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Inter-group Relations and Migrant Integration in European Cities: Inter-group Relations and Migrant Integration in European Cities

Parte de: IMISCOE Research Series

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No disponible.

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Migration; Urban Geography / Urbanism (inc. megacities, cities, towns); Political Science

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Tipo de recurso:

libros

ISBN impreso

978-3-319-45019-3

ISBN electrónico

978-3-319-45021-6

Editor responsable

Springer Nature

País de edición

Reino Unido

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Tabla de contenidos

Mutagenesis for Crop Breeding and Functional Genomics

Joanna Jankowicz-Cieslak; Chikelu Mba; Bradley J. Till

Genetic variation is a source of phenotypic diversity and is a major driver of evolutionary diversification. Heritable variation was observed and used thousands of years ago in the domestication of plants and animals. The mechanisms that govern the inheritance of traits were later described by Mendel. In the early decades of the twentieth century, scientists showed that the relatively slow rate of natural mutation could be increased by several orders of magnitude by treating and cereals with X-rays. What is striking about these achievements is that they came in advance of experimental evidence that DNA is the heritable material. This highlights one major advantage of induced mutations for crop breeding: prior knowledge of genes or gene function is not required to successfully create plants with improved traits and to release new varieties. Indeed, mutation induction has been an important tool for crop breeding since the release of the first mutant variety of tobacco in the 1930s. In addition to plant mutation breeding, induced mutations have been used extensively for functional genomics in model organisms and crops. Novel reverse-genetic strategies, such as Targeting Induced Local Lesions IN Genomes (TILLING), are being used for the production of stable genetic stocks of mutant plant populations such as , barley, soybean, tomato and wheat. These can be kept for many years and screened repeatedly for different traits. Robust and efficient methods are required for the seamless integration of induced mutations in breeding and functional genomics studies. This chapter provides an overview of the principles and methodologies that underpin the set of protocols and guidelines for the use of induced mutations to improve crops.

Part I - Introduction | Pp. 3-18

Chemical and Physical Mutagenesis in

Fatemeh Maghuly; Souleymane Bado; Joanna Jankowicz-Cieslak; Margit Laimer

Mutagenized populations are important resources to generate and identify desirable genetic variation of useful traits for crop improvement. When the lack of genetic variability hampers the breeding progress, mutagenesis can introduce genetic variation, reveal gene function, and aid in the characterization of candidate genes involved in biological functions. Mutagenized populations are useful for screening for altered phenotypes and physiological responses, and as a genomics tool. is a semi-wild, economically important shrub useful as a source of biofuel or in soil reclamation, but it requires genetic improvement in order to select the best genotypes for these purposes. Therefore, this chapter describes the general methods for mutation induction (chemical and physical mutagenesis) using ethyl methanesulfonate (EMS) treatment, gamma irradiation, X-rays, and the procedures that can be used to generate large numbers of induced mutants in different tissues of . under in vitro and in vivo conditions.

Part II - Mutation Induction and Chimera Dissociation | Pp. 21-38

Chemical Mutagenesis and Chimera Dissolution in Vegetatively Propagated Banana

Joanna Jankowicz-Cieslak; Bradley J. Till

Random mutagenesis has been widely used for forward-genetics and crop breeding since the application of ionising radiation on cereals described in the late 1920s. The development of high-throughput and accurate mutation discovery technologies has enabled reverse-genetic screening of mutant populations in the twenty-first century. The majority of mutation-based approaches in crops have involved seed-propagated species. Large bodies of data are available on the spectrum and density of induced mutations for some mutagens. It is well established that genetic chimerism caused by random accumulation of different mutations in different cells is resolved by sexual propagation and that by the second-generation post-mutagenesis (termed the M), plants are no longer genetically mosaic. Vegetatively propagated species, however, are quite different as they primarily undergo mitotic propagation. In the absence of meiosis, procedures must be implemented to remove mosaicism and generate plant material that is genotypically homogeneous and suitable for forward- and reverse-genetic screening and breeding. We have previously developed a Targeting Induced Local Lesions IN Genomes (TILLING) platform for the vegetatively propagated triploid banana to investigate the density and spectrum of induced mutations and mechanisms by which tissue culture materials become genotypically homogeneous. Here we provide a detailed protocol for meristematic isolation, mutation induction and dissolution of chimeric sectors focusing on the use of chemical mutagen ethyl methanesulfonate (EMS).

Part II - Mutation Induction and Chimera Dissociation | Pp. 39-54

Mutation Induction Using Gamma Irradiation and Embryogenic Cell Suspensions in Plantain ( spp.)

Jorge López; Aymé Rayas; Arletys Santos; Víctor Medero; Yoel Beovides; Milagros Basail

Bananas and plantains ( spp.) are among the world’s most important crops and are considered as a poor man’s crop in tropical and subtropical countries. For this reason, they play a very important role in tropical regions’ food security. Several pathogens throughout the tropical areas of the world have become a threat for production, including “black sigatoka” ( Morelet) which is the most damaging disease for plantations in Cuba. It is present in all areas of the country, and it replaced “sigatoka disease” () as the main threat. Chemical control and cultural practices reduce damages, but they are not solving the problem. Genetic variations are the basic tools to develop new cultivars with better traits, such as tolerance against various environmental stresses, resistance against pests and diseases, and improved yield and quality. Tissue culture techniques offer the opportunity for variation induction, handling of large plant populations using established selection methods, and rapidly cloning selected variants. All these strategies can increase the efficiency of mutagenic treatments and subsequent screening of mutant materials. Somatic embryogenesis (SE) is also an excellent system for clonal propagation and mutation induction. The present chapter describes a protocol on how to use embryogenic cell suspensions (ECS) in plantain ( spp.) using both in vitro gamma irradiation and plant regeneration in order to achieve genetic improvement. The process involves a series of steps to properly select ECS for irradiation and the posttreatment handling for plant regeneration as well as mutant selection during acclimatization phase and under field conditions.

Part II - Mutation Induction and Chimera Dissociation | Pp. 55-71

Optimisation of Somatic Embryogenesis in Cassava

Kenneth E. Danso; Wilfred Elegba

Somatic embryogenesis, an efficient regeneration system that is being used successfully in genetic transformation, can be coupled with mutation induction to breed for cassava varieties with desired traits. The embryogenesis system requires the initiation of totipotent cells which can be used as targets for mutagenic treatments. However, initiation of these totipotent cells is low, highly genotypic dependent and has low plant conversion rate. Thus, for its successful application in mutation induction, the system needs to be optimised to overcome these drawbacks. To optimise the system, totipotent cells are initiated on embryo initiation medium (EIM) which consisted of Murashige and Skoog (Physiol Plant 15:473–497, 1962) basal salts supplemented with picloram and 2,4-dichlorophenoxy acetic acid (2,4-D) to produce callus. After 21 days, calli produced are cultured for embryo maturation on maturation medium (EMM) or can also be treated with mutagenic agents for mutant induction. The resulting primary embryos are recycled three consecutive times, each by fragmentation of the cotyledons followed by culture on embryo initiation medium to produce more matured embryos. Somatic embryos produced are then successfully converted into plants by abscisic acid pretreatment in embryo maturation medium or by air desiccation under the laminar flow hood. The methodology described offers optimised, reproducible procedures of somatic embryogenesis for its incorporation into mutation breeding programmes in cassava.

Part II - Mutation Induction and Chimera Dissociation | Pp. 73-89

Creation of a TILLING Population in Barley After Chemical Mutagenesis with Sodium Azide and MNU

Iwona Szarejko; Miriam Szurman-Zubrzycka; Malgorzata Nawrot; Marek Marzec; Damian Gruszka; Marzena Kurowska; Beata Chmielewska; Justyna Zbieszczyk; Janusz Jelonek; Miroslaw Maluszynski

Since the development of the Targeting Induced Local Lesions in Genome (TILLING) strategy, it has been applied in both plants and animals in many studies. The creation of an appropriate population is the first and most crucial step of TILLING. The goal is to obtain a highly mutagenized population that allows many mutations in any gene of interest to be found. Therefore, an effective method of mutation induction should be developed. A high mutation density is associated with saving time, costs, and the labor required for the development of a TILLING platform. The proper handling of the mutated generations, the establishment of a seed bank, and the development of a DNA library are essential for creating a TILLING population. The database in which all of the data from the molecular and phenotypic analyses are collected is a very useful tool for maintaining such population. Once developed, a TILLING population can serve as a renewable resource of mutations for research that uses both forward and reverse genetic approaches. In this chapter, we describe the methods for the development and maintenance of a TILLING population in barley.

Part II - Mutation Induction and Chimera Dissociation | Pp. 91-111

Site-Directed Mutagenesis in Barley by Expression of TALE Nuclease in Embryogenic Pollen

Maia Gurushidze; Stefan Hiekel; Ingrid Otto; Götz Hensel; Jochen Kumlehn

In this chapter, a detailed protocol for the induction of targeted mutations in barley using customized transcription activator-like effector nucleases (TALENs) is provided. As explant for the introduction of TALEN expression constructs, embryogenic pollen cultures are used which consist primarily of haploid cells able to be converted via pollen embryogenesis and genome duplication into fertile doubled haploid plants. Thanks to the haploid nature of these target cells, a mutation induced by TALE nucleases in just one allele can be readily detected in vitro and thus genetically fixed primary mutant plants obtained in one generation.

Part II - Mutation Induction and Chimera Dissociation | Pp. 113-128

Doubled Haploidy as a Tool for Chimaera Dissolution of TALEN-Induced Mutations in Barley

Maia Gurushidze; Hannes Trautwein; Petra Hoffmeister; Ingrid Otto; Andrea Müller; Jochen Kumlehn

Site-specific genome engineering is a breakthrough technology that facilitates the functional validation of genes and offers versatile novel opportunities of crop improvement. In the approach described in this chapter, the two units of transcription activator-like effector nucleases (TALENs) required for site-directed cleavage activity are separately used to produce homozygous transgenic lines, each carrying only one unit of the TALEN pair. Crossings of these plants result in pairwise combination of both TALEN units, which causes their activation during early zygotic embryogenesis in the hybrid caryopses and facilitates site-directed mutagenesis with unprecedented efficiency in a Triticeae species. As revealed by sequencing of target-specific PCR amplicons, the individual primary mutants are not only heterozygous for the target gene but also chimaeric typically harbouring multiple mutant alleles. We demonstrate the highly efficient production of homozygous mutant lines from the chimaeric primary mutants using haploid microspores as embryogenic founder cells for the generation of doubled haploid plants.

Part II - Mutation Induction and Chimera Dissociation | Pp. 129-141

Field Evaluation of Mutagenized Rice Material

Sydney D. Johnson; Dennis R. Taylor; Thomas H. Tai; Joanna Jankowicz-Cieslak; Bradley J. Till; Alpha B. Jalloh

Since the discoveries of the beneficial effects of some mutations on plants, scientists have made use of both physical and chemical mutagens to develop new varieties of crops and ornamentals. More than 3200 varieties have been produced through mutation induction, and these have contributed towards improving food security in many countries.

Proper field techniques can greatly enhance the chances of identifying desirable phenotypes. The protocol described here deals mainly with field techniques successfully employed and developed in the evaluation of rice mutants for over 8 years in the uplands and the hydromorphic lowlands at the Rokupr Agricultural Research Centre (RARC) of the Sierra Leone Agricultural Research Institute (SLARI) between 2005 and 2012 to evaluate gamma and X-ray-treated rice seeds.

Part III - Phenotypic Screening | Pp. 145-156

Root Phenotyping Pipeline for Cereal Plants

Michal Slota; Miroslaw Maluszynski; Iwona Szarejko

The proposed system for the phenotypic analysis of root traits that is presented here enables the precise description of the root growth kinetics of cereal plants. The designed pipeline is composed of a drip irrigation system to supplement plants with a medium, a high-resolution root system scanning facility and a method for comprehensive image analysis. The system enables low-effort, accurate and highly repeatable analysis of features of the root system of cereal seedlings and young plants until the early tillering stage. This system employs an automatic drip irrigation line, which is controlled remotely by a programmable logic controller (PLC). The PLC adapter used facilitates the automated control of all system modules, thus allowing the rate of the medium flow to be adjusted for the supplementation of plants. The system employs measuring sensors for the continuous monitoring of the parameters of the culture medium. This continuous sensing of medium parameters can be applicable for mineral nutrition studies and abiotic stress response testing. The installed drip lines are injected into transparent acrylic tubes (500 mm high, 32/30 mm in outer and inner diameter, with a circular opening in the bottom of 3 mm in diameter) that are filled with glass beads. The acrylic tubes are placed in opaque cover tubes that permit the non-destructive observation of the growth of the root system. Enhanced imaging quality contributes to an increase in the precision of the results that are obtained in the course of the analysis of root parameters using specialised root scanners coupled with the WinRHIZO system. This novel phenotyping pipeline permits noninvasive observation of root system growth adjusted for the subsequent root image acquisition with a reduced background noise. The method combines automated control of plant growth conditions with good imaging quality and high replicability of growth parameters.

Part III - Phenotypic Screening | Pp. 157-172