Mutation breeding

About: Mutation breeding is a research topic. Over the lifetime, 531 publications have been published within this topic receiving 6730 citations. The topic is also known as: variation breeding.

The Use of Gamma Irradiation in Plant Mutation Breeding

Abstract: In plant breeding programs, one of the oldest methods is mutation breeding. Currently, mutation breeding has became popular among the breeders and scientists again with its use in plant biotechnology and due to some restrictions on the other techniques such as hybridization, cross breeding, and transgenic plants. Physical mutagens (X-rays, UV light, neutrons-alpha-beta particles, fast and thermal neutrons, especially gamma rays) are used more widely than chemical (ethyl methanesulfonate [EMS]) ones to artificially induce mutations (mutagenesis). However, among the physical mutagens, gamma-rays are widely used. During the irradiation of the seeds with ionizing radiation to generate mutants with desirable traits, reactive oxygen species (ROS) or free radicals can generate in cells. Although, these radicals/species generally can be very dangerous for the cell compartments, they can take an important role as a signal molecule activation of genes of antioxidant enzymes and proline, which are defense systems against these radicals in plant cells. In this chapter, usability of gamma-irradiation to provide the permanent gene expression of antioxidant enzymes and proline through the production of reactive oxygen species (ROS) is discussed.

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

Haploid and Doubled Haploid Technology

Abstract: The microspore culture technique has its wide applications in plant genetic research and breeding programmes in oilseed Brassicas due to its relative simplicity, efficiency in haploid and doubled haploid production, mutation and germplasm generation, and gene transformation. Various factors could influence microspore embryogenesis and haploid production including donor plant genotype, donor plant physiology, microspore developmental stage, culture conditions, culture environment and pretreatments. Stress is also an essential component during embryogenesis induction in microspore culture. Efficient plant regeneration from microspores mostly occurs through direct embryogenesis ensuring minimal occurrence of cytogenetic abnormalities. Appropriate stress conditions such as chilling, partial desiccation, cotyledon excision, and successive subculture of microspore-derived embryos could promote plant development in oilseed rape. Medium renovation, phytohormones and plant growth regulators, and chromosome doubling agents such as colchicine treatment also affect plant regeneration in Brassica species. Compared to colchicine treatments of microspore-derived embryos and plants, immediate colchicine treatment of isolated microspores results in high embryogenesis and diploidisation and low chimeric percentages. The ploidy level of microspore-derived plants of Brassica species could be estimated by different methods at various stages. Mutation breeding techniques are widely used in plant breeding for producing useful mutants and variants. Microspore culture also provides an ideal method for mutation because the mutated traits can be fixed in homozygous condition by chromosome doubling, which can enforce to obtain target mutation traits efficiently. Ultraviolet irradiation, mutagenic agents ethyl methane sulphonate and sodium azide could be applied to isolated microspores and the derived embryos of rapeseed. Utilization of microspore-derived embryos for production of desired traits such as the altered fatty acids, disease resistance and glucosinolate compositions through mutagenesis and selection is advancing and also discussed.

Importance of genetic transformation in ornamental plant breeding

Abstract: Most of the economically important ornamental plants are cut flowers, which are produced by vegetative propagation. For many years, new varieties of ornamental plants have been produced by cross-hybridization and mutation breeding techniques, separately or in combination. Similar to mutation breeding, genetic transformation would also be a useful way of making a one-point improvement of a trait in original cultivars bred by cross-hybridization. Mutation breeding can change a dominant trait to a recessive one mostly. In other words, genetic transformation produces an "additive" one- point improvement, whereas mutation breeding produces a "subtractive" one-point improvement. Furthermore, genetic transformation can modify target traits by direct incorporation of related genes. Genetic transformation methods will be used in the near future as standard breeding tools in combination with traditional breeding methods.

Selection of Novel Cowpea Genotypes Derived through Gamma Irradiation.

Abstract: Cowpea (Vigna unguiculata [L.] Walp.) yields are considerably low in Namibia due to lack of improved varieties and biotic and abiotic stresses, notably, recurrent drought. Thus, genetic improvement in cowpea aims to develop cultivars with improved grain yield and tolerance to abiotic and biotic stress factors. The objective of this study was to identify agronomically desirable cowpea genotypes after mutagenesis using gamma irradiation. Seeds of three traditional cowpea varieties widely grown in Namibia including Nakare (IT81D-985), Shindimba (IT89KD-245-1) and Bira (IT87D-453-2) were gamma irradiated with varied doses and desirable mutants were selected from M2 through M6 generations. Substantial genetic variability was detected among cowpea genotypes after mutagenesis across generations including in flowering ability, maturity, flower and seed colours and grain yields. Ten phenotypically and agronomically stable novel mutants were isolated at the M6 each from the genetic background of the above three varieties. The selected promising mutants’ lines are recommended for adaptability and stability tests across representative agro-ecologies for large-scale production or breeding in Namibia or similar environments. The novel cowpea genotypes selected through the study are valuable genetic resources for genetic enhancement and breeding.