Studies On Biological Effects And Mutagenic Mechanisms Of Wheat Implanted By ～7Li～(3+) Ion Beams

The present thesis studied the radation biological effects on Wheat in M1 generation,the meqenic effectS on Wheat i4 M2 genefation, seedling genomic DNA variation in M3generation of three mutwts and the physical mechanisms of 7Li3+ ion beams which wereiInPlanted into What seeds with different energy and doses. The results are as followstl) Ion bearns imPlantation inhibited the germination rate, root length, seedling height andsurvival rate ct al. in Ml generation. In addition, ion imPlanation could inducemorphologicaI whants of the seedlings, chromosome aberraions in root tip ce1ls, andthe ultrastrUctUre aberrations in the leaf cells of the seedlings.2) There were many tyPes of mutaions in M2 generation, such as plan shaPe, spikeshaPe and sterility etc. Ainong the treatmellts, 7Li3+ ion beams with 32MeV,l.4l6x l0lz ions/cm2 could induce the highest mutation frequency(l3.4%) and usefiJlmulation frequency(4.l2%) in M2 generation, and the mutational spectrum wasbrohdeSt. So ths tfeatment was regarded as the most suitable one fOr mutationbreeding.3) RAPD analysis of seedling genomic DNA variation in M3 generation of three mutantsshowed their DNA sequences had changed. This result confirmed that the implantationof vLis+ ion beams could induce genetic mutation in wheat.4) vLis+ ion beams wth specific energy could implant into the embryos of the wheat'seeds and the inner target nuclear reaction 'H('Li,;Be)n occurred to produce 7Be ions,therefore it could induce genetic mutation. When the energy was 32MeV the doseranged from zero to l.4l6xl0l2 ions/cm', the natural logarithir of the number ofhydrogen atoms which reacted Wth 7Li3+ ions had significant correlation with thebio1ogical damage ratCs of wheat in Ml generation.'The results of the studies on biological. effects and mutagenic mechanisms of wheatimPlated by 7Li3+ ion beams demonstfated that, 7Li3+ ion implantation technique hadsPecial mchgenic characteristics, and it couId induce high mutation frequency. So it wasexpected to have bright prospects in mlltation breeding and creating new germplasms.