Showing papers on "Plant breeding published in 1993"

Marker-assisted selection

Abstract: The use of polymorphic single genes to facilitate the process of plant breeding was proposed early in this Century (Sax, 1923). The basic principle is that selection for characters with easily detectable phenotypes can simplify the recovery of genes of interest linked to them and more difficult to score. The first marker loci available were those that have an obvious impact on the morphology of the plant. Genes that affect form, coloration, male sterility or disease resistance among others have been genetically analysed in many plant species. In some well characterized crops like maize, tomato, pea, barley or wheat, tens or even hundreds of such genes have been assigned to different chromosomes (O’Brien, 1990).

Plant breeding: principles and prospects.

Abstract: Introduction. Genetic systems and population structure. Genetic systems, recombination and variability. Population structure and variability. Sources variation. Plant genetic resources. Induced mutations. Interspecific hybridization by sexual means. Chromosome manipulation and polyploidy. Somatic hybridization. Gene cloning and identification. Gene transfer to plants: approaches and available techniques. The role of gene technology in plant breeding. Assessment of variation. Biometrical genetics in breeding. Biochemical characterization of populations. Manipulation of genetic systems. Self- and cross-incompatibility systems. Male sterility. Apomixis. Micropropagation and somatic embryogenesis. Andro- and parthenogenesis. Selection methods. Selection strategies and choice of breeding methods. Marker-assisted selection. Gametophytic and sporophytic selection. In vitro selection. Adaptation. Genotype x environment interaction and adaptation. Augmenting yield-based selection. Resistance to abiotic stresses. Resistance to parasites. Specific trait breeding. Breeding for improved symbiotic nitrogen fixation. Photosynthetic and respiratory efficiency. Breeding for efficient root systems. On the utilization of renewable plant resources. Epilogue. The need for comprehensive plant breeding strategy.

Cucumber: Cucumis sativus L.

Abstract: Publisher Summary Cucumber, Cucumis sativus L., is a member of the Cucurbitaceae, which comprises 90 genera and 750 species. It is one of the oldest cultivated vegetable crops and is cultivated in nearly all countries of temperature zones. It is a thermophilic and frost-susceptible plant species, growing best at temperatures above 20 °C. This chapter highlights the use of this vegetable and reviews its cytology, genetics, germplasm resources, and reproductive biology. The taste and demands of the consumer varies according to country. Special varieties must be bred that set fruit under suboptimal temperature conditions. The demands of the processing industry concerning outer appearance—fruit shape, size, and color—also varies depending on the preservation process and the corresponding country. Therefore, cucumber breeders must consider several different breeding aims. General breeding objectives in cucumber are resistance to diseases and animal pests, maintenance of resistance in existing varieties, fruit quality, and fruit yield. Additionally, breeding aims such as parthenocarpy, constancy of femaleness, germination, and fruit set at suboptimum temperatures may be of importance in special breeding programs. Unlike many other plant species, there are different sex types in cucumber, which are of different value in breeding and concerning yield potential. By using sex inheritance and influencing sex expression, the breeding methods of self-pollinated and open-pollinated plants can be applied to cucumber. Thus, the cucumber breeder needs complete knowledge of sex inheritance and of potential ways of influencing sex expression. The chapter provides an overview of the selection of cucumber breeding methods and these methods. There have been several reports on the possibility of applying in vitro techniques in plant breeding of cucumber. The chapter describes techniques that are applicable to the improvement of cucumber.

The genetic maps of wheat and their potential in plant breeding

Abstract: The further improvement of bread wheat (Triticum aestivum) varieties represents a particularly difficult challenge for UK breeders. As one of the world's primary food sources, a great deal of effort over the past 30 years by breeders has resulted in remarkable improvements in yield. The doubling of UK wheat yields since 1970 has been due to the release of varieties with much improved yield potential which are also compatible with the increasingly intensive farming methods that we have witnessed over the same period. Of course in recent years the goal posts have moved once again. The EC grain mountains and the erosion of price support for the European wheat growers - likely to be further exacerbated by the result of the current GATT talks - indicate a move towards sustainability and lower labour, energy and chemical inputs in the future. The farmer of the 1990s and beyond will expect high yielding crops with lower variable costs and added value from stable industrial quality, targeted probably at higher cost speciality products. With some estimates of the cost of producing and releasing a new wheat variety as high as £14 million it is not surprising that breeders are now turning to molecular genetic studies to help them assemble optimum combinations of genes that will allow them to produce the ideal varietal phenotype for the farmer of the 21 st century.

Linkage mapping of sbm-1, a gene conferring resistance to pea seed-borne mosaic virus, using molecular markers in Pisum sativum

Abstract: The location of sbm-1 on the Pisum sativum genetic map was determined by linkage analysis with eight syntenic molecular markers. Analysis of the progeny of two crosses confirmed that sbm-1 is on chromosome 6 and permitted a more detailed map of this chromosome to be constructed. The inclusion of Fed-1 and Prx-3 among the markers facilitated the comparison of our map with the classical genetic map of pea. The sbm-1 gene is most closely linked to RFLP marker GS185, being separated by a distance of about 8 cM. To determine the practical value of GS185 as a marker for sbm-1 in plant breeding programs, the GS185 hybridization pattern and virus-resistance phenotype were compared in of a collection of breeding lines and cultivars. Three GS185 hybridization patterns were discerned among the lines. A strong association was found between one of these patterns and resistance to PSbMV.

Viewpoint: selection for improved drought response in cool-season grasses.

Abstract: Water limits the establishment, growth, and production of cool-season grasses on semiarid rangelands, and plant improvement programs for these areas must be capable of screening breeding lines for response to drought. Although many techniques to evaluate various morphological and physiological characteristics have been proposed, few have been used successfully in plant breeding programs. Consequently, a need exists to identify and develop rapid, reliable screening techniques that can assess integrated plant response to drought in large plant populations. Improved seedling emergence has been achieved in Russian wildrye [Psathyrostachys juncea (Fischer) Nevski] by selecting for emergence from a deep seeding depth and long coleoptiles. Water uptake by roots is critical, and screening for enhanced seedling root growth in cool-season grasses offers considerable promise. In spite of the important role that stomatal control has in regulating plant water loss, limited success has been achieved in incorporating desirable stomatal characteristics into improved grass cultivars. Although osmotic adjustment appears beneficial in some crop species, more research is needed before cool-season grasses should be selected based on osmotic adjustment. Selection for improved water-use efficiency in cool-season grasses based on carbon isotope discrimination is a promising approach. Successful incorporation of these various traits into improved cool-season grass cultivars necessitates close cooperation between breeders and physiologists.

Molecular cytogenetics — biology and applications in plant breeding

Abstract: Cytogenetic manipulation of the chromosome complements of crop plants continues to be one of the most important methods available to plant breeders for introducing new variation into varieties of crops (see e.g., Law 1981, Gale and Miller 1987). Molecular cytogenetic analysis of the chromosomes of crops is a vital part of understanding their evolution, genetics, genetic recombination and karyotypic stability.

The role of gene technology in plant breeding

Abstract: Plant breeders have made spectacular progress in the improvement of many crop species over the last 60 years. In wheat, rice and maize for example about 50% of the increase in the yield over the period 1930–1975 has been attributed to improved varieties; the remainder derives from greater and more efficient use of fertilizers and crop management. Recent advances in genetics, cell and molecular biology, particularly recombinant-DNA technology, provide new opportunities for manipulation of the genome to meet the varying demands of breeders.

Genetic engineering and plant breeding, especially cereals

Abstract: Over the last 5000 years cereals have been bred for food, feed, and beverages by selection of spontaneous mutations and random hybrids. Since the turn of the century, crosses with defined parents, and since 1927 artificially induced mutations, have been used to create variability on which selection of new varieties is based. It is pointed out that hybrid corn and transfer of rust‐resistant genes from wild species into chromosomes of bread wheat was preceded by decades of basic research. Genetic transformation is an additional tool for the breeder to introduce novel genes in a rational manner and will complement but not replace the existing efficient breeding methods. Genetic transformation has been demonstrated in maize, rice, and wheat, while techniques to obtain transgenic barley plants are still being developed. Our present knowledge on the endosperm‐specific expression of storage proteins and the modulation of this expression by transcriptional activators is reviewed. Breeding strategies for ...

Breeding for nutritional stability in kodo millet

Abstract: Stability analysis for protein and carbohydrate content was carried out in 30 diverse genotypes of kodo millet (Paspalum serobiculatum L.) grown at four locations. Genotype X environment linear interactions were significant for both the traits. Genotypes IPS-147, IPS-200, IPS-198, IPS-112, IPS-66, IPS-138, IPS-115 appeared stable; hence they may be of use in breeding stable cultivars for these traits.

The use of microorganisms in plant breeding

Abstract: The manipulation of genes between individuals within the same species and even between individuals from different species and genera has been the foundation of plant breeding for the last 100 years. The whole process relies on natural recombination of genes during meiosis in hybrid genotypes resulting from sexual hybridization of suitable parents. Selected recombinants having the desired gene combination are isolated over a period of one or more generations and exploited as pure lines in inbreeding crops and as hybrids or heterozygous open pollinated populations (synthetics) in outbreeding crops.

Progress and Prospects for Using Biotechnology in Plant Breeding

Abstract: This paper presents an overview of the/progress, problems and prospects of incorporating biotechnology tools such as wide crossing, tissue culture, molecular genetic maps and markers, and genetic engineering into crop breeding programs.