Showing papers on "Mutation breeding published in 2005"

In vitro mutagenesis - : a quick method for establishment of solid mutant in chrysanthemum

Abstract: Ray florets of Chrysanthemum morifol ium Ramat. cvs. Flirt, Puja, Maghi and Sunil were treated with 500 and 1000 rad gamma rays and cultured on MS medium supplemented with different concentrations and combinations of growth regulators. The frequency of d irect shoot regeneration decreased in gamma-ray-treated florets. Radiation effect was found on plant -regeneration from gamma-ray-treated floret explants and also on plant height, size of leaf and flower. Five solid flower colour/floret shape mutants with slight changes in ray floret morphology have been detected and established. In vitro mutagenesis through direct regeneration helpe d in the development of solid mutants without di plontic selection in a relatively short period of time. IN the floriculture industry there is always demand for new and novel varieties. Mutation breeding is an established method for crop improvement and has played a major role in the development of many new flower colour/shape mutants in ornamentals 1–3 . Conventionally, in vegetatively propagated ornamentals, rooted cuttings are treated with gamma rays before planting. In these treated plants mutation appears as chimeras, which remains the main bottleneck in mutation breeding. In chimeric tissue, mutated cells are present along with the normal cells. During subsequent cell division, the mutated cells compete with the surrounding normal cells for survival (called diplontic selection). If these mutated cells survive in diplotic selection, they are expressed in plants. In our laboratory, a technique has been standardized for the management of such chimeric tissues through direct shoot regeneration from flower petals 4–6

Determining Some Yield and Quality Characteristics of Mutants Induced from a Durum wheat (Triticum durum Desf.) Cultivar

Abstract: Mutation breeding is one of the breeding methods used successfully in durum wheat for selecting lines with increased agronomic values. The aim of this study was to select mutant lines having a better agronomic potential than the mother variety Gediz-75 in the M6 and M7 generations. The mutants were derived from the variety Gediz-75 of durum wheat (Triticum durum Desf.). The seeds were either irradiated with gamma rays at Cobalt 60 ( 60 Co) or treated with ethyl-methane-sulfonate (EMS). Eighteen selected mutants and the mother variety Gediz-75 were examined in the M6 and M7 generations for yield and quality characteristics. The experiments were organized in a randomized complete block design with 3 replications. Gdem-2 and Gdem-12 showed yield stability across different environments, but the increases were not significant compared with Gediz-75. Therefore, more information on the new years and locations would greatly facilitate the evaluation of these lines. Gdem-4 had percentages of yellowberry kernels close to those of Gediz-75 in M7. This high quality line is a promising parent candidate for quality breeding. The utilization of the high spike length of Gdem-2-1 by crossing to the mother variety or other varieties could give rise to new lines whose agronomic features could be superior to those of both parents.

Mutation breeding, evolution, and the law of recurrent variation.

Abstract: In the present paper the history of the rise and fall of mutation breeding as an autonomous branch of breeding research is documented as well as its positive side effects for plant breeding and biology in general. Perhaps the most important generalization on the basis of the total outcome of mutation breeding will be termed “the law of recurrent variation”. It states that “treating homozygous lines with mutagenic agents generates large, but clearly finite, spectra of mutants. This consistently occurs when the experiments are carried out on a scale adequate to isolate the potential of alleles causing phenotypic and functional Correspondence/Reprint request: Dr. Wolf-Ekkehard Lönnig, Max-Planck-Institut for Plant Breeding Research Carl-von-Linné-weg 10, 50829 Cologne, Federal Republic of Germany. E-mail: loennig@mpiz-koeln.mpg.de deviations (saturation mutagenesis).However, due to almost Wolf-Ekkehard Lönnig 46 invisible residual effects of changes in redundant sequences and/or of further chromosome rearrangements, the corresponding saturation curve is asymptotically approaching its limit for the micro-quantitative part of variation.” Also, reasons are given why the law is relevant for heterozygotes and allogamous species as well, and the genetical basis of the law is briefly defined. In addition, arguments are presented why the overoptimism and euphoria at the beginnings of the period of mutation breeding are to be evaluated in connection with the basic assumptions of the synthetic theory of evolution − i.e. the assurance that mutations and selection constitute the entirely sufficient explanation of the origin of all species and higher systematic categories of the plant and animal kingdoms alike. This point established, the question is discussed whether the finite nature of the mutant spectra found in plant breeding research might also have repercussions on the present theory of the origin of species. Providing an affirmative answer of the applicability of the law of recurrent variation not only to cultivated plant and animal lines but also to species in the wild, the statements and assertions of the synthetic theory as quoted below will have to be revised.

Non-GMO approach for the improvement of heavy metal accumulation and extraction of high yielding crop species for efficient phytoextraction of contaminated soil

Abstract: Some plants able to take up heavy metals from contaminated soils offer a possibility to clean up sites contaminated with heavy metals. Plants thus act as a solar driven pump, which can extract and concentrate heavy metals from the environment. Since most of the metal hyperaccumulating wild plants only produce very low biomass and most of plants producing high biomass accumulate only moderate amounts of metals, the current research is mainly focused on the overcoming of this deficiency to optimise metal phytoextraction. The main goal of this EC financed study was aimed at improvement of phytoextraction through improved metal extraction of high yielding oil crops, such as Helianthus annuus L. and Brassica juncea L. producing a high biomass. The use of their oil and biomass for technical purpose (lubricants, biogas and energy) allows to produce an additional value from this in situ decontamination technique and to improve the economical balance of phytoextraction. The enhancement of metal accumulation properties of sunflower and Indian mustard by non-GMO approach and of stimulated metal bioavailability in the soil were the main milestones of the present study. Classical fertilisers were used to lower soil pH, increasing metal availability from the soil and conventional biotechnological approaches were used as an alternative to genetic engineering to enhance both metal accumulation and extraction efficiency of oil crops. The first field experimentation (2002) was mainly focused on the screening of 15 commercial sunflower cultivars growing on a contaminated field in Rafz (Switzerland) to select the cultivar with the naturally highest potential to accumulate and extract metals from contaminated soil, and to assess the effect of classical fertilisers on metal accumulation/extraction of the sunflower cultivars. Highly significant differences of heavy metal accumulation and extraction were found between cultivars. Cadmium extraction varied by a factor of 4, Zn extraction by factor of 3 and Pb extraction by a factor of 14 between the cultivars with the highest and lowest metal extraction treated with the same fertiliser. Sulphate fertilisation significantly enhanced Zn and Pb extraction, whereas ammonium nitrate enhanced Cd extraction by most of the sunflower cultivars. Cultivar Salut showed the highest Cd, Zn and Pb extraction and was chosen for the next mutation breeding. Classical mutation breeding techniques were assumed to be efficient to improve the efficiency of metal accumulation of high yielding crops. Therefore, in vitro breeding was used to improve metal uptake of Indian mustard and chemical mutagenesis using ethyl methanesulphonate (EMS) was additionally applied for sunflowers, hybrid cultivar Salut and genetically homogenous inbred lines. Somaclonal variation of tissue culture was used as a source of genetic variability to increase the potential of metal accumulation in Indian mustard. After the selection of B. juncea callus cultures on a medium spiked with 10-200 μM of Cd or Pb, new somaclonal variants were regenerated from metal tolerant callus cells. A subsequent screening of 30 new B. juncea regenerants growing on a hydroponic medium spiked with toxic metals showed that 7 new somaclones (23 %) possessed a significantly higher shoot metal extraction than the control plants. The best regenerant showed a 6 times higher Cd, a 3 times higher Zn and a 4 times higher Pb extraction in the shoots than the control. Prior to the mutation breeding of sunflower, the effects of toxic metals on the growth, metal accumulation in shoot and root, metal translocation of control sunflower cultivars were investigated on a hydroponic medium spiked with toxic metal. Based on phytotoxic effects of roots and shoots the assessed sunflowers showed the following tolerance towards toxic metals: Pb >> Zn > Cd. The effect of the chemical mutagenesis on the efficiency of metal accumulation and extraction was first assessed on a hydroponic system, spiked with Cd, Zn and Pb. The results show that the EMS mutagenesis affected metal uptake, root and shoot metal accumulation and root to shoot metal translocation in mutant variants. We obtained M1 sunflower mutants with an enhanced metal accumulation, mutants with a lower metal accumulation and mutants without changed metal accumulation characteristics compared to the control plants. The next two field experiments in 2003 and 2004 were focused on the screening of 500 sunflower mutants of M1 generation and 300 sunflower mutants of M2 generation on the metal contaminated Rafz site to assess the effect of mutagenesis on yield, metal accumulation and extraction. The M1 sunflower mutants showed a 2-3 times higher Cd, Zn and Pb concentration in shoots, but a considerably reduced growth, as compared to control cultivars due to the phytotoxic effect of the mutagen. The sunflower mutants of M2 generation also showed a 2-3 times higher metal shoot accumulation than the control plants, and even more the metal extraction of the best M2 sunflower mutants "Giant Mutant 14/190/04" was increased 7.5 times for Cd, 8.2 times for Zn and 9.2 times for Pb extraction compared to the control plants. Theoretical calculations of phytoextraction potential of sunflower point out that the best sunflower mutant can produce up to 26 t dry matter yield per ha and remove 13.3 kg Zn per ha and year at the metal contaminated site in Rafz (Switzerland), that is a gain of factor 9 compared to Zn removal of control sunflowers. From a practical point of view this improvement looks very promising for boosting future phytoextraction research.

Microwave mutation breeding new technology for crops

Abstract: The invention is a new technique for mutagenically breeding crops, adopting 2400-2500 MHz microwave with central wavelength 120 mm to radiate wet seeds, budding seeds, buds and growing points for a certain time, where the microwave can make mutagenesis on some specific DNA fragments of the crop cells to cause genetic variation of the crops, and especially, the 2450 MHz microwave has the best effect. By multi-generation oriented selection of single variational plant, it breeds a new stable variety of crop that has object character. As compared with laser mutagenesis, Co60 and space mutagenesis, it has good mutagenesis orientating property, low cost, simple and safe operation and high breeding efficiency.