Zeatin

About: Zeatin is a research topic. Over the lifetime, 2467 publications have been published within this topic receiving 64092 citations. The topic is also known as: Zeatin & (E/Z)-zeatin.

Plant growth biostimulant activity of the green microalga Desmodesmus subspicatus

Abstract: The plant biostimulant activity of the green microalga Desmodesmus subspicatus was investigated, focusing on its potential application to organic crops. Different concentrations of D. subspicatus biomass suspensions were applied to tomato seedlings (Solanum lycopersicum) via a foliar spray. The treatments promoted root growth and foliar area, which increased when the suspension was applied at concentrations of 1 g L−1 and 0.4 g L−1, respectively. To elucidate the major constituents responsible for this potential activity, the biomass of D. subspicatus was submitted to aqueous extraction and dialysis (1 kDa cut-off), giving rise to the non-dialyzable fraction E (12.3%). Size-exclusion chromatography performed on fraction E using a Bio-Gel P-2 column yielded six subfractions. Gas chromatography-mass spectrometry (GC–MS) and nuclear magnetic resonance (NMR) analyses of the E subfractions revealed the presence of glycosides as major constituents (approx. 81%), including one acidic glycoside, [6-sulfo-α- D -quinovopyranosyl-(1→1)-glycerol], and two neutral galactosyl glycosides, [α- D -galactopyranosyl-(1→6)-β- D -galactopyranosyl-(1→1)-glycerol] and [β- D -galactopyranosyl-(1→1)-glycerol]. Ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) analyses of fraction E resulted in the identification of the phytohormone zeatin (35 μg g−1). To evaluate the biostimulant potential of fraction E, different concentrations (0.5, 1.0, 1.5, and 2.0 g L−1) were tested for their effects on tomato seed germination, hypocotyl volume, and length. All tested concentrations induced increased hypocotyl lengths and volumes compared with standard treatment (water), at rates equivalent to those in response to a commercial product derived from Ascophyllum nodosum brown seaweed. These results indicated that the biomass suspension and aqueous extract of D. subspicatus showed plant growth biostimulant activity. Glycosides, together with zeatin, may play important roles in biostimulant activity.

Development of Agrobacterium-Mediated Transformation of Pear (Pyrus communis L. ) with Cotyledon Explants and Production of Transgenic Pears Using ACC Oxidase cDNA

Abstract: To develop a transformation system for pear cultivars (Pyrus communis L.), we investigated the ability of cotyledon explants produced from seeds of mature fruit to regenerate, and monitored transgene expression during the early stages of the transformation procedure. The greatest shoot regeneration was induced on MS medium, supplemented with 2μM NAA and 30μM TDZ for ‘La France’ cotyledons (40%), and supplemented with 8μM NAA and 30μM TDZ for ‘Bartlett’ cotyledons (75%). Of the three cytokinins (TDZ, BA and Zeatin) examined, TDZ was the most effective for adventitious bud formation. To investigate the transfer of genes into pear cotyledon explants, we used a modified GUS gene that is expressed in plant tissues exclusively. Gene transfer was measured via transient expression of the GUS gene. The greatest frequency of gene transfer (82.7%) occurred when the explants were co-cultivated in the dark for 7 days after being inoculated with Agrobacterium tumefaciens strain EHA101 without pre-culture. A practical transformation was also conducted, in which carnation cDNA encoding an ACC oxidase (DC-ACO) was induced into cotyledon explants of two pear cultivars. Four transgenic ‘Bartlett’ seedlings and two ‘La France’ seedlings were obtained. Simultaneously, three lines of nontransformed control plant that had the same genome as the transgenic plants were obtained by inducing regeneration of a noninoculated cotyledon derived from the same seed as an inoculated cotyledon. PCR and Southern blot analyses confirmed the integration of the transgene in the genomes of all the transgenic lines.

Plant Regeneration from Mesophyll and Cell Suspension Protoplasts of Sweet Potato, Ipomoea batatas (L.) Lam.

Abstract: Mesophyll protoplasts of sweet potato, variety Chugoku No.25, were isolated from shoot tip cultures grown in vitro. After the surface of the leaves was scratched with sterilized carbo-rundum, they were plasmolyzed for I hour in 0.3 M sorbitol and 0.05 M CaCl2. The enzyme solution for isolation contained 0.1%Pectolyase Y-23, 2 % Cellulase Onozuka RS, 5 mM CaCl2 and 0.5 M mannitol in a modified K3 medium (Kao and Michayluk 1981). The crude protoplast suspension was filtered through a nylon mesh and protoplasts were isolated by discontinuous density gradient centrifugation. The initial medium used was a modified KM8p medium (Kao and Michayluk 1975) sup-plemented with 0.1 mg/l zeatin (ZEA), 0.1 mg/1 2, 4-dichlorophenoxyacetic acid (2, 4-D). 0.5 M mannitol and 10 g/l sucrose. The cell colonies formed were plated on a mQdified MS medium (Murashige and Skoog 1962) for callus forma-tion containing 20 g/l sucrose, 2 g/l Gellan Gum, 0.5 mg/l 2, 4-D and I mg/1 abscisic acid (ABA) with or without 0.5 mg/l kinetin (KlN) or 0.5 mg/l ZEA. Furthermore, the calli were transferred to a MS medium for regeneration supplemented with 30 g/l sucrose, 2 g/l Gellan Gum and 1 mg/l KlN or 0.5 mg/l ZEA. Compact calli were induced on the medium supplemented with ZEA, and regenerated plants were obtained. The effects of silver nitrate (AgNO3) and drying on plant regeneration were investigated. AgNO3 was not effective for plant regeneration, but the drying treatment for 3 days prior to transfer to the medium for regeneration was effective. Cell suspension protoplasts were isolated from the embryogenic calli initiated from the shoot apical domes in the same manner as used for mesophyll protoplast isolation. The initial culture medium and the callus proliferation medium were identical to those used for mesophyll protoplast. Drying treatuent was also effective to enhance the frequency of adventitious bud formation, and regenerated plants were obtained.

Cytokinins from Apple Extract and Coconut Milk

Abstract: Cytokinin containing extracts of young apples and of coconut milk were purified and subjected to chemical treatments designed to modify the chemical natures of the cytokinins Chromatographic comparisons were then made between the cytokinins of the treated and untreated extracts and zeatin and zeatin nucleoside

The possible involvement of cytokinins in the pathogenicity of Helminthosporium maydis

Abstract: Green islands/infection sites recorded higher cytokinin activity than surrounding tissue as well as non-inoculated tissue. This activity in infected areas increased with time of incubation while in tissue surrounding the green islands and non-inoculated tissue, cytokinin activity decreased with time of incubation. The culture filtrate extracts of H. maydis had cytokinin activity which increased with growth of the fungus. Cytokinin activity of thin-layer Chromatographic fractions from tissue and culture filtrate extracts revealed that a major portion of the activity was confined to Rf zone 0.6 to 0.8 which co-chromatographed with zeatin and zeatin riboside. Presence of zeatin and zeatin riboside in tissue and culture filtrates was confirmed by high performance liquid chromatography. Cytokinin substances, such as zeatin and zeatin riboside, increase at infection sites with growth of the pathogen suggesting they may be involved in the pathogenicity of H. maydis on maize.