An aberrant plastid ribosomal RNA gene cluster in the root parasite Conopholis americana

The plastid ribisomal RNA (rRNA) operon of the achlorophyllous root parasite Conopholis americana was completely sequenced. Full-length rRNA genes are retained in the gene cluster, but significant divergence has occurred in the 16S, 23S and 5S genes. Both the 16S–23S intergenic spacer and the 4.5S–5S intergenic spacer have suffered substantial deletions, including the two tRNA genes typically found in prokaryotic and plastid 16S–23S spacers.     

Agrobacterium and plant genetic engineering

Erratum

Agrobacterium and plant genetic engineering     

Tissue culture and plant propagation of Gomphrena officinalis — a Brazilian medicinal plant

Leaf and stem segments of Gomphrena officinalis originated from aseptically grown seedlings were used to initiate cultures. Callus production was obtained on gelled Murashige & Skoog medium supplemented with 6-benzylaminopurine alone (1.0, 5.0 or 10.0 mgl^-1) or combined with -naphthalene acetic acid (0.1, 0.5 and 1.0 mgl^-1) after 10 to 15 days of culture, and can be transferred to fresh medium every 30 days. The combinations of 5.0 or 10.0 mgl^-1 of 6-benzylaminopurine with 0.1 mgl^-1 of -naphthalene acetic acid were found to be the best for shoot regeneration. Adventitious shoot formation occurred after 50 to 60 days of culture in leaf and internode stem explants. Nodal segments developed actively growing lateral buds after 30 days of culture. Gelled Murashige & Skoog medium containing 10 mgl^-1 of indole-3-butyric acid was considered optimal for the rooting of shoots. Rooted plants transferred to potting soil could be successfully established.Abbreviations BA 6-benzylaminopurine - IAA indole-3-acetic acid - IBA indole-3-butyric acid - MS Murashige & Skoog - NAA -naphthalene acetic acid     

Foliar regeneration of the endangered Red Vanda,Renanthera imschootiana Rolfe (Orchidaceae)

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, 2 g l^-1 peptone, 44.4 M benzyladenine (BA) and 10.7 M naphthaleneacetic acid (NAA). Subculture of the tissues in medium enriched with 10% coconut water and 35 g l^-1 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 4.4 M BA, 10.7 M 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.Abbreviations BA benzyladenine - NAA naphthaleneacetic acid     

Genome modifications in protoplast-derived tobacco plants: Contents of repetitive DNA sequences

Plasticity of the tobacco genome was studied by testing the DNAs of protoplast-derived regenerants with three different repetitive DNA sequences by the method of quantitative DNA/DNA hybridizations. A large population of 91 regenerants belonging to 35 different protoclones was analysed and a high degree of heterogeneity in the contents of the different DNA repeats was detected. The contents of middle repetitive sequences of two types were more stable or changed in the same direction, while the highly repetitive sequence varied independently and displayed a significant reduction in comparison with the two other sequences. Comparing the variation within the subpopulations of plants of the same clonal origin and the variation among the protoclones led to a conclusion that the pre-existing DNA variability in the starting plant material and/or thein vitro stress during the very early stages of protoclone regeneration played a decisive role in the formation of modified genomes in regenerants.     

Distribution of rhodanese in plants

To study the distribution of rhodanese (E.C. 2.8.1.1) in plants, rhodanese activity was assayed on 13 cyanogenic and 12 non-cyanogenic species. All the species tested had the enzyme activity. This phenomenon leads to a hypothesis that the enzyme is generally distributed in plants.     

Aeration: A simple method to control vitrification and improve in vitro culture of rare australian plants

Summary Aeration of tissue cultured rare Australian plantsConostylis wonganensis S.D. Hopper (Haemodoraceae);Diplolaena andrewsii Ostenf.;Drummondita ericoides Harvey (Rutaceae);Eremophila resinosa F. Muell. (Myoporaceae);Eucalyptus ‘graniticola’ (Myrtaceae);Lechenaultia pulvinaris C. Gardner (goodeniaceae); andSowerbaea multicaulis E. Pritzel (Liliaceae) has been found to reduce vitrification in sensitive species as well as significantly improving shoot quality and transfer to soil in most study species. A simple 7-mm hole with a double-layer insert of filter paper in the polypropylene screw lids of the culture vessel decreased shoot vitrification over a 4-wk culture period. The method has implications for facilitating the tissue culture of other rare Australian plants and reducing the occurrence of this developmental abnormality.     

Reversed animal-plant interactions: the evolution of insectivorous and ant-fed plants

Insectivorous plants and ant-fed plants represent the two ways in which plants have evolved to utilize directly nutrients derived from animals. This paper addresses the limitations under which selection acts to favour the evolution of one or the other of these nutrient-gathering tactics. Both tactics have evolved independently at least six times under similar ecological conditions, indicating that the evolutionary solutions to ecological problems are limited by the historical make-up of communities and are, to some extent, predictable. Both insectivorous and ant-fed plants evolve in environments with very low levels of availability of nutrients in the substrate; the primary use of the animal-food is probably nitrogen; the vast majority of species are perennial, and most species are tropical or subtropical, although some insectivorous genera are primarily temperate.
Although these two nutrient-gathering tactics evolve in response to similar ecological problems, whether plants evolve an insectivorous habit or the ant-fed habit depends on the growth forms of the plants and the habitats in which they grow. Most insectivorous plants evolve as herbs in wet, sterile soils or in sterile aquatic habitats; ant-fed plants evolve as epiphytes on trees in open-canopied habitats. These kinds of animal-plant interactions are relatively rare because the environments in which they are favoured by selection are uncommon.     

Production of submerged aquatic plant communities of Doodhadhari lake Raipur, (M.P. India)

The biomass of submerged aquatic plant communities was studied periodically during two annual growth periods. Najas minor contributed 78% to the total standing biomass. Ceratophyllum demersum, Hydrilla, Nelumbo nucifera, Trapa bispinosa and Potamogeton crispus contributed towards the rest of the biomass. The production was 0.64 g./m.²/day for the growing seasons of one year.     

盐性条件下植物内生真菌多样性及其生态学功能研究

<正>据统计,盐化土壤在地球上所占比例超过7%,我国盐渍土面积约9 900万hm2,土壤盐渍化对农业生产的影响已成为一个全球性的问题。盐生植物是盐渍化土壤中的天然植物类群,可显著降低土壤盐分,改善盐碱土壤肥力及土壤微生物种群结构。内生真菌生活在植物体内,可促进其宿主生长,增强宿主的抗干旱和抗病虫害能力。长期生活于盐渍化土壤中的盐生植物具有耐盐碱、耐旱等特性,其体内也因积累大量的Na+和Cl-成为一个高盐的微环境。有研究表明,内生真菌在盐胁迫条件下能促进盐生植物的生