Molecular Markers Analysis Of Variations In Genome Of Arabidopsis Thaliana Induced By Carbon-ion Beam And ?-ray Irradiations

As a new breeding method,heavy-ion beam irradiations have been widely used in plant science.Heritable variations of plants were induced by heavy-ion beams.Compared with traditional breeding,available mutants induced by heavy-ion beams were acquired in short breeding period and can be screened as new cultivars or germplasms for research and application in breeding.So far,heavy-ion beam irradiations have played an important role in breeding research.Molecular marker is a genetic marker based on DNA nucleotides sequences variations among individuals,representing genetic polymorphism in DNA level.In recent years,DNA molecular marker technique has been applied in relationship identification,phylogenetic systematics and breeding.Most of researches concentrate on the genetic relationship of plants or microorganisms among different cultivars or accessions.However,there are rare report has been published so far to assess genetic polymorphism of mutants populations.In present study,in order to investigate the effects of carbon-ion beams and ?-rays on DNA polymorphism of A.thaliana,genetic polymorphism of genome DNA of M1 and M3 plants induced by carbon-ion beam and ?-ray irradiations were analyzed by ISSR and RAPD.In addition,the connections between genetic polymorphism and phenotypic changes of A.thaliana M3 plants were investigated to verify artificial screening.The polymorphism of M1 plants induced by half lethal dose of carbon-ion beam and ?-ray irradiations was analyzed by ISSR and RAPD.The average polymorphism rates were 12.87% and 9.01% by ISSR and RAPD induced by carbon-ion beams;and the average similarity coefficients were 0.89 and 0.90,respectively.The average polymorphism rates were 7.67% and 1.45% by ISSR and RAPD induced by ?-rays;and the average similarity coefficients were 0.93 and 0.98,respectively.The result showed that both carbon-ion beams and ?-rays can induce changes of genetic polymorphism in M1 plants.The genetic polymorphism of M1 plants induced by carbon-ion beams is higher than ?-rays.The polymorphism detected by ISSR is higher than RAPD.The genetic polymorphism of genome DNA of M3 plants induced by carbon-ion beams and ?-rays was assayed by ISSR and RAPD.The average polymorphism rates were 17.64% and 22.79% by ISSR and RAPD induced by carbon-ion beams;and the average similarity coefficients were 0.79 and 0.85,respectively.The average polymorphism rates were 12.10% and 2.82% by ISSR and RAPD induced by ?-rays;and the average similarity coefficients were 0.81 and 0.91,respectively.All the results showed that M3 plants with conspicuous and unconspicuous phenotypes induced by carbon-ion beam and ?-ray irradiations showed heritable genetic polymorphism variations.The genetic polymorphism of M3 mutants induced by carbon-ion beams is higher than ?-rays.However,polymorphism detected by ISSR is lower than RAPD induced by carbon-ion beams and higher than RAPD induced by ?-rays.Besides,the dendrograms are constructed using UPGMA method.C-1011# and C-1025#(shared common mutation phenotype of precocity),?-685# and ?-814#(shared common mutation phenotype of long petioles)were gathered by ISSR and RAPD.In summary,the genetic polymorphism of M1 plants and M3 mutants induced by carbon-ion beams are higher than ?-rays,indicating that heavy-ion beam irradiations mutation breeding is more advantageous than conventional ionizing radiations.Average molecular polymorphism of M1 plants is lower than M3 mutants.The probable reason is that some of M1 plants seeds were induced random mutations and some damages induced by irradiations were repaired.However,M3 mutants isolated have heritable variations.Most of genetic polymorphism detected by ISSR is higher than RAPD,illustrating that sensitivity of ISSR is higher than RAPD and easier to detect polymorphic loci.Some results are identical evaluated by molecular markers clustering and phenotype clustering.Therefore,connections can be established between genetic variations and phenotypic changes by clustering analysis and to verify the accuracy of phenotypic screening,and to screen mutants in molecular level to eliminate the influence of growth conditions and stages.