Effect Of Heavy Ion Beam Irradiation Research Articles

Comprehensive effects of heavy-ion beam irradiation on sweet potato (Ipomoea batatas [L.] Lam.).

Sweet potato is a major root crop with nutritious tuberous roots. The mechanism of tuberous root development has not yet been adequately elucidated. Genetic resources are required to develop the molecular understanding of sweet potato. Heavy-ion beams were applied to hexaploid sweet potato for an increase in genetic variation, after which the comprehensive effects of heavy-ion beam irradiation were investigated. In vitro cultured shoots with an axillary bud of 'Beniharuka' were irradiated with Ar-ions at a dose of 1-5 Gy and C-ions at a dose of 5-20 Gy, and three irradiated lines were separated from each irradiated shoot. The shoot regeneration was inhibited at high doses of each ion irradiation. Ar-ion irradiation had an especially high biological effect on shoot regeneration. A total of 335 lines were obtained, consisting of 104 and 231 lines derived from Ar- and C-ion irradiation, respectively. The change in the DNA content of the lines was analyzed by flow cytometry to evaluate the irradiation-induced damage to the DNA. The two lines demonstrated significant differences in the DNA content and changes at the chromosome level. The screening for the morphological mutants was conducted in the field. Some irradiated lines showed inhibited or no tuberous root phenotype as mutant candidates. Additionally, the high-yield mutant candidates were dominated by Ar-ion irradiation. It was indicated that heavy-ion beam mutagenesis is effective in broadening the range of the phenotypes corresponding to tuberous root formation in hexaploid sweet potato.

Mutagenic Effects of Heavy-Ion Beam Irradiation to Plant Genome

Mutagenic Effects of Heavy-Ion Beam Irradiation to Plant Genome

Comprehensive identification of mutations induced by heavy-ion beam irradiation in Arabidopsis thaliana.

Heavy-ion beams are widely used for mutation breeding and molecular biology. Although the mutagenic effects of heavy-ion beam irradiation have been characterized by sequence analysis of some restricted chromosomal regions or loci, there have been no evaluations at the whole-genome level or of the detailed genomic rearrangements in the mutant genomes. In this study, using array comparative genomic hybridization (array-CGH) and resequencing, we comprehensively characterized the mutations in Arabidopsis thaliana genomes irradiated with Ar or Fe ions. We subsequently used this information to investigate the mutagenic effects of the heavy-ion beams. Array-CGH demonstrated that the average number of deleted areas per genome were 1.9 and 3.7 following Ar-ion and Fe-ion irradiation, respectively, with deletion sizes ranging from 149 to 602,180 bp; 81% of the deletions were accompanied by genomic rearrangements. To provide a further detailed analysis, the genomes of the mutants induced by Ar-ion beam irradiation were resequenced, and total mutations, including base substitutions, duplications, in/dels, inversions, and translocations, were detected using three algorithms. All three resequenced mutants had genomic rearrangements. Of the 22 DNA fragments that contributed to the rearrangements, 19 fragments were responsible for the intrachromosomal rearrangements, and multiple rearrangements were formed in the localized regions of the chromosomes. The interchromosomal rearrangements were detected in the multiply rearranged regions. These results indicate that the heavy-ion beams led to clustered DNA damage in the chromosome, and that they have great potential to induce complicated intrachromosomal rearrangements. Heavy-ion beams will prove useful as unique mutagens for plant breeding and the establishment of mutant lines.

Mutagenic effects of heavy-ion beam irradiation on in vitro nodal segments of Artemisia annua L.

Artemisia annua L. is a commercial source of artemisinin. Nevertheless, artemisinin content within the plant is relatively low and varies depending on genotype and environment. To broaden the genetic variability, the mutation effect of 12C-ion beam irradiation on A. annua was examined. Irradiation at 2.5 Gy had a slight lethal effect to nodal segments while a noticeable lethal effect was observed at 5 and 10 Gy. Furthermore, at higher doses (20 and 50 Gy), a severe lethal effect was observed. Mutations at the DNA level of axillary bud-derived shoots were performed by RAPD. The mutation frequency at 10 Gy was about 1.7 and 2.1 times higher than that at 2.5 and 5 Gy, respectively. After growth and artemisinin production observation of 72 irradiated mutants, around 14 and 7 % of them showed higher artemisinin content and artemisinin yield compared to the controls, respectively. The highest artemisinin content in a mutant was 1.43 % DW, which was 3.2-fold higher than the original wild type. Additionally, the highest artemisinin yield in mutants was 3.68 mg/plant, which was around 1.4-fold higher than in the wild type. Moreover, irradiated mutants exhibited antibacterial activity against S. aureus, but the wild types did not. This study presents an effective application of heavy ion beam irradiation to create variations and improve artemisinin production in A. annua.

Effect of heavy-ion beam irradiation on the level of serum soluble interleukin-2 receptors in hamster cheek pouch carcinoma model.

Soluble interleukin-2 receptor (sIL-2R) is a glycoprotein derived from α chain of interleukin 2 receptors of mononuclear as well as T-cell membranes. The aims of this study were to detect the changes of serum soluble interleukin-2 receptor (sIL-2R) levels following heavy-ion beam irradiation in the hamster model with cheek pouch carcinoma, as well as to examine the impact of immune status of the hamster cheek pouch carcinoma model using heavy-ion beam irradiation. sIL-2R serum levels were detected by radioimmunoassay (RIA) in 40 hamsters bearing cheek pouch carcinoma prior to and following exposure to heavy-ion beam irradiation, and 8 normal animals served as the control. The sIL-2R serum level in hamster cheek pouch carcinoma model was significantly increased as compared to the normal control group (P<0.05). Results showed that an increase in the irradiation dose led to a gradual decrease in the sIL-2R serum level. Additionally, a statistical significance was observed compared to the tumor group (P<0.05). In conclusion, alterations in serum sIL-2R expression have an effect on the hamsters cheek pouch carcinoma model subsequent to heavy-ion beam irradiation. An increase in the irradiation dose indicated a decreased tendency in serum sIL-2R content. Detection of serum level changes may lead to an improved understanding of heavy-ion irradiation in vivo immune status, which is crucial for clinical diagnosis and prognosis. It can also provide a sensitive indicator to help estimate the effects of heavy-ion cancer targets.

Promotion of somatic embryo production from embryogenic calluses of monocotyledonous and dicotyledonous plants by heavy-ion beam irradiation

Effect of heavy-ion beam irradiation on the growth and development of embryogenic calluses was examined in the liliaceous monocotyledon Tricyrtis hirta and the umbelliferous dicotyledon Daucus carota. Embryogenic calluses of T. hirta were irradiated with 5, 10, 20 or 50 Gy of 12C6+, 14N7+ or 20Ne10+ ions, and those of D. carota were irradiated with 5, 10, 20 or 50 Gy of 14N7+ ions. In both species, irradiation at 10–50 Gy inhibited growth of embryogenic calluses, and callus growth rate decreased as irradiation dose increased. Interestingly irradiation at low doses greatly promoted somatic embryo production from embryogenic calluses in both species. In T. hirta, calluses irradiated with 5 and 10 Gy 12C6+ ions, 10 Gy 14N7+ ions, and 5 Gy 20Ne10+ ions produced more than twice as many embryos as the control, non-irradiated calluses. In D. carota, embryogenic calluses irradiated with 5 Gy 14N7+ ions produced more than one and a half times as many embryos as the control. Somatic embryo production in both species was inhibited by irradiation at 20 and 50 Gy.

LET-dependent effects of heavy-ion beam irradiation in Arabidopsis thaliana

We irradiated Arabidopsis thaliana with several kinds of heavy-ion beams to investigate the linear energy transfer (LET)-dependent effects of heavy-ion beam irradiation. First, dry seeds were irradiated with C, N, Ne, Ar, or Fe ions at doses ranging from 5 to 400 Gy to compare the flowering and mutation rates among the ion species. The sensitivity of the flowering and mutation rates to irradiation differed markedly among the ion species. Of the ion species, N (30 keV mm � 1 ) was the most effective at inducing albino plants. Second, we examined the effects of LET on mutation induction. The LET of C, N, Ne, and Ar ion beams was controlled at 30-640 keV mm � 1 . Regardless of ion species, irradiation with the same LET value resulted in the same flowering rate and mutation rate. Thus, the LET of ion beams seems to be an important factor affecting mutagenesis. We found a 440-bp deletion in the hy (elongated hypocotyl) mutant that was isolated from M2 progeny. These fundamental data on LET-dependence can be used to develop advanced technologies for plant mutagenesis.

Biological effects of heavy-ion beam irradiation on cyclamen

The biological effects of heavy-ion beam irradiation on cultured tissues of cyclamen were investigated by establishing an irradiation-mediated mutation breeding protocol for producing a new variety of cyclamen. Initially, a callus, a somatic embryo, and a plantlet were irradiated with 12 C 6� ion beam at doses of 10, 20, 40, 60, and 80 Gy. Distinct mutants were not obtained in plants regenerated from the irradiated cultured materials. Next, we used the tuber of cyclamen as a target for irradiation. Irradiation (8-16 Gy) of 8-15 mm diameter tubers produced male sterility, change in petal colour, and petal form. Mutation induction by heavy-ion beam irradiation to the tuber is useful for changing flower characteristics of cyclamen.

Effect of heavy ion-beam irradiation on plant growth and mutation induction in &lt;i&gt;Nicotiana tabacum&lt;/i&gt;

Ion-beam mutagenesis is a highly effective way to rapidly create new cultivars. To optimize conditions for heavy ion mutagenesis, we irradiated tobacco (Nicotiana tabacum L.) tissues at various developmental stages with heavy ion beams of various doses and examined the effects of irradiation by monitoring plant growth and mutation induction. The effects differed among irradiated tissues. Sensitivity to heavy ion-beam irradiation increased in the following order: dry seeds, imbibed seeds, and culture tissues. We isolated three white flower mutants. One, BWF1, was found to be a novel mutant, in which the synthesis of proanthocyanidin was up-regulated. The others may have a mutation in some regulatory genes involved in the flavonoid biosynthetic pathway. These results suggest that the developmental state of plant tissues is critical for efficient plant mutagenesis, and that the broad spectrum of mutations may be induced by heavy ion-beam irradiation at molecular level.