Robert H. Hamilton

Plant regeneration from callus tissue of Gossypium hirsutum L.

Abstract The regeneration of plants from cotton callus (Gossypium hirsutum L. cv. Coker 310) is described. Somatic proembryoids developed spontaneously after two years in culture on a modified Linsmaier and Skoog (LS) medium. The percentage of calli-forming proembryoids was increased to about 30% by prolonged culture without naphthalene acetic acid (NAA) and kinetin. Development of proembryoids was enhanced by transferring proembryoids to media lacking NH4NO3 but containing double the standard KNO3 concentration and gibberellic acid (GA). Root initiation and growth was promoted by lowering the glucose concentration to 5 g/1.

Intracellular Localization of Growth Hormones in Plants

Autoradiographic studies of Allium cernuum and Vicia faba root-tip cells treated with indoleacetic acidmethyl-C14 or 2,4-dichlorophenoxyacetic acid-carboxyl-C14 revealed nuclear and cytoplasmic labeling of the cells. The cytoplasmic labeling decreased with time after the removal of the labeled auxin, but nuclear and chromosomal labeling was retained for at least 120 hours.

A rapid isotope dilution method for analysis of indole-3-acetic acid and indoleacetyl aspartic acid from small amounts of plant tissue

A method is described for analysis of indole-3-acetic acid and indoleacetyl aspartic acid in plant tissue. Methanolic extracts are purified on two small columns prior to HPLC using an electrochemical detector. In,vivo amounts are calculated by isotope-dilution analysis. The method requires only 1 g of tissue, results in relative high recoveries, and is sensitive to the 20 pmol range or below. Typical results using light-grown Pisum,sativum cv. Little Marvel tissue are given. This report is the first determination of the natural level of the aspartate derivative in growing plant tissues.

Dieldrin: Extraction of Accumulations by Root Uptake

Certain forage crops can absorb and translocate the chlorinated hydrocarbon insecticide dieldrin from soil or sand. An extraction technique routinely used for analyses of residues does not quantitatively remove this internal chemical, but a method employing chloroform-methanol extraction leads to essentially quantitative recovery.

Transfer of the tumor inducing factor in Agrobacterium tumefaciens.

Summary The Crown-gall tumor inducing factor in Agrobacterium tumefaciens bacterial strain C-58 may be removed by culture at 36°C and it can be reintroduced by inoculation into tomato tumors previously induced by the virulent strain TT-133-1.

Advances in pesticide metabolite identification through the use of plant tissue cultures

Plant tissue cultures are powerful tools for metabolism studies. Culture conditions can be selected which mimic conditions of whole plants or conditions can be employed to mass-produce selected metabolites such as aglycons or conjugates. Culture variables that affect metabolism are medium composition, age of tissue cultures, concentration of test chemical, and the source of plant tissue. The type of culture, such as suspension cultures, callus tissue cultures, differentiated tissue or organ cultures will also influence the type of metabolites obtained. Ease of standardizing conditions makes tissue culture suitable to comparatively examine metabolism in different plant species and strains and in different plant parts such as tissues derived from leaves and roots. Recent advances with plant tissue cultures involve studies of the mechanism of action or selectivity of growth regulators and herbicides, and the use of resistant strains to investigate mechanisms of biological detoxification.

Genes with Mutations Causing Herbicide Resistance from the Cyanobacterium Synechococcus PCC 7002

The cyanobacterium Synechococcus PCC 7002 (Agmenellum quadruplicatum) was chosen for the isolation and characterization of mutant genes which convey resistance to some commonly used herbicides. The goals of this project are to investigate the mechanisms by which resistance is achieved and to transfer the resistances into agronomically useful plants.