Barley for Food and Health: Science, Technology, and Products

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IMPROVING THE BARLEY CROP 37 Mutations When used in connection with plant breeding, the term mutant or mutation has a hazardous and even an intimidating connotation that often causes unwarranted concern. Mutant barley plants occur spontaneously (naturally) as a result of errors in normal cell processes (e.g., DNA replication), may be induced by a number of chemical or radiation treatments, or may occur following cell and tissue culture propagation. Mutagenesis research has been reported and reviewed extensively in the scientific literature (Hockett and Nilan 1985). Regardless of the mutations source, mutant barleys should not be considered as dangerous or undesirable. In effect, natural and induced mutations have been a mainstay in producing genetic variation since the advent of green plants; without genetic variation, improvement of a species would not be possible. Mutant barley may be utilized directly, providing an “instant” cultivar, but more often, potentially useful mutations (especially when induced via chemicals or radiation) are accompanied by other mutations, which must be removed by an appropriate breeding method such as backcrossing. Both spontaneous and mutant variants may provide evidence of genes at previously unknown loci as well as new alleles in improved adapted genetic backgrounds, thus supplementing and complementing a conventional breeding program. Mutagenesis has been used extensively for development of new and improved cultivars and has provided new methods of analyzing genetic fine structure and understanding genetic control (Hockett and Nilan 1985). A relatively recent development in mutation strategy enables a directed approach to identifying mutations in specific genes. This procedure is described as targeting induced local lesions in genomes (TILL- ING). Using this strategy, single-base-pair changes can be identified in a specific gene of interest (McCallum et al. 2000; Till et al. 2003). Slade et al. (2005) identified a range of waxy phenotypes in the wheat TILLING population, suggesting that similar starch variants may be identified in barley. Using the TILLING technique, point mutations and deletions in the powdery mildew resistant genes in barley, mlo and mla, have been identified (Mejlhede et al. 2006), presenting an opportunity to study resistance to these parasitic fungi. A mutant barley resistant to powdery mildew was produced over 60 years ago by Freisleben and Lein (1942) (cited by Ganeshan et al. 2008). As of 2007 there were 256 various mutant barley varieties listed in the FAO/IAEA Mutant Varieties database (FAO 2007). A number of mutant barleys have been identified with genotypes expressing useful genetic characters—with important implications for the food and brewing industries. The genetic background in the spontaneous high-amylose starch mutant found in Glacier by Merritt (1967) may prove to be invaluable in developing high-amylose starch barleys for use in specialty foods. Induced mutants are also sources of valuable traits, such as increased kernel protein (Doll 1973), high lysine (Jensen 1979), proanthocyanidin-free (Jende-Strid 1976), high β-glucan (Eslick 1981), low β-glucan (Aastrup et al. 1983), and high-amylose starch (Merritt 1967; Morrell et al. 2003). The high-β-glucan barley (Prowashonupana) produced by Eslick (1981) is an example of an instant cultivar, as it is now being grown commercially without further modification.
38 BARLEY BIOTECHNOLOGY: BREEDING AND TRANSGENICS This barley is being utilized as a source of soluble dietary fiber for specialty foods. The lysine gene lys3a from the Danish high-lysine mutant Bomi 1508 (Jensen 1979) was transferred successfully into a high-yielding, high-lysine feed cultivar through a series of cross-breeding programs. Feeding trials with monogastric animals have effectively demonstrated the nutritional quality of the protein in this barley (Munck 1992). Identity preservation is essential when growing specialty cultivars, which may add significantly to the cost of production. The cost must be weighed against the value of the product. In areas of the world where quality protein is in short supply, high-lysine barley would be invaluable as a source of protein for humans. Haploids Haploid plants have one set of complete chromosomes representing the basic genetic complement, which is one-half of the normally observed diploid chromosome number in an organism. Methods of production and uses of haploids in barley breeding have been reviewed (Kasha and Reinbergs 1976; Anderson and Reinbergs 1985; Fedak 1985; Pickering and Devaux 1992). Methods of producing haploids include ovary culture (in vitro gynogenesis), chromosome elimination (bulbosum technique), anther culture (in vitro androgenesis), microspore culture, interspecific hybridization, and use of a haploid initiator gene (hap) thatwas found by Hagberg and Hagberg (1980). Production of double haploids from the original haploid is necessary for the system to work. In the case of haploids-derived anther cultures, spontaneous doubling often occurs (Luckett and Darvey 1992). In other systems, where spontaneous doubling occurs rarely, treatment with colchicine, a toxin derived from autumn crocus, Colchicum, efficiently produces double haploids, allowing for the recovery of homozygous inbred lines in a single generation. Pickering and Devaux (1992) suggested several applications of haploids in addition to producing new cultivars: early identification of superior hybrid combinations, detection of linkages associated with quantitatively inherited characters, calculation of recombination values between linked genes, and evaluation of pleiotropic (multiple) effects of specified genes. In comparing haploid breeding with single-seed descent and pedigree breeding it was concluded that growth performance means, ranges, and frequencies of superior genotypes were similar (Park et al. 1976; Reinbergs et al. 1976). Each method was superior in one or more comparative measures; however, when the 10 best lines from each method were compared, there were no differences in yield (Kasha and Reinbergs 1979). In a comparison of seven crosses using pedigree and doubled-haploid derived lines, Turcotte et al. (1980) reported that superior lines were produced by the haploid technique. The culture of haploids is a growing field in the plant improvement sector, having the advantage of producing plants that are totally homozygous and constituting pure lines that can be used in pedigree or other methods of breeding. Additionally, ease of selecting among homozygous lines and time savings are
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BARLEY FOR FOOD AND HEALTH Science,
Page 5 and 6: On a Seed “This was the goal of t
Page 7 and 8: Cover design by Jean Rose Johnston.
Page 10 and 11: CONTENTS Preface xiii 1 Barley Hist
Page 12 and 13: CONTENTS ix Infrared Processing, 12
Page 14: CONTENTS xi Asia, 221 Barley Mixed-
Page 17 and 18: xiv PREFACE In the concluding two c
Page 19 and 20: 2 RELATIONSHIP OF HUMANS AND BARLEY
Page 27 and 28: 10 RELATIONSHIP OF HUMANS AND BARLE
Page 35 and 36: 2 Barley: Taxonomy, Morphology, and
Page 37 and 38: 20 BARLEY: TAXONOMY, MORPHOLOGY, AN
Page 49 and 50: 3 Barley Biotechnology: Breeding an
Page 51 and 52: 34 BARLEY BIOTECHNOLOGY: BREEDING A
Page 53: 36 BARLEY BIOTECHNOLOGY: BREEDING A
Page 73 and 74: 4 Barley: Genetics and Nutrient Com
Page 75 and 76: 58 BARLEY: GENETICS AND NUTRIENT CO
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88 BARLEY: GENETICS AND NUTRIENT CO
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96 BARLEY PROCESSING: METHODS AND P
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98 BARLEY PROCESSING: METHODS AND P
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100 BARLEY PROCESSING: METHODS AND
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134 EVALUATION OF FOOD PRODUCT QUAL
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7 Barley Food Product Research and
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146 BARLEY FOOD PRODUCT RESEARCH AN
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8 Health Benefits of Barley Foods I
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180 HEALTH BENEFITS OF BARLEY FOODS
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9 Current Status of Global Barley P
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206 CURRENT STATUS OF GLOBAL BARLEY
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208 CURRENT STATUS OF GLOBAL BARLEY
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10 Barley Foods: Selected Tradition
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212 BARLEY FOODS: SELECTED TRADITIO
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APPENDIX 1 Glossary: Botany and Pla
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APPENDIX 2 Glossary: Food and Nutri
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APPENDIX 3 Glossary: Barley Terms T
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APPENDIX 4 Equivalent Weights and M
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SOURCES OF BARLEY AND BARLEY PRODUC
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Rancho Cucamonga, CA 91730 Ph: 888-
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SOURCES OF BARLEY AND BARLEY PRODUC
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E-mail:Tony.Steeper@csiro.au Web: h
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BARLEY RESOURCE ORGANIZATIONS 241 P
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INDEX Air classification, 102, 122-
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INDEX 245 Meat and barley casserole
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