Showing papers on "Plant breeding published in 1983"

Molecular markers in plant breeding

Abstract: s ince Mendel's discoxeries more than a century ago, people ha,,e been monitoring, inducm,.z, and mappimz sin,.z, le eene markers in hmher plants. A elance at the v, ell-populated linkage maps of crops such as tomato or maize proxldes convincing e,,idence c,f the anloutl[ of work thai has been focused oil this area of research. Uniil the last 10 to 15 .,,'ears, most of the singlc gene markers used m higher plant genetics were those affecting morphological characters. Common example<, are genes causing dwarfism, chlorophyll deficiencies or altered leaf morphoh',gy. Though these markers have serx ed v, ell m ', arious types of basic and applied research, their use in many areas of plant breeding has been ,,ery limned. The de,,elopment m recent ,,'ears of protein and DNA marker,, offers the possibility of dexeloping new approaches to breeding procedures. The purpose of this article is to revie',~ some of tile present uses of molecular markers m plato breeding and to speculate about future applications. Tile greater ullhty of molecular markers derixes from 5 inherent properties that disiingtiish them fronl morphological markers. (1) Genotypes of molecular loci can be determined at the v, hole plant, tissue, and cellular levels. Phenot.\\'pes of most morphological markers can only be distinguished at the v, hole plant level. (2) A relati,.ely large number of r, aturally occurring alleles can be found at molecular marker loci. Distlngmqmble alleles at morphological marker loci occur lets frequently and often muq be induced through the application of exogenous mutagens. (3) U,mallv no deleterious effects are associated with alternate alleles of molecular markers. This is not the case with morphological markers, v.hich are often accompamed by undesirable phenotypic effects. (4) Alleles of most molecular markers are codommant, allov, ing all possible genoiypes to be distinguished in an.,,' segregating generation. Alleles at morphological marker loci usually interact m a dominant-recessixe manner, prohibiting their t|'.,e in rnany crosses. (5) With morphological marker loci, strong epistatic effects limit the nt, mber of segregating markers that can be unequi,.ocally scored in the same segregating generation. Fewer epistatic or pleiotropic effects are observed with molecular markers, thus a virtually limitless number of segregating markers can be monitored in a tingle population. Based on the level at v, hich the genes are detected, molecular markers can be dpdded into two classe~-protein markers and DNA markers.

Contributions of conventional plant breeding to food production.

Abstract: Within a relatively short geological time frame, Neolithic man, or more probably woman, domesticated all the major cereal grains, legumes, and root crops that the world's people depend on for most of their calories and protein. Until very recently, crop improvement was in the hands of farmers. The cornerstones of modern plant breeding were laid by Darwin and Mendel in the late 19th century. As the knowledge of genetics, plant pathology, and entomology have grown during the 20th century, plant breeders have made enormous contributions to increased food production throughout the world. There have been major plant breeding break-throughs for maize and wheat, and promising research activities to raise yields in marginal production environments are ongoing. Since it is doubtful that significant production benefits will soon be forthcoming from the use of genetic engineering techniques with higher plants, especially polyploid species, most research funds for crop improvement should continue to be allocated for conventional plant breeding research.

Induced Mutations in Plant Breeding

Abstract: 1 Introduction- 2 Methods for Inducing Mutations- 21 Mutagenic Agents and Related Problems- 22 The Chimerical Structure of the M1 Plants- 3 The Selection Value of Mutant Genes- 4 The Seed Production of Mutants and the Alteration of Quantitative Characters- 41 The Alteration of Quantitative Characters- 42 Mutants with Increased Seed Yield- 43 Released or Approved Mutant Varieties- 5 The Utilization of Mutants in Crossbreeding- 51 The Incorporation of Mutant Genes into the Genomes of Varieties or Strains- 52 The Joint Action of Mutant Genes- 521 Negative Interactions- 522 Positive Interactions- 6 The Alteration of the Shoot System by Means of Mutations- 61 Mutants with Reduced Plant Height: Erectoides Types, Semidwarfs, Dwarfs- 611 Barley- 612 Rice- 613 Bread and Durum Wheat Other Gramineae- 614 Dicotyledonous Crops- 62 Mutants with Increased Plant Height- 63 Mutants with Altered Stem Structure- 631 Branching, Tillering- 632 Stem Bifurcation- 6321 Bifurcated Mutants- 6322 Bifurcated Recombinants- 633 Stem Fasciation- 6331 Fasciated Mutants- 6332 Fasciated Recombinants- 634 Mutations in Fiber Plants- 7 Alterations of Flower Shape, Color and Function- 71 Flower Shapes and Flower Colors in Ornamentals- 72 Inflorescences- 73 Genetic Male Sterility- 8 Leaf Mutants of Agronomic Interest- 9 Mutations Affecting the Root System- 10 The Alteration of Flowering and Ripening Times- 101 Earliness- 102 Lateness- 103 Changes of the Photoperiodic Reaction- 11 Mutations in Vegetatively Propagated Crops and Ornamentals- 12 Heterosis- 13 Disease Resistance- 131 Resistance Against Fungi, Bacteria, and Viruses- 1311 Barley- 1312 Rice- 1313 Bread and Durum Wheat- 1314 Oats- 1315 Maize- 1316 Pearl Millet- 1317 Sugarcane- 1318 Dicotyledonous Crops- 132 Resistance Against Animal Pathogens- 133 Herbicide Tolerance- 14 Drought Resistance, Heat Tolerance, Winterhardiness- 15 Shattering and Shedding Resistance- 16 The Pleiotropic Gene Action as a Negative Factor in Mutation Breeding- 161 The Alteration of Pleiotropic Patterns Under the Influence of Changed Genotypic Background or Environment- 162 Mutations of Closely Linked Genes- 17 The Penetrante Behavior of Mutant Genes as a Negative Factor- 18 The Adaptability of Mutants to Altered Environmental Conditions- 181 The Reaction of Mutants to Different Natural Environments- 182 The Reaction of Mutants Under Controlled Phytotron Conditions- 19 The Alteration of Morphological and Physiological Seed Characters- 191 Seed Size- 192 Seed Shape- 193 Seed Color- 194 Physiological Seed Characters- 20 The Alteration of Seed Storage Substances- 201 Seed Proteins- 2011 The Characterization of Seed Proteins- 2012 Factors Influencing Protein Content and Composition- 20121 Environmental Factors- 20122 Endogenous Factors- 2013 Seed Protein Content of Different Varieties of the Same Species- 2014 Alteration of Seed Proteins Through Mutant Genes- 20141 Protein Mutants in Cereals- 20142 Protein Mutants in Legumes- 202 Seed Carbohydrates- 2021 Maize- 2022 Barley and Other Cereals- 2023 Peas- 203 Seed Lipids- 21 Other Plant Substances- 22 The Nutritional Value of Mutants- 221 Maize Mutants- 222 Barley Mutants- 223 Sorghum Genotypes- 224 Pea Mutants- 23 General Aspects of Mutation Breeding with Regard to the Improvement of Seed Storage Substances- References

Current status of crop plant germplasm

Abstract: Crop plants are the basis of our food supply. The demand for the highest possible productivity, as the human population increased in number, has in effect narrowed the gene base of our crop plants to only the most productive cultivars. Never before in human history have the rates of extinction for the ancestral forms of our basic agricultural plants been as high as they are now. Both the USDA through the National Plant Germplasm System (NPGS) at the national level and the International Board of Plant Genetic Resources (IBPGR) at the international level have active programs to collect, store, and evaluate this germplasm for present and future use. The scope and status of these programs are reviewed in detail. Clearly the future of plant breeding, and, therefore agriculture and the world food supply, rest on the genetic potential of plant genetic resources now being stored in gene banks. The location and holdings of these gene banks are reviewed. For the future, both the nations which possess this genetic d...

Agricultural Applications of Plant Protoplast Fusion

Abstract: Plant protoplasts can be fused and the fusion products cultured to produce somatic hybrid plants. This technique has been used to produce germplasm previously unavailable to the plant breeder. Several researchers have emphasized production of hybrids between distantly related, sexually incompatible species, but many of these hybrids are sterile, precluding incorporation into a breeding program. Hence, to transfer traits such as disease and herbicide resistance, emphasis has shifted to production of hybrids between more closely related species. Novel variation has been observed in such somatic hybrids due to segregation of mixed organelles, cytoplasmic and nuclear gene recombination, and somaclonal variation. The unique gene combinations made possible by protoplast fusion ensure that new plant varieties will soon be derived from somatic hybridization.

Manipulation of leaf area and its effect on grain yield in droughted wheat

Abstract: Modification of crop leaf area could have considerable consequences on grain yield where soil water is limited. To test this, leaf area was artificially reduced to examine the effect on three wheat cultivars in two different drought situations-one where all the water was supplied just prior to sowing, and the other where half of the water was supplied before sowing and half after sowing on eight separate occasions. Leaf area was modified by detillering and two leaf-cutting treatments, Plants were grown individually in pots 1 m tall by 0.1 m diameter at a crop density of 100 plants/m2. Leaf area and water use were measured weekly for all plants, and at maturity the yields of grain, straw and leaves, and the yield components, were measured. The defoliation treatments reduced total cumulative leaf area by about one-half. This in turn reduced the rate of early water use and resulted in the highest grain yields and harvest indices. The ratio of leaf weight to total plant weight was inversely associated with yield both within and across treatments, suggesting an excessive investment in leaves. This was also indicated in an adjacent experiment where the same cultivars, watered daily, had a similar leaf weight to that of the droughted plants, yet yielded considerably more grain. Water use efficiency (the ratio of above-ground dry weight to total water used) also had a significant influence on grain yield. These results suggest that it may be worth while modifying leaf area development in wheat genetically to improve yields under some dryland conditions.

Approaches to the Genetic Analysis and Breeding of Brewer's Yeast

Abstract: Man has subjected many plants to breeding to suit his needs better. Some plant species have been bred for thousands of years. In modern times plant breeding has become increasingly intentional and systematic. Saccharomyces yeasts belong, according to their use, to man’s old, cultivated plants, but with the exception of pure culture selection (Hansen 1888) they have undergone little intentional or systematic breeding.

Colchicine-induced variants in sunflower

Abstract: Seedlings of the F1 sunflower hybrid between inbred lines AHA 232 (cytoplasmic male sterile, non-branched) and RHA 274 (male fertile, homozygous for dominant fertility restorer and recessive branching) were treated with 0.5 per cent colchicine in lanolin applied to the newly exposed growing point after separation of the cotyledons. Of the 100 treated seedlings 54 survived to produce flowers and 50 set at least some seed. Ten of the treated F1 plants exhibited the recessive characters, branching or male sterility, originally present in heterozygous condition. These plants were usually chimeras with two or more sectors. A further 15 treated F1 plants produced aberrant F2 segregation ratios at the loci governing recessive branching or male sterility, or obvious mutants for such characters as rust resistance, height and maturity. The present results are compared and contrasted with earlier studies of colchicine-induced variants in sorghum, flax and barley. It is concluded that colchicine is a powerful mutagen in at least some genotypes of several crop species and further, that colchicine induced variants, like somaclonal variants, both of which apparently develop from a mass of undifferentiated tissue, may be a source of novel genotypes for plant breeding programs.

Some Factors Causing Variation in the Yield of Individual Plants of Wheat

Abstract: Seeds of wheat (cv. Warimba) were sown by broadcasting to achieve a crop density of 160-180 plants m-2. The emergence date of each seedling was recorded. For each plant, measurements were made of the distance to neighbouring plants, and the weights and yields of these neighbours. Broadcasting the seed had ensured that there was variation in the distance to neighbours and also variation in the area postulated to be occupied by each plant. These areas varied in shape. Regression analysis was used to evaluate the effect of rapidity of emergence, the area available to a plant and the effect of competition from neighbours on the yield of each plant. Those plants that emerged 5 days after seeding on average had three times the yield of plants that emerged on day 12; however, there was very great variation around the regression, and emergence accounted for only 3.8 % of the variation in yield. Variation in the area available to a plant accounted for 14.3 % of the variation in yield and a competitive index made up of the size and distance away of neighbours accounted for 8.3 %. Each of these factors had a statistically significant effect on final yield. When they were combined in a multiple regression they accounted for only c. 20% of the variation, and 80% remains unexplained. Competition was shown to vary from plant to plant; it was not solely a communal effect reducing plants similarly. The shape of the area postulated as being available to a plant could not be shown to have an effect on its yield. The results are discussed in reference to measures of competition and the difficulties experienced by plant breeders when attempting to select among single plants for yield.

Chromosome Structure in Cereals: The Analysis of Regions Containing Repeated Sequence DNA and Its Application to the Detection of Alien Chromosomes Introduced into Wheat

Abstract: The concept of chromosome engineering of plants is well established in plant breeding. As early as 1937 Blakeslee and Avery commented in their article on chromosome doubling by colchicine that “with increasing knowledge of the constitution of chromosomes and of methods whereby their structure and behavior may be altered, there arises an opportunity for the genetic engineer who will apply knowledge of chromosomes to building up to specification forms of plants adapted to the surroundings in which they are to grow, and suited to specific economic needs.” The colchicine doubling technique which inspired this comment was taken up by plant breeders who had been interested in producing wheat-rye hybrids. Routine production of colchicine doubled wheat-rye hybrids with some fertility allowed intensive plant breeding for improved fertility, yield, seed quality, etc. (14,29,46). The breeding effort has resulted in recent years in many farmers around the world growing triticale as a crop. More directed chromosome engineering has been carried out for introducing alien chromosome segments carrying disease resistance (37,55,56).

Protoclonal Variation in a Dutch Commercial Cultivar of Potato (Solanum Tuberosum L. cv. Bintje)

Abstract: The occurrence of spontaneous variation among the protoplast-derived plants of commercial potato cultivars (1, 2) stimulated great interest both from the point of using it in plant breeding, and because it may be undesirable when stable reproduction of a specific genotype is essential. The possible role of the ploidy alterations in causing changes in the morphologies of plants regenerated from protoplasts of tetraploid cultivar “Bintje” was discussed by us in an earlier paper (3). It was indicated that the regeneration of plants with altered phenotype and/or ploidy from the same callus was suggestive of generation of variation during culture phase.

Studies on the Application of Tissue Culture for Plant Breeding I. Effect of genotype and other combined factors on the callus induction and plant regeneration in anther culture of rice

Abstract: Rice (Oryza sativa L.) anthers collected from different genotypes were cultured to investigate the priority to increase callus production rate among several factors affecting on callus formation. Rice varieties, F hybrids and F plants differed greatly in their abilities to produce callus from anthers, and it was confirmed that the culturability of rice anther was a heritable characteristic. Cold shock treatment before plating anthers promoted callus formation rate, but combined effect with genotype having high culturability was more significant. The response to sucrose concentration in culture medium in callus induction rate was different between rice genotypes, but combined effect with genotype was not significant. Single supplement of NAA to R medium increased callus production rate remarkably only in rice genotype having high culturability. Conclusively selection of genotypes is most important to increase callus initiation frequency from rice anthers.

Studies on the Application of Tissue Culture for Plant Breeding

Abstract: Rice (Oryza sativa L.) anthers collected from different genotypes were cultured to investigate the priority to increase callus production rate among several factors affecting on callus formation. Rice varieties, F hybrids and F plants differed greatly in their abilities to produce callus from anthers, and it was confirmed that the culturability of rice anther was a heritable characteristic. Cold shock treatment before plating anthers promoted callus formation rate, but combined effect with genotype having high culturability was more significant. The response to sucrose concentration in culture medium in callus induction rate was different between rice genotypes, but combined effect with genotype was not significant. Single supplement of NAA to R medium increased callus production rate remarkably only in rice genotype having high culturability. Conclusively selection of genotypes is most important to increase callus initiation frequency from rice anthers.