EFFECTS OF VISIBLE AND ULTRAVIOLET RADIATION ON THE GERMINATION OF PHACELIA TANACETIFOLIA

Schulz , Sister M. Richardis , O.P., and Richard M. Klein . (N. Y. Bot. Gard., N. Y., N. Y.) Effects of visible and ultraviolet radiation on the germination of Phacelia tanacetifolia. Amer. Jour. Bot. 50(5): 430–434. Illus. 1963.—Germination of Phacelia tanacetifolia was suppressed by exposure to white light increasing with intensity and length of illumination. The light effect decayed during 24 hr of darkness. Seeds were most sensitive to the suppressive effects of light 13–17 hr after the beginning of imbibition. Light suppression was caused by a photocatalytic reaction. Wavelengths causing the suppression lie in the far-red, red, blue, near-ultraviolet and far-ultraviolet regions of the spectrum. At equal energies, blue light was less effective than far-red, red or ultraviolet radiation. There was no evidence for the existence of the phytochrome system. Simultaneous irradiation with red and blue light or simultaneous irradiation with red and far-red induced a synergistic repression of germination. The presentation of different wavelengths in various sequential patterns markedly altered the germination response. An interaction between elevated temperatures and visible radiation affecting germination response was also noted.     

GROWTH INDUCTION IN CULTURES OF HAPLOPAPPUS GRACILIS. I. THE BEHAVIOR OF THE CULTURED CELLS

Blakely , L. M., and F. C. Steward . (Cornell U., Ithaca, New York.) Growth induction in cultures of Haplopappus gracilis. I. The behavior of the cultured cells. Amer. Jour. Bot. 48(5): 351–358. Illus. 1961.—Because of the unusual cytology of Haplopappus gracilis (2n = 4), a study has been made of the growth of its stem tissue in culture. Although growth may occur on a basal medium supplemented in various ways, it was stimulated for present purposes by the use of a basal medium containing casein hydrolysate, coconut milk (2–10% by volume) and naphthaleneacetic acid (0.5 p.p.m.). A definite synergism between coconut milk and naphthaleneacetic acid was demonstrated. The general form of the colonies so obtained responds to the composition of the medium, and certain effects of pigmentation indicate that the biochemistry of the cultured tissue is also a function of the conditions. The Haplopappus cultures were maintained in liquid culture either in the form of free cells or of the small cell clusters to which they readily gave rise. The form of typical cells and cell clusters is described, and stress is laid upon the range of growth forms that are encountered. Variations in suspensions of cells, or small cell clusters, may be investigated by the application of simple microbiological techniques. Haplopappus gracilis is thus a useful material for the further study of growth and morphogenesis by tissue culture techniques.     

EFFECT OF 2-CHLOROETHYLTRIMETHYLAMMONIUM CHLORIDE ON FERN GAMETOPHYTES

Kelley , A. G., and S. N. Postlethwait . (Purdue U., Lafayette, Ind.) Effect of 2-chloroethyltrimethylammonium chloride on fern gametophytes. Amer. Jour. Bot. 49(7): 778–786. Illus. 1962.—2-chloroethyltrimethylammonium chloride (CCC) promotes growth of fern gametophytes by stimulating the rate of cell division. The transition from filamentous to biplanar to triplanar cell division is hastened, resulting in earlier and more numerous gametangia on treated prothalli. Growth is stimulated in the range of 10^-4 m –10^-2 m CCC, with the optimal effect at 10^-3 m CCC. The time sequence of rhizoid production is altered by 10^-2 m CCC; the resultant production of rhizoids by prothalli treated with 10^-2 m CCC does not exceed that of controls.     

GROWTH FACTOR INTERACTIONS IN THE TISSUE CULTURE OF TUMOROUS AND NONTUMOROUS NICOTIANA GLAUCA-LANGSDORFFII

Schaeffer , Gideon W., Harold H. Smith and Marion P. Perkus . (Brookhaven Natl. Lab., Upton, N. Y.) Growth factor interactions in the tissue culture of tumorous and nontumorous Nicotiana glauca-langsdorffii. Amer. Jour. Bot. 50(8): 766–771. Illus. 1963.—Tissues representing tumorous and nontumorous Nicotiana glauca-langsdorffii were cultured on high (5 ×) and low (1 ×) concentrations of a modified White's basal medium containing 2.9 × 10^–6m indoleacetic acid. The growth responses of tissues of both the tumorous and nontumorous genotypes to supplements of kinetin, glutamine, inositol and nucleic acid constituents added singly and in all combinations were noted on high-salt media. The nucleic acid components inhibited growth and were omitted from low-salt media. The best growth response was observed with glutamine and inositol for tissues from the tumorous hybrid and with glutamine, inositol and kinetin in the nontumorous type. Kinetin was a distinct and consistent requirement for rapid growth of nontumorous tissues, but no appreciable kinetin effect could be observed with tissues from the tumorous genotype.     

Scopolin, a Biochemical Marker for Resistance to Thielaviopsis basicola in Callus and Crown-Gall Tissue Cultures of Tobacco

Scopolin concentration increased in tissue cultures where Thielaviopsis basicola growth ceased (primary and established callus cultures of the resistant tobacco cultivar Ky 170) while it decreased in tissue cultures where fungal growth persisted (primary and established callus cultures of the susceptible tobacco cultivar Ky 151 and crown-gall cultures of Ky 170 and Ky 151). The concentration of chlorogenic acid, scopoletin, and two other unknown soluble phenols varied after inoculation and no, correlation with tissue culture resistance could be established. Incorporation of Agrobacterium tumefaciens T-DNA in the genome of both cultivars induced a drastic reduction of scopolin in inoculated tissue cultures. T-DNA incorporation had less, influence on uninoculated tissues. Scopolin at concentrations found in tissue cultures was not toxic to the fungus.     

THE GROWTH AND DIFFERENTIATION OF CULTURED BARLEY EMBRYOS

Norstog , Knut . (Wittenberg U., Springfield, Ohio.) The growth and differentiation of cultured barley embryos. Amer. Jour. Bot. 48(10): 876–884. Illus. 1961.—Cultures of excised embryos of barley, Hordeum vulgare L., were made on a number of different media. Growth on White's medium was promoted by adding coconut milk. In the absence of coconut milk, amino acids did not promote growth and differentiation. Embryos as small as 60 μ were successfully grown in vitro. Smaller embryos had the capacity to initiate root and shoot primordia but did not possess the ability to form such embryonic organs as the scutellum and epiblast. Proembryos developed shoots and roots only after a period of irregular growth in which unorganized masses of cells were formed. Multiple centers of shoot initiation were observed in such embryos. The results of the study suggest that, in barley at least, embryonic form may result from an interaction between the embryo and nutritional, spatial and other factors within the ovule.     

GROWTH AND SEXUAL REPRODUCTION OF APHANOMYCES EUTEICHES AS AFFECTED BY THE OXIDATION STATE OF SULFUR

Davey , C. B., and G. C. Papavizas . (Crops Res. Div., ARS, USDA, Beltsville, Md.) Growth and sexual reproduction of Aphanomyces euteiches as affected by the oxidation state of sulfur. Amer. Jour. Bot. 49(4): 400–404. Illus. 1962.—Growth and sexual reproduction of Aphanomyces euteiches Drechs., as affected by the oxidation state of sulfur (S), were studied in synthetic media containing d -glucose, dl -glutamic acid, mineral salts phosphate buffer, and various S sources. Organic and inorganic S sources representing some oxidation numbers (valences) were added to the media at concentrations to provide a range from 0 to 128 mg S/liter. The initial reaction in both liquid and solid media was adjusted to pH 6.2. Liquid cultures were maintained at that pH by periodic adjustment. Oxidized S with oxidation number +6 or +4 was not utilized by the fungus, whereas good growth was obtained in the presence of S with oxidation numbers of 0 or -2. Although differences existed among isolates as to relative rates of utilization of the various S sources, there was complete conformity among isolates as to which sources were utilized for growth. Some isolates did not utilize all available S sources for sexual reproduction.     

Metal tolerance in tissue cultures of anthoxanthum odoratum

Tissue cultures were initiated from one non-tolerant (S20) and two zinc and lead tolerant (T92 and T94) clones of Anthoxanthum odoratum. Growth of callus from the non-tolerant clone was reduced by the presence of zinc, lead, copper and nickel, whereas callus from the two tolerant clones showed no reduction of growth in the presence of zinc and lead but growth was reduced by copper and nickel. The specificity of metal tolerance shown by the parental material was maintained in the callus. Tolerant and non-tolerant callus accumulated similar amounts of zinc and lead.     

CALCIUM AND THE CONTROL OF LIGNIFICATION IN TISSUE CULTURES

Lipetz , Jacques . (Rockefeller Inst., New York, N. Y.) Calcium and the control of lignification in tissue cultures. Amer. Jour. Bot. 49(5): 460–464. Illus. 1962.—Crown-gall tissues of Helianthus, Parthenocissus, Nicotiana, habituated Nicotiana, normal carrot, and Parthenocissus tissues grown in vitro on media low in calcium show an increase in lignification. The lignin is deposited not only on the walls of tracheids but on the walls of parenchymatous cells as well. Transferring the tissues to media containing higher calcium concentrations inhibits this excess lignification. Neither strontium nor magnesium could be substituted for calcium. These studies indicate that the availability and concentration of inorganic ions play a role in the control of lignification.     

MITOSIS IN SUSPENSION CULTURES OF HIGHER PLANT CELLS IN A SYNTHETIC MEDIUM

Torrey , J. G., J. Reinert , and N. Merkel . (Harvard U., Cambridge, Mass.) Mitosis in suspension cultures of higher plant cells in a synthetic medium. Amer. Jour. Bot. 49(4): 420–425. Illus. 1962.—A cytological study was made of plant tissue cultures growing in liquid synthetic medium. Mitoses in cell suspension cultures of root callus tissues of Daucus carota L., Convolvulus arvensis L. and Haplopappus gracilis (Nutt.) Gray were found to occur frequently in the first 2 weeks of culture with the highest frequency at about 7 days. No mitoses were observed after 3 weeks, although fresh weight and the number of free-floating cells in the suspension continued to increase for the entire culture period of 4–6 weeks. Mitoses were most frequent in tissue pieces, but occasional mitoses in single isolated cells in suspension were observed in each type of tissue. Normal mitoses were observed in diploid and polyploid cells of all 3 types of tissues cultures. Little evidence of nuclear or chromosomal aberrations was observed in these cultures.     

GROWTH AND DEVELOPMENT OF THE WATER MOLD RHIZIDIOMYCES IN PURE CULTURE

Fuller , Melvin S. (Brown U., Providence, R. I.) Growth and development of the water mold Rhizidiomyces in pure culture. Amer. Jour. Bot. 49(1): 64–71. Illus. 1962.—A method for growing pure cultures of many of the single or few-celled phycomycetous fungi such as Rhizidiomyces is described. This method facilitates both qualitative and quantitative study of such fungi during their growth and development. Zoospores of Rhizidiomyces start to grow within 3 hr after being placed in a liquid medium, and are ready to discharge new zoospores after about 40 hr growth at 25 C. The single nucleus of the zoospore goes through many synchronous mitotic divisions during the development of the mature multinucleate cell. Under carefully controlled environmental conditions, sporangium discharge occurs in a definite and predictable manner. Observations suggesting a possible mechanism of sporangium discharge are presented and discussed.     

STUDIES ON THE GIANT KELP,MACROCYSTIS. I. GROWTH OF YOUNG PLANTS

Neushul , M., and F. T. Haxo . (Scripps Inst. Oceanography, La Jolla, Calif.) Studies on the giant kelp, Macrocystis. I. Growth of young plants. Amer. Jour. Bot. 50(4): 349–353. Illus. 1963.—The growth of entire young plants of Macrocystis pyrifera was studied in the sea and in the laboratory. Measurements were made of plants in natural stands and of plants transplanted to submerged rafts. Macrocystis was raised in laboratory tanks under controlled conditions of light and temperature. Maximum growth rates in the laboratory paralleled those observed in the sea, plants doubling in area every 16–20 days and in length every 20–30 days under optimum conditions. The transplantation experiments and diving observations demonstrated the important influence of biological activity on the establishment and growth of young plants in the sea.     

THE EFFECT OF BENZIMIDAZOLE ON CATION UPTAKE BY PLANT ROOTS

Klingensmith , M. J. (Colgate U., Hamilton, N.Y.) The effect of benzimidazole on cation uptake by plant roots. Amer. Jour. Bot. 48(8): 711–716. Illus. 1961.—A number of benzazole compounds were examined for their effect on cation uptake. Benzimidazole was found to almost double the uptake of potassium by excised barley roots in a 6-hr period. Chlorobenzimidazole also enhanced the absorption of potassium but not to the same extent. This stimulation of potassium accumulation was found to be insensitive to cyanide but was dependent on the temperature of the ambient solution. There was also an increased accumulation of potassium by roots of intact barley plants with benzimidazole treatment without interference with subsequent transport of the potassium. Benzimidazole also stimulated uptake of sodium and calcium by excised barley roots but not at identical levels. Results are discussed in the light of various theories of ion absorption.     

GROWTH INDUCTION IN CULTURES OF HAPLOPAPPUS GRACILIS. II. THE BEHAVIOR OF THE NUCLEUS

Mitra , J., and F. C. Steward . (Cornell U., Ithaca, New York.) Growth induction in cultures of Haplopappus gracilis. II. The behavior of the nucleus. Amer. Jour. Bot. 48(5): 358–368. Illus. 1961.—Cells of Haplopappus, which have been stimulated to grow under the influence of coconut milk and such synergists as naphthalene or 2,4-dichlorophenoxy acetic acid, can be cultivated as free cells, as small cell clusters, or as peripheral cells on a cultured colony or mass. Such cells display forms and cell lineages, the general pattern of which is reminiscent of those that may occur in early embryogeny. To this extent, Haplopappus resembles what has previously been observed in the growth of free cells of carrot. The form of the normal chromosome of Haplopappus (2n = 4) is described with respect to root tip cells. The range of effects which may be observed in the nuclei of the cultured cell is also described. Such variations as the following were encountered: (1) multinucleate giant cells which may divide by internal segmentation; (2) polyploidy, giving rise to highly polyploid nuclei up to, and even in excess of, 64 chromosomes; (3) somatic pairing; (4) haploidy; (5) pseudochiasmata, with the evident implication of somatic “crossing-over”; (6) chromosome breaks, reunions and bridges, such as are commonly associated with effects of radiation and with chemical mutagens. Attention is drawn to the usefulness of this material for the further experimental investigation of the biochemical basis for the cytological events which are here described, and, if the variant cells may be cloned, of the relationship between the aberrant nuclear cytology and the ability of the cells or colonies to differentiate or to undergo morphogenesis.     

THE ONTOGENY OF THE APOTHECIA OF PYRONEMA DOMESTICUM

Moore , Elizabeth J. (Cornell U., Ithaca, N. Y.) The ontogeny of the apothecia of Pyronema domesticum . Amer. Jour. Bot. 50(1) : 37–44. Illus. 1963.—A single hyphal strand produces a cluster of antheridia and ascogonia, each pair of like or unlike sexual differentiation. Each cluster forms 1 apothecium. Plasmogamy is followed by nuclear migration from the antheridium, and an ascogenous system develops from each ascogonium. Concurrently, a sterile system of hyphae arises from the stalk cells supporting the ascogonia and antheridia. Apothecial expansion occurs as a result of the continuous proliferation of all structural elements. Comparisons are made with the closely related and easily confused P. omphalodes (= P. confluens).     

THE EFFECT OF DIFFERENT LIGHT CONDITIONS AND SUCROSE ON THE GROWTH AND DEVELOPMENT OF THE GAMETOPHYTE OF THE FERN,ONOCLEA SENSIBILIS

Miller , J. H. (Yale U., New Haven, Conn.), and P. M. Miller . The effect of different light conditions and sucrose on the growth and development of the gametophyte of the fern, Onoclea sensibilis. Amer. Jour. Bot. 48(2): 154–159. Illus. 1961.—Gametophytes grow rapidly under the highest intensity white fluorescent light used, 400 ft.-c. Growth is correspondingly less at 220 and 28 ft.-c., and at the lowest light intensity the gametophytes are markedly longer than wide. One percent sucrose added to the medium reverses the growth limitation imposed by low light intensity and produces a morphology comparable to that found under higher intensities. Sucrose does not sustain heterotrophic growth in total darkness, but permits growth if the gametophytes are given low dosages of red light. The effect of red light is reversible by far-red illumination.     

INTERACTION OF IONIZING AND VISIBLE RADIATION IN MUTATION INDUCTION IN NEUROSPORA CRASSA

Klein , Richard M. (New York Bot. Gdn., New York, N.Y.), and Deana T. Klein. Interaction of ionizing and visible radiation in mutation induction in Neurospora crassa. Amer. Jour. Bot. 49(8): 870–874. 1962.—Conidia of the purple adenineless strain of N. crassa were irradiated with 25 kr of X rays and then exposed to far-red or red radiations or to far-red followed by red radiation. Far-red light, without effect on un-irradiated conidia, augmented the genetic damage caused by X rays as measured by survival (colony count), back mutation to adenine prototrophy, and the induction of mutants affecting colony morphology. Post-X-irradiation with red light ameliorated the severity of X-radiation as measured by survival and back mutation. The potentiation of X-ray-induced genetic damage by far-red light could be completely negated by subsequent exposure to red light.     

ATTEMPTS TO OBTAIN BACTERIA-FREE PLANTS OF PSYCHOTRIA PUNCTATA (RUBIACEAE): GROWTH AND ROOT FORMATION IN CALLUS CULTURES

Attempts were made to obtain bacteria-free plants of Psychotria punctata from tissue cultures. Stem explants and callus derived from them were induced to form roots but failed to form buds on Linsmaier and Skoog medium and 96 chemical modifications of it, including most of those known to induce bud formation in other species. Roots formed with ample IAA (2 mg/liter or more) and a low kinetin concentration (0.25 or 0.50 mg/liter). Adenine inhibited root formation in these media, but tyrosine did not. Tyrosine did lower the percentage of calluses commencing growth. When enzyme-hydrolyzed lactalbumin (1.3 g/liter), kinetin (0.5 mg/liter) and IAA (5 mg/liter) were added to Linsmaier and Skoog medium modified by decreasing inorganic nitrogen and increasing inorganic phosphate, callus grew at the fastest rate observed (increasing threefold in fresh weight in three weeks) and formed numerous roots. This was adopted as the stock callus medium. Casein hydrolysates also stimulated growth but less so than lactalbumin hydrolysate. When lactalbumin hydrolysate or a casein hydrolysate lacking tryptophan was supplied, growth occurred without added auxin if sufficient cytokinin was added. Cytokinin was required at unusually high concentration and was tolerated at still higher concentration. Formation, elongation, and branching of roots persisted on a saturated solution of BA which inhibited callus growth about 70 % and delayed callus senescence. Light caused earlier callus senescence after growth had ceased but did not affect callus growth or root formation. Light-induced senescence was prevented by a high cytokinin concentration.     

Indoleacetic Acid synthesis in soybean cotyledon callus tissue

Growth of an auxin-requiring soybean cotyledon callus tissue (Glycine max L., Merr. var. Acme) was promoted by tryptophan, tryptamine, indole, indoleacetamide and, to a very slight degree, anthranilic acid. When tryptophan-3-¹⁴C was supplied in the growth medium, labeled indoleacetic acid (IAA) was found in both the tissue and the medium. Medium, from which the cells had been removed, was also found to convert labeled tryptophan to IAA. Soybean callus contained 0.044 μmole/g free tryptophan, but this is apparently not available for conversion to IAA. These results suggest that while exogenously supplied trytophan could elevate a specific internal pool where IAA synthesis occurs some of the growth on a tryptophan medium can be accounted for by external conversion.     

THE OCCURRENCE OF TRICHOSCLEREIDS IN THE MONSTEROIDEAE (ARACEAE)

Nicolson, Dan H. (Cornell U., Ithaca, N. Y.) The occurrence of trichosclereids in the Monsteroideae (Araceae). Amer. Jour. Bot. 47(7): 598–602. Illus. 1960.—A study was made on the presence, distribution, and frequency of trichosclereids within the leaf-blade, petiole, and stem of 32 species of Monsteroideae and I species of Pothoideae. Trichosclereids occurred in all species studied. Distribution and frequencies of trichosclereids were variable. Trichosclereids occurred more consistently in the petiole than in the leaf-blade or stem tissues. A new report of trichosclereids outside of the Monsteroideae, in Pothos repens (Lour.) Druce of the Pothoideae, is made. The tribe Spathiphylleae (Spathiphyllum and Holochlamys) was found to be characterized in part by large numbers of trichosclereids occurring in groups within the leaf-blade.