translocated into wheat and replaces usually one of the three short arms of the group-1 chromosomes of wheat. These arms carry several loci encoding the gluten fraction of the storage proteins, and the 1RS arm carries locus Sec-1 encoding rye storage proteins (secalins) which is disadvantageous to wheat quality, especially the bread-making quality. Thus, its utilization is limited at some degree due to its negative effect on the quality.Although the high molecular weight glutenin represent about 10% of the total wheat seed storage protein, they play an important role in breadmaking quality, and the composition of high molecular weight glutenin subunits (HMW-GS) was one of the most important index of the quality breeding. Therefore, both 1BL/1RS translocation and the HMW-GS determined the wheat making-quality.Chuannong18//Chuannong19 and Chuannong21//Chuannong22 were hybridized to construct the recombinant inbred lines (RIL) and advanced backcross population. It was to evaluate the feasibility of summer planting in Chengdu Plain for construct the genetic population. And the common wheat Chuannong18 with 1BL/1RS translocation chromosome was hybridized with Chuannong19 as male and female parent respectively, and F₂ progenies were employed to investigate the transmissibility of 1BL/IRS translocation and the effect of the 1BL/1RS translocation on inheritance of HMW-GS. The major results as following.1. The cross combination both Chuannong 18×Chuannong 19 and Chuannong 21 Chuannong 22 were carried out in April 2005. The continuous fertilizion was to be used to summer plant in Yaan firstly, and the RILs with 136 lines and 174 lines used for QTL mapping in this study were abtained at F₅ generation by single-seed descent method from above cross.2. The biological characterizition of summer planting wheat using continuous fertilizion show that emerge tidily after the seed in 2-4℃48 hours, no less than 24 tillers were produced, and both the creeper and suberect seedlings could ear normally. And its botanical trait exhibited that the plant height was less than 40 cm, the ears were smaller than that planted in winter, but the spikelet number reached 21-22, and most kernels were thin. The heading stage was not same with that of planting in winter completely. And the winter wheat could not be planted in summer easily, and the wheat planted in summer more years would be insensitive to cold. The powdery mildew and gibberella could be investiged in summer planting, but it would be not accurate to construct the genetic population for QTL about yield and yield composition, because some agricultural trait lost in summer planting. The generation being selected in breeding must be planted in the normal season of the local.3. F₂ obtained from both cross in the prensent study deviate from a 3:1 ratio (the plant with 1BL/1RS and without 1BL/1RS) significantly at 0.01 level, and the number of plant with 1BL/1RS was less than 75%. It mean that there is the negative selecting stress on the gametes carrying 1BL/1RS translocation during the process of fertilization from F₁ to F₂. Therefore, the translocation chrommosome could not be transmmited completely, and the transmissibility in male was lower than in female. Perhaps, in the heterozygote of 1RS. 1BL, 1RS is non-homologous regional with 1BS, and it interrupt the parallelism between genome.4. All HMW-GS can be transmitted to hybrid F₁ as dominance from both parents. In F₂ progenies, the band patterns on Glu-A1 was accord with Mendel's laws of gene independent assortment, 1: N was 3: 1, but on Glu-B1 in Chuannong 19×Chuannong 18, (7+8): (7+8+9): (7+9) was not 1: 2: 1. The combination of the genes which control Glu-A1 and Glu-B1 in Chuannong 18×Chuannong19 was not (N, 7+8): (N, 7+9): (1, 7+8): (1, 7+9): (N, 7+8+9): (1, 7+8+9)=1: 1: 3: 3: 2: 6 either. The results showed furthermore that there is the negative selecting stress on the gametes carrying 1BL/1RS translocation during the process of fertilization of F₁, which resulted the deviation of F₂ separation.5. A variant HMW-GS was found in one of the hybrid F₁ grains of Chuannong 18×Chuannong 19. To confirm the veracity of the hybrid, the HMW-GS and the gliadin pattems of F₂ from the variant were evaluated, the variant HMW-GS and 1BL/1RS translocation chromosome were found in some of the F₂ grains. The SSR markers were also used to identification the variant, and the results showed that the variant grain was the descendant of the two parents. The variant of HMW-GS pattems was (1, 7+8, x+9, 2+12), SDS-PAGE analysis demonstrated the variant subunit was between the 1D×5 and 1B×7, which was similar with 1B×6. 6. Two paris of primers specific to Glu-1Bx gene were used to PCR amplification. There were not different strip between the variant plant and two parents, and the three clones were sequenced and biased on NCBI which were proved to be homologous with 1B×7 coding region completely. The results showed that the variation took place in the repetitive domain which made the molecular become higher, and the sequence of N-terminal andi C-terminal region changes too, which made the primers specific to Glu- 1Bx cannot amplify the gene of variant subunit.