No abstract

An in vitro method was developed to regenerate large numbers of phenotypically uniform plants from the basal parts of the leaves of flowering plants of Renanthera imschootiana Rolfe. Differentiation of up to 10 shoot buds free of callus and protocorm-like bodies occurred in 10-12 weeks from the base of a single leaf implanted in Mitra et al. (1976) medium supplemented with 2% sucrose, 2gl -l peptone, 44.4 txM benzyladenine (BA) and 10.7 I~M naphthaleneacetic acid (NAA). Subculture of the tissues in medium enriched with 10% coconut water and 35 g 1 i ripe banana pulp resulted in the production of highest average number of 40 shoots in 12 weeks. No difference in the regeneration potential was observed among the three young leaves while mature leaves did not respond. All the leaves of the regenerated shoots were easily recultured to increase shoot multiplication. Shoots readily formed roots on transfer to a medium containing 4.41xM BA, 10.7 IxM NAA and 1% activated charcoal. All regenerated plants examined were normal diploids with 2n = 38. Foliar meristem culture appears to have great potential for ex situ conservation and propagation of this extremely endangered orchid.

Clonal propagation of Adhatoda beddomei C.B. Clarke (Acanthaceae), a rare medicinal shrub, was achieved through callus-free axillary meristem proliferation from stem node explants of field-grown plants cultured in SH medium. Shoot multiplication was a function of cytokinin activity but sustained growth of the shoots was dependent on the synergistic effect with the auxin, IAA. An optimum number of 5-10 shoots per explant were obtained in 6 weeks using 3.0 mg.l(-1) BAP, 0.5 mg.l(-1) 2-ip and 1.0 mg.l(-1) IAA, Upon subculture, vertical halves of the precultured node with the differentiated shoots yielded a larger aggregate number of shoots (23-27) than the uncut precultured node left intact (15-17). Shoot multiplication was rapid and consistent over prolonged periods when the hormonal concentrations were reduced to 1.0 mg.l(-1) BAP and 0.2 mg.l(-1) IAA during subculture, and reculture of the nodal explants derived from shoot cultures. Rooting of 3-5 cm shoots thus obtained was greatly accelerated in stationary liquid medium containing 0.2 mg.l(-1) IBA or IAA. Hardening of the rooted plantlets in the humidity chamber was essential for high frequency (95%) survival. Micropropagated plants established in the field flowered after fifteen months and were free from apparent defects in cytological, growth and flowering characteristics.

Genetic diversity was estimated in 13 accessions of the otherwise self pollinated Mucuna pruriens (L.) DC. (velvetbean) comprising varieties pruriens and utilis collected from tropical humid forest using 15 RAPD primers. Similarity index value of 0.68 based on Nei and Li's similarity coefficient indicated high degree of genetic variability. Analysis of various genetic diversity indices like total heterozygosity, Nei's gene diversity, percentage of polymorphic loci, expected and observed number of alleles and Shannon index strongly suggests that variety pruriens is genetically more diverse than variety utilis. Chemical analysis with respect to 3,4-dihydroxy-L-phenylalanine (L-DOPA) content showed uniform distribution. Cluster analysis showed grouping of accessions into two major clusters and tendency of accessions of variety pruriens to group according to their geographical locations. Bootstrap analysis confirmed the robustness of the phenogram. The putative hybrid MMP6 with relatively low similarity value index and low L-DOPA content was promising as food or fodder.

Photosynthetic properties of cell suspension cultures derived from the callus proliferation of eladophyll explants of Chamaecereus sylvestrii Spegazzini were studied. High content of chlorophyll (105-120 [xg/g fresh weight), cyanide sensitive Oi uptake and maximal rates of O, evolution (100-115 ^mol/mg Chi X h) and COj fixation (13()-150 nmol/mg Chi x h) were some of the properties of the exponential phase cells. Determination of the component reactions, viz. photosystems I and II and photophosphoryiation of the chloroplasts isolated from the cells, indicated normal development and functioning of the photosynthetie machinery.Studies on the enzymatic reactions as well as the determination of the early produets of "CO2 fixation in light in these eells implicated the operation of both autotrophic and non-autotrophic pathways, the latter being less pronounced. The diurnal oscillation of titratable acidity and malate content found in the intact eladophyll tissues was absent in the cultured cells. Evidences for a rapid and continuous drain of carbon from malate into the citrate and isocitrate components of the TCA cycle via pyruvate after decarboxylation, and then into the amino acid pool are presented. The absence of large vacuoles and the rapid turnover of malate are considered to account for the lack of diurnal fluctuation of organic acide in the cell cultures.