bluuebunny/crossref_metadata_2025 huggingface dataset:
FURTHER STUDIES OF GAMMA‐IRRADIATED WHEAT AND THEIR RELEVANCE TO USE OF MITOTIC INHIBITION FOR DEVELOPMENTAL STUDIES
Authors: Haber Alan H. , Foard Donald E.
Published: January 2018

After gamma irradiation of wheat grain, embryos can germinate and grow without detectable mitotic figures and without increases in tissue‐cell numbers. Roots growing without DNA synthesis after irradiation show the 2 striking examples of normal nuclear behavior on the anatomic level that occur in unirradiated roots: (1) trichoblast nuclei migrate into the root hairs and change shape; and (2) nuclei in sieve‐tube elements and vessel elements disappear. Nuclei that do not synthesize DNA do synthesize RNA, some of which moves into the cytoplasm. Therefore, the irradiation that prevents DNA synthesis and mitosis has not completely inactivated all nuclear functions. On a purely descriptive level, the irradiation that prevents cell division seems to prevent the initiation at the apical “meristem” of immature vascular elements but does not prevent maturation in those vascular elements detectable before irradiation. Although the ultimate extent of growth is reduced in those structures which suffer radiation‐induced mitotic inhibition, it is not reduced in those structures (epiblast, coleorhiza, root hairs) which develop without cell division in unirradiated controls and, therefore, have no mitosis for the radiation to inhibit. This established generalization leads to the inference that the smaller sizes attained by gamma‐plantlet roots and leaves may be attributed largely or almost entirely to the radiation‐induced mitotic inhibition rather than to other actions of radiation. Irrespective of the validity of this last inference, the extent of growth theoretically possible without cell division is at least as great as the observed growth of gamma‐plantlets under given experimental conditions. Also reported are variations in radiation sensitivity among different batches of grain, among different organs within the same embryo, and among different cell types within the same organ. These variations are discussed with reference to suggestions and precautions concerning the use of radiation‐induced mitotic inhibition for developmental studies.
EVIDENCES OF COMMON‐AB HETEROKARYOSIS IN SCHIZOPHYLLUM COMMUNE
Authors: Middleton Richard B.
Published: January 2018

Since preliminary experimental evidence for the existence of common‐ABheterokaryons inSchizophyllum communewas inconclusive, experiments were performed to test for and to characterize these heterokaryons. Prototrophic mycelia regularly result from the growing together of pairs of mutant strains of identical mating type which carry non‐allelic nutritional deficiencies. Since crossfeeding through a dialyzing Cellophane membrane does not occur, the prototrophic common‐ABmycelia apparently have both parental nuclear types within a common cytoplasm. Hyphal tips isolated from the peripheries of these prototrophic mycelia usually are not prototrophic. The distributions of the parental nuclear types in the subcultured prototrophic mycelia, as revealed by grid sampling, are irregular in pattern and extent; these patterns probably reflect the nuclear ratios in the transfer inocula, as well as the distributions of nuclear types in various parts of the inocula. Since a common‐ABprototroph typically consists of regions containing a single nuclear type as well as regions containing both nuclear types, marked fluctuations of the estimated nuclear ratio occur upon subculture, and many small transfer‐inocula are not prototrophic as they contain only a single auxotrophic nuclear type. The patterns of nuclear distributions in prototrophic common‐ABmycelia are probably maintained by the restriction of nuclear migration.
FOLIAR ABSORPTION—AN ACTIVE UPTAKE PROCESS
Authors: Jyung W. H. , Wittwer S. H.
Published: January 2018

Mechanisms of foliar absorption of phosphate and rubidium in primary leaves of bean seedlings were resolved by a newly developed leaf‐immersion and leaf‐washing technique. Uptake was expressed as “specific absorption,” defined as mμmoles/cm2 leaf X 24 hr from a known concentration of substance in an external solution maintained in a known environment. Criteria for active uptake included time‐course analysis, temperature, oxygen, and energy dependence, sensitivity to metabolic inhibitors, accumulation against a concentration gradient, irreversibility, and pH dependence. The results suggest that the over‐all process of foliar absorption of rubidium and phosphate by bean leaves, beginning with zero time and extending over a 24‐hr period, is metabolic. It is proposed that carriers play an important role in uptake and that they are proteinaceous.
EFFECT OF FAR‐RED ILLUMINATION DURING THE PHOTOPERIOD ON FLORAL INITIATION OF CHENOPODIUM AMARANTICOLOR
Authors: Kofranek Anton M. , Sachs Roy M.
Published: January 2018

Könitz reported that far‐red irradiation near the middle of the photoperiod of an inductive cycle completely inhibited flower initiation in Chenopodium amaranticolor. The present studies with C. amaranticolor and other short‐day plants have not revealed any such effect of far‐red treatments on flower initiation or development. Thus, since Bünning's proposal of a diurnal variation in the sensitivity of plants to far‐red light is based solely on Könitz's data, it would appear to require further verification.
EFFECTS OF GIBBERELLIC ACID ON THE ANATOMY OF SOYBEANS (GLYCINE MAX)
Authors: Bostrack Jack M. , Struckmeyer B. Esther
Published: January 2018

Apical organization and the ontogeny of leaves of the ‘Hawkeye’ variety of soybean plants were examined. The initial region of the shoot apex consisted of a corpus and a 2‐layered tunica. Cells of the inner tunica layer were responsible for the initiation and development of leaves and stipules which were not significantly affected by foliar applications of a 50 mg/liter aqueous solution of gibberellic acid (GA). Initiation of leaves and stipules was simultaneous, but the early growth of the latter was more rapid. At the sixth or seventh node, the growth of the leaf primordia surpassed that of the stipules. There was meristematic activity in the stipular primordia to about the fifth node after which growth continued by cell enlargement. Stipels were initiated in the subepidermal layer of cells of the fourth leaf primordium, and development was completed at the eighth or ninth node. Gibberellic acid did not affect the size or shape of the stipels. Chlorosis of leaves and a reduction in size of the leaflets was apparent in GA‐treated plants. Terminal leaflets of treated plants had a slightly thinner lamina, smaller cells in the palisade layer and a greater amount of intercellular space. Increased cell elongation caused an early elongation of the internodes of the treated plants. Reduction of cell diameter resulted in a reduction in diameter of stems in GA‐treated plants. In response to GA, more lignified xylem parenchyma was produced, and partial collapse of relatively thin‐walled vessel elements and tracheids occurred. The extension of axillary shoots of GA‐treated plants was delayed temporarily, but once their extension began, they quickly surpassed the growth of the axillary shoots of untreated plants. Cell elongation was a major factor in the rapid extension of axillary shoots of treated plants. Anthesis was delayed and the number of pods per plant reduced in treated plants grown in long days. Only axillary flowers developed on treated and untreated plants grown in long days; however, the shoot apex of treated and untreated plants became floral in short days. The transition from the vegetative to the reproductive phase was delayed in treated plants.
A CHROMATOGRAPHIC STUDY OF CESPITOSE ZINNIAS
Authors: Torres Andrew M. , Levin Donald A.
Published: January 2018

A chromatographic survey of the 7 taxa of the subg. Diplothrix (Zinnia‐COMPOSITAE) and several artificial hybrids was undertaken to obtain information, supplemental to that from cytogenetic and morphological studies, bearing on the ancestry of the polyploid taxa. Conclusions derived from the chemotaxonomic technique have agreed in each instance with those from other approaches. In addition, chromatographic data provided new insight into relationships among the species of the Diplothrix diplo‐polyploid complex. The n = 10 diploid species, Z. juniperifolia and Z. oliyantha, produced a chromatographic pattern designated A1,3; the third diploid, Z. acerosa, produced a different pattern called the A2. The pattern designations conform to the genomic appellations. Tetraploid Z. acerosa and Z. citrea exhibited both patterns, and Z. grandiflora (n = 21) and Z. anomala (n = ca. 42) both exhibited the A1,3 pattern only. These results substantiated the previously determined genomic relationships, and supported the hypothesis that the ancestry of Z. citrea involved Z. juniperifolia and 2n Z. acerosa, that of 4n Z. acerosa involved Z. oligantha and 2n Z. acerosa, that of Z. grandiflora and Z. anomala involved Z. juniperifolia and Z. oligantha.
A CHEMOTAXONOMIC STUDY OF BAPTISIA LEUCOPHAEA VAR. LAEVICAULIS (LEGUMINOSAE)
Authors: Brehm B. G. , Alston R. E.
Published: January 2018

A comprehensive chromatographic study of Baptisia leucophaca var. laevicaulis was carried out. with particular emphasis upon intraspecific variation in phenolic compounds within a single population, among populations representing the range of the species, and at different developmental stages. In addition, more limited analyses were made of alkaloids and free amino acids. Among phenolic compounds the patterns were generally consistent; hence they were reliable species indicators. Some individual variation among phenolics occurred within the population which was selected for most complete analysis. In addition, 2 chemical races were disclosed, represented in a series of geographically contiguous populations. These chemical races did not correlate at all in their distributions with previously recognized morphologically distinct subspecies or varieties. No attempt was made to give formal recognition to the chemical races. The species B. bracteata, an east‐coast taxon resembling closely B. leucophaea, was chromatographically indistinguishable from B. leucophaea, and despite the widely divergent allopatric distribution of these taxa, the genetic differences separating them may be slight. Contrary to expectations, the individual differences and developmental changes in alkaloids of different plants were so great that at present these compounds cannot be utilized as markers in interspecific hybridization. In contrast, the free amino acids of all plants investigated yielded closely similar distribution patterns, and the amino acid patterns of leaves, flowers and even seeds were generally quite similar. The chromatographic studies did not support the recognition of separate species within the Baptisia leucophaea complex of Texas and adjacent states. While B. minor, B. nuttalliana, B. sphaerocarpa and B. leucantha are clearly distinct chromatographically from B. leucophaea, in contrast, B. laevicaulis, B. cuneata and B. bushii were indistinguishable from B. leucophaea.
HISTOGENESIS AND GENETICS OF A PLASTID‐CONTROLLED CHLOROPHYLL VARIEGATION IN TOBACCO
Authors: Burk L. G. , Stewart R. N. , Dermen Haig
Published: January 2018

A mosaic pattern of leaf variegation in a sector on a normal green tobacco seedling resulted from maturation of both green and white cells within the tissue derived from the second histogenic layer (L–II) of the shoot apex. While mature cells of L–II origin contained either green plastids or colorless plastids, single cells in young leaves contained both normal green plastids and colorless, defective mutant plastids. The genetic determiner of the defective plastid type, designated DP1, was located in the plastid itself. Only a small number of mutant plastids were found in anyone cell. A threshold number of DP1 above which green plastids were inhibited and below which they developed normally is suggested. Random segregation of DP1 and dP1 in cytokinesis, close to the threshold value and without loss of either determiner, could account for the small, intermingled patches of green and white cells derived from the mosaic histogenic layer. The mosaic histogen usually remained mosaic; however, complete segregation during mitosis to DP1 or dP1 occasionally occurred in sectors within which lateral buds developed in a stabilized condition, either normal or mutant (green or white). Occasional replacement of L–III by L–II apparently introduced the mosaic condition into L–III of the original variegated plant and resulted in an additional pattern of variegation. Patterns of variegation in which the sporogenous tissue was derived from a stable L–II with homoplastidic cells produced only green or only white offspring. Variegated seedlings were obtained only when L–II was mosaic. Contrasting statements on the inheritance of variegations appearing in the literature result from failure to describe accurately the pattern of variegation. Description in terms of plastid types in mature histogens is essential, and plastid segregation in somatic tissue of mosaic L–II must be determined. Variegation should only be used as a general term and further described as stable when the histogens are homoplastidic or mosaic when the histogens are heteroplastidic. Complete description of the inheritance of a plastid mutant must record inclusion or loss in successive cell generations of sexual seedlings. DP1 is inherited only maternally and is found in fewer of the offspring than expected on the basis of its segregation in mitosis. When present in the egg cell and, therefore, the zygote, DP1 can be included in all 3 histogenic layers of the seedling, thereby producing many more variegated patterns than were possible from the original mosaic plant.
TRUE‐BREEDING COLCHICINE‐INDUCED MUTANTS FROM SORGHUM HYBRIDS
Authors: Franzke Clifford J. , Sanders Mary E.
Published: January 2018

Colchicine treatment of sorghum seedlings of both F1 hybrids and of their pollen parent lines resulted in complex mutant plants the majority of which were true‐breeding. Recessive irradiation‐induced characters originally homozygous in the pollen parent lines and heterozygous in the hybrids did not appear in any of the mutants or their self progenies. Recessive normal characters apparently absent in the pollen parent lines and heterozygous in the hybrids appeared in some mutants and bred true in their self progenies. These results are consistent with the hypothesis that colchicine‐induced mutants arise through chromosome substitution (Sanders and Franzke, 1964, Jour. Arnold Arb. 45: 36). Since sorghums with 2n = 20 are believed to be of polyploid derivation, interchangeable chromosomes carrying different alleles could be present in true‐breeding lines. There is evidence that diploid mutant complements may result from reduction of polyploid nuclei. Since the proportion of true‐breeding mutants was as large from the highly heterozygous seedlings as from the homozygous seedlings, segregation of chromosomes during reduction must be primarily by c‐pairs which later separate as the homologues of a new cell. Plants from such cells would be equivalent to doubled haploids. With colchicine treatment, true‐breeding lines have been obtained from multiple hybrids in a single step rather than after many generations of selling.
DEVELOPMENT OF CULTURED BARLEY EMBRYOS I. GROWTH OF 0.1–0.4‐mm EMBRYOS
Authors: Norstog Knut
Published: January 2018

Excised embryos of barley were cultured on a synthetic medium and their growth rate was determined to be at least equal to that of natural embryos in vivo. Embryos, 0.4 mm when excised, averaged 3.5 mm in length after 10 days’ culture. Morphogenetically, the development of cultured embryos and proembryos (0.15–0.25 mm) duplicated normal embryogenesis. Some embryos continued to grow in culture and became up to 4.5 times larger than natural embryos, but most of the increase was due to scutellar overgrowth. Proembryos of 0.1 mm length or less did not follow normal development patterns but formed protocorm‐like embryos with several shoots and roots. It is suggested that embryonic form in barley may be determined in later stages of proembryonic growth, since earlier proembryos exhibited morphogenetic plasticity in culture.
EFFECTS OF GAMMA‐IRRADIATION OF CORN SEED ON THE RESPIRATION AND GROWTH OF THE SEEDLING
Authors: Woodstock Lowell W. , Combs Michael F.
Published: January 2018

The effect of presowing, gamma‐irradiation treatments on the growth and respiration of germinating corn was investigated. Exposures of 40 and 80 krads caused marked inhibition in seedling growth and inhibited the rate of respiration, measured as oxygen uptake per seedling. A decrease in respiration rates, at these doses, could be detected within 1 day after planting, well before emergence of the radicle. Lower doses which were not markedly growth‐inhibiting did not appear to inhibit respiration. A highly significant correlation was found between respiration rates at 1 day and shoot lengths of 3‐day‐old seedlings. The degree of correlation so measured was higher for shoots than for roots and was lowered by growth‐inhibiting doses of irradiation. The results indicate that rates of respiration during the first stages of germination may be an important factor in subsequent seedling growth and may provide the basis for predicting the growth of the shoot.
MORPHOLOGY OF HYPOCREA SCHWEINITZII
Authors: Hanlin Richard T.
Published: January 2018

Coiled initials embedded in a stroma develop into multicellular, multinucleate ascogonia. Hyphae grow up around the ascogonia to form a prosenchymatous perithecial wall. As the ascocarp develops, an apical meristem produces cells that elongate downward into the centrum, forming long filaments, the apical paraphyses. The ascogonium produces multinucleate ascogenous cells which form a basal layer in the centrum. The ascogenous cells produce asci that grow up among the apical paraphyses, which disintegrate as the ascocarp matures. The asci are unitunicate, with a simple thickened cap punctuated by a pore. This pattern of development is typical of the Nectria‐type.
COMPARATIVE MORPHOLOGY OF THE CARPEL IN THE ROSACEAE. VIII. SPIRAEOIDEAE: HOLODISCEAE, NEILLIEAE, SPIRAEEAE, ULMARIEAE
Authors: Sterling Clarence
Published: January 2018

The carpels of the Holodisceae, Neillieae, Spiraeeae, and Ulmarieae are usually separate from one another; most have open sutures, and their ovules tend to be monotegmic. The ovules are epitropic in Holodisceae, Spiraeeae, and Ulmarieae; they may be pleurotropic, apotropic, or epitropic in the Neillieae. In many species the carpels are partly fused with the floral cup. Only in Luetkea and some species of Spiraea and Stephanandra are the ovular and wing bundles separate at the base of the locule; in the other species ventral bundles persist above that level before dividing. In species with open sutures, the ovules are mostly bitegmic, and the ovular bundles tend to be separate from the wing bundles at the insertion level. An evolutionary trend towards fusion of the two ventral bundles with each other and with the dorsal bundle is shown. In Filipendula the dorsal bundle may be absent. A possible relationship between the Spiraeoideae and the Pomoideae is discussed.
RADIOSPHAERA NEGEVENSIS SP. N., A NEW CHLOROCOCCALEAN DESERT ALGA
Authors: Ocampo‐Paus Roseli , Friedmann I.
Published: January 2018

Radiosphaera negevensis n. sp. f. negevensis and f. minor f.n. were isolated in culture from a surface growth of algae on desert soil and subsequently found in other desertic habitats. The characteristics which distinguish between the genera Radiosphaera and Actinochloris are discussed.
B‐CHROMOSOMES, THEIR ORIGIN AND RELATION TO MEIOSIS IN INTERSPECIFIC LOLIUM HYBRIDS
Authors: Hovin A. W. , Hill Helen D.
Published: January 2018

The following Lolium species were shown to have 14 chromosomes: L. canariensis Steud. (= L. gracile Parl.), L. loliaceum (Bory and Chaub.) Hand.‐Mazz., L. multiflorum Lam., L. perenne L., and L. temulentum L. B‐chromosomes in addition to the normal complement were observed during metaphase I and anaphase I for L. persicum Boiss. and Hohen., L. remotum Schrank, L. rigidum Gaud., L. strictum Presl. (= L. rigidum?), and for several synthesized interspecific hybrids. General absence of B‐chromosomes in diakinesis suggested that they originated by misdivision of A‐chromosomes during prometaphase I. The B‐chromosomes reached a maximum of eight but the number varied for microsporocytes of the same plant. B‐chromosomes appeared spontaneously in progenies from sibbing of hybrid plants without supernumeraries but were also eliminated in the F2 from other sibbings. Degree of chromosome pairing during meiosis was unrelated to the subsequent presence of B‐chromosomes. Normal pairing of seven bivalents was typical for L. perenne × L. multiflorum, L. perenne × L. rigidum, L. multiflorum × L. loliaceum, and L. rigidum × L. loliaceum. Between five and seven bivalents were recorded for L. multiflorum × L. persicum, L. multflorum × L. remotum, L. multiflorum × L. strictum, L. rigidum × L. persicum, L. rigidum × L. remotum, L. rigidum × L. strictum, and L. rigidum × L. temulentum. The results indicated that these Lolium species have a common and generally undifferentiated genome suggesting relatively recent speciation.
THE CYTO‐ECOLOGY OF FOUR SPECIES OF TRILLIUM FROM WESTERN NORTH CAROLINA
Authors: Serota Cornelia Ann , Smith Ben W.
Published: January 2018

The major center of variability in the genus Trillium occurs in the southern Appalachian mountains of the eastern United States. The karyotypic variation existing within T. cuneatum Raf., T. grandiflorum (Michx.) Salisb., T. erectum L., and T. gleasoni Fern., the four most abundant Trillium species in western North Carolina, was analyzed and compared with the variation in gross morphology and the ecological associations of the respective species. The number of types of each kind of chromosome (A‐E), as exhibited following “nucleic acid starvation” by cold treatment, varied widely from species to species. Chromosome types varied within each species and within populations in the numbers, sizes, and positions of euchromatic and heterochromatic segments. No 10‐chromosome karyotype and only one 5‐chromosome complement was found to be duplicated in any two plants which belonged to different species. Trillium cuneatum with eight chromosome types was morphologically stable and occurred in a limited geographic area. Trillium gleasoni, characteristically adapted to elevations near 2,000 feet, contained 32 chromosome types and exhibited a high morphological variability. Trillium erectum (25 types) and T. grandiflorum (23 types) were also intermediate in morphological variability. These two species had the widest geographical range. Karyotypes were analyzed from pure stands of each of the four species and for each species from mixed stands of two or more of the species growing in close association. These Trillium species are maintaining a high level of karyotypic and gross morphological variability within comparatively limited geographical areas. None of the observed karyotypes in any species is likely to have arisen by recent interspecific hybridization. The composite karyotype of each species could be used as an aid to classification in the genus Trillium.
THE GAMETOPHYTE OF SCHIZAEA DICHOTOMA
Authors: Bierhorst David W.
Published: January 2018

Fourteen collections of gametophytes of Schizaea dichotoma, corresponding to the broadest taxonomic circumscription of the species, are described from New Caledonia. The gametophyte is subterranean, mycorrhizic and non‐green. It is basically filamentous with uniseriate growing points each ending with an apical cell with a single transverse cutting face. Cells of apical cell derivation divide to produce packets of cells which usually stand out as distinct joints in the older fleshy cylindrical axis. Branching is frequent, initiated as singular cellular bulges at the acropetal ends of the joints, and results in a bushy appearing plant. Thinner, non‐septate rhizoids are produced in the same position as branches. Antheridia are typically schizaeaceous and are produced on short antheridiophores, one to several on each. Archegonia are produced in the same position as antheridiophores and vegetative branches. They are rather ordinary save for the terminal knob formed by the bulging of the four terminal neck cells and the distinct jacket which lines the venter and most of the neck canal. The possible phylogenetic relationship between the uniseriate filament and fleshy axis derived ontogenetically from a multicellular apical meristem is discussed in the context of the Schizaeaceae and vascular plants in general.
THE EFFECT OF pH ON THE UPTAKE AND ACCUMULATION OF PHOSPHATE AND SULFATE IONS BY BEAN PLANTS
Authors: Hendrix John E.
Published: January 2018

Phosphate uptake above pH 6.0 followed the concentration of H2PO4. Sulfate studies were used to aid evaluation of phosphate data. Phosphate absorption was nearly linearly proportional to transpiration at pH 4.0; at pH 8.7, phosphate absorption occurred only early in the experiments. It was inferred that phosphate entered as H2PO4; that which entered at pH 8.7 did so as the result of a depressed pH at the absorption sites.
REQUIREMENTS OF TWO TEMPERATURE‐SENSITIVE MUTANT STRAINS OF NEUROSPORA CRASSA FOR GROWTH AT ELEVATED TEMPERATURES
Authors: Wainwright Ruth Rogers , McVeigh Ilda
Published: January 2018

Two mutant strains of Neurospora crassa failed to grow at 32 C in a minimal medium in which they grew well at 25 C. Both grew in the medium at 30 C after a relatively long lag phase, although the amount of growth at the maximum stationary phase was much less than in similar cultures incubated at 25 C. The addition to the minimal medium of relatively high concentrations of polyethylene glycol “400” or of any one of several sugars or inorganic salts increased growth of each strain at 30 C and enabled each to grow to a limited extent at 32 C. Concentrations of NaCl, polyethylene glycol “400” and glucose most favorable for growth at 30 and 32 C were inhibitory at 25 C. The osmotic pressures exerted by the media containing optimum concentrations of NaCl, of polyethylene glycol “400” or of lactose for the growth of each strain at 30 or at 33 C were within the same general range. Possible explanations of the effects of increased osmotic pressure of the medium upon growth of the strains at elevated temperatures are discussed.
INDUCTION OF FLORAL PRIMORDIA IN ISOLATED NODAL EXPLANTS OF CESTRUM DIURNUM IN VITRO
Authors: Caplin Samuel M. , Griesel Wesley O.
Published: January 2018

Nodal explants of the LSD plant Cestrum diurnum, each consisting of a short piece of stem with leaf and axillary bud, produced flower primordia in culture on White's basal medium after removal from stems grown on 16‐hr day and subjected to 8‐hr daily photoperiods. No flower primordia formed in the absence of leaves or with leaves excised during the rapidly expanding phase of growth. The presence of 1/16 of a leaf blade was, however, enough to provide for floral initiation. Young mature leaves induced flower initiation equally well whether the leaf was erect, with only the stem portion in contact with the agar culture medium, or inverted, with the leaf blade making contact, whereas, when erect, fewer older leaves induced flower initiation and tended, in addition, to abscise. In a survey involving light intensity (1–1000 ft‐c) and number of daily cycles (1–9) flower primordia were induced to form on 1 ft‐c with 1 short day, increasing percentagewise to an optimum of about 81 ft‐c in 7 days. The number of flowers per bud was little affected by light intensity but increased progressively with the number of daily cycles.
GIBBERELLIN‐INDUCED INHIBITION OF FLORAL INITIATION IN FUCHSIA
Authors: Sachs R. M. , Kofranek A. M. , Shyr Shiow‐Ying
Published: January 2018

The ‘Lord Byron’ cultivar of Fuchsia hybrida is a long day plant for which GA acts as an inhibitor of flower initiation. At the dosages required to inhibit initiation (0.025 μg per plant) GA also promotes increased stem elongation but causes no other departures from normal development. Similar tests with auxins, antiauxins, kinins, and other substances showed no effect on flower initiation at dosages equivalent to that for GA. At 10‐ to 100‐fold greater dosages, auxins, kinins, and anti‐auxins inhibit not only flower initiation but also vegetative development. Thus the effect of GA on flower initiation appears to be unique, although other hormonal substances, such as abscisin, have not been tested. GA‐induced inhibition is directly proportional to the dosage applied and inversely to the strength of long day induction (as measured by the number of long days). GA is most effective when applied to the terminal bud rather than to the mature leaves, suggesting that it is active at the site of flower initiation rather than in the leaves. If it is applied after translocation of the floral stimuli from the leaves, GA does not prevent flower initiation. Regardless of the dose applied, GA is less effective if applied later rather than earlier during LD induction. The inhibitory effect persists for several days. For example, an 0.85 μg dosage causes an 8–10‐day delay in initiation; lower dosages have reduced effects. GA inhibits flower initiation but has no effect upon flower development. The rate of bud development is the same in GA‐treated and control plants. Apparently no more than one to two axillary buds immediately below the apical meristem are receptive to long day‐induced floral stimuli from the leaves. Regardless of the daylength conditions axillary buds more basal do not initiate flowers but develop into branch axes. The effect of a long day treatment persists for a very short time, perhaps no longer than the inhibition caused by minimal GA dosage. Thus flower initiation continues for a very short time following the end of long day induction. The significance of these findings is discussed in relation to the many reports of GA‐induced inhibition as well as promotion of flower initiation. In particular, the discussion concerns the nation that flower initiation in fuchsia may be controlled by a gibberellin‐like transmissible inhibitor.
TRANS‐CINNAMIC ACID AND SOME RELATED COMPOUND EFFECTS ON ORNITHOGALUM CAUDATUM POLLEN
Authors: Goss James A.
Published: January 2018

Fresh pollen of Ornithogalum caudatum was germinated in the absence or presence of trans‐cinnamic acid (t‐CA), trans‐cinnamaldehyde (t‐CAld) and related compounds, and germination percentage studied. Hydrocinnamic acid, t‐CA, and t‐CAld reduced germination to 50% of the control at 20–40 mg/liter. Hydrocinnamaldehyde, 3‐phenyl‐1‐propanol and phenylacetic acid gave 50% reduction at 70–80 mg/liter, and caffeic acid, ferulic acid, phenethyl alcohol, coumarin, styrene, phenylalanine or ethyl cinnamate required 200 mg/liter or more for similar reduction in germination percentage. The inhibition of germination by t‐CA could not be overcome by indole acetic acid and vice versa, indicating a lack of antiauxin activity.
ANATOMY OF GIBBERELLIN‐INDUCED STEM ABSCISSION IN COTTON
Authors: Bornman C. H. , Addicott F. T. , Lyon J. L. , Smith O. E.
Published: January 2018

In an investigation of the abscission responses of excised cotyledonary nodes (explants) of cotton to applications of gibberellic acid, applications to the petiole stumps accelerated petiole abscission only. Applications to stem stumps accelerated petiole abscission and induced stem abscission in approximately 30% of the explants. Following stem applications, petiole abscission always preceded stem abscission by at least 1 day. Morphologically, both the petiole and stem abscission zones, as well as the changes which took place within them during abscission, appeared identical.
THE TRANSITION FROM FILAMENTOUS TO TWO‐DIMENSIONAL GROWTH IN FERN GAMETOPHYTES. I. THE REQUIREMENT FOR PROTEIN SYNTHESIS IN GAMETOPHYTES OF PTERIDIUM AQUILINUM
Authors: Davis Bill D.
Published: January 2018

Two‐dimensional (2‐D) development of gametophytes of Pteridium aquilinum was estimated by the percentage of plants with at least one cell wall at an oblique angle, relative to the long axis. Inhibition of cell division per se was assayed by counting the cell number per filamentous (1‐D) gametophyte. Specific concentrations of 8‐azaguanine, 5‐fluorouracil, p‐fluorophenylalanine, actinomycin D, streptomycin, and cycloheximide were found to selectively inhibit 2‐D development. A reduction in the percentage of 2‐D gametophytes was accompanied by a reduction in the relative protein content (protein per dry weight). A comparable association was found only during the initial stages of 2‐D development; after 5 days the relative protein content decreased as the percentage of 2‐D gametophytes increased. Different intensities of white light resulted in a 10‐fold difference in the percentage of 2‐D plants with no alteration of the relative protein content. These results demonstrate that no strict relationship between 2‐D development and relative protein content occurred in these gametophytes.
SYNTHETIC AGROPYRON‐ELYMUS HYBRIDS: III. ELYMUS CANADENSIS X AGROPYRON CANINUM, A. TRACHYCAULUM, AND A. STRIATUM
Authors: Dewey Douglas R.
Published: January 2018

Hybrids were produced with relative ease from controlled crosses of Elymus canadensis L. with European Agropyron caninum (L.) Beauv., North American A. trachycaulum (Link) Malte ex H. F. Lewis, and Asian A. striatum Nees ex Steud. All hybrids appeared to be completely sterile and were, for the most part, morphologically intermediate between their parents. The E. canadensis × A. caninum hybrids were exceptionally vigorous and leafy and may have some potential as forage grasses if fertility can be achieved. All parent plants were tetraploid, 2n = 28, and they behaved cytologically as alloploids. Chromosome pairing in the hybrids indicated that both E. canadensis genomes were closely homologous with those of A. trachycaulum and somewhat less homologous with those of A. caninum. Interchanged and inverted chromosome segments apparently constitute the major differences between E. canadensis, A. trachycaulum, and A. caninum genomes; however, cryptic structural differences must also exist. Partial homologies were detected between one A. striatum and E. canadensis genome, but their other genomes were distinctly different. The genome relations between the parent species were expressed in terms of the following genome formulas: E. canadensis, S1S1X1X1; A. trachycaulum, S2S2X2X2; A. caninum, S3S3X3X3 : and A. striatum S4S4YY or X4X4YY, where “S” refers to a genome derived from A. spicatum and “X” and “Y” are genomes of unknown origin.
RELATION OF FLOWER COLOR TO OPTICAL‐DENSITY SPECTRA OF INTACT TISSUE AND OF ANTHOCYANIN EXTRACTS
Authors: Stewart R. N. , Asen S. , Norris K. H. , Massie D. R.
Published: January 2018

Data from measurements of optical density of intact tissue and of anthocyanins in extracts resolved on cellulose thin layer plates were compared with visual evaluations of color quality and intensity in poinsettia, rose, and snapdragon. Visual evaluation was in good agreement with both instrumental and chemical determinations. However, the number or kinds of anthocyanins present could not be predicted from the visual evaluation or from the spectra of the fresh tissue. Data from the resolved extracts did not provide a basis for predicting the optical‐density spectrum or the color of the intact tissue. In addition to the genetic factors which have been shown to control (1) the type of anthocyanin, (2) the amount of anthocyanin, and (3) the distribution of anthocyanins within the flower, we suggest another group of genes which apparently affect color through control of structural modification of individual anthocyanins in the living cell through shift in pH, metal chelation, and/or copigmentation. Such genes are apparently responsible for the modification of red color within the Wh Wh genotype of poinsettias containing both pelargonidin and cyanidin glycosides and for a very similar pink color in a snapdragon and a rose, each containing a single anthocyanin, a pelargonidin glycoside, and a cyanidin glycoside, respectively.
GROWTH AND DEVELOPMENT OF LITCHI CHINENSIS AS AFFECTED BY SOIL‐MOISTURE STRESS
Authors: Nakata Shigeru , Suehisa Robert
Published: January 2018

The effects of soil‐moisture tension on growth and floral development of field‐grown Litchi chinensis, a woody subtropical fruit tree, were investigated. Floral initiation and fruit set were promoted by a high soil‐moisture tension for 6 months, beginning with June, 1967, or for 4 months, beginning with October, 1967. The normal floral‐initiation period in Hawaii is during the period November to January. The apical meristematic tissue, judged from the number of branches flowering, was apparently not adversely affected by a soil‐moisture stress, provided adequate water was available during the floral‐bud development period. Low soil‐moisture tension (0.3 bar) throughout the experimental period was inhibitory for floral bud initiation. High soil‐moisture tension inhibited growth of the trunk and the emergence of flush‐growths. Flowering was correlated significantly, and negatively, with growth. Leaf nitrogen and potassium levels were unaffected by water stress, but the phosphorus levels in leaf and stem were lowered by high‐moisture tension. Hydrolysis of starch under moisture stress, reported for some species, was not evident in the Litchi. No correlation between trophic constituents and flowering was observed.
GENOME RELATIONS AMONG DIPLOID ELYMUS JUNCEUS AND CERTAIN TETRAPLOID AND OCTOPLOID ELYMUS SPECIES
Authors: Dewey Douglas R.
Published: January 2018

Synthetic triploid hybrids of Elymus junceus Fisch. (2n = 14) × E. innovatus Beal (2n = 28) averaged 7.05I, 6.73II, and 0.16III in 92 metaphase‐I cells. The hybrids were totally sterile. Elymus innovatus apparently contains a genome closely homologous with the E. junceus genome. Natural tetraploid hybrids of E. innovatus × E. dasystachys Trin., E. dasystachys × E. triticoides Buckl., and E. triticoides × E. cinereus Scribn. & Merr. generally formed 14 bivalents at metaphase I; and subsequent meiotic stages were correspondingly regular. Nevertheless, none of the hybrids set seed. The four tetraploid species may be represented by the basic genome formula JJXX, where J is an E. junceus‐like genome; and X is a genome of undetermined origin. The E. junceus genome likely exists in other long‐anthered cross‐pollinating Elymus species. Genome relations were difficult to interpret in a natural 42‐chromosome hybrid of E. dasystachys × octoploid E. cinereus, which averaged 8.51I, 13.82II, 1.85III, and 0.08IV in 39 metaphase‐I cells. Although octoploid E. cinereus likely arose from the tetraploid form, the genomes of the octoploid have become somewhat restructured.
LASIOSTROBUS GEN. N., A STAMINATE STROBILUS OF GYMNOSPERMOUS AFFINITY FROM THE PENNSYLVANIAN OF NORTH AMERICA
Authors: Taylor Thomas N.
Published: January 2018

Structurally preserved gymnospermous pollen cones are described from coal ball petrifactions collected from the Mattoon Formation (upper Pennsylvanian) of southeastern Illinois. Specimens range from 1.3‐3.1 cm long and up to 2.4 cm in maximum diam; none of the cones is complete at the base. The vascular system consists of 6 tangentially flattened endarch collateral primary vascular bundles that parallel the cone axis giving rise to pairs of microsporophyll traces. Xylem elements have scalariform secondary wall thickenings. Closely spaced, spirally arranged fleshy microsporophylls are broadly attached to the cone axis, and extend distally forming a compact unit. The apical organization of one specimen is described in detail and compared with vegetative and fertile apices of extant plants. Seven to ten elongate sporangia (pollen sacs) are attached for almost their entire length in a single row on the abaxial surface of each microsporophyll. Polysaccate pollen grains are small, spherical, and apparently inaperturate. Transmission and scanning electron microscopy is used to delimit pollen grain features at the ultra‐structural and ultraarchitectural level. The new pollen cone is compared with staminate strobili of extant and fossil members of both the cycadales and coniferales.
THE POLLINATION ECOLOGY OF PEDICULARIS IN COLORADO
Authors: Macior Lazarus Walter
Published: January 2018

The pollination ecology of seven Pedicularis species was studied in the montane‐alpine ecotone of the Front Range of the Colorado Rocky Mountains. No species was found to self‐pollinate, and all species were primarily pollinated by bumblebees (Bombus Latr.). Foraging behavior of insects was recorded cinematographically and stereophotographically and correlated with the form and operation of the pollination mechanism of each species. Further correlations were made between phenology of flowering and development of pollinator colonies, altitudinal distributions of plant and pollinator species, pollinator bionomics and analyses of corbicular loads for 1014 Pedicularis pollinators, and interspecific pollination coactions of sympatric plant species. The concepts of caste adaptation of pollinators, multiple adaptation of pollinators, fidelity of foragers, competition for pollinators, sharing of pollinators, and coadaptive evolution in stress environments are evaluated in view of the data presented.
CHROMOSOME NUMBERS IN THE HYPOCREALES. II. ASCUS DEVELOPMENT IN NECTRIA CINNABARINA
Authors: El‐Ani Arif S.
Published: January 2018

The cytology of ascus development in Nectria cinnabarina was investigated with the orceinsmear technique, from crozier formation to ascospore maturation. At prophase I synapsis occurs while the chromosomes are still contracted, and the nucleus passes through dictyotene, a diffuse stage rarely seen in plants. A haploid complement of five chromosomes has been precisely determined. The first two divisions in the ascus constitute meiosis, and the third (mitotic) is followed by ascospore delimitation. A fourth division takes place in the ascospore, which is subsequently divided by a septum into two uninucleate cells. Of all species of Nectria thus far investigated N. cinnabarina is the only species in which additional nuclear divisions in the ascus do occur, accounting for the multinucleate condition in the ascospore cells. The bearing that this distinctive nuclear condition has on phylogeny and evolution in the Hypocreales is discussed.
THE EFFECT OF LIGHT QUALITY AND INTENSITY ON SEXUAL EXPRESSION IN EQUISETUM GAMETOPHYTES
Authors: Hauke Richard L.
Published: January 2018

A series of experiments to determine the effect of light quality and light intensity on sexual expression in Equisetum gametophytes showed that one species, E. arvense, is strongly affected by light intensity; another species, E. hyemale, is strongly affected by light quality; and a third species, E. fluviatile, is relatively unaffected by either light quality or light intensity. Supplementation of mineral media with sucrose indicates that this light effect is not photosynthetic, and in fact suggests that sucrose itself has a morphogenetic effect on sexual determination in Equisetum gametophytes.
INDUCTION OF XYLOGENESIS IN PITH PARENCHYMA EXPLANTS OF LACTUCA
Authors: Dalessandro Giuseppe , Roberts Lorin W.
Published: January 2018

Explants of pith parenchyma excised from Romaine lettuce heads (Lactuca sativa Linn. var. Romàna) exhibited xylogenesis after four days dark incubation on a Murashige and Skoog (1962) medium containing auxin (IAA, NAA, or 2,4‐D), cytokinin (zeatin, kinetin, or benzyladenine), sucrose, and agar. With the exception of 2,4‐D, xylogenesis required both an exogenous auxir and cytokinin. The greatest numbers of tracheids were produced by the IAA (5.0 mg/liter)‐zeati (0.1 mg/liter) and 2,4‐D (0.07 mg/liter)‐zeatin (0.1 mg/liter) treatments, whereas the most effective treatment for callus formation was the NAA (0.5 mg/liter)‐zeatin (0.1 mg/liter) medium. In the absence of exogenous cytokinin, 2,4‐D stimulated xylogenesis after 14 days culture at a concentration of 0.02 mg/liter, but was ineffective at 0.07 mg/liter and 0.2 mg/liter. The 2,4‐D treatment induced tracheids to form in small meristematic nodules; aberrant tracheids were also observed. Different patterns in the differentiation of tracheids were associated with the various auxin‐eytokinin treatments. All IAA‐cytokinin treatments produced perpendicular strands around the periphery and tracheid formation throughout the lower half of the explants. The pattern of IAA‐induced xylogenesis was modified by the particular cytokinin employed. Treatment with NAA‐cytokinin induced horizontal strands which were branched, and the xylogenesis pattern was the same regardless of the cytokinin employed. The xylogenesis pattern produced by 2,4‐D‐cytokinin varied with the 2,4‐D concentration, and was independent of the cytokinin employed. Small numbers of tracheids were observed in explants cultured under xylogenic conditions and treated with caffeine (1000 mg/liter) for the inhibition of cytokinesis.
DETECTION AND EVALUATION OF PLANT GROWTH RESPONSES TO ENVIRONMENTAL CONDITIONS
Authors: Lewis A. J. , Haun J. R.
Published: January 2018

The rate of leaf development was used for detecting and evaluating growth responses of carnations to environmental factors. Studies were conducted in two separate greenhouses with different temperature, humidity, and soil moisture conditions. Quantitative morphological stages of leaf growth were recorded on a daily basis until buds formed at which time daily bud diam measurements were begun. The cumulative data were transformed into growth rates. Environmental data were obtained daily. Lags in the effect of each environmental factor on growth were obtained by simple correlation analyses using environmental data on the day of growth and each of five previous days. Multiple regression analyses using leaf growth rate or bud growth rate as the dependent variable and environmental data with appropriate lags as independent variables were conducted to determine the relationship of the various environmental factors to growth rate. Equations were developed to predict plant growth under varying environmental conditions.
ABSENCE OF PHOTOCHROME DARK REVERSION IN SEEDLINGS OF THE CENTROSPERMAE
Authors: Kendrick Richard E. , Hillman William S.
Published: January 2018

The dark transformations of phytochrome were investigated in two members of the Centrospermae: Mirabilis jalapa L. (Four o'clocks) hypocotyl hooks and Spinacia oleracea L. (Spinach) hypoeotyls plus cotyledons. After an exposure to red light, decay of total phytochrome was observed in both species. No evidence was found for the dark reversion of Pfr2 to Pr in sections kept in buffer or when decay was inhibited by sodium azide. The rate of loss of total phytochrome under continuous illumination in Mirabilis hypocotyl tissue depended on the Pfr/Ptotal ratio whether maintained by the red or blue regions of the spectrum. The lack of reversion in the species investigated here, as in Amaranthus caudatus L. (Love‐lies‐bleeding) another member of the Centrospermae, suggests that the order is an exception among dicotyledons and in this respect resembles the monocotyledons.
BUD FORMATION IN EXCISED STEM SEGMENTS OF VERBASCUM THAPSUS
Authors: Caruso John L.
Published: January 2018

Excised internodal segments of flowering specimens of Verbascum thapsus, with and without vascular tissues, were grown on a nutrient medium which lacked added growth regulators such as auxin and cytokinin. Stem segments which contained vascular tissues formed numerous buds in superficial layers of newly formed tissue within two weeks after transfer of the explants to the medium. Tangential cell divisions in the cambium and phloem are thought to be primarily responsible for the newly formed tissue. A regenerated bud displays dendritic trichomes on its first leaf primordium, whereas the earliest that such trichomes appear on intact seedlings is on the second foliage leaf primordium. Pith explants without vascular tissues become brown in a matter of two to three weeks with no visible sign of growth. Endogenous growth regulators supplied by vascular tissues are believed to be major factors in bud formation in excised internodal segments of this species.