Molecular Mapping and Character Tagging in Brassica juncea—I. Degree,Nature and Linkage Relationship of RFLPs and Their Association With Quantitative Traits

For molecular mapping and character tagging in Indian mustard (Brassica juncea), cultivar Varuna and exotic collection BEC 144 were chosen on the basis of morphological and molecular differences. High degree of RFLP was detected between them using genomic DNA clones of Pst! subgenomic library as probes. Of the 48 probe — enzyme combinations, 89.5% were polymorphic. Majority of the probes revealed duplicate loci and a high frequency of null alleles (71.4%). Segregation analysis in the F² population revealed significant deviation from expected 1:2:1 ratio for 32% of the markers. Using the computer package MAPMAKER, 15 markers could be placed in six linkage groups which covered a total length of 173.9 eM. Based on single factor analysis of variance, three significant marker-quantitative trait associations viz. BJG 59a primary branches/plant, BJG 42Gb - secondary branches/plant and BJG 433-days to f1owering could be identified. The BEC 144 alleles at the quantitative trait loci (QTL) in the marked genomic regions enhanced the trait expression. The putative gene action at these loci was found to be non-additive.     

Molecular Markers for Seed Oil Content in Indian Mustard

With the objective of identifying molecular markers for the seed oil content in mustard (Brassica juncea), which is known to be quantitatively inherited, 94 F₆ generation recombinant inbred lines (RILs) developed from an intervarietal cross (Varuna × BEC144), were characterised. Oil content, determined by pulsed nuclear magnetic resonance technique, varied from 25.7% to 52.3% among the RILs. The frequency distribution of the trait was normal with mean 39.24 and standard deviation 4.52. Bulked segregant analysis of the RILs enabled fast and efficient screening of 219 random decamer primers for identification of informative primers. Single factor analysis of variance revealed significant association of oil content with three RAPD markers, viz., OPH11₁₃₅₀, OPJ06₁₂₀₀ and OPL05₆₀₀ which individually explained 6% of the trait variance. Molecular data indicated dispersion of desirable quantitative trait loci in the two parent varieties.     

Effects of glycol structure on the transesterification equilibria of oxo-osmium(VI) esters

We report equilibrium data on reactions between the N,N,N′,N′-tetramethylethylenediamine oxo-osmium(VI) ester of thymine with a variety of polyhydroxylated compounds including sugars, glycosides, sugar alcohols, and nucleosides. Some rate data are also included. The cis-furanosidic nucleosides showed the largest equilibrium constants; among the pyranosidic systems, the cis (ae) structure was preferred.     

Enhanced Biosynthesis of Sulfide Oxidase by Arthrobacter Species Using Response Surface Methodology

Response surface methodology was used to develop a fermentation medium for the enhanced biosynthesis of a novel sulfide oxidase by Arthrobacter species strain FR‐3. The interactive effect of the medium components – such as glucose as the carbon source, and tryptone and yeast extract as the nitrogen source – was evaluated by a 2³‐factorial central composite statistical design. Glucose and yeast extract were found to be the more influential medium constituents compared to tryptone since they had lower coefficients of linear effect, P‐values (< 0.02). The optimal fermentation medium components for the enhanced production of sulfide oxidase were recorded as glucose (8.98 g/L), tryptone (10.62 g/L) and yeast extract (7.3 g/L). Optimization of the medium constituents increased the experimental enzyme yield by 54 % compared to the unoptimized medium. This is the first report on the overproduction of sulfide oxidase by using response surface methodology.     

Ecotypic variation of in vitro plantlet formation in white clover (Trifolium repens)

Sixteen Trifolium repens (white clover) genotypes of diverse geographic origin were tested for differences in organogenic potential of petiole and root derived explants. Significant differences were observed between ecotypes and explant types with respect to callus initiation and plantlet regenerability. The observed differences are attributed to existing genotypic variability as well as origin of explant tissue.     

Biological characteristics of the peptides α and β isolated from bovine seminal plasma

The bull seminal plasma peptides α andβ have been examined for their biological properties. While both the peptides were able to inhibit the human chorionic gonadotropin-dependent uterine response in the mouse, α alone exhibits the property of suppressing post-castrational rise in gonadotropin in appropriate animal models. This suggests that the peptideβ must be acting directly on the ovary to suppress estrogen production and, consequently, the uterine weight increase. Such a possibility was confirmed when α andβ were examined by the coupled bioassay which is capable of discriminating between pituitary feedback factors and those acting directly on the gonad. In a test system designed to examine chronic effects, both α andβ showed evidence of acting directly on the ovary to inhibit human menopausal gonadotropin-induced estrogen production. Such a direct action could not be correlated with the relative potencies of these peptides when examined for their follicle stimulating hormone-receptor binding inhibitor and lutinizing hormone-receptor binding inhibitor activities.     

Molecular Mapping and Character Tagging in Mustard (Brassica juncea) II. Association of RFLP markers with Seed Coat Colour and Quantitative Traits

In Brassica juncea, segregation of 44 RFLP markers generated by homologous genomic DNA clones as probes was studied in a F₂ population obtained from an intervarietal cross. Linkage relationship among the markers was established using computer package ‘MAPMAKER’. Twenty five of the markers could be arranged in nine linkage groups, covering a total of 243.3 cM. Marker BJG357c showed tight linkage (3.9 cM) with yellow seed coat colour locus (r ₁). Based on single factor analysis of variance,17 significant marker-trait associations could be established in respect of six quantitative traits viz. days to flowering, plant height, number of primary branches, secondary branches per primary branch, siliquea per secondary branch, and seeds per siliqua. The proportion of phenotypic variation explained by individual marker-trait association ranged from 3.0% to 33.2%. The putative gene action at majority of the marked genomic regions was found to be partial dominance to dominance.