Studies On Wheat Mutants Induced By Nitrogen Ion Beam Implantation

In recent years a new technique in term of ion beam implantation has been proved an effective means of inducing mutation. By implanting any kinds of ions like N~+, Ar~+, Fe~+, or Zn~+ with a certain amount of energy into an organism, the process including ion mass deposition, energy deposition, charge exchange and their complex effects takes place, resulting in the genetic effect such as base substitutions(including base transitions and transversion), deletions and insertions of a single base or small DNA fragments on DNA level, even chromosome breakage and transloction on chromosome level. The mutation mechanism and biological effects of mutation induced by ion beam implantation were much different from other physical radiations. This technique has been extensively employed in genetic engineering, plant wide cross, germplasm enhancement and many breeding programs since it was introduced into biological fields.Mutation induced by ion beam implantation, to some extent, are repeatable and directional and characterized as limited physiological damages, wide mutation spectrum, and high mutation frequency in comparison with that by other inducing methods. The methods and the doses of ion beam implantation used in different organisms were detailed. Biological effects of ion beam implantation on receptor plants in Ml and M2 and its application in crop breeding were well documented. However, the systematical investigation for mutants by this method is still limited. Even though the explorations of mutation mechanism on DNA level were performed by RAPD in several laboratories, the drawbacks of this technology usually make the research results inconclusive.In this study, we treated a doubled haploid wheat line, Yi4212, as a receptor with nitrogen ion beam implantation and 60 mutant lines were developed. Their some developmental, agronomical and economical traits of the self-pollination offsprings were evaluated. The loss and gain of gliadin bands in acid-PAGE were observed in the mutant lines. Then we used microsatellite marker and AFLP technique to unravel the SSR variation and the deletions and length polymorphisms of amplification products were found in 25 SSR loci. The results suggested that the mutations induced by ion beam implantation were relevant to multiple traits and loci. The mutants application and the mutation mechanism were also discussed in this paper.