Efficient in vitro propagation of Agave parrasana Berger

An efficient method for the in vitro propagation of Agave parrasana Berger, an important ornamental plant species native to the state of Coahuila, México, was developed. Proliferation of good quality shoots was achieved on agar-solidified basal MS medium supplemented with L₂ vitamins and 13.3 μM benzyladenine. Rooting was successful in the basal medium with no growth regulators; however, a light intensity of 100 μmol m^-2 s^-1 was found to promote better rooting than 25 μmol m^-2 s^-1. This revised version was published online in June 2006 with corrections to the Cover Date.     

Somatic embryogenesis in Agave tequilana Weber cultivar azul

Somatic embryogenesis was achieved from leaves of Agave tequilana Weber cultivar azul utilizing MS medium supplemented with L2 vitamins and the addition of cytokinins: 6-benzylaminopurine (BA), 1-phenyl-3(1,2,3-thiadiazol-5-yl)urea (TDZ), 6-(γ-γ-dimethylamino)purine (2ip) and 6-furfurylaminopurine (KIN), combined with the auxin 2,4-dichlorophenoxyacetic acid (2,4-D). Differences among the six genotypes studied with regard to their embryogenic response in culture were found. Embryos produced by genotype S3 under a hormone regime of high cytokinin (44.4 to 66.6 μM BA) compared to auxin (4.5 μM 2,4-D) contained chlorophyll, whereas those produced when auxin was high compared to cytokinin (9.0 and 13.6 μM 2,4-D and 1.3 and 4.0 μM BA, respectively) were whitish and morphologically similar to their zygotic counterparts. Somatic embryos matured and germinated after transferring the embryogenic calli to maturation and germination medium without growth regulators and enriched with organic nitrogen. Microscopic observations demonstrated a unicellular origin for production of indirect somatic embryos.     

Cellular and molecular changes associated with somatic embryogenesis induction in Agave tequilana

In spite of the importance of somatic embryogenesis for basic research in plant embryology as well as for crop improvement and plant propagation, it is still unclear which mechanisms and cell signals are involved in acquiring embryogenic competence by a somatic cell. The aim of this work was to study cellular and molecular changes involved in the induction stage in calli of Agave tequilana Weber cultivar azul in order to gain more information on the initial stages of somatic embryogenesis in this species. Cytochemical and immunocytochemical techniques were used to identify differences between embryogenic and non-embryogenic cells from several genotypes. Presence of granular structures was detected after somatic embryogenesis induction in embryogenic cells; composition of these structures as well as changes in protein and polysaccharide distribution was studied using Coomassie brilliant blue and Periodic Acid-Schiff stains. Distribution of arabinogalactan proteins (AGPs) and pectins was investigated in embryogenic and non-embryogenic cells by immunolabelling using anti-AGP monoclonal antibodies (JIM4, JIM8 and JIM13) as well as an anti-methyl-esterified pectin-antibody (JIM7), in order to evaluate major modifications in cell wall composition in the initial stages of somatic embryogenesis. Our observations pointed out that induction of somatic embryogenesis produced accumulation of proteins and polysaccharides in embryogenic cells. Presence of JIM8, JIM13 and JIM7 epitopes were detected exclusively in embryogenic cells, which supports the idea that specific changes in cell wall are involved in the acquisition of embryogenic competence of A. tequilana.     

Light-Intensity and Leaf-Area Are Important Factors Development Tubers of Yam

Russian Journal of Plant Physiology - Foliar area is the most important part of the plant as light energy (photons) which has an impact in biomass production is collected there. Mathematical models...     

Effect of plant growth regulators on plant regeneration of Dioscorea remotiflora (Kunth) through nodal explants

Dioscorea remotiflora (Kunth) is an important wild plant that produces tuberous roots used as a source of food in the Western part of Mexico. Lack of planting material and inefficiency of traditional methods of propagation are the main constraints for implementing large-scale cultivation. In contrast, tissue culture techniques allow increasing multiplication and rapid production of plant material. In this regard, leaves or nodal segments were incubated on MS, B5 and WPM culture media with different PGRs in order to obtain an efficient micropropagation protocol. Leaves explants were unable to inducing shoots or callus. However, nodal segments produced axillary shoots and/or callus in all culture media. MS containing 2.33???M KIN was the most suitable to inducing shoots; an average of 6.6 shoots per segment for 100?% explants was obtained, which displayed also the greater number of nodes (5.0) and leaves (7.9) per segment. A decrease on shoot proliferation was observed combining BA or KIN with 2,4-D or NAA. However, small brownish callus were induced on 100?% of segments using 2.33???M KIN with 5.37???M 2,4-D or 9.30???M KIN plus 2.69???M NAA. In contrast, by adding 2.69???M NAA, 66.4?% of the nodal segments formed shoots and produced also yellowish friable callus on the base of the shoots. Shoots were easily rooted with 8.28???M IBA (96.9?%), displaying the greatest root and shoot biomass, but maximum number of tuberous roots, and root or tuberous root biomass was produced increasing IBA (20.7???M).     

Effect of liquid seaweed extracts on growth of tomato seedlings (Solanum lycopersicum L.)

Seaweed extracts are used as nutrient supplements, biostimulants, or biofertilizers in agriculture and horticulture to increase plant growth and yield. In this study, we examined the effect of liquid seaweed extracts (LSEs) made from Ulva lactuca, Caulerpa sertularioides, Padina gymnospora, and Sargassum liebmannii as biostimulants on the germination and growth of tomato (Solanum lycopersicum) under laboratory and greenhouse conditions using foliar and soil drench applications of LSEs. We assessed LSEs at different concentrations (0.2, 0.4, and 1.0 %) on germination parameters (percentage, index, mean time, energy, and seedling vigor index) and growth parameters (plumule length, radical length, shoot length, root length, fresh weight, and dry weight) of tomato seedlings. Our results indicate that seeds treated with LSEs of U. lactuca and P. gymnospora at lower concentrations (0.2 %) showed enhanced germination (better response in germination rate associated with lower mean germination time, high germination index and germination energy, and consequently greater seedling vigor and greater plumule and radicle length). Application as a soil drench was found to be more effective in influencing the height of the plant (up to 79 cm) than the foliar spray application (75 cm). Plants receiving LSEs of U. lactuca and P. gymnospora showed increased shoot length, root length, and weight. Furthermore, U. lactuca and P. gymnospora were found to be more successful and better candidates for developing effective biostimulants to improve the growth of tomato plants. This study provides important information on the identification and utilization of Mexican seaweed resources for agriculture and is the first study to report on the uses of these seaweeds as a source of liquid extracts as biostimulants in agriculture.