Dynamics of essential oil biosynthesis in relation to inflorescence and glandular ontogeny inSalvia sclarea

Changes in the essential oil concentration, composition and glandular morphology of Salvia sclarea L. were studied at different stages of inflorescence maturity. The chemical composition of oil was determined by GC–MS, NMR and the peak enrichment technique. The oil yield at bud stage on a fresh basis was minimum (0.08%), peaked at full bloom stage (0.18%) and was followed by sharp decline on maturation (0.07%). The main components of the oil were linalool (36.6–41.9%) and linalyl acetate (13.2–19.2%). The maximum percentage composition of various constituents was coincident with full bloom stage. β -Humulene (6.4–8.9%), α -cadinene (t–1.5%), β -caryophyllene (t–1.4%), β - caryophyllene oxide (0.4–1.4%) and sclareol (0.3–1.8%) present in the oil showed gradual increase in percentage over the different stages of maturity, with no significant turnover losses at maturation stage. Turnover of essential oil (61.1% loss) and monoterpenes (23.6% loss) occurred late in development at full maturity. Scanning electron microscopy (SEM) was used to follow the changes in the oil secretory glands over different temporal phases of maturation. The decline in oil concentration and monoterpene constituents compared very well with the observed deterioration and lyses of secretory glandular system. An abrupt fall in oil concentration apparently appears due to differential evaporation of the more volatile constituents, rather than as a dynamic balance between biosynthetic and catabolic processes

Comparative analysis of genetic diversity using molecular and morphometric markers in Andrographis paniculata (Burm. f.) Nees

Andrographis paniculata is a medicinal plant of immense therapeutic value. The present study was aimed to elucidate its genetic diversity based on morphochemical and RAPD markers from 53 accessions belonging to 5 ecogeographic regions. Analysis of variance and D2 statistics revealed significant differences in all the metric traits and sufficient inter-cluster distances indicating considerable diversity among the accessions. The complementary approach of RAPD was used to evaluate the genetic dissimilarities among all the accessions using 6 highly polymorphic primers. The average proportion of polymorphic loci across primers was 96.28%. The molecular genetic diversity based on Shannon index per primer averaged 5.585 with values ranging from 3.08 to 8.70 indicating towards wide genetic base. RAPD based UPGMA and D2 cluster analysis also revealed that various accessions available in different eco-geographic regions might have originated from native places of wild abundance. Similarity matrices were generated for molecular markers and morphometric data to determine the degree of congruence between the two. A highly significant but low correlation(r = 0.547, P < 0.001) was obtained thus implying the correspondence between the two. The species is hermaphroditic and a habitual inbreeder. The present study yielded a typical triangular congruence between its breeding system, morphometric traits and RAPD markers thus elucidating the usefulness of complementary approaches to make diversity analysis more explanatory and purposeful for optimum genetic amelioration and effective conservation of its genotypic variability