Showing papers on "Molecular breeding published in 1999"

DNA shuffling of subgenomic sequences of subtilisin.

Abstract: DNA family shuffling of 26 protease genes was used to create a library of chimeric proteases that was screened for four distinct enzymatic properties. Multiple clones were identified that were significantly improved over any of the parental enzymes for each individual property. Family shuffling, also known as molecular breeding, efficiently created all of the combinations of parental properties, producing a great diversity of property combinations in the progeny enzymes. Thus, molecular breeding, like classical breeding, is a powerful tool for recombining existing diversity to tailor biological systems for multiple functional parameters.

Comparison of PCR-based molecular marker analyses of Musa breeding populations

Abstract: Progress in the breeding of plantain and banana has been restricted by the complex genetic structure and behaviour of cultivated polyploid Musa. Genetic improvement has been hindered due to the large amount of space required for growth and maintenance of plant populations, in addition to the long growth cycle and the low levels of fertility and seed viability characteristic of cultivated genotypes. Molecular marker assisted breeding has the potential to dramatically enhance the pace and efficiency of genetic improvement in Musa. This study was conducted to compare different PCR-based marker systems (RAPD, VNTR and AFLP) for the analysis of breeding populations generated from two diverse Musa breeding schemes. All three assays detected a high level of polymorphism between parental genotypes and within progeny populations. As expected, AFLP assays had by far the highest multiplex ratio while VNTR analysis detected the highest levels of polymorphism. AFLP analysis of a full-sib tetraploid hybrid population confirmed previous reports based on VNTR analysis, of a high frequency of recombination during 2n (3x) gamete formation by a triploid plantain landrace. In addition, both VNTR and RAPD analyses of a full-sib triploid hybrid population suggested a high frequency of homoeologous recombination during n (2x) gamete formation by tetraploid hybrids. In general, there was a poor correlation between estimates of genetic similarity based on different types of marker. The implications of these findings for the molecular breeding of Musa crops are discussed.

A genetic linkage map for Stevia rebaudiana

Abstract: To lay a foundation for molecular breeding efforts, the first genetic linkage map for Stevia rebaudiana has been constructed using segregation data from a pseudo test-cross F1 population. A total o...

Breeding and genetics.

Abstract: Three complete diallel crosses using purebred bucks and does of four rabbit breeds (Californian, C; Chinchilla, Ch; New Zealand White, N and Semigiant White, S) were realized in different periods (1968-1970 and 2003-2004), involving 6293 preweaning records. The traits studied were: total born (TBorn), born alive (BornA), viability at birth (ViabB), number weaned (NW), proportion of weaned litters (PWL) and viability at weaning (ViabW). A generalized linear mixed model using the PROC GLMMIX of SAS was applied, which considered the fixed effects of breed of the doe and the buck (4 classes each), experiment (3 trials), doble and triple interactions between all fixed effects, and the random effect of parity (5 levels).The does from breeds S and N excelled the others in viabilities and NW, while the bucks from N breed showed disadvantages in viabilities. The interaction effect between the doe and buck breeds identified the best crosses for NW, as SN, SCh and CS, over NCh, and C. The dam and sire breeds*experiment interactions were significant for ViabB, NW and ViabW. Differences between the breed of the doe were only found in experiment 1 and 2 with advantages for the N doe breed. The effect of buck breed was only significant in experiment 2, for ViabB, where C excelled N, and in ViabW the S breed excelled the rest. The triple interaction was significant in ViabW. It showed the best correspondence in merit order between experiment 1 and 3 with correlations of 0.5. The best three crosses across experiments were: SN, ChS, and ChN, which, along with the CS cross and the S and N dam breeds are recommended for commercial crossbreeding schemes.

Rice bacterial blight resistance genes and their utilization in molecular breeding

Abstract: Presently more than 20 bacterial blight resistance genes have been identified using near-isogenic lines with a single resistance gene as international differentials. Among them at least 9 genes have been localized on the rice genetic map and physical map. Two genes Xa21 and Xa1 have been cloned through an approach of positional cloning. The cloned Xa21 gene has been introduced into several widely used rice varieties.

Molecular breeding of flower color of Torenia hybrida

Abstract: Molecular breeding is a powerful method of plant breeding because it can change a specific characteristic of a plant without changing other desirable characteristics. Flower color is predominantly influenced by two types of pigments; flavonoids and carotenoids. The anthocyanin biosynthetic pathways of many plants have been well established (Holton et al, 1995) and conserved (Fig. 1). Chalcone synthase (CHS) and dihydroflavonol 4-reductase (DFR) are the first specific enzymes in flavonoid and anthocyanin biosynthesis, respectively. The presence of flavonoid 3′5′-hydroxylase (F3′5′H), cytochrome P-450 (Holton et al, 1993), is almost critical to the production of blue to purple anthocyanins. The flower color is reddish in its absence.

DNA Markers and Animal Molecular Breeding

Abstract: The types, characteristics, and forming mechanisms of DNA markers were briefly introduced. The author elucidated the applying strategy of genome molecular breeding based on DNA markers, reviewed the research progress of DNA markers in each application fields, and indicated the existing problems in molecular breeding.

Molecular Breeding of Barley for Droughted Low Input Agricultural Conditions

Abstract: Molecular genetic markers and other enabling technologies are now sufficiently developed for exploitation in breeding programmes. They allow the possibility of accelerating, and improving the efficiency, of breeding for abiotic and biotic stress tolerances. Barley is a good model species in which to demonstrate this. Barley is a diploid species in which genetic analysis is relatively easy, its short life cycle and inbred nature has also provided for good physiological research. The results of genetic and physiology studies can now be exploited more efficiently in breeding using the tools of contemporary biotechnologies. A programme of work has been initiated aimed at developing more stable yields in barley (Hordeum vulgare) for droughted, low input agricultural conditions of Mediterranean rim countries. Various molecular breeding approaches are to be compared which vary in gene donors, recipients and methods. Two of the approaches exploit wild barley (H. spontaneum) as a source of genetic variation for abiotic stress tolerance, the third uses an adapted landrace. Results from controlled environment experimentation will be compared with field performance in naturally stressed environments of N. Africa. The work will provide a testing ground for the application of ideas and technologies developed from research.

Application of molecular markers in crop breeding

Abstract: Molecular markers have been applied in studing construction of molecular linkage genetic map,genetic diversity,gene location and detection of introgression gene of cropsMolecular markers such as RFLP,RAPD,AFLP and SSR have characteristics of overcoming the defects of the classic genetic markers,and can be utilized extensively in molecular assisted breeding

Microsatellite marker and its application in the study of swine genetics and breeding

Abstract: In this paper,the application of microsatellite marker was reviewed in the study of swine genetics and breeding, for instance, construction of genetic lindage map, marker assistal Selection,mapping of quantitative trait loci (QTL ), evaluation of genetic diversity and parentage testing etc..Microsatellite marder has many advantages such as a great quantity, extensive dispersion around the genome, high polyomorphism, Mendelian codominant inheritance, rapid and convenient detection,and exhibits fine application prospects in the field of genetics study and breeding .