Irradiated Seeds Research Articles

Effect of soaking and ionising radiation on various antinutritional factors of seeds from different species of an unconventional legume, Sesbania and a common legume, green gram ( Vigna radiata)

Seeds of three different species of Sesbania (Sesbania aculeata, S. rostrata and S. cannabina) and one species of Vigna ( Vigna radiata) were γ-irradiated at dose levels of 2, 4 and 6 kGy after aqueous soaking and the effects of the irradiation on the proximate composition, various antinutrients and viscosity were studied. Crude protein, crude lipid, crude fibre, ash, nitrogen free extract (NFE) and energy value did not differ appreciably between raw seeds and those soaked and irradiated after soaking, for all the samples. When compared with respective raw and soaked seed materials, irradiation significantly ( P<0.05) increased the total phenolic contents. No significant effect was observed on the reduction of phytic acid and canavanine contents, whereas approximately 50% reduction of lectin activity was observed at the highest dose of irradiation (6 kGy) in different Sesbania spp. On the other hand, non protein amino acid, canavanine and lectin activities against cattle blood erythrocytes were not detected in raw, soaked, or soaked followed by irradiated seeds of V. radiata. The highest radiation dose level of 6 kGy in S. aculeata and S. rostrata and 4 and 6 kGy in S. cannabina and V. radiata were significantly effective ( P<0.05) in reducing saponin content. Among the various Sesbania and V. radiata seed samples, irradiation at 2–6 kGy in S. aculeata significantly ( P<0.05) reduced the trypsin inhibitor activity in a nondose-dependent manner when compared with raw and soaked samples. Particularly, the irradiation at a dose level of 6 kGy significantly ( P<0.05) reduced viscosities of different spp. of Sesbania and V. radiata seed samples and this might be due to the depolymerisation of non-starch polysaccharides (NSPs).

照射セルロースに特有なラジカルのESRピークによる照射イチゴの検知

The method of detecting low-dose irradiated strawberries by identifying ESR peak of irradiated cellulose component was studied. Ratio of peak height (S) of high magnetic field cellulose component, and noise width (N) of either irradiated or unirradiated seeds of strawberries were compared. In this study, sample was identified to be irradiated when S/N ratio of ESR spectrum of 4 min. sweep time was above 0.7. In the case of S/N ratio below 0.7, when the S/N ratio of integrated ESR spectrum, obtained from measuring 10 times with 1 min. sweep time was above 1.0, the sample was identified to be irradiated. The result suggests that S/N ratio is a good marker to detect the irradiation. The strawberries irradiated above 0.5kGy was able to bedetected after 3 days storage at room temperature, after 21 days refrigeration and after 60 days freezing, respectively.

GAMMA RAY - INDUCED MITOTIC ABNORMALITIES IN Helianthus annuus L. VARIETY EKIZ 1 / LOS RAYOS DE GAMMA CAUSA ANORMALIDADES MITOTICAS EN Helianthus annuus L. VARIEDAD DE EKIZ 1 / LES ANORMALITÉS MITOTIQUES CHARGÉÉS DES RAYONS GAMMA

SUMMARYIn this study, mitotic effects of gamma rays on Ekiz 1 variety belonging to Helianthus annuus L. (2n= 34) in the M0 (first irradiated seeds), M1 and M2 generations have been investigated. Seeds (M0) were irradiated with gamma rays at 10, 20, 30, 40 and 50 kR doses. Percentage of total abnormalities in the M0, M1 and M2 generations increased parallel to the increasing dose of radiation. These abnormalites have been observed as C-metaphase, chromosome stickiness, laggards and bridges with or without fragment. Mitotic index (M.I.) in the M0, M1 and M2 generations has decreased parallel to the dose increase. When the generations are compared, both the amounts of decrease in mitotic index and in the percentage of mitotic abnormalities were mostly observed in M0.

Alfalfa Seed Germination and Yield Ratio and Alfalfa Sprout Microbial Keeping Quality Following Irradiation of Seeds and Sprouts

Foods can be treated with gamma radiation, a nonthermal food process, to inactivate foodborne pathogens and fungi, to kill insects on or in fruits and vegetables, and to increase shelf life. Gamma irradiation is especially well suited for these treatments because of its ability to penetrate commercial pallets of foods. Irradiated fruits, vegetables, poultry, and hamburger have been received favorably by the public and are now available in supermarkets. The use of irradiation on fresh alfalfa sprouts was studied to determine its effect on keeping quality as related to aerobic microbial load. After an irradiation dose of 2 kGy, the total aerobic count decreased from 105–8 to 103–5 CFU/g, and the total coliform counts decreased from 105–8 to 103–0 CFU/g. The results showed that the sprouts maintained their structure after irradiation, and the keeping quality was extended to 21 days, which is an increase of 10 days from the usual shelf life. The effect of various doses of irradiation on alfalfa seeds as measured by percent germination and yield ratio (wt/wt) of sprouts was determined. There was little effect on the percent germination, but as the dose increased, the yield ratio of alfalfa sprouts decreased. As the length of growing time increased, so did the yield ratio of the lower dose irradiated seeds (1 to 2 kGy). The irradiation process can be used to increase the shelf life of alfalfa sprouts, and irradiating alfalfa seeds at doses up to 2 kGy does not unacceptably decrease the yield ratio for production of alfalfa sprouts.

The use of simulation in the EPR spin probe technique for detection of irradiated seeds

An electron paramagnetic resonance (EPR) spin probe study of irradiated wheat seeds was performed depending on irradiation dose. The structural changes in the membrane integrity were followed using aqueous solutions of 4-hydroxy-TEMPO (TANOL) spin probe and a line broadening material. In the studies dry seed embryos were kept in these solutions for 150 min. The spectra were recorded at various times of air drying process. The simulation of these spectra indicated a decrease in the water content of the embryos depending on the increasing irradiation dose. This indicates the increase in the permeability of the membranes as a result of the radiation damage. From the decay curves it is possible to determine about irradiation dose, however, this approach is not very successful at close irradiation doses.

Influence of He-Ne laser irradiation of soybean seeds on seed mycoflora, growth, nodulation, and resistance to Fusarium solani.

Laser irradiation of soybean seeds for 3 min caused a clear reduction in the number of seed-borne fungi which became more pronounced as the irradiation time was extended. Pretreatment of the seeds with methylene blue, methyl red and carmine enhanced the effect of laser. Rhizoctonia solani, Alternaria tenuissima, Cercospora kikuchii and Colletotrichum truncatum were completely eliminated when the seeds were pretreated with a dye and irradiated for 10 min. Seed germination was stimulated on exposure of the seed to 1-min irradiation. At such dose, most of the dyes were accelerators while the higher doses were inhibitory to seed germination. Chlorophyll a, chlorophyll b and carotenoid content of developed plants differed, depending on the irradiation dose and dye treatment of the seeds. In seeds irradiated for 1 or 3 min, chlorophyll a formation was less affected than chlorophyll b formation. In seeds irradiated for 10 min, both the chlorophyll contents were decreased especially in the presence of some applied dyes. On the other hand, there was an increase in carotenoid content of soybean leaves when the laser dose increased. The number and dry mass of nodules were mostly greater (as compared to the corresponding control), when the seeds irradiated for 1 or 3 min were pretreated with methyl red, chlorophenol red, crystal violet and methylene blue. Irradiation of pre-sowing seeds greatly protected soybean stands against F. solani. The disease incidence differed somewhat when the irradiated seeds were pretreated with dyes. The reduction in disease incidence was accompanied by accumulation of high proline and phenol levels in the infected root tissues of soybean, suggesting that these compounds have a certain role in the prevention of disease development.

Susceptibility of potato plants grown from tubers irradiated with stimulation doses of gamma irradiation to potato tuber moth, Phthorimaea operculella Zeller (Lep., Gelechiidae)

The feeding behaviour of potato tuber moth, Phthorimaea operculella Zeller (Lep., Gelechiidae), reared on leaves and tubers of potato plants, which were irradiated as seed (tubers) with stimulation doses of gamma irradiation (1, 3, 5 and 10 Gy), was studied. Significant differences in the larvae and pupae developmental time, pupal weight, mortality, fecundity and percentage egg hatch, were observed between insects fed on plants which resulted from the irradiated seeds and those of the control. It appears that leaves of potato plants grown from irradiated seeds particularly those of 3 Gy, became more attractive to the larvae, although the resulting tubers, with the exception of those of 10 Gy, became more resistant to potato tuber moth. Storing the tubers at ambient temperature conditions affected the degree of larval sensitivity. The leaves and tubers of 10 Gy‐irradiated seeds became more suitable for insect development, indicating that the later dose may inhibit the production of secondary plant metabolities and chemical compounds.

Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance

Dry seeds of Leucadendron laureolum (Lam.) Fourc. (Proteaceae) were exposed for different intervals (range: 7 to 84 days) to visible, UV-A and UV-B radiation of different biologically effective dose (range: 0 to 11.43 kJ m-2 d-1). Changes in seed germination, physiology and ultrastructure, and residual UV effects on seedling performance, were examined. Germination was depressed in seeds following short (7-day) exposures to UV radiation. This depression was intensified with increased UV exposure dose, and most pronounced at shorter UV-B wavelengths. Also glutathione reductase (GR) activities increased in seeds exposed to shorter UV-B wavelengths, but these were unaffected by irradiation dose level in the UV-B range. Electrolyte leakage rates from UV-irradiated seeds were unaltered, which indicated that germination depression did not result from intrinsic membrane damage. The reversal of germination depression (UV-induced dormancy) in UV-irradiated seeds by red light pointed to the possible involvement of phytochrome in this photo-response. Germination depression disappeared in seeds after 56-days irradiation, possibly due to photoreceptor damage by excess UV light. At this stage, all UV irradiated seeds, irrespective of treatment wavelength or dose level, exhibited increased electrolyte leakage rates, which indicated membrane perturbation. Also, increased GR activities were observed in irradiated seeds, but these were proportionately smaller in seeds exposed to shorter wavelength UV-B radiation (9.1 to 35.8% increase) than longer wavelength UV-A (73.4% increase) and visible (97.7% increase) radiation. This implied a metabolic limitation for scavenging of free radicals and peroxides in aging seeds exposed to UV-B radiation, which pointed to accelerated seed deterioration. It was indirectly supported by ultrastructural evidence of sub-cellular damage (lipid coagulation and plasmalemma withdrawal from cell walls) in embryonic tissues of seeds after 84 days UV-B exposure, and reflected in decreased leaf numbers, photochemical efficiencies, and foliar chlorophyll a and carotenoid levels in seedlings cultured from these seeds.

Identification of Low-dose Irradiated Seeds using the Neutral Comet Assay

The single-cell gel electrophoresis assay (comet assay) was used to identify seeds irradiated with low doses of 60Co gamma radiation. Soya beans, lentils, sunflower, sesame and linseed were used in the experiments. The doses given were 0.1, 0.2, 0.5 or 1.0 kGy. Samples of lentil and sunflower were also given a dose of 25 Gy. The analyses were made independently by the authors in Mol (G.K.) and Uppsala (H.C.) about 1 year after irradiation (about 1 week for 0.5 kGy and 25 Gy). In Mol the evaluation was performed using a computer-assisted image analysis system, while in Uppsala the identification was made by simple eye inspection with a fluorescence microscope. We found that all the samples could be identified by either means, including the one irradiated with 25 Gy. Image analysis permits a detailed analysis of the migration patterns of DNA as well as homogeneity study of the samples.

Biological Effects of Carbon Ions with Medium Energy on Plant Seeds

The biological effects of 46.6 MeV/u 12C6+ ions on four kinds of plant seeds were studied at the Heavy Ion Research Facility in Lanzhou (HIRFL), Institute of Modern Physics (IMP), Academia Sinica. The results show that germination of the seeds is inhibited by exposure to ions. In root tip cells of irradiated seeds, a great variety of chromosomal aberrations were observed. Sensitivities in terms of inhibition of germination and induction of chromosomal aberrations in the four species are correlated.

Reduction of gramine concentration by γ-irradiation in seedlings of Hordeum vulgare var. Amaginijo

The effects of γ-irradiation on gramine concentration in seedlings of barley ( Hordeum vulgare var. Amaginijo) were investigated. Similarly to other barley cultivars, this amine appeared in shoots of sprouting seedlings and its concentration increased in the course of subsequent development to attain a maximum around the ninth day. Exposure of two-day-old seedlings to γ-radiation resulted in significant reductions of the concentration as compared with non-irradiated control, dependent upon the radiation dose, whilst the five-day-old seedlings were slightly affected. Seeds were more radioresistant than younger seedlings, when the decline in gramine quantity was taken as a marker of radiation effect. Longer storage of irradiated seeds enhanced the decrease of this compound in seedlings. At relatively low doses, gramine concentration was successively recovered to reach the control level during further growth. This decline of gramine content could not be correlated solely with watercontent of seeds and oxygen did not seem to be a critical factor. On the basis of these results, probable mechanisms for radiation-induced reduction of the amine concentration are discussed. In these experiments it was found that changing patterns of gramine content were in close parallel with those of growth.

Karyological and cytological effects of gamma rays on pollen ontogenesis and viability and on the tapetum of Nicotiana tabacum L. var. xanthi Dulieu.

Gamma irradiation of seeds (100 to 1000 Gy) or inflorescences (3000 Gy) of Nicotiana tabacum L. var. xanthi Dulieu mainly induced chromatoclastic effects affecting the microspore mother cells (MMCs) during meiosis: chromosome fragmentation, chromosome stickiness promoting the formation of chiasmas even between non-homologous chromosomes, single or multiple chromosomal bridges during anaphases and telophases I and II and irregular chromosomal disjunction.In plants raised from irradiated seeds, the frequency of abnormal meiotic figures and the rate of pollen sterility were directly related to the gamma ray dose. Gamma irradiation also induced the early dysfunction of the tapetum (tapetal degeneration was already visible at pachytene) with nuclear pycnosis or an expanded and sticky chromatin network and this no doubt contributed to pollen sterility.

Chemical modification of postirradiation damage under varying oxygen concentrations in barley seeds.

The influence of ascorbic acid, potassium permanganate and caffeine on the postirradiation seedling injury of dry barley seeds was studied, irradiated (350 Gy 60Co gamma-rays) in vacuo and post-hydrated with varying oxygen concentrations in the soaking medium. The oxygen concentration in the post-hydration medium (OCHG) was adjusted at 0%, 10%, 30%, 50%, 80% and 100%. A linear response between the seedling injury and O2 concentration in the range of 0-80% was observed. These chemicals potentiated, protected or exerted no effect, depending upon the OCHG. Thus, ascorbic acid did not exert any effect on seeds post-hydrated at OCHG of less than or equal to 30%, but afforded radio-protection at OCHG of greater than or equal to 50%. Caffeine, on the other hand, potentiated the postirradiation injury at OCHG of less than or equal to 30%, exerted no influence at OCHG of approximately 50% and afforded radioprotection at OCHG of greater than or equal to 80%. Potassium permanganate enhanced the injury at OCHG of less than or equal to 10%, exerted no effect at OCHG of approximately 30% and afforded radioprotection at OCHG of greater than or equal to 50%. The possible radiation-chemical events in the dry irradiated seeds following their post-hydration containing different OCHG and the three test chemicals which are known free radical scavengers are discussed.

Control Processes in the Induction and Relief of Thermoinhibition of Lettuce Seed Germination

Germination of lettuce seeds (Lactuca sativa L. cv Grand Rapids) in the dark was nearly 100% at 20 degrees C but was inhibited at 27 degrees C and higher temperatures (thermoinhibition). A single 5-minute exposure to red light completely overcame the inhibition at temperatures up to 28 degrees C, above which the effectiveness of single light exposures gradually declined to reach a negligible level at 32 degrees C. However, the promotive effect of light could be extended to 34 degrees C by repeated irradiations. At any one temperature, increased frequency of irradiations increased germination percentage, and with each degree increase in temperature, increasingly frequent irradiations were necessary to elicit maximal germination. Loss of the effectiveness of single irradiations with increase in temperature may result either from acceleration of the thermal reversion of the far red-absorbing form of phytochrome or decrease in seed sensitivity toward a given percentage of the far red-absorbing form of phytochrome. Using continuous red light to induce germination, the role of endogenous C(2)H(4) in germination at 32 degrees C was studied. Ethylene evolution from irradiated seeds began to increase 2 hours prior to radicle protrusion, whereas the dark-incubated (nongerminating) seeds produced a low, constant amount of C(2)H(4) throughout the 24 hour incubation period. Inhibition of C(2)H(4) synthesis with 2-aminoethoxyvinyl glycine and/or inhibition of C(2)H(4) action with 2,5-norbornadiene blocked the promotive effect of light. Exogenous C(2)H(4) overcame these blockages. The results showed that participation by endogenous C(2)H(4) was essential for the light-induced relief of thermoinhibition of lettuce seed germination. However, light did not act exclusively via C(2)H(4) since exogenous C(2)H(4) alone in darkness did not promote germination.

Aneuploidy detection with a short-term hexaploid wheat assay

A new type of assay for the identification of agents causing aneuploidy is described. This assay takes advantage of allohexaploid wheat in which monosomic and nullisomic cell lineages can be genetically detected. The wheat strain used (Neatby's virescens) was homozygous for a pair of recessive alleles ( ν 1) which in homozygous condition interfere with normal pigmentation of the leaves at low temperature whereas at higher temperature nearly normal green color formation is permitted. In a single dose this allele cannot suppress the formation of green color even at low temperature, i.e., it is hemizygous ineffective. This locus is in the short arm of chromosome 3B near the centromere. As a consequence of non-disjunction of this chromosome twin sectors may be detected, in which the monosomic cell lineages appear green whereas the trisomic sectors display with color on a cream-colored background at low temperature. This genetic system can also be used for the detection of deletions or duplications involving the short arm of chromosome 3B, and to some extent the A- and the D-genome homeologues. We have determined the pattern of differentiation of the shoot apex and on that basis we can separate the independent genetic events from reappearance of the sectors of common origin in the successive leaves. Such an understanding of development of the leaf sectors permits a quantitative estimation of the genetic response of the plants to mutagenic factors. We have found that X-rays, γ-rays, p-fluorophenylalanine, 3-aminotriazole, caffeine, vinblastin sulfate, benzo[ a]pyrene and auramine significantly increased aneuploidy, and diethylstilbestrol, sulfacetamide, safrole and dichlorvos caused some increase of sectoring. Cytological data on root tips of irradiated seeds support the interpretation of the mechanism of sector formation in the leaves. The test is simple, fast, inexpensive, and it does not require elaborate facilities or highly trained technicians. The trials were well reproducible during a period of 3 years in 2 laboratories. Therefore we consider the new assay a useful complement to other tests of chemicals or physical agents that may cause non-disjunction and other chromosomal aberrations in human populations.

Biological and genetic effects of combined treatments of sodium azide, gamma rays and EMS in barley

Dry seeds of diploid barley were subjected to mutagenic treatments of sodium azide, gamma rays and EMS alone or in combination. Damage (reduction in seedling height, plant height and fertility), the frequency of chimeras in the M 1 generation, and the frequency of chlorophyll-deficient mutations as well as morphological mutations in the M 2 generation induced by combined treatments were greater than those by either of the single treatments. Synergistic increase in the frequency of chimeras, chlorphyll-deficient mutations and morphological mutations were observed in both sodium azide post-irradiation treatments and pre-EMS treatments; interaction among the mutagens in the treatment combinations on M 1 damage was generally subtractive. An 8- to 16-hr soaking period of irradiated seeds in distilled water prior to sodium azide treatment significantly increased chlorophyll mutation frequency, as compared to that from the non-soaking treatment. Damage and frequency of chimeras, chlorophyll mutations and morphological mutations were consistently reduced by the soaking treatment in sodium azide plus EMS treatments.

Absence of storage effects on radiation damage after thermal neutron irradiation of dry rice seeds.

Storage effects on dry rice seeds equilibrated to 6.8% moisture content were examined after irradiation with X-rays of 5, lO, 20 and 40 kR and with thermal neutrons of 2.1, 4.2, 6.3 and 8.4×1013Nth/cm2. Reduction in root growth was estimated from dose response curves after storage periods of 1 hr to 21 days. The longer the storage period, the greater enhancement of radiation damages in X-irradiated seeds. There were two components in the storage effect, i. e., a rapid increase of radiosensitivity within the first 24 hr and a slow increase up to 21 days. An almost complete absence of a storage effect was observed after thermal neutron exposure, in spite of considerably high radioactivities of the induced nuclides, 56Mn, 42K and 24Na, which were detected from gamma-ray spectrometry of the irradiated seeds. The present results suggest that the contributions of gamma-rays from the activated nuclides and of inherent contaminating gamma-rays are little or negligible against the neutron-induced damage, and that the main radiobiological effects of thermal neutrons are ascribed to in situ radiations, i, e., heavy particles resulting from neutron-capture reaction of atom. A mechanism underlying the absence of storage effect after thermal neutron irradiation was briefly discussed on the basis of radical formation and decay.

Triple testcross analysis of F2 and irradiated F2-derived lines of Pisum sativum L.

The triple testcross breeding design was applied to a set of F7 and RF7 pure-breeding lines derived from normal and irradiated F2 seeds of the cross 'Bonneville' × T 163. Two phenotypically extreme lines and their F1 were used as testers in both control and irradiated materials. Epistasis was, in general, not an important component of variation. Additive component was the most important, while dominance was detected in 3 of 10 cases. The additive and dominance components in general decreased following irradiation as a result of additive and dominance effects of induced new alleles being smaller than those generated by the original alleles they replaced.Key words: triple testcross, irradiation, single seed descent, genetic anaylsis, pea.

Gibberellin‐biosynthesis and ‐sensitivity mediated stimulation of seed germination of Sisymbrium officinale by red light and nitrate

Light stimulated seed germination of Sisymbrium officinale (L.) Scop, (hedge mustard) by means of two different mechanisms. Light effect I was absolutely dependent on the simultaneous presence of nitrate. Without nitrate, red (R) irradiated seeds did not escape from the antagonizing action of far‐red (FR) irradiation. The data indicated that nitrate acted as a cofactor at the level of the FR absorbing form of phy‐tochrome (Pfr). The combined action of R and nitrate could be replaced by addition of the gibberellins 4 and 7 (GA,4+7). This action could be inhibited by the growth re‐tardant tetcyclacis, an inhibitor to GA biosynthesis in cell free systems and intact plants. The action of tetcyclacis was fully neutralized by GA4+7. It is concluded that the combination of R and nitrate stimulated GA biosynthesis. Omission of nitrate from the incubation medium enabled the study of light effects apart from G A biosynthesis. In such conditions R stimulated the sensitivity to GA4+7, (light effect II). The two light effects could also be distinguished by their different reactions to the temperature of a pre‐treatment in water and darkness. The sensitivity to R and nitrate was subject to breaking and induction of dormancy. Both processes were stimulated at rising temperatures. Due to a different optimum, breaking of dormancy prevailed at lower temperatures and induction of secondary dormancy at more elevated temperatures. The sensitivity to GA4+7 rose and fell in a comparable way during dark incubation at a broad range of temperatures. The capacity of light to stimulate GA4+7, action did not diminish at higher temperatures, it even tended to rise. The study indicated that seed germination is regulated by an increase in both the levels of GAs and the sensitivity to GAs.

Biological effects of heavy ions in Arabidopsis seeds

Irradiation of dry seeds of Arabidopsis with heavy ions (HZE-particles) produced by UNILAC-accelerator (GSI, Darmstadt) yielded aberrations in varied developmental endpoints such as survival rate and embryo vitality. The damage increased with particle density and charge. Cross sections in the range of 0.2–1.0 μm 2 for Ne and Ar and 2.0–10.0 μm 2 for Xe were estimated. Soaked seeds were more sensitive than dry seeds (cross-section 2.0–10.0 μm 2 for Ar). The induced total damage in the irradiated seeds was estimated adding the different damages weighted by certain factors. These results will be used as base data for the interpretation and evaluation of spaceflight experiments on the biological effects of cosmic radiation.