CHEMICAL COMPOSITION, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF ESSENTIAL OIL FROM LIME BASIL (OCIMUM AMERICANUM): A POTENT SOURCE FOR NATURAL ANTIOXIDANT

Objective: GC and GC MS based analysis of the essential oil from leaf samples of Ocimum americanum were done. The essential oil composition, In vitro antioxidant and antimicrobial activity of the essential oil of O. americanum were evaluated in this research to explore its potential for future use. Methods: The component identification was achieved by the GC–MS analysis. Radical-scavenging activities of the plant essential oil were determined by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) activity. Antimicrobial activity of the essential oil was done using standard pathogenic strains in disc diffusion method. Results: GC and GC/MS analysis of the plant essential oil resulted in the identification of 19 compounds representing 100% of the oil. Citral (47.18%) and β - citral (36.57%) were the two major constituents. The essential oil subjected to analysis of its antioxidant activity using 2, 2- diphenyl-1-1picrylhydrazyl (DPPH) showed higher activity as compared to the standard. The oil was also screened for its antimicrobial activity and the inhibition was recorded against pathogenic microorganisms. Conclusion: Both the antimicrobial and anti oxidant activity of Ocimum americanum showed its potential for further use as natural antioxidant and preservative. Essential oil from the medicinal plants is one of the promising natural compounds for preparation of safer antimicrobial and antioxidant agent. Antioxidants conventionally used in food industries are obtained by chemical synthesis, but their use, reserved for certain categories of food is regulated by dose limits. Leaves of Ocimum americanum L. contain citral rich essential oil which is a potent source for natural antioxidants and biologically active compounds

Genetic diversity analysis in the section Caulorrhizae (genus Arachis) using microsatellite markers

Diversity in 26 microsatellite loci from section Caulorrhizae germplasm was evaluated by using 33 accessions of A. pintoi Krapov. & W.C. Gregory and ten accessions of Arachis repens Handro. Twenty loci proved to be polymorphic and a total of 196 alleles were detected with an average of 9.8 alleles per locus. The variability found in those loci was greater than the variability found using morphological characters, seed storage proteins and RAPD markers previously used in this germplasm. The high potential of these markers to detect species-specific alleles and discriminate among accessions was demonstrated. The set of microsatellite primer pairs developed by our group for A. pintoi are useful molecular tools for evaluating Section Caulorrhizae germplasm, as well as that of species belonging to other Arachis sections

Chickpea

The narrow genetic base of cultivated chickpea warrants systematic collection, documentation and evaluation of chickpea germplasm and particularly wild Cicer species for effective and efficient use in chickpea breeding programmes. Limiting factors to crop production, possible solutions and ways to overcome them, importance of wild relatives and barriers to alien gene introgression and strategies to overcome them and traits for base broadening have been discussed. It has been clearly demonstrated that resistance to major biotic and abiotic stresses can be successfully introgressed from the primary gene pool comprising progenitor species. However, many desirable traits including high degree of resistance to multiple stresses that are present in the species belonging to secondary and tertiary gene pools can also be introgressed by using special techniques to overcome pre- and post-fertilization barriers. Besides resistance to various biotic and abiotic stresses, the yield QTLs have also been introgressed from wild Cicer species to cultivated varieties. Status and importance of molecular markers, genome mapping and genomic tools for chickpea improvement are elaborated. Because of major genes for various biotic and abiotic stresses, the transfer of agronomically important traits into elite cultivars has been made easy and practical through marker-assisted selection and marker-assisted backcross. The usefulness of molecular markers such as SSR and SNP for the construction of high-density genetic maps of chickpea and for the identification of genes/QTLs for stress resistance, quality and yield contributing traits has also been discussed

Basic density, diameter and radial variation of Vanuatu Whitewood (Endospermum medullosum): potential for breeding in a low density, tropical hardwood

Vanuatu whitewood (Endospermum medullosum L.S. Smith) is an economically important timber species for Vanuatu. Inter- and intraprovenance genetic parameters for stem diameter at breast height, basic density and radial variation in density, were estimated for two provenances selected from a 12.4-year-old open-pollinated seed orchard on Espiritu Santo Island, Vanuatu. Kole provenance exhibited the highest mean basic density, greatest mean diameter and greatest radial variation in density across the stem.\ud \ud Mean basic density at breast height was 345±2 kg/m³. Growth rings were not visually discernable and colour was homogenous across all samples. For radial variation determination, each pith-bark core was sectioned into four equi-length subcores (A-D). Subcore density increased consistently and significantly from pith to bark, with mean basic density of 308±3, 327±3, 343±3 and 359±3 kg/m³ for cores A-D respectively.\ud \ud The narrow-sense heritability estimate (h²) was low (0.26±0.2) for diameter, with a moderate coefficient of additive genetic variation (CV(A) = 17.61%). Estimated h² for density was moderate (0.49±0.24), with a low coefficient of additive genetic variation (CV(A) = 5.39%). Though the precision of these estimates is modest, reflective of the small sample size, indications are that the heritable genetic variation in both growth and quality traits will result in economic gain from a recurrent selection and breeding program

Variation in growth traits and wood density in whitewood (Endospermum medullosum): a major timber species in Vanuatu

A breeding program aimed at increasing economic value of whitewood plantations in Vanuatu and conserving declining genetic resources will take direction from the results of this study. Genetic parameters for stem diameter breast height over bark (DBHOB), straightness and branching were estimated in an 11.4-year-old whitewood breeding population on Espiritu Santo Island. Wood density variation in one subpopulation was also studied. Trees with the fastest growth and best form were from Espiritu Santo. Growth and form trait heritability estimates (h2= 0.10-0.16) were low to moderate, with moderate phenotypic variation (CVP = 17-36%). DBHOB at 11.4-years and 4-years were very closely genetically correlated (rA = 1.00 ± 0.17). Mean unextracted wood basic density at breast height was 330 (SD±21) kg/m3, or similar to mature-tree densities. Economic gain in growth traits can be expected from a recurrent selection and breeding program given the heritable genetic variation indicated in this study. Conserving genetic diversity in this species is a high priority