Showing papers on "Mutation breeding published in 2019"

Comparison and Characterization of Mutations Induced by Gamma-Ray and Carbon-Ion Irradiation in Rice (Oryza sativa L.) Using Whole-Genome Resequencing.

Abstract: Gamma-rays are the most widely used mutagenic radiation in plant mutation breeding, but detailed characteristics of mutated DNA sequences have not been clarified sufficiently. In contrast, newly introduced physical mutagens, e.g., heavy-ion beams, have attracted geneticists’ and breeders’ interest and many studies on their mutation efficiency and mutated DNA characteristics have been conducted. In this study, we characterized mutations induced by gamma rays and carbon(C)-ion beams in rice (Oryza sativa L.) mutant lines at M5 generation using whole-genome resequencing. On average, 57.0 single base substitutions (SBS), 17.7 deletions, and 5.9 insertions were detected in each gamma-ray-irradiated mutant, whereas 43.7 single SBS, 13.6 deletions, and 5.3 insertions were detected in each C-ion-irradiated mutant. The structural variation (SV) analysis detected 2.0 SVs (including large deletions or insertions, inversions, duplications, and reciprocal translocations) on average in each C-ion-irradiated mutant, while 0.6 SVs were detected on average in each gamma-ray-irradiated mutant. Furthermore, complex SVs presumably having at least two double-strand breaks (DSBs) were detected only in C-ion-irradiated mutants. In summary, gamma-ray irradiation tended to induce larger numbers of small mutations than C-ion irradiation, whereas complex SVs were considered to be the specific characteristics of the mutations induced by C-ion irradiation, which may be due to their different radiation properties. These results could contribute to the application of radiation mutagenesis to plant mutation breeding.

Phenotypic and molecular cytogenetic variability in calendula ( Calendula officinalis L.) cultivars and mutant lines obtained via chemical mutagenesis

Abstract: The morphological, meiotic and chromosomal variability were studied in two cultivars of Calendula officinalis L. and their mutant lines obtained though chemical mutagenesis using diethyl sulphate (DES) (0.04%, 0.08%) and dimethyl sulphate (DMS) (0.025%, 0.05%). The studied cultivars displayed different sensitivity to DMS and DES mutagens. More M1 plants with morphological changes were observed in C. officinalis cv. ‘Zolotoe more’ than in cv. ‘Rajskij sad’. DMS and DES at low concentrations had positive effects on main agro-metrical traits in both cultivars including plant height, inflorescence diameter and number of inflorescences per plant. Dose-dependent increase in number of various meiotic abnormalities was revealed in both mutant lines. Comparative karyotype analysis and FISH-based visualization of 45S and 5S rDNA indicated a high level of karyotype stability in M1 and M2 plants. Seed treatments with DMS and DES at certain concentrations resulted in higher yields of inflorescences in M1 plants compared to the control. In M2 generation, dose-dependent reduction in the yields of inflorescences was observed. Our findings demonstrate that DMS and DES at low concentrations have great potential in calendula mutation breeding.

Determination of mutagenic sensitivity to gamma rays in ginseng ( Panax ginseng ) dehiscent seeds, roots, and somatic embryos

Abstract: Ginseng (Panax ginseng) has a low genetic diversity and a narrow pool of genetic resources. Mutagenesis is one of the most powerful methods for inducing genetic variation in this species, but little research has been performed in ginseng. In this study, various tissues, including dehiscent seeds, 1-year-old roots, and somatic embryos were irradiated at different doses of gamma rays (20–400 Gy and zero dose as a control) to determine the most optimal concentration and tissues for the successful use of mutagenesis in ginseng breeding. The results revealed that high gamma doses (> 100 Gy) were detrimental to all irradiated tissues. A gradual and significant reduction in germination, emergence, and seedling growth were found as gamma irradiation dose increased. The reduction in survival rates and seedling growth by irradiation at serial doses showed that the LD50 of ginseng was 20–80 Gy, although the irradiation doses were tissue dependent. Based on our results, the optimal doses of gamma rays for inducing mutation in ginseng are < 20, 40, and 60–80 Gy for 1-year-old roots, dehiscent seeds, and somatic embryos, respectively. Given the fact that ginseng somatic embryos are less sensitive to gamma rays than other tissues, the combination of in vitro culture and mutagenesis could be more effective than the conventional method for mutation breeding in ginseng. These results provide a good basis for radiation sensitivity of ginseng and are useful as a guideline for ginseng mutation breeding.

Assessment of Phenotypic Variations and Correlation among Seed Composition Traits in Mutagenized Soybean Populations.

Abstract: Soybean [Glycine max (L.) Merr.] seed is a valuable source of protein and oil worldwide. Traditionally, the natural variations were heavily used in conventional soybean breeding programs to select desired traits. However, traditional plant breeding is encumbered with low frequencies of spontaneous mutations. In mutation breeding, genetic variations from induced mutations provide abundant sources of alterations in important soybean traits; this facilitated the development of soybean germplasm with modified seed composition traits to meet the different needs of end users. In this study, a total of 2366 'Forrest'-derived M2 families were developed for both forward and reverse genetic studies. A subset of 881 M3 families was forward genetically screened to measure the contents of protein, oil, carbohydrates, and fatty acids. A total of 14 mutants were identified to have stable seed composition phenotypes observed in both M3 and M4 generations. Correlation analyses have been conducted among ten seed composition traits and compared to a collection of 103 soybean germplasms. Mainly, ethyl methanesulfonate (EMS) mutagenesis had a strong impact on the seed-composition correlation that was observed among the 103 soybean germplasms, which offers multiple benefits for the soybean farmers and industry to breed for desired multiple seed phenotypes.

Metabolome-based discrimination of chrysanthemum cultivars for the efficient generation of flower color variations in mutation breeding.

Abstract: The color variations of ornamental flowers are often generated by ion-beam and gamma irradiation mutagenesis. However, mutation rates differ significantly even among cultivars of the same species, resulting in high cost and intensive labor for flower color breeding. We aimed to establish a metabolome-based strategy to identify biomarkers and select promising parental lines with high mutation rates using Chrysanthemum as the case study. The mutation rates associated with flower color were measured in 10 chrysanthemum cultivars with pink, yellow, or white flowers after soft X-ray irradiation at the floret-formation stage. The metabolic profiles of the petals of these cultivars were clarified by widely targeted metabolomics and targeted carotenoid analysis using liquid chromatography-tandem quadrupole mass spectrometry. Metabolome and carotenoid data were subjected to an un-supervised principal component analysis (PCA) and a supervised logistic regression with least absolute shrinkage and selection operator (LASSO). The PCA of the metabolic profile data separated chrysanthemum cultivars according to flower color rather than mutation rates. By contrast, logistic regression with LASSO generated a discrimination model to separate cultivars into two groups with high or low mutation rates, and selected 11 metabolites associated with mutation rates that can be biomarkers candidates for selecting parental lines for mutagenesis. This metabolome-based strategy to identify metabolite markers for mutation rates associated with flower color might be applied to other ornamental flowers to accelerate mutation breeding for generating new cultivars with a wider range of flower colors.

Development and evaluation of diverse promising rapeseed (Brassica napus L.) mutants using physical and chemical mutagens

Abstract: Genetic variability is a prerequisite for any plant breeding program, and mutagenesis is a proven way of creating new variation within a crop germplasm. Novel genetic variability in rapeseed was induced by gamma rays, Ethyl Methane Sulphonate (EMS) and combined mutagen treatment, using various doses and concentrations. The objective was to evaluate and compare the obtained M2 mutants for important quantitative traits in two contrasted environments. Data on phenological, morphological and agronomic parameters were recorded. A large variability was observed and mutagenic treatments had a significant effect on all traits studied. Compared to control plants, mutant genotypes derived from seeds treated with low EMS concentrations during moderate time were earlier and characterized by a higher number of pods per plant. For high concentration of EMS during long time and for combinations of physical and chemical mutagens, a significant decrease in plant height and stature was noticed, as compared to control. Besides, plants derived from gamma rays-treated seeds exhibited the highest 1000-seed weight. The novel induced variability may be integrated in rapeseed breeding program as a new germplasm with improved agronomic traits. Particularly, EMS1-7-stable mutant may be exploited to develop efficiently and quickly a new rapeseed cultivar with some desirable traits. The present study highlights once more the possibility to bring novel genetic diversity for rapeseed desirable traits improvement through mutation breeding.

Mutation Breeding of a N-methyl-N-nitrosourea (MNU)-Induced Rice (Oryza sativa L. ssp. Indica) Population for the Yield Attributing Traits

Abstract: Difficulties in breeding new rice cultivars that have a high yield, are acceptable quality, and are tolerant to environmental stresses have been the major constraint of rice production in many developing countries, as these traits are determined by multiple genes associated with complicated and uncontrollable gene segregations.Furthermore, the gene/QTL (quantitative trait locus) introduced to the cultivar is unstable due to the interaction among the active genes, which determine the phenotypic performance, not yet been well understood or controllable. In this study, the N-methyl-N-nitrosourea (MNU)-induced mutation was applied to the heterozygote of the F1 generation from the cross between TBR1 (female) and KD18 (male parent). The phenotype and genotype of the M2 and M3 generations were evaluated and showed that the mutant population phenotypes, including the plant height, semi-dwarfism, amylose content, protein content, gel consistency, grain yield, and spikelet fertility, varied. Interestingly, no segregation among the genotypes in the M2 and M3 generations was observed, while the genotypes of the control population were either paternally inherited or indeterminable when using 28 polymorphism simple sequence repeat (SSR) markers that were identified on parental lines from 200 markers. The MNU-induced mutation caused maternal inheritance in the segregating populations, as primarily important agronomic traits were maternally succeeded from the female line TBR1. The findings of this study indicated that, through the use of MNU, the breeding of rice cultivars with close genetic backgrounds (similarity coefficient = 0.52) could be shortened by the maternal control of important qualities, such as pest and disease resistance and high yield, thus contributing to sustainable rice production for rice farmers. Further examination of rice cultivars with a greater difference in the genetic background should be subsequently conducted.

Determination of Proper Gamma Radiation Doses in Sunflower Varieties

Abstract: In this study, different gamma radiation doses were applied to two sunflower varieties seeds to determine their effects on some plant characteristics in plants and to determine GR50 doses for effective mutation dose values in mutation breeding studies. The effect of gamma irradiation on the germination percentage and seedling height (cm) of two sunflower varieties were investigated at different doses (0, 50, 100, 150, 200, 250, 300, 400 and 500 Gy). Gamma radiation was applied to seeds from Cesium-137 (137Cs) source. The trial was conducted as a split-plot experimental design in three replications. As a result, germination percentages of sunflower varieties were not affected with increasing radiation doses. But, as parallel to increasing doses applied of gamma radiation dose seedling height (cm) were affected negatively. On the other hand, the doses that decrease growth by 50 percent (GR50) for AS508 and Nantio were found to be 148 Gy and 165 Gy, respectively. Keywords: Helianthus annuus L, GR50 dose, M1 plants. DOI: 10.7176/JSTR/5-9-04

Molecular characterization of Helianthus tuberosus L. treated with ethyl methanesulfonate based on inter-simple sequence repeat markers

Abstract: Mutation breeding is one of the most effective techniques in plant breeding. Mutagens are used to induce variation in plants. Ethyl methanesulfonate is considered the most effective mutagen among chemical mutagens. The doses and treatment durations of the used mutagens become important to create an effective mutation. Four different doses of ethyl methanesulfonate (0.0, 0.2, 0.4 and 0.6%) were used to treat the tuber eyes for two different time periods (3 and 6 h) in the present study. After treatment, molecular characterization was examined in plants developed from ethyl methanesulfonate-treated tuber eyes by inter-simple sequence repeat method in order to determine the genetic differences which ethyl methanesulfonate treatments led to create in plants. The research showed that there was a 7–48% similarity rate of the plants from the eyes treated with ethyl methanesulfonate. The genetic similarity rate was 7% between 0.4% dose of ethyl methanesulfonate for 3 h and its 0.2% dose for 6 h, but it was 82% for the control groups (untreated-ethyl methanesulfonate). The lowest similarity rate (10%) between control groups (untreated-ethyl methanesulfonate) and EMS treatments occurred at 0.4% dose of ethyl methanesulfonate for 3 h.

Mutation Breeding in Barley: Historical Overview.

Abstract: The discovery of radioactivity at the end of the nineteenth century played a key role in a series of historical landmarks that would lead to contemporary mutation breeding in agricultural crops. The aim of the earliest experiments was to test the effects of radiation on living organisms beginning with fruit flies. Exposure of plants to X-rays provided the first incontrovertible proof that phenotypic changes could be induced. Chemicals were a second type of mutagen tested from the 1940s and both forms are used today. This chapter is an overview of some of the historical developments that led to the use of mutagenesis in plants, with a focus on barley, a model species for mutation genetics and breeding as well as a major cereal crop. Perhaps the most well-known examples of mutant barley cultivars are Diamant, Golden Promise, and their hybrids.

Induction of flower-colour mutation by synchrotron-light irradiation in spray chrysanthemum

Abstract: Chrysanthemum is one of the most important ornamental plants. Mutation breeding is an important tool in breeding of chrysanthemum, and many cultivars have been produced through mutation breeding by using radiation such as gamma ray, etc. Although ion-beam irradiation is now widely used as a mutagen in the mutation breeding of plants, synchrotron light, another form of radiation, has not been used as a mutagen. Therefore, this study was conducted to clarify whether synchrotron light can be used as a new mutagen in chrysanthemum breeding. Five cultivars of spray chrysanthemum were subjected to synchrotron-light irradiation. As a result of the irradiation, the survival rate decreased as the absorbed dose increased. Flower-colour mutations were observed in three cultivars. There were varietal differences in survival rates and the frequencies of flower-colour mutation. Flowers of the mutants showed various colour patterns such as a deeper and paler colour than the original flowers. In the mutant of a cultivar with a marginal picotee, the proportions of picotee changed. A moderate absorbed dose of synchrotron-light irradiation for flower-colour mutation was found to be 11 to 23 Gy. These results indicate that synchrotron light can be used as a new mutagen in the mutation breeding of chrysanthemum.

Cashew Nut (Anacardium occidentale L.) Breeding Strategies

Abstract: Cashew nut (Anacardium occidentale L.) is a tropical, cross-pollinating tree native to South America. Vietnam ranks first in global production of cashew nuts with shells. World average productivity stands at 8136 hg/ha, but in most cashew-growing countries production is below the world average. Low yield is because of lack of soil profile correction, irrigation and pest control and prevalence of orchards of trees grown from seed selections and grafted genotypes. The tree bears male (staminate and bisexual), hermaphrodite and pistillate flowers on the same panicle. Only, 4–6% of flowers are pollinated and reach maturity to bear fruit, the rest are shed away at various stages of development. Generally, the gene pool expands through hybridization with different adaptive values, as long as the hybrids are able to produce segregating progeny in subsequent generations. Evidence of hybrid vigor with an increase of up to 153% in nut yield has been noted as compared to plants derived from out-crossed pollination. Uniform planting materials is a very important input for crop productivity. Cashew improvement programs include development of new commercial varieties having dwarf/semi-dwarf canopy, large nut size with higher shelling percentage, higher kernel grade and tolerance to biotic and abiotic stresses. A hybridization method has been standardized for breeding cashew varieties. Technologies like molecular markers, mutation breeding, molecular breeding, in vitro approach and transgenic breeding and other techniques are expediting the process of analyzing and assessing traits. With the advancements in genetics and molecular biology, genetic engineering has become the primary issue in molecular breeding. The present chapter highlights the propagation methods, improvement through conventional breeding, molecular genetic diversity, molecular breeding and conservation strategies.

Mutagenic effects of gamma irradiation on oil palm (Elaeis guineensis Jacq.) seedling germination and growth.

Abstract: Mutation induction has been used to generate genetic variability in most crop plants. This research was conducted to assess genetic variation induced by gamma radiation on the various treatment designated as M1, M2, M2M1 at 10 Gy. A randomised complete block design with four replicates was used for the experiment. Parameters such as percentage germination, root length, leaf area, plant height and stem/trunk circumference were taken from 4to 12-month seedlings after planting. Data was analysed using GenStat (12th edition), which revealed significant differences in germination and growth of these oil palm seedlings. The study shows that percentage germination as well as growth parameters were stimulated in the M1 seedlings but inhibited in the M2 and M2M1 populations.

Variability studies in rice ( Oryza sativa L.) using induced mutation

Abstract: Rice (Oryza sativa L. 2n=24) is the most important cereal crop cultivated widely in many parts of the world. Creation of genetic variability is the basic step in any crop improvement programme. Mutation breeding has been a controversial issue for many years. In recent times, many successful results have been reported and a number of mutants have been released as cultivars. The material consisted of rice variety PY-5 whose M2 generation was studied with four sets of well dried 200 seeds were selected for treating with ethyl methane sulfonate. The concentrations of the mutagens used for four sets were 0.2, 0.4, 0.6 and 0.8 percent. In M2 generation, the bulked seeds of Ml were sown treatment wise along with control (non-treated). In M2 generation, observations we taken for six important yield component characters viz., plant height, number of productive tillers per plant, length of the primary panicle, length of boot leaf, 100 grain weight and grain yield per plant. Statistical parameters like mean, variance, co-efficient of variation(CV), heritability and genetic advance as percent of mean were computed for all traits studied adopting the standard statistical method. In the current investigation, mean for different traits shifted both in the positive and negative directions due to mutagenic treatments. The mean value recorded the positive shift for characters such as length of boot leaf, number of productive tillers per plant, panicle length and grain yield per plant in M2 generation. Both positive and negative shift was found in plant height and 100 grain weight. In the present investigation, significant variation has been observed in the mutant populations for the traits, number of productive tillers per plant, panicle length and grain yield per plant. Mutants having significantly high number of productive tillers, panicle length and grain yield per plant were selected from the plants treated with 0.8 percent.

Mutation breeding in vegetable crops: A review

Abstract: Mutation breeding generally plays a very important role in vegetable crops. Among the different present approaches, mutagenesis and mutation breeding and the isolation of improved or novel phenotypes in conjunction with conventional breeding programmes can result in mutant varieties endowed with new and desirable variation of agrometrical traits. Induced mutations and its related technologies play very well in this ground and this overall strategy helps to trace the crop genetic diversity along with its biodiversity maintenance. Such induced mutagenesis, a crucial step in vegetable crop improvement programme, is now successful in application due to the advancement and incorporation of large-scale selection techniques, micro propagation and other in vitro culture methods, molecular biology tools and techniques in modern crop breeding performance. Molecular mutation breeding will significantly increase both the efficiency and efficacy of mutation techniques in crop breeding. Thus, mutation assisted plant breeding will play a crucial role in the generation of ‘designer crop varieties’. This paper provides a comprehensive overview of the various techniques and workflows available to researchers today in the field of mutation breeding, and how these tools complement the ones already used in traditional breeding.

OPTIMIZATION OF GENETIC VARIABILITY INDUCTION BY BUD IRRADIATION OF THE Fremont MANDARIN

Abstract: Among mutation breeding methods, gamma irradiation has been most widely used to induce mutation in mandarin and develop seedless. The objective of this study was aimed at identification of mutants with elite characters. 95 plants were obtained from irradiation of Fremont mandarin according to two doses 50 Gy to 70 Gy. They were grafted on macrophylla rootstock and planted in the fields of El Menzeh (INRA, Morocco) at 3x5 m² spacing. The physical and chemical quality of the fruit and juice (weight, peel color, juice content, acidity, soluble solids and maturation index) was evaluated. The statistical analysis of all studied characters showed highly significant variations among the mutants from mandarin Fremont buds irradiation. The application of mutation breeding method was aimed at identification of mutants which possess positive agro-morphological and quality characteristics.

Determination of optimal mutagen dosage and its effects on morpho-agronomic traits in putative mutants of ‘amasya’ apple

Abstract: Mutation breeding is one of the efficient ways to create new genotypes. The starting material of this study was the ‘Amasya’, a Turkish apple cultivar. This study aimed to identify optimal mutagen dosage that is the most important prerequisite to create a proper mutant population, and evaluate the genetic variability for morpho-agronomic traits (e.g. tree height and fruit number) in the putative apple mutants of ‘Amasya’ irradiated at the optimal mutagen dosage. In the first year of the study, to determine the optimal mutagen dosage, dormant ‘Amasya’ scion woods were irradiated at 0, 10, 20, 30, 40, 50 and 60 gray dosages using 60Co source. The optimal mutagen dosage was determined as 29.01 gray for ‘Amasya’ concerning the 50% shoot length reduction in comparison to the non-irradiated control plants. In the following year, more or less 2000 dormant ‘Amasya’ scion woods were irradiated at the optimal mutagen dosage to generate a mutant population of ‘Amasya’ apple cultivar. Mutation frequency based on the visual observations of plant abnormalities was observed. Then three years, genetic uniformity was analyzed through the growth of the mutant population, and mutation frequency (%) determined. These results indicated that there was considerable genetic variability in response to irradiation for evaluated traits. Most of the plants in the putative mutant population, nearly 80%, had a significantly shorter tree height and trunk cross-sectional area than standard ‘Amasya’. The mutants/genotypes identified in this study could be used improvement of new promising apple cultivars with good agronomical traits.

Mutation breeding method of high-yield YT-011A bacterial strain and fermentation medium

Abstract: The invention relates to a mutation breeding method of a high-yield YT-011A bacterial strain. The mutation breeding method specifically comprises the steps that atmospheric and room temperature plasma(ARTP)-NT6 compound mutation is adopted to conduct iterative mutation on an original bacterial strain, streptomycin resistance breeding is conducted in an assisted mode, and a high-yield mutant bacterial strain is obtained. In addition, the invention provides an optimized fermentation medium aiming at the high-yield mutant bacterial strain. By adopting the ARTP-nitroso-guanidin (NTG) iterative compound mutation and combining streptomycin resistance screening, the high-yield YT-011A mutant bacterial strain is obtained, the yield increasing rate of the mutant bacterial strain generally reach 50% or above, wherein YT-AN94 mutant bacterial strain can reach 70%, meanwhile, the mutant bacterial strain has good hereditary stability, and thus later scale production is enlarged advantageously; byadjusting nutrient compositions of the fermentation medium, good compound with the mutant bacterial strain is achieved, yield increasing of the mutant bacterial strain YT-011A is further promoted, andthe good applicability is achieved; and especially for the obtained YT-AN94 mutant bacterial strain, the yield increase rate reaches 120% under the optimized fermentation medium, and economic benefits for producing YT-011A through microbial fermentation engineering are significantly improved.

Method for constructing efficient wheat radiation induced mutation breeding system

Abstract: The invention discloses a method for constructing an efficient wheat radiation induced mutation breeding system. By means of the method, dry seeds subjected to irradiation treatment with gamma rays of300Gy60Co serve as parent seeds to be densely sown and sown lately, and flower synchronization is promoted; wheat parent seeds which are not subjected to radiation treatment serve as female parent seeds, parent seeds subjected to radiation treatment serve as male parent seeds, and hybridization is carried out; compared with hybridized F1-generation seeds, low measurement radiation treatment operation is simple; compared with conventional non-radiation hybridization, the possibility of variation is large; compared with variation hybridization that the radiating that the current generation subjected to radiation is adopted as female parents and parents which are not subjected to radiation are adopted as male parents, the variation degree is larger; conventional-density cell planting is adopted by low generations F2 and F3, more variation types can be kept, and meanwhile the method can be used for screening the density tolerance of a material.

Genetic Improvements in Pea (Pisum sativuml.) Through Irradiation by Gama Rays

Abstract: Mutation breeding using radiation has been shown to be an effective and important tool in incorporating specific desirable agronomic values characteristics in vegetable crops including pea (Pisum sativum L.). In the present study, dry seeds of ‟Master - B” Pea cultivar were exposed to 0, 10, 20 and 30 Krad doses of gamma rays, and variability in growth characteristics, earliness, and seed yield were investigated in M1, M2 and M3 generations. Analysis of variance showed significant difference among M1-plants as well as M2 and M3-families for the studied traits with higher variability in high doses of gamma ray treatments. In M3–generation, lines with significant increases in yield parameters such as number of pods per plant and number of seeds per plant were obtained. Mutant line number 8 was out yielded in terms of number of pods and seeds per plant. These results indicate that induced mutation breeding by gamma ray is a valid and effective crop breeding method in pea.

Corn breeding method

Abstract: The invention discloses a corn breeding method. The corn breeding method comprises the following steps of S1, selecting high-quality parent plants to form a parent group, performing directed group hybridization and free pollination to obtain F1 hybridized combination seeds; S2, performing F1 morphology, fertility and disease resistance selection, selecting plants containing target chromosomes by combining with cytological identification for continuous selfing for 3 years, and in the third year, during selected selfing, performing mutation breeding with 0.05% EMS (ethyl methane sulfonate) through the pollen tube pathway technique to obtain mutant plants; S3, selecting dwarfed mutant plants containing target chromosomes by combining with cytological identification for continuous selfing for2 years, and in the second year, and during continuous selfing, performing test crossing to obtain target seeds in the following year. The corn breeding method achieves recombination of favorable genes through breeding means to culture selfing lines high in combining ability and disease resistance and good in comprehensive performance.

High-efficiency mutation breeding method of red beech leaf color mutant

Abstract: The invention relates to a mutation breeding method of a forest tree leaf color mutant, and discloses a high-efficiency mutation breeding method of a red beech leaf color mutant. The high-efficiency mutation breeding method mainly comprises the following steps that (1) full seeds of red beech after air separation are stored and germinated in wet sand at 2-6 DEG C; (2) when 15-30% of the seeds arerevealed, a mixed solution of 0.5mol/L calcium chloride and 0.02mol/L ethylmethane sulfonate is used for soaking the seeds for 60-80 min; (3) the seeds are rinsed with water for 3-5 times and then sown, management is performed according to a conventional method, after one month, branches with leaf color mutation gradually appear, mutant strains can reach about 0.28%, and the leaf color mutant strains are marked; (4) at the beginning of March of a following year, the branches with stable leaf color mutation are selected and grafted on red beech rootstocks which are 1-2 years old and 0.8-1.3cm in ground diameter, and routine management is performed after grafting; and (5) buds on the leaf color mutation branches are taken for further grafting and expanding propagation, and new red beech leafcolor seedlings are cultivated.

Molecular profiling of chickpea mutants isolated from EMS and gamma rays treatments.

Abstract: Conventional mutation breeding techniques have often been used to improve yield, disease and pest resistance in crop plants. In the present attempt, two well-known mutagenic agents ethyl methane sulphonate and EMS were employed in order to induce genetic variability variety of chick pea Co -4 obtained from Tamil Nadu Agricultural University. The seeds were treated with different concentrations of EMS (10-50 mM) and Gamma rays (20-60 kR). A total of 369 mutants which alter the height, leaf structure, colour of flower, seed, size of pod, duration of the plant were isolated and characterized. Among them, five true breeding mutants namely Early flowering mutant (EFM), Bold pod mutant (BPM), Bold seed mutant BSM), High yielding mutant (HYM) and High protein content mutant (HPC), which directly influenced the economic value of the crop were selected for further study. The results revealed a significant positive increase in the qualitative traits among the mutant lines. The RAPD profiling of isolated mutants revealed a total of 129 bands, among them 92 were polymorphic with an average of 70.99 percentage of polymorphism. Apart from 28 bands, all the bands seemed to be mutation. The presence of new bands and absence of existing bands might be the reason for quality improvement of chickpea. The RAPD is considered as an excellent marker to differentiate mutants from their parents, to assess genetic variation and phylogenetic relationship.