Screening Of Novel Mutations Induced By ⁶⁰Co γ-ray In Partial Tetraploid Wheat

Tetraploid wheat (AABB,2n= 4x= 28) is various in genetic diversity and morphological. With strong ecological adaptability and insect resistance, alkali resistance, tetraploid wheat is widely used as resource for wheat breeding. However, human activities and natural calamities decreased the biological diversity and narrowed the genetic variability. In this study, seven species including 10 accessions of tetraploid wheat were radiated with 60Co y-ray. Follow the treatment, germination energy, germination rate, mutations of agronomic traits, cytogenetics, high-molecular-weight glutenin subunits (HMW-GSs) and gliadin were observed, which could be used for future selection and utilization of the radiated progenies.Main results were as follows:1. Different species has different suitable dose of radiation intensity:Triticum dicoccum Schrank (PI434999) is the most sensitive to the treatment and this dose of radiation is lethal dose to it. The seed viability of T. polonicum (As304) and T. carthlicum (As293) are affected with a germination ratio of 35% and 40%, respectively. T. dicoccoides (As835) and T. dicoccoides (As838) shew mutations in special traits, chromosome pairing in meiosis, HMW-GS and gliadin. It is an suitable dose for T. dicoccoides radiation-mutations. As to other tetraploid wheat, 100Gy 60Co y-ray radiation is an insufficient dose to induce mutation.2. Mutations of agronomic traits were observed at the mature stage:compared with CK, T. dicoccoides (As838) 239-7 stalk with wax powder, T. carthlicum (As293) 250-1 was senescence, dwarf were observed in both T. turgidum (As2255) 253-10 and T. polonicum (As302) 224-14.3. Chromosome pairing in meiosis of pollen mother cells:univalents, trivalents, quadrivalents and lagging chromosomes in meiosis were detected in few cells of the observed accessions and also normal matching rings and rod bivalent were observed in most cells. Univalents were observed in T. dicoccoides (As838) 239-7 and varied agronomic character as 11 secondary tillerings and stalk with wax powder also generated. Its chromosome pairing formula is 2n= 28= 0.44 Ⅰ+12.26 Ⅱ (ring)+1.32 Ⅱ(rod)+ 0.08Ⅲ.4. lAx was silent in T. dicoccoides (As835) 237-9-5 and T. dicoccoides (As838) 239-8-2. A novel HMW-GS was detected in T. polonicum (As304) 230-7-1 and its electrophoretic mobility was between 1By8 and 1Dy12 which were the HMW-GSs of Chinese Spring. Un-normal chromosome pairings are linked with HMW-GSs mutations. lAx was silent in T. dicoccoides (As835) 237-9-5 and T. dicoccoides (As838) 239-8-2, their chromosome pairing formulas are 2n= 28=0.44 Ⅰ+1.05Ⅱ (rod)+11.79Ⅱ (ring)+ 0.21Ⅲ+0.53Ⅳ and 2n= 28= 1 Ⅰ+0.64Ⅱ(rod)+12.32Ⅱ (ring)+0.36Ⅲ, respectively. There are univalents, trivalents, quadrivalents and lagging chromosomes in the pollen mother cells in T. polonicum (As304) 230-7, its chromosome pairing formula is 2n= 28-0.10 Ⅰ+12.11Ⅱ(ring)+1.41 Ⅱrod)+0.10Ⅲ0.18Ⅳ. A novel HMW-GS was detected in seed of T. polonicum (As304) 230-7 numbered 230-7-1 and its electrophoretic mobility was between 1By8 and 1Dy12 which were the HMW-GSs of Chinese Spring. These could be used as research resources for study on mutation mechanisms of HMW-GSs.5. Gliadin mutations were observed only in M1 of radiated T. dicoccoides (As838). No gliadin mutation occurred in other radiated tetraploid wheat.6. The mutations of the radiated plants could be used as resources for future wheat breeding.