Gamma ray-induced mutations have been widely used to improve existing crop germplasm and create novel genetic variation. In the current study, a multi-year experiment was carried out to induce and isolate mutants with desirable agro-morphological traits and improved grain hardness through evaluation of induced mutant populations generated in soft-textured wheat variety HPW 89 irradiated with gamma ray dose of 250, 300 and 350 Gy. Mutagen sensitivity studies revealed a higher frequency of biological damage and seedling mortality for doses beyond 300 Gy in the M1 generation. However, the mutagenic treatments in the M2–3 populations significantly altered the magnitude of the biometrical traits. Results from the variability and association studies among traits showed that biological yield per plant, 1000-grain weight, spike length, grains per spike and plant height may be prioritized for higher genetic gain and could be used as selection criteria parameters. Multivariate analysis indicated induction of heterogeneity among mutant populations. Overall, 250–300 Gy doses were found ideal for a successful wheat mutation programme and 293 agro-morphologically superior wheat mutants were identified, out of which 108 had semi-hard grain texture based on single kernel characterization system. Among these, nine mutants were found to have the highest grain hardness index due to induced changes in one or both puroindoline genes. Hence, these mutants identified for several traits along with harder grain texture will serve as important genetic resource in future wheat-breeding programmes.

Radiotherapy is an important component in the treatment of breast cancer. However, the individual tumor response to radiation is variable, reflecting both the intrinsic properties of the tumor and its microenvironment as well as the different, inherited sensitivity of the patient's normal tissue when exposed to the effect of ionizing radiation. These differences have inspired research to discover the underlying signal transduction pathways and to understand when they pertain to the tumor, the host or both. In fact, understanding the mechanisms underlying radiosensitivity of breast cancer not only does it permit to design more effective radiation treatments, but it sheds light on the complexities of tumor-host interactions in this disease.

Introduction. Many shoots or bud-like structures are lost in the final stage of plant micropropagation because of being too short for handling. Yellow and red lights induce in vitro plant growth of some species, and blue light reduces it instead. Yellow cellophane film passes through from the yellow to red light spectrum but cuts off the blue one. Growth of banana in vitro shoots was thus compared with or without yellow-cellophane-film shading. Materials and methods. Field-grown banana normal and dwarf variant plants of Nanicão cv. (Musa sp., AAA group, Cavendish subgroup) derived from micropropagation were re-established in vitro. They were then transferred to MS medium without growth regulator in test tubes covered by yellow cellophane film under cool white fluorescent lamps at a light intensity of 46 μmol·m–2·s–1. Shoot growth was measured as height was evaluated after (20 and 30) days of culture. Results and discussion. The yellow-cellophane-film shading stimulated the growth of banana in vitro shoots. When cultured under the yellow-cellophane-film shading for 20 days, the normal true-to-type plants showed an increase of about 25% in shoot height compared with the plants cultured without cellophane film. Similar growth response was also observed on the in vitro shoots of the dwarf plants but the increment was only about 12%. This shading technique can aid shoot elongation and consequently reduction of plantlet loss at the final stage of plant micropropagation. The differing sensibility of the normal true-to-type plants and dwarf variants to the yellow-cellophane-film shading may be used for reduction of the dwarf variant population in banana micropropagation. Conclusion. Yellow-cellophane-film shading stimulates growth of banana in vitro shoots.

The effect of gamma irradiation on the time-course mortality and radiosensitivity indices in 1- and 10-day-old adult Tribolium anaphe, T. brevicornis, T. castaneum, T destructor and T. freemani, was studied. Longevity was always adversely affected by irradiation, and it was linearly dependent on the dose rate. Except for 10-day-old adults, all the insects died within 12 weeks of γ-irradiation at 4 and 5 krad. In addition, T. destructor was markedly more radioresistant at all dose levels, and lived longer than the other species. The mean survival times of adults were generally shorter in females than in males for all species. The radiosensitivity indices did not vary widely among the species, but decreased as the dose increased in all the species, indicating that the resistance of the species was dose-dependent.

Introduction. Banana is a worldwide important fruit crop, and improved clones which are resistant/tolerant to different biotic and abiotic stresses are very much required. In this regard, prospects of in vitro mutagenesis are high and relevant. Materials and methods. The in vitro cultures (individual and multiple shoots) and in vivo plant materials (suckers and hardened plants) of banana cv. Basrai (AAA) were exposed to 60Co gamma ray doses ranging from 0-100 Gy. Radio-sensitivity of suckers and in vitro individual shoots was assessed by recording data on survival, multiplication ratio, days to root initiation, root number, root length, shoot length, plant height, number of leaves, leaf area and chlorophyll content. Results. Increase in the dose of gamma-rays resulted in corresponding decrease in the growth of the explants. Further, as a trend, the in vivo explants were observed to be more vulnerable than the in vitro ones. This offers possibilities of obtaining live plant materials even at high doses thereby increasing the probability of higher frequency of mutations. Lower doses of 10 and 20 Gy had an enhancing effect on the multiplication ratio of in vitro multiple shoot cultures. Conclusion. The in vivo and in vitro plant materials exhibited differential response to gamma-irradiation. The results obtained from the present studies will be useful in refining strategies for in vitro mutation induction aimed at banana improvement.

Eggs (1, 2 and 3-day-old), larvae (early and late) and 4-day-old pupae of the rice moth, Corcyra cephalonica (Stainton), were treated with 60Co gamma-radiation at doses from 0 to 100 krads. Evaluation of moth radiosensitivity by the survival of treated eggs, larvae and pupae led to the following sequence of stages in order of increasing radioresistance: for the eggs, 1, 2 and 3-day-old; for larvae and pupae, early larvae (5 days after hatching), late larvae (5 days before pupation) and 4-day-old pupae. Twenty five kiloradians was found to be the most likely unit for disinfestation by radiation of C. cephalonica.