Showing papers on "Mutation breeding published in 2006"

Assessment of Genetic Variability Induced by Chemical Mutagenesis in Elite Maize Germplasm via SSR Markers

Abstract: A breeding program, aimed at utilizing chemical mutagenesis and mutation breeding for induction of additional genetic variation in well-known elite maize (Zea mays L.) lines and hybrids, has been conducted in Bulgaria since 1973. The phenotypic variation created by chemically induced mutagenesis included important quantitative traits, such as grain yield, high protein content, reduced flowering time, changes in grain type, improved general (GCA) and specific combining ability (SCA) as well as improved abiotic stress tolerance. Twelve mutant lines obtained by chemical mutagenesis, followed by recurrent reciprocal mutation breeding (RRMB), and their initial lines Oh43, Oh40b, C103, B37, and a Pioneer brand hybrid 3737, were assessed for the induced genetic variability using 18 SSR markers. The mutant inbred lines, chosen because of their improved GCA and SCA for grain yield and proven predominance in Bulgarian breeding programs, showed shifts in their flowering time as compared with the initial inb...

Problems and Prospects of Banana Breeding in India

Abstract: Banana breeding programme in India involves maintenance of various genetic resources of banana, of which triploids constitute the maximum share over diploids or tetraploids. RAPD studies conducted in these clones exhibit many distinct genotypes. During a hybridization programme, although many crosses were made, seed set and seed germination were relatively poor in many crosses. Male fertility in banana hybrids could be assessed by pollen output per anther; pollen viability and pollen size, which vary from cross to cross, and also from ploidy to ploidy. Ploidy levels in hybrids are estimated by phenotypic appearance (scoring technique) and confirmed either by stomatal density, size and number of chloroplast per guard cell pair or root tip mitosis. However, flow cytometry appears to be the most reliable method in many disputed cases. Generation of parthenocarpic hybrids depends largely upon selection and utilization of parents with parthenocarpic pedigree in a breeding programme. Evaluation of hybrids and parents indicated the nature of inheritance with respect to plant height and suckering habit but no definite trend could be ascribed to the traits of bunch orientation. Diploid x Diploid breeding approach has led to identification of a superior triploid hybrid, NPH 02-01, while Triploid (with AB)xDiploid approach has led to the development of a promising diploid hybrid H.212 and a triploid hybrid H.96/7 (ABB). Similarly, the Triploid x Diploid breeding programme resulted in development of many potential tetraploids that need further improvement. Innovative breeding approaches through in vitro mutation breeding and in vitro polyploidazation resulted in the development of many potentially useful variants. Breeding for resistance against biotic stresses such as Fusarium wilt and nematodes holds promise in banana, and, biochemical mechanisms for resistance in resistant genotypes/hybrids have been elucidated.

Study on mutagenic effects of avilamycin-producing strain induced by N~+ ion implantation

Abstract: Mutagenic effects of avilamycin-producing strain induced by N+ ion implantation have been investigated. The experimental results indicated that the survival rate curve took a "saddle" shape and the unique mutation effects of N+ ion implantation were presented. To obtain high-yield avilamycin-producing strain, the ion implantation dose of 5×1015 cm-2(the mutation rate was 20.9%-26.2%) was used and screening of streptomycin-resistant mutant was done in the study on breeding mutation. The SVN-116 mutant was obtained, with an avilamycin yield of 79.6-82.9 mg·L-1 that was 1.414-1.472 times as much as the original strain.

A Comparative Study on Mutagenic Effects of Space Flight and γ-rays Irradiation in Rice

Abstract: Objective) The experiment was conducted to study the mutagenic effects of space environment on seedling growth in M1, plant height and heading date in M2 in rice. (Method) Two types of lines of growth promotion (GP) and growth suppression (GS) were selected from the recombinant inbred lines derived from a cross between a sensitive japonica Lemont and a nonsensitive indica Teqing to compare mutation frequency and mutagenic efficiency for plant height and heading date in M2 generation. (Result) Space environment resulted in 34.9% higher seedling height in GP group than in the control and 39.1% lower in GS group than in the control, and there was no difference in seed fertility between the two groups. In M2, mutants of plant height and heading date can be induced by space treatment in both the two groups with lower mutation frequency and mutagenic efficiency in GP group than in GS group. There were no significant differences in physiological damages in M1 between the two groups after γ-rays irradiation treatment. Mutation frequency and mutagenic efficiency of heading date in M2 were higher in GS group than in GP group, and opposite was true for mutagenic efficiency of plant height although the mutation frequency varied between the two groups. The mutation frequencies of plant height and heading date induced by space environment were obviously lower than those by γ-rays

Application and progress of mutation breeding method of microbial drugs producing strain

Abstract: The original strains producing microbial drugs are always low.To meet the requirement of industrial pro- duction it is necessary to improve their characters by mutation breeding method.Some physical and chemical muta- tion breeding methods with their application were introduced in detail and some screening methods to obtain high yield mutants were reviewed.