Small Buds Research Articles

The influence of bud state of bit planting material on shoot emergence of banana cv. Williams in North Queensland

The time from planting to shoot emergence of 3 classes of planting material of banana cv. Williams was studied in the field in North Queensland. Two classes of bits (0.55-1.6 kg), 1 with large lateral buds (forward bits) and the other with small lateral buds (backward bits), and 1 class of suckers (0.55-1.75 kg) were compared. Regressions were fitted using a Mitscherlich equation that described the spread in the population of the time to emergence of the 3 classes of planting material. There was 96% shoot emergence from forward bits and 71% from backward bits by the time of replanting (85 days after planting). The time to 50% of maximum shoot emergence (mean � s.e.) was 31 � 0.2 days for forward bits and 38 � 0.4 days for backward bits; the time to shoot emergence of the former was less variable. Suckers produced 100% shoot emergence by the time of replanting, took the least time to 50% of maximum shoot emergence (29 � 0.1 days) and were the least variable of all classes in time to shoot emergence.

Temperature Relations for Bud Growth in the Root Geophyte Pediomelum subacaule and Ecological Implications

Pediomelum subacaule (Leguminosae) is a tuberous root geophyte endemic to cedar glades of the southeastern United States. The annual shoot of P. subacaule emerges in early spring and dies with the onset of drought in late spring or early summer, by which time a small (< 1.0 mm in length) perennating bud has formed at the top of the root, about 50 mm below the soil surface. In a phenology study conducted in a non-temperature-controlled greenhouse, little bud growth occurred in July and August (ca. 32/21 C), but by mid-November the buds had reached a height of about 20 mm. The buds grew very little from mid-November to mid-February. From mid-February to late March, however, they grew an additional 30 mm and emerged at the soil surface in March. New absorbing roots were produced in March. After 36 wk, buds on roots incubated at 15/6, 20/10, and the simulated summer-autumn-winter-spring temperature sequence elongated 50 mm, while those incubated at 5, 25/15, 30/15, 30/20, and 35/20 C elongated to only 11-31 mm. New absorbing roots were produced only by roots incubated at 15/6, 20/10, and the sequence of simulated habitat temperatures. The temperature relationships of bud growth in P. subacaule are a phenological adaptation of this drought-intolerant species to its summer-dry habitat.

The origin, development, and degeneration of the pronephros in Caretta caretta.

An SEM and TEM study revealed details of the development of the pronephros of Caretta caretta. The pronephros develops and degenerates over 13 days from day 7 to day 20 in embryos incubated at 33°C. Podocytes, with primary branches, secondary branches, and pedicles, on a basal lamina, can be seen from day 11, as can ciliated pronephric tubule ostia opening into the coelom. At this stage the embryo has four pharyngeal arches with unfused mandibular processes, and small fore-limb buds each with an apical ectodermal ridge. Maturation of the pronephros occurs between days 15 and 17. Degeneration begins around day 18 and is advanced by day 20 when the embryo has a fully developed face, fore-limbs with digits, and the carapace and plastron have formed.

Relative Changes in Polyamines during Citrus Flower Development

Several stages of citrus (Citrus sinensis L. Osbeck. cv. Valencia) flowers, from very small bud (stage 1) to anthesis (stage 6), were evaluated for free and conjugated polyamines. The concentration of putrescine and spermidine synthesis increased markedly during the early stages, and then declined as the flower buds grew. At anthesis, putrescine and spermidine concentrations had increased significantly. Spermine concentration was very low and showed no significant change during the first three floral developmental stages; however, by stages 5 and 6, spermine concentration showed a slight but significant increase. Eighty percent of the total polyamine content in fully developed flowers is localized in the reproductive organs and only 20% is localized in the petals and the calyx. This study relates changes in conjugated and free polyamines to citrus flower growth.

A candidate protein kinase C gene, PKC1, is required for the S. cerevisiae cell cycle

Probes derived from cDNAs encoding isozymes of rat protein kinase C (PKC) were used to screen the genome of the budding yeast S. cerevisiae. A single gene (PKC1) was isolated that encodes a putative protein kinase closely related to the α, β, and γ subspecies of mammalian PKC. Deletion of PKC1 resulted in recessive lethality. Cells depleted of the PKC1 gene product displayed a uniform phenotype, a characteristic of cell division cycle (cdc) mutants, and arrested cell division at a point subsequent to DNA replication, but prior to mitosis. Unlike most cdc mutants, which continue to grow in the absence of cell division, PKC1-depleted cells arrested growth with small buds. PKC1 may regulate a previously unrecognized checkpoint in the cell cycle.

Lithium ions interfere with pattern control in Hydra vulgaris.

LiCl in concentrations exceeding 0.5 mM affects morphogenesis in Hydra vulgaris (formerly named H. attenuata) by interfering with the foot-forming system(s). Pulse treatment of Hydra bearing small buds or of animals that develop a bud within 14 h after the end of treatment prevented foot formation at the bud's base in a concentration-dependent manner. With increasing concentrations of Li+ or length of treatment in increasing percentage of the buds remained permanently connected to the parent by a bridge of tissue thus forming a stable secondary axis. Instead of the normal ring-shaped foot a patch of basal disc tissue developed or the bud failed to differentiate foot tissue at all. Long-term culture of animals in 1 mM LiCl inhibited budding from the second day of treatment onwards and detachment of existing buds was delayed. After 4 days of treatment 15%-30% of budless or bud-bearing animals developed up to three patch-like basal discs at various positions along the body axis; these usually grew out one above the other on the same side of the animal but never at the same transverse level. Besides these patch feet broad belts of foot tissue were observed in the lower gastric region. After 1 week of treatment half of the animals developed a constriction located usually in the lower two-thirds of the body axis. The tissue adjacent to this constriction and particularly above it differentiated into mucus-secreting foot tissue. Subsequent separation into two morphologically intact polyps occurred occasionally. When treatment was stopped, budding restarted within the next 3 days at several positions along the body axis whether or not secondary feet or a constriction existed. Buds grew out in different budding zones, which persisted for several days. This burst of budding led to up to 7 buds per animal within 3 days. After about 1 week the animals regulated to normality or became epithelial, i.e. they lost their stem cells during and after treatment.

Developmental Anatomy of Axillary Meristems of Araucaria cunninghamii Released from Apical Dominance Following Shoot Apex Decapitation In vitro and In vivo

The in vitro and in vivo development of hoop pine (Araucaria cunninghamii Aiton ex D. Don) axillary meristems into buds following release from apical dominance by decapitation was followed by light microscopy. Stem segments, containing three to five axillary meristems, were excised from the mainstem of hoop pines 2 yr of age and cultured in vitro. The meristems were quiescent; did not possess an apical dome, leaf primordia, or vascular or provascular connections with the stem stele; and were buried beneath the stem surface. Following excision a noticeable increase in nuclear size and cytoplasmic content was apparent in the cells of the axillary meristems at day 3. Mitotic activity was observed at the base of the axillary meristem at day 6 and was soon followed by dedifferentiation of a crescent of thick-walled cells that cradled the adaxial surface of the meristem. At day 9, the first cell divisions had occurred in the surface layers of the axillary meristem, concomittant with the early stages of procambial strand development via basipetal dedifferentiation of cortical parenchyma. At day 12, the axillary meristem had developed into a small bud with an apical dome and one or two leaf primordia. At day 18, sufficient increase in volume had occurred for the bud to rupture the stem surface. Subsequent development involved further bud growth and strengthening of vascular connections. Meristems that developed into buds in vivo followed a similar progression, although in material where sclereid bands had differentiated in the cortex the procambial strands were deflected from a direct connection with the stem stele. The results indicate that the commonly held distinction between preventitious and adventitious buds in woody plants (i.e., the presence of a vascular connection from the bud to the primary xylem in the former) is not applicable to hoop pine. The results provide a contrast with decapitation studies in herbaceous angiosperms.

Effects of sowing date, plant density and year on growth and yield of Brussels sprouts (Brassica oleracea var. bullata subvar. gemmifera)

SummaryIn field experiments in 1983–85 in Northumberland, UK, early sowings achieved a leaf area index (LAI) of 3·5, capable of intercepting 90–95% total incident solar radiation, earlier than late sowings. As there was a close relationship between total dry weight, bud dry weight and amount of intercepted solar radiation, early sowings invariably outyielded later ones. The efficiency of energy conversion of radiation was 1·28, 2·05 and 2·11 g/MJ for total dry weight and 0·97, 0·83 and 0·67 g/MJ for bud dry weight in 1983, 1984 and 1985, respectively. Harvest index ranged from ca. 25% in 1985 to 40% in 1984.Increasing plant density from 2·22 to 6·66 plants/m2 advanced and increased maximum LAI and total and bud dry weight per m2 but had an adverse effect on distribution of dry matter. Maximum total dry weights were achieved at or slightly after maximum LAI. The onset of rapid bud growth coincided with maximum total standing dry weight and was advanced by early sowing but largely unaffected by plant density.Early-sown crops produced more buds than late-sown ones because of a longer growing season. Plant density had a large effect on the number of buds per m2, which was almost directly proportional as the number of buds per plant was not severely affected. However, individual bud size was restricted as a result of competition for assimilates. Approximately 80% of buds finally recorded had been produced before significant bud growth had occurred.Total bud fresh yields averaged over all sowing dates reached 17 t/ha in 1983 and 31 t/ha in 1984. The lower yield in 1983 was the result of late sowing caused by unfavourable weather. Early sowings significantly outyielded late ones because of earlier onset of rapid bud growth which gave a longer growing period. The effect of plant density on total sprout yield was less pronounced than that of sowing date but effects on yield per plant were large.Yields of buds in the freezing grade (20–30 mm) increased rapidly between late September and early to mid-November in both 1983 and 1984 and reached 7·5 and 8·8 t/ha, respectively. The difference between freezing-grade yields in the two years (1·3 t/ha) was much less than the difference between total yields (14 t/ha). Late sowing in 1983 restricted bud growth resulting in a higher proportion in the freezing grade. Plant density had a greater effect on freezing-grade yield than on total yield. Low planting densities gave high yields of small buds at early harvests but denser planting gave higher yields at later harvests. Generally, increases in bud fresh weight over the harvest period were greater than those in bud dry weight because of water uptake. The average dry matter content of buds declined by 2–5 % from October to January.The experiments confirmed that manipulation of sowing date and planting density is an effective way of spreading harvest date throughout the season in order to achieve an orderly sequence of crops for the fresh market and for processing.

Development and ethylene production of buds and florets of cut freesia inflorescences as influenced by silver thiosulphate, aminoethoxyvinylglycine and sucrose

Inhibition of ethylene production with aminoethyoxyvinylglycine (AVG) or blocking of ethylene action with silver thiosulphate (STS) did not affect the ageing of blooming freesia florets, while these treatments had beneficial effects on the development of small buds at the apex of the inflorescence. Although AVG effectively inhibited ethylene production and so prevented the sharp ethylene peak that normally occurs in the smaller buds of an inflorescence about 3 days after harvest, the dying of these buds was not prevented. Application of sucrose had a more beneficial effect on inflorescence development particularly if combined with AVG or STS. Apparently, a deficiency of carbohydrates is the main cause of the dying of freesia buds. Ethylene plays a secondary role in this event.

A galactose-dependent cmd1 mutant of Saccharomyces cerevisiae: involvement of calmodulin in nuclear division.

The coding region of a yeast calmodulin gene was fused to a galactose-inducible GAL1 promoter, and a conditional-lethal mutant of Saccharomyces cerevisiae, in which the expression of calmodulin was regulated by galactose, was constructed. The mutant grew normally in galactose medium, but in glucose medium, in which the promoter was repressed, it ceased growing after 12-15 h. The growth arrest was associated with a decrease in intracellular calmodulin levels: after 12 h, no intracellular calmodulin protein was detectable. Analysis of the terminal phenotype showed that when the cell stopped growing, it had a bud, a nucleus after S-phase and a short mitotic spindle. Thus, the defect was mainly in nuclear division. Bud growth was partially inhibited in these cells: 27% of the cells stopped growing with a small bud. Furthermore, calmodulin-deficient cells showed elevated rates of chromosome loss, possibly as the result of a defect in the precise segregation of chromosomes.

A New Species of Vigna (Leguminosae: Papilionoideae) from Southern Africa

On a plant collecting mission in the Eastern Highlands of Zimbabwe in January 1987, a plant community was found at the edge of Udu Dam, Nyanga containing Vigna oblongifolia A. Rich. and what appeared to be another Vigna species which, while superficially similar, was clearly distinct due to the darker and shorter leaves and the distinctly winged peduncles. Although the unknown species had small flower buds, no open flowers or pods were apparent. The site was revisited in April and flowering specimens and a few ripe pods were collected. After comparison with herbarium sheets and published descriptions (Wilczek 1954; Verdcourt 1970, Gillet et al. 1971; Mar&chal et al. 1978) it became apparent that this was a previously undescribed species belonging to subgenus Haydonia (Wilczek) Verdc. Two other specimens of this taxon, which had also been collected at Nyanga, were found in the National Herbarium, Harare. During examination of material at the herbarium of the Botanical Research Institute, Pretoria, a further sheet of this taxon was found, labelled Vigna venulosa (Huntley 3424). This specimen was collected in Angola and is distinct from the other material labelled V. venulosa which mainly has a West African distribution.

Pattern formation in the facial primordia.

Pattern formation is the developmental process that leads to the spatial ordering of cell differentiation. We have explored the problem of pattern formation in the development of the face of chick embryos. At early stages, the developing face consists of a series of small buds of tissue, the facial primordia that encircle the primitive mouth. The concepts of positional information provide a framework for considering how the patterns of differentiated cells are generated in the face. We suggest that the cranial neural crest cells must first be informed to which facial primordium they belong and then of their position within that primordium. The cells of the early primordia appear indistinguishable. However, when the mesenchyme cells are placed in high-density culture, cartilage differentiates. The extent and pattern of cartilage differentiation is characteristic for the cell population of each facial primordium. Myogenic cells also differentiate in the cultures, but the proportion of myogenic cells is independent of the extent of chondrogenesis. Within the facial primordia, a set of epithelial-mesenchymal interactions appears to be required for outgrowth and pattern formation along the proximodistal axis of the chick beaks. In culture, face epithelium locally inhibits cartilage differentiation and suggests that another set of epithelial-mesenchymal interactions may be involved in cell patterning. The mechanisms involved in specifying the mediolateral axis of the face, for example, the midpoint of the upper beak, are not known. Vitamin A derivatives, collectively known as retinoids, affect the development of the face of chick embryos and lead to a specific facial defect. Upper beak development is inhibited but the lower beak develops normally. The response to retinoids could be related to the specification of cells to belong to the facial primordium that will form the upper beak. Alternatively, retinoids may interfere with positional cues that operate to inform cells of their position within that primordium.

Rapid Clonal Propagation of Papaya in Vitro from Mature Field-grown Trees

Abstract Rapid development of axillary branches on rooted cuttings from mature field-grown papaya (Carica papaya L.) trees was promoted by removal of stem apices and application to the cut surface of a mixture containing 225 mg BAP/liter of lanolin. Small axillary buds were removed from these branches and cultured, initially on solid medium, and then in liquid medium on a roller drum at 3 rpm in Drew and Smith (DS) medium containing 1 µm BAP + 1 µm NAA. After two or three subcultures on the roller drum with alternate periods on hormone-free basal medium, apically dominant shoots were produced. Growth of axillary buds subsequently occurred on DS medium containing 1 µm BAP + 0.25 µm NAA. Cultures also were established from buds of 6-month-old trees, followed by enhanced axillary shoot growth on DS medium containing 2 µm BAP + 0.5 µm NAA. Roots initiated on actively growing shoots when incubated at 27°C in a 12-hr photoperiod on a reduced mineral medium containing 10 µm IBA. Rooted shoots were established in a high-humidity (&gt;90%) cabinet in a glasshouse and planted in the field. Field plants were characterized by a reduced juvenile stage, excessive vegetation at the lower nodes, and production of flowers and fruit close to the ground. Chemical names used: N6-benzylaminopurine (BAP); 1H-naphthaleneacetic acid (NAA); 1H-indole-3-butyric acid (IBA).

Investigations of endocrine cells in the gastrointestinal tract and pancreas during the metamorphosis of an anuran ( Alytes obstetricans L.): Histochemical detection of APUD cells

Endocrine cells were detected at premetamorphosis, prometamorphosis, climax, and juvenile stages using an amine-inducing fluorescence technique with or without previous l-3,4-dihydroxyphenylalamine ( l-DOPA) treatment. At premetamorphosis, serotonin cells exhibited yellow fluorescence in the gut primary epithelium of the l-DOPA untreated animals. In the treated animals, green fluorescent APUD cells could be seen in addition to the serotonin cells. In the pancreas, numerous clusters of fluorescent APUD cells were observed. At prometamorphosis the number of fluorescent cells increased in the intestinal primary epithelium and, close to the basal membrane, numerous small regenerative buds devoid of fluorescent cells appeared. In the pancreas of l-DOPA-treated animals, two types of APUD cells could be distinguished by their different fluorescence intensities. At the climax stage, the stomach developed and APUD cells were detectable in the gastric glandular buds. The degenerated primary intestinal epithelium was progressively removed in the intestinal lumen. At this stage, the regenerative buds of the secondary epithelium exhibited APUD cells. In the disorganized pancreas, the induced fluorescence decreased strongly. At the juvenile stage, cords of APUD cells displayed a cytoplasmic green fluorescence in the pancreas. In the stomach and intestine, serotonin and APUD cells were numerous.

The yeast GTP-binding YPT1 protein and a mammalian counterpart are associated with the secretion machinery

A yeast GTP-binding protein, the YPT1 gene product, has been found to function early in the secretion pathway. The ypt1-1mutation causes a phenotype reminiscent of early secretion-defective mutants, including accumulation of membranes and vesicles as well as a partial defect in secretion and incomplete glycosylation of invertase. Immunofluorescence localization studies using affinity-purified antibody directed against the YPT1 protein showed punctate staining of the cytoplasm of growing yeast cells and very intense staining of small buds, where membrane growth and secretion are most active. The punctate cytoplasmic staining is changed in a mutant ( sec7) under conditions that cause aberrant Golgi structures to accumulate. The pattern of immunofluorescence obtained when mouse cells were stained with the antibody coincided closely with the pattern observed with wheat germ agglutinin, suggesting that a mammalian counterpart of the yeast YPT1 protein is located in the Golgi apparatus. These results are interpreted as suggesting that GTP-binding proteins may act to direct intracellular vesicle traffic.

Effects of low X-ray doses in Saccharomyces cerevisiae.

Three strains of Saccharomyces cerevisiae with different capacities for repair of radiation damage (RAD, rad18, and rad52) have been tested for their colony forming ability (CFA) and growth rates after application of small X-ray doses from 3.8 mGy to 40 Gy. There was no reproducible increase in CFA observable after application of doses between 3.8 mGy and 4.7 Gy. X-ray doses of 40 Gy causing an inactivation of CFA from 90% to 50%, depending on the repair capacity of the strains used, caused a reduced increase in optical density during 2 h buffer treatment in comparison to unirradiated cells. This reduction however, is reversible as soon as the cells are transferred into nutrient medium. One hour after transfer into growth medium the portions of cells with large buds (G2 and M phase) and cells with small buds (S phase) are drastically different in irradiated cells from those obtained in unirradiated cells. The time necessary for separation of mother and daughter cells is prolonged by X-ray irradiation and the formation of new buds is retarded.

Ethylene production, ACC and MACC content of freesia buds and florets

Changes in ethylene production, ACC and MACC content of buds and florets of detached freesia inflorescences were studied. It was found that most of the ethylene produced by freesia inflorescences came from small buds at the apex of the inflorescence. This increase in ethylene production coincided with an increase in ACC and MACC content. Between Days 4 and 5, both ethylene production and ACC content decreased strongly while the amount of MACC was still increasing. About 95% of the ACC found in buds came from the anthers. The surge in ethylene production was followed by death of the buds. It is concluded that detachment of inflorescences leads to a stress situation for the small buds at the apex of the inflorescence. In these buds the ethylene biosynthesis is stimulated.

Pleiotropic plasma membrane ATPase mutations of Saccharomyces cerevisiae.

We isolated a large number of mutations in the structural gene for the plasma membrane ATPase (PMA1) of Saccharomyces cerevisiae. These mutations were selected by their resistance to the aminoglycoside antibiotic hygromycin B. Biochemical analysis of purified membrane preparations showed that the plasma membrane ATPase activity of the mutants was reduced as much as 75%. Intragenic complementation of pma1 mutants suggested that the yeast plasma membrane ATPase was a multimeric enzyme. The pma1 mutants were apparently defective in maintaining internal pH; more than half of the mutants were unable to grow either at a low pH or in the presence of a weak acid. Most pma1 mutants were also osmotic pressure sensitive. At a very low temperature (5 degrees C) many pma1 mutants were unable to grow and were arrested as unbudded cells. The three most severely affected mutants were also unable to grow in the presence of NH4+. The most extreme mutant exhibited a severe defect in progression through the cell cycle; on synthetic medium, the cells progressively accumulated nucleus-containing small buds that generally failed to complete bud enlargement and cytokinesis. Most of the pleiotropic phenotypes of pma1 mutants could be suppressed by the addition of 50 mM KCl but not NaCl to the medium.

Pleiotropic plasma membrane ATPase mutations of Saccharomyces cerevisiae.

We isolated a large number of mutations in the structural gene for the plasma membrane ATPase (PMA1) of Saccharomyces cerevisiae. These mutations were selected by their resistance to the aminoglycoside antibiotic hygromycin B. Biochemical analysis of purified membrane preparations showed that the plasma membrane ATPase activity of the mutants was reduced as much as 75%. Intragenic complementation of pma1 mutants suggested that the yeast plasma membrane ATPase was a multimeric enzyme. The pma1 mutants were apparently defective in maintaining internal pH; more than half of the mutants were unable to grow either at a low pH or in the presence of a weak acid. Most pma1 mutants were also osmotic pressure sensitive. At a very low temperature (5 degrees C) many pma1 mutants were unable to grow and were arrested as unbudded cells. The three most severely affected mutants were also unable to grow in the presence of NH4+. The most extreme mutant exhibited a severe defect in progression through the cell cycle; on synthetic medium, the cells progressively accumulated nucleus-containing small buds that generally failed to complete bud enlargement and cytokinesis. Most of the pleiotropic phenotypes of pma1 mutants could be suppressed by the addition of 50 mM KCl but not NaCl to the medium.

Multiple methods of visualizing the yeast vacuole permit evaluation of its morphology and inheritance during the cell cycle.

The vacuole of the yeast Saccharomyces cerevisiae was visualized with three unrelated fluorescent dyes: FITC-dextran, quinacrine, and an endogenous fluorophore produced in ade2 yeast. FITC-dextran, which enters cells by endocytosis, had been previously developed as a vital stain for yeast vacuoles. Quinacrine, which diffuses across membranes and accumulates in acidic compartments in mammalian cells, can also be used as a marker for yeast vacuoles. ade2 yeast accumulate an endogenous fluorophore in their vacuoles. Using these stains, yeast were examined for vacuole morphology throughout the cell division cycle. In both the parent cell and the bud, a single vacuole was the most common morphology at every stage. Two or more vacuoles could also be found in the mother cell or in the bud; however, this morphology was not correlated with any stage of the cell division cycle. Even small buds (in early S phase) often contained a small vacuole. By the time the bud was half the diameter of the mother cell, it almost always bore a vacuole. This picture of vacuole division and segregation differs from what is seen with synchronized cultures. In ade2 yeast, the bud usually inherits a substantial portion of its vacuole contents from the mother cell. We propose that vacuolar segregation is accomplished by vesicular traffic between the parent cell and the bud.