Showing papers on "Mutation breeding published in 2004"

Mutation Breeding for Crop Improvement

Abstract: Crop improvement programmes through induced mutations were initiated about seven decades ago, immediately after the discovery of mutagenic effects of X-rays on Drosophila by Muller in 1927, and barley and maize by Stadler in 1928. During 1950–60, several countries including China, India, the Netherlands, USA and Japan took up the task of crop improvement through mutation breeding approaches. A coordinated programme on mutation breeding was also initiated in rice in south east Asia in 1964 by IAEA. Over 2252 mutant varieties of crop plants including cereals, oilseeds, pulses, vegetables, fruits, fibres and ornamentals have been developed by the end of the 20th century. More than 60% of these mutant varieties were developed and released after 1985. While 1585 varieties were released as direct mutants, the rest were released through cross breeding with mutants. Most of the mutant varieties (around 89 %) have been developed using physical mutagens (X-rays, gamma rays, thermal and fast neutrons), with gamma rays alone accounting for the development of 60 % of the mutant varieties. A wide range of characters which have been improved through mutation breeding include plant architecture, yield, flowering and maturity duration, quality and tolerance to biotic and abiotic stresses. Mutation breeding has made a significant contribution to the national economy of the countries like China, India, Japan, Pakistan and USA. With the release of more than 305 mutant cultivars belonging to 56 plant species, India has also become a major recognised centre for work on induced mutations and the second largest contributor of the mutant varieties in the world. In recent years interest has rekindled in mutation research, since induced mutagenesis is gaining importance in plant molecular biology as a tool to identify and isolate genes and to study their structure and function. These studies will definitely have a major impact on the future crop improvement programmes.

Induced of plastid mutations in soybean plant (Glycine max L. Merrill) with gamma radiation and determination with RAPD.

Abstract: The aim of our study was to induce with radiation of atrazine resistant and tolerated mutants in Coles, Amsoy-71 and 1937 soybean varieties. Atrazine that is photosynthetic inhibitor is the most important herbicide of S-triazin group, and shows toxic effect on soybean plant. For the improvement of the atrazine resistant plants with mutation breeding, the seeds belonging to the three varieties were irradiated with 200 Gy of gamma radiation dose. The irradiated seeds were sown in the field and at the end of harvesting season, every pod at node situated on the main stem was picked up separately and M 2 generations were obtained. At the plants, which were obtained from M 2 generation, chlorophyll mutants were determined and atrazine selection was made. The percentage of chlorophyll mutants for Amsoy-71, Coles and 1937 soybean varieties were found as 1.07, 1.48 and 1.32, respectively. At the end of atrazine selection, the percentages of atrazine resistant plants for Amsoy-71, Coles and 1937 soybean varieties were 0.80, 0.60 and 0.53, respectively. The percentages of atrazine tolerated plants were 1.07, 1.18 and 1.05, respectively as well. In our research; the differences among the mutants replying to atrazine in various concentrations were examined by using RAPD procedure as the molecular marker techniques in comparison with polymorphism. In the study done by using 14 primers; according to the amplification results, the differences between atrazine resistant plants were shown.

Mutation breeding in sunflower for resistance to alternaria leaf spot

Abstract: SUMMARY Genetic variability for resistance to Alternaria leaf spot disease (Alternaria helianthi) can be induced by radiation or chemical mutagens. The objectives of this study were to create genetic variability in cultivated sunflower and to select lines resistant to Alternaria leaf spot. In the first experiment, sunflower seeds of the genotype HA BR 104 were irradiated with 150 and 165 Gy of gamma rays. Seeds were sown in the field at the Embrapa Soybean experimental station, in Londrina, PR, Brazil and M1 plants were harvested in bulk. M2 ,M3 and M4 plants were screened for disease resistance under natural infection in the field. Plants were evaluated for Alternaria leaf spot symptoms, using a diagrammatic scale from 0 (no symptoms) to 5 (maximum infection). Before flowering, plants showing no symptoms of Alternaria leaf spot (grade 0) or less than 5% diseased leaf area (grade 1) were bagged for self-pollination. Self-pollinated plants and open-pollinated plants from 150 Gy and 165 Gy populations with no or mild disease symptoms were selected. In the second experiment, sunflower seeds of the genotypes HA 300 and HA BR 104 were treated with ethyl methanesulfonate (EMS) at 0.015 mol dm -3 . Selected M2 and M3 were screened for disease resistance in the field. From the EMS treatment, 300 M3 plants with no disease were recovered. All these lines will be tested for combining ability. The best lines will be used for hybrid production.

Root hair mutants of barley

Abstract: Almost sixty mutants with shortened or reduced root hairs or without root hairs at all have been isolated among 2000 M1 plant progenies (20000 M2 seeds) of the spring barley cultivar “Lux” after sodium azide mutagenesis One group of 25 mutants show fairly stable phenotype while 33 lines have unstable, indistinct or segregating phenotypes The mutants were selected after 3 to 4 days growth in tap water on black filter paper Root hair mutants were quite common, although not as common as chlorophyll mutants Some of the unstable phenotypes may reflect responses to gases like ethylene or CO2 Shortened root hairs were sometimes a pleiotropic effect of other mutations, such as dwarf or chlorophyll mutants Introduction Root hairs are small, tubular, 1-2 mm long extensions of single epidermal cells of the root surface Their primary function seems to be to extend the surface of the root, thereby improving access to strongly bound nutrients like phosphorus, iron, zink, silicon and other micronutrients (Peterson and Farquhar 1996, Bibikova and Gilroy 2003) Root hair variation was first investigated in clover by Caradus (1979) There is one tomato mutant “cottony root” with longer root hairs than normal (Hochmuth et al 1985) Root hair mutants have been investigated extensively in Arabidopsis, where a large collection of mutants is available (Grierson et al 2001, Schiefelbein and Somerville 1990, Schiefelbein 2000) Root hair mutants have been studied in barley by Gahoonia et al (2001) and by Szarejko et al (2003) Root hairs are not absolutely necessary for plant growth, because root hairless mutants of barley, rice and maize grow quite well, if nutrients are readily available (Wen and Schnable 1996, Ma et al 2001, Gahoonia et al 2001)At present about 40 genes are known to be involved in Arabidopsis root hair formation (Grierson et al 2001, Parker et al 2001) Methods Seed of “Lux” barley (Sejet Plant Breeding, Denmark) were soaked overnight in tap water, then treated with 15 millimolar sodium azide in 01 molar sodium phosphate buffer, pH 3, for 25 hours according to the IAEA manual on mutation breeding (2 Ed) After rinsing in tap water and air drying, the M1 seeds were sown in the field the same day Spikes, 4-6 per M1 plant, were harvested 9 or 16 seeds were germinated on 7 × 11 cm black filter paper in transparent polystyrene boxes 8 × 12 × 3 cm with almost tight-fitting lids The germination took place in 5 ml of tap water at room temperature for 3 or 4 days 05 mg Thiram decreased but did not eliminate fungal contamination Scoring for root hair mutants was done directly through the transparent lid under a stereo microscope Results and discussion The agar growth technique of isolating Arabidopsis root hair mutants did not work well for barley in our hands as there were many problems with infection The chlorophyll mutation frequency of the mutagenized “Lux” material was 7 % of the M1 progeny and 09 % of the M2 seedlings, comparable to that obtained with other barley cultivars from which low-phytate mutants were isolated (Rasmussen and Hatzack 1998) The results show that root hair mutants can also be easily isolated in other plants than Arabidopsis Most of the mutants are viable and some of them can undoubtedly be used as genetic markers, or in investigations of root hair physiology, root architecture, nutrient uptake, and the function and importance of mycorrhiza Some of the mutants show unstable, variable or indistinct phenotypes Some of these instabilities may be caused by lack of control of gases such as ethylene or CO2 which influence root hair formation (Pitts et al 1998, Ohashi et al 2003, Muller and Schmidt 2004) The large majority of mutants are recessive, judged by the segregation ratios of mutant/wild type among the M2 seeds No crossing experiments have been done Due to other commitments the work on the root hair mutants has been discontinued at an early stage Therefore the mutants have not been grown further than to M3 (M4 seeds) They need further purification of other unwanted mutations and more examination of phenotype stability An important group of mutants without characterisation are the completely sterile root hair less which could presumably have defects in the tip growth mechanism common to pollen tube and root hair

Molecular characterization of chemical mutagenesis induced diversity in elite maize germplasm

Abstract: Three classical breeding Iowa Super Stiff Stalk (SSS) inbred lines B37, B73 and B84, one Lancaster inbred Oh43 and mutant lines obtained by chemical mutagenesis followed by mutation breeding as follows: two of B37 and four of Oh43 were selected for molecular characterization. The mutant inbred lines were chosen because in addition to the improved GCA and SCA for grain yield, proven by their predominance in the Bulgarian breeding programs, they showed shifts in the flowering time as compared to the initial inbreds. Molecular markers (micro satellites and other PCR-based DNA markers) were used for characterization of maize genotypes and determination of the induced by chemical mutagenesis genetic variability in maize germplasm. The tested nine SSR markers (umc 1001, umclO14, umcl057, umcll81, umcl0lS, umc 1029. umcl003, umc 1033 and umcl035) can discriminate between the initial classical breeding inbred lines and the originating mutant inbreds. Allelic diversity was also studied by PCR amplification with specifically de-signed primers in the coding regions and flanking sequence of two genes: dwarf8 (d&: chromosome 1, 198.5 cM), and indeterminate l (id1; chromosome 1. 175.0 cM). These are considered candidate genes for variation in plant height and/or flowering time, based on mutant phenotypes and chromosomal locations near major QTLs. Single nucleotide polymorphisms and indels were detected in the region flanking the SH2 domain of dwarf8 gene in some of the mutant inbreds as a result of SSCP and sequencing analyses. However, these polymorphisms could not be associated with the observed variations in flowering time. PCR analysis of the promoter region dwarf8 showed a variant fragment of about 1 kb in the inbred line Oh43 that was not present in any other initial and mutant in-bred lines included in the study. PCR amplification of the 5' end of the Id1 coding sequence revealed polymorphic bands in the mutant lines XM535, XM521, XM250-l, XM98-8 and XM85-105, as well as in the classical breeding line B73. The data, presented here demonstrate the usefulness of chemical mutagenesis for generation of genetic diversity within the elite maize germplasm. Some of this variation may affect the major genes in the QTLs. Our initial data revealed mutagenesis induced polymorphisms in the coding sequences of two important for the determination of flowering time transcription factors. Further molecular analyses of the proposed model systems may complement the trait association efforts and will help to directly identify the major genes in the QTLs.

Breeding of a New Indica Rice Mutant Line “Zhe 101” for Resistance to Blast and Bacterial Leaf Blight by Space Mutation

Abstract: Air-dried seeds of indica rice variety Zhe 9248 were carried by recoverable satellite (RS) for space mutation. Mutagenic effects of outer space environment (OSE) of 175-354 km above sea level on rice plant were studied. Results showed that the germination percentage of the seeds and characters of SP 1 generation had no evident change. Segregation of major characters such as plant height,growth period duration(GPD),length of panicle,1000-grain weight and so on,appeared in the SP 2 generation resulting from RS. Mutant line Zhe 101 selected from the mutant progenies showed significant improvement in GPD,disease resistance and yield. Resistance to the blast and bacterial leaf blight disease was tested by inoculating the mutant with 20 strains of Magnaporthe grisea artificially from six blast regions, and dominant pathotype Ⅳ of Xanthomonas campestris pv. oryzae in Zhejiang Province. The average resistance scales were only 1.4 and 1.7 for leaf blast,and 1.6 and 1 3 for neck node blast, in 2001 and 2002 respectively. The average scale of bacterial leaf blight disease resistance was 1.4 in 2002. The mutant line Zhe 101 was resistant to 14 blast fungus strains. The rate of blast resistance for Zhe 101 was higher than that of its parent and CK. The mutant is likely to be used in breeding for variety improvement.

Study on application of aerospace techniques in rice mutation breeding

Abstract: Dry seeds of rice varieties were carried by high altitute balloon, recoverable satellite and space craft for space mutation and its biological effects were analyzed compared with 60 Co γ\|radiation. The new varieties Hangyu No.1, R2036 and Hangxiang No.10 were developed. Some mutants including large grain and tiller dwarf were identified and bred. Space mutation has its characteristics with small radiation damage and normal seed setting rate and relative higher mutation frequency for some traits compared with 60 Co γ\|radiation. Mutation frequency of space mutation greatly varies according to different genotypes and traits. Radiation sensitivity of space environment has no significant correlation with that of 60 Co γ-radiation.