N-ion Beam Research Articles

Low-energy N-ion beam produced new fragrant Sangyod Phatthalung rice lines for increasing production of fermented rice vermicelli

Low-energy ion beam served as a novel mutation induction tool treated seeds of red, low-amylose and non-aromatic Sangyod Phatthalung rice (Oryza sativa L. cv. Sangyod Phatthalung) for new mutant rice lines, specifically suited to the rice vermicelli production. Seven thousand dehulled rice seeds were bombarded with 50-kV-accelerated mixed nitrogen ions to a fluence of 4 × 1016 ions/cm2. Seven stable photoperiod-insensitive lines were obtained and studied for their agricultural traits, grain characteristics related to the rice vermicelli production and to confirm their genetic changes. Primarily, these mutants were shorter and produced a higher number of panicles than the wild-type. After 4-month storage, the flour obtained from the mutants exhibited better water absorption index and pasting properties, resulted in an increased rice vermicelli production yield. Genotypic changes in the mutagenized lines were confirmed. The results demonstrated that low-energy N-ion beam irradiation could induce rice mutations to benefit food industry.

Low-energy N-ion beam biotechnology application in the induction of Thai jasmine rice mutant with improved seed storability

Abstract Low-energy heavy-ion beam is a novel biotechnology used for mutation induction in plants. We used a low-energy N-ion beam to induce mutations in Thai jasmine rice (Oryza sativa L. cv. KDML 105) to improve the yield and seed quality. Seeds of BKOS6, a Thai jasmine rice mutant previously induced by ion beams, were re-bombarded with 60-kV-accelerated N-ions (N++N2+) to fluences of 1–2 × 1016 ions/cm2. The resulting mutant, named HyKOS21, exhibited photoperiod insensitivity, semi-dwarfness, and high yield potential. Seed storability of the mutant was studied in natural and accelerated ageing conditions and compared to that of KDML 105 and six other Thai rice varieties. In both testing conditions, HyKOS21 mutant had the highest seed storability among the tested varieties. After storage in the natural condition for 18 months, HyKOS21 had a seed germination percentage nearly two times as that of the original KDML 105. Biochemical analysis showed that the lipid peroxidation level of the mutant seeds was the lowest among those of the tested varieties. Furthermore, an expression analysis of genes encoding lipoxygenase isoenzyme (lox1, lox2, and lox3) revealed that the mutant lacked expression of lox1 and lox2 and expressed only lox3 in seeds. These results may explain the improved seed longevity of the mutant after storage. This work provides further evidence of the modification of biological materials using a low-energy ion beam to produce rice mutants with improved yield and seed storability. The benefits of this technology, to create new varieties with improved values, could serve for local economic development.

Ultra-low-energy (

Since ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range, it is very interesting to know effects from ultra-low-energy ion interaction with DNA for understanding ion-beam-induced genetic mutation. Tens-keV Ar- and N-ion beams were decelerated to ultra-low energy ranging from 20 to 100eV, or only a few to 10eV/u, to bombard naked plasmid DNA. The bombarded DNA was analyzed using gel electrophoresis for DNA form changes. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks after bombarded by tens-eV ion beam. N-ion beam was found more effective in inducing DNA change and mutation than Ar-ion beam. The study demonstrated that the ion bombardment with energy as low as several-tens eV was able to break DNA strands and thus potentially to cause genetic modification of biological cells. The experimental results were discussed in terms of direct atomic collision between the ions and DNA atoms.

Expression of OsSPY and 14-3-3 genes involved in plant height variations of ion-beam-induced KDML 105 rice mutants

The culm length of two semidwarf rice mutants (PKOS1, HyKOS1) obtained from low-energy N-ion beam bombardments of dehusked Thai jasmine rice (Oryza sativa L. cv. KDML 105) seeds showed 25.7% and 21.5% height reductions and one spindly rice mutant (TKOS4) showed 21.4% increase in comparison with that of the KDML 105 control. A cDNA-RAPD analysis identified differential gene expression in internode tissues of the rice mutants. Two genes identified from the cDNA-RAPD were OsSPY and 14-3-3, possibly associated with stem height variations of the semidwarf and spindly mutants, respectively. The OsSPY gene encoded the SPY protein which is considered to be a negative regulator of gibberellin (GA). On the other hand, the 14-3-3 encoded a signaling protein which can bind and prevent the RSG (repression of shoot growth) protein function as a transcriptional repressor of the kaurene oxidase (KO) gene in the GA biosynthetic pathway. Expression analysis of OsSPY, 14-3-3, RSG, KO, and SLR1 was confirmed in rice internode tissues during the reproductive stage of the plants by semi-quantitative RT-PCR technique. The expression analysis showed a clear increase of the levels of OsSPY transcripts in PKOS1 and HyKOS1 tissue samples compared to that of the KDML 105 and TKOS4 samples at the age of 50–60 days which were at the ages of internode elongation. The 14-3-3 expression had the highest increase in the TKOS4 samples compared to those in KDML 105, PKOS1 and HyKOS1 samples. The expression analysis of RSG and KO showed an increase in TKOS4 samples compared to that of the KDML 105 and that of the two semidwarf mutants. These results indicate that changes of OsSPY and 14-3-3 expression could affect internode elongation and cause the phenotypic changes of semidwarf and spindly rice mutants, respectively.

Heavy-ion beam-induced sterile mutants of verbena (Verbena*hybrida) with an improved flowering habit

Sterile mutants of Verbenahybrida were isolated at high frequency from nodal cultures of developed plants irradiated with heavy-ion beams. Sixty four in vitro-cultured nodes of fertile cultivars 'Temari Sakura' (FS), 'Temari Coral Pink' (FC) and 'Temari White' (FW) were irradiated with 1 to 10Gy of 14 N-ion beam (1890MeV). Lateral shoot development of FS, FC and FW was not affected by irradiation with up to 10Gy. After open-pollination, shoots with inflorescence forming unenlarged ovaries were selected and propagated several times by cutting. Shoots were grown to flowering and the selection process for isolating stable sterile mutants was carried out by the same method. Finally, one mutant out of 104 FS lateral shoots (5Gy), one mutant out of 115 FC shoots (5Gy) and 3 mutants out of 108 FC shoots (10Gy) were successfully isolated. With the exception of sterility all these mutants showed normal morphology. Two sterile mutants SS and SC, which were isolated from 5Gy-irradiated FS and FC, respectively, were characterized by their flowering habits. These two mutants grew well, had a larger number of inflorescences, and a better longevity compared with their parental cultivars. These results show that heavy-ion beam irradiation is an excellent tool for isolating sterile mutants without alterations in others important traits at a high frequency. In addition, the characterization of SS and SC indicated that they have different sterile phenotypes: male and female gametes of SS are non-functional, in contrast, SC exhibits self- incompatibility, which results in mutants unable to produce seeds.

The effect of ion beam bombardment on the properties of Ta(C)N films deposited from pentakis-diethylamido-tantalum

TaN or TaCN films were deposited using a single source, pentakis-diethylamido-tantalum as diffusion barrier for copper metallization. N- and Ar-ion beams with energy of 120 eV were used for bombarding the film during growth to improve the film quality. The films deposited using N-ion beam showed a resistivity of approximately 950 μΩ cm and a density of 7.65 g/cm 3. The use of the N-ion beam, however, drastically degraded the step coverage of the film (∼5% at the 0.5 μm contact holes with aspect ratio of 3:1). On the other hand, the films deposited using an Ar-ion beam showed a resistivity of approximately 600 μΩ cm and a density of 8.26 g/cm 3. The step coverage measured at the same contact was approximately 40%. The resistivity and density of the thermally-decomposed film were also measured for comparison and were found to be approximately 10 000 μΩ cm and 5.85 g/cm 3, respectively. Finally, the diffusion barrier performance of 50 nm thick films against Cu was investigated by X-ray diffractometry. The Cu/N- or Ar-ion beam bombarded film/Si structures showed formation of η″-Cu 3Si after annealing at 650 °C for 1 h, while Cu/thermally-decomposed film/Si showed this only after annealing at 600 °C.

Ion Beam Induced Metallorganic Chemical Vapor Deposition of Titanium Nitride Films as a Diffusion Barrier Between Cu and Si

ABSTRACTWe have deposited TiN films by using ion-beam-induced chemical-vapor-deposition (IBICVD). Tetrakis-dimethyl-amido-titanium (TDMAT) was used as a precursor. N2 and Ar gas were used to generate the plasma and the ions in the plasma were extracted by using two electrically isolated grids. The energy of ion beam was about 115–127 eV. The use of N-ion beam significantly lowers the resistivity and carbon content of TiN film (∼320 μΩ-cm, 15 at.%), compared with the thermally decomposed film (∼6000 μΩ-cm, 36 at.%). The use of Ar ion beam also considerably lowers the resistivity of films (∼800 μΩ-cm), but does not reduce the carbon content. The step coverage of the thermally-decomposed film was about 70 %, while the step coverages of the films deposited using N2 and Ar ion beams were about 0 and 30 %, respectively, in 0.5 μm x 1.5 μm contacts. The etch-pit test showed that 50-nm-thick films deposited by using N2 and Ar ion beams prevent the diffusion of Cu into the Si substrate up to annealings at 550 °C and 600 °C for 1 hour, while the thermally decomposed film fails at 500 °C.

Effect of target density on the features of charge equilibrium attainment in a beam of fast nitrogen ions

The mathematical simulation of the process of passage of ions through matter with the velocity V = 4 × 10 8 cm/s has revealed that the target thickness at which the charge equilibrium is attained in fast N-ion beam, depends nonmonotonically on the interatomic distance in the target.