Dormancy in peach (Prunus persica L.) flower buds

Summary Peach buds (floral and vegetative) were periodically collected from midsummer until the spring flowering and sprouted under continuous light, 100% relative humidity and 20–25°C. Treatments with 200 ppm gibberellin A₃ (GA₃) or chilling (2–4°C for 30 days before planting) were applied. Vegetative buds showed well-defined phenological stages: pre-dormancy, true dormancy, and end of dormancy. Both GA₃ and chilling treatments shortened the sprouting times of vegetative dormant buds close to those in predormancy. Isolated floral buds were irresponsive under all conditions and did not sprout even with the GA₃ or chilling treatments. In a comparative study with buds immediately after collection anatomical analysis demonstrated that vegetative buds were almost completely developed by midsummer/early automn and remained in a resting state until the end of winter. Floral buds developed continuously over the same period. Both types of verticils began to differentiate in midsummer. Sepals and petals developed mainly in late summer, androecious floral parts developed throughout the resting period, while gynoecious floral parts showed differentiation in late winter. The flower was completely formed a few days prior to blossoming. Thus, in isolated peach buds fertile verticils are not sufficiently developed during the resting time to allow sprouting.     

鄱阳湖四种水鸟的栖息地利用与水深和食物的关系

为了了解水深和食物资源对水鸟栖息地利用的影响,2012 ~ 2013年越冬期,采用样方法,对鄱阳湖沙湖的白鹤 (Grus leucogeranus)、小天鹅 (Cygnus columbianus)、东方白鹳 (Ciconia boyciana) 和白琵鹭 (Platalea leucorodia) 4种水鸟的数量、觅食地和休息地的水深以及主要食物——沉水植物冬芽的密度和生物量进行了调查。每个样方为150 m? 150 m的栅格,全湖共设置152个样方。结果显示,10月份沉水植物冬芽的平均水深为 (124.2 ± 12.0) cm。4种水鸟觅食地的水深均显著高于其休息地的水深 (白鹤：Z = 11.96, 小天鹅：Z = 4.69, 东方白鹳：Z = 14.44, 白琵鹭：Z = 29.33, 所有P < 0.01);对于2种食冬芽的水鸟,白鹤觅食地的水深、冬芽生物量、取食深度以及休息地水深均显著低于小天鹅 (觅食地水深: Z = 8.56, 冬芽生物量: Z = 2.93, 取食深度: Z = 14.69, 休息地水深: Z = 4.34, 所有P < 0.05),但两者觅食地的冬芽密度差异不显著 (Z = 0.6, P = 0.55);对于2种食鱼性水鸟,东方白鹳觅食地水深、取食深度和休息地水深均显著大于白琵鹭 (觅食地水深: Z = 10.60; 取食深度: Z = 9.35; 休息地水深: Z = 8.47, 所有P < 0.01)。回归分析表明,白鹤、东方白鹳、白琵鹭的觅食个体数量均与水深呈二次项关系,个体数量最大的觅食地水深分别为23.9 cm,33.0 cm和22.6 cm;白鹤、小天鹅的觅食个体数量均与冬芽生物量呈线性关系。3种涉禽均只能分布在一定的水深范围内,且同种食性的水鸟利用不同的水深从而减少在空间生态位的重叠。     

In nature dormant buds and in vitro dormant-like buds ofFraxinus excelsior L.

Summary Microcuttings ofFraxinus excelsior, sampled from adult trees during the period of cell cycle blockage of bud in G_0–1, developed long rejuvenated sprouts on the Woody Plant Medium (WPM) with benzylaminopurine (BAP) (4.0 mg/l) and indolebutyric acid (IBA) (0.03 mg/l). These sprouts had the ability to enter a resting period, building dormant-like buds when maintained on the original WPM. Sprouts developed from subcultures also entered a resting period without any transfer. Comparison of in nature buds in active growth and dormancy with buds of growing sprouts and in vitro dormant-like buds revealed similarity in behaviour at the shoot apical level. In particular, in dormant-like buds in a constant environment, shoot apical functioning was suppressed while the cell cycle of the shoot apex was blocked at the G_0–1 phase, like in nature dormant buds.Abbreviations a.u. arbitrary unit - BAP benzylaminopurine - CF cumulative frequency - d₁, d₂ diameters of the shoot apex - IBA indolebutyric acid - P_n last opposite primordia of range n - WPM woody plant medium     

Die überwinterungsknospen des Krausen Laichkrauts (Potamogeton crispus) als Nahrung für den H?ckerschwan (Cygnus olor) auf dem Federsee

Summary In the highly eutrophicated, shallow Lake Federsee no submersed macrophytes grew, until 1982 a waste water pipeline around the lake was put in operation. In 1983Potamogeton crispus began to colonize the lake and its abundance increased from year to year. The growth cycle, however, remained very short and the macrophyte always died off between the end of June and the middle of July, after having developed large numbers of resting buds. Simultaneous with the increasing canopies ofPotamogeton a rise of Mute Swans in summer and autumn was observed, and because of the absence ofPotamogeton and other new food plants it was suggested that at this time the bird mainly feeds on the resting buds ofPotamogeton. This was confirmed by investigation of excrements, which sometimes consisted mainly of remnants of resting buds. Therefore it is supposed that Mute Swans essentially affect the recolonization of the lake byPotamogeton crispus and by this way also slow down the reestablishment of a diverse flora and fauna.     

Symplastic connection is required for bud outgrowth following dormancy in potato (Solanum tuberosum L.) tubers

To gain greater insight into the mechanism of dormancy release in the potato tuber, an investigation into physiological and biochemical changes in tuber and bud tissues during the transition from bud dormancy (immediately after harvest) to active bud growth was undertaken. Within the tuber, a rapid shift from storage metabolism (starch synthesis) to reserve mobilization within days of detachment from the mother plant suggested transition from sink to source. Over the same period, a shift in the pattern of [U-(14)C]sucrose uptake by tuber discs from diffuse to punctate accumulation was consistent with a transition from phloem unloading to phloem loading within the tuber parenchyma. There were no gross differences in metabolic capacity between resting and actively growing tuber buds as determined by [U-(14)C]glucose labelling. However, marked differences in metabolite pools were observed with large increases in starch and sucrose, and the accumulation of several organic acids in growing buds. Carboxyfluorescein labelling of tubers clearly demonstrated strong symplastic connection in actively growing buds and symplastic isolation in resting buds. It is proposed that potato tubers rapidly undergo metabolic transitions consistent with bud outgrowth; however, growth is initially prevented by substrate limitation mediated via symplastic isolation.     

Pear bud metabolism: seasonal changes in glucose utilization

Utilization of glucose, uracil and valine by flower and leaf buds of seedling pear trees (Pyrus calleryana Decne.) from the time of flower bud initiation to flowering was investigated. A very high rate of glucose utilization through the pentose phosphate pathway was observed throughout the development of buds. There was no difference in the type of glucose metabolism between flower and leaf buds except immediately before flowering, when the metabolism in flower buds was shifted toward the glycolytic pathway. Such a shift did not occur in leaf buds. The incorporation of uracil and valine into the nucleic acid and protein fraction of buds, respectively, was high throughout bud development, perhaps indicating a high rate of turnover in the resting buds. Incorporation of both compounds decreased when buds started to expand prior to flowering.     

Regulation of Bud Rest in Tubers of Potato, Solanum tuberosum L: VIII. Early Effects of Gibberellin A(3) and Abscisic Acid on Ultrastructure

Using the electron microscope, we compared the effects of abscisic acid and gibberellin A₃ on excised buds from resting potato (Solanum tuberosum L.) tubers. Cells of abscisic acid-treated buds became progressively more vacuolated during a 12-hour time course study as compared with control (water) and gibberellin A₃-treated buds. Concentric configurations of endoplasmic reticulum were present in apical cells of freshly excised buds. After about 6 hours these configurations began to open and disperse, and after 12 hours, intact concentric configurations were no longer evident. Both abscisic acid and gibberellin A₃ induced opening and dispersal of the concentric configurations, sometimes as early as 0.5 hour after excision and treatment with hormones.     

Seasonal Changes of the Antioxidative Systems in Foliar Buds and Leaves of Field-grown Beech Trees (Fagus sylvatica,L.) in a Stressful Climate

The activities of superoxide dismutase, ascorbate peroxidase, monodehydroascorbate radical reductase, and dehydroascorbate reductase and the contents of ascorbate, chlorophyll and soluble protein were determined in beech (Fagus sylvatica, L.) foliage over two or three seasons. Four important stages of leaf development were distinguished: resting buds, emerging, mature and senescent leaves. Foliar buds in spring, prior to the emergence of new leaves, contained a lower chlorophyll content but a higher protein content and higher activities of ascorbate peroxidase and monodehydroascorbate radical reductase than mature leaves in summer. By contrast, superoxide dismutase and glutathione reductase activities and ascorbate contents were higher in mature leaves than in swollen foliar buds. Dehydroascorbate reductase activity was low in all developmental stages. Resting buds in winter contained activities of superoxide dismutase, ascorbate peroxidase and monodehydroascorbate radical reductase that were similar to those found in mature leaves in summer, whereas the contents of total and reduced ascorbate were 6- and 20-times lower, respectively, in buds than in mature leaves. The low foliar concentration of reduced ascorbate in resting buds, despite high monodehydroascorbate radical reductase activity, suggests that the regeneration of ascorbate might be limited by the availability of reductant. High antioxidative capacity was conferred by mature beech leaves and may be an important protection measure for coping with the large fluctuations in temperature and exposure to elevated ozone concentrations in summer.     

<Emphasis Type="Italic">In vitro</Emphasis> regeneration of mature <Emphasis Type="Italic">Pinus sylvestris</Emphasis> buds stored at freezing temperatures

Changes of morphogenic competence in mature P. sylvestris L. buds due to frozen storage were investigated. The highest callus formation was registered on explants stored at –18°C for three months, but on explants stored for five months, it was also higher than in the control. Budding and development of needles in vitro was observed only for buds frozen three to five months. Peroxidase activity was lowest in these buds. In contrast, polyphenol oxidase activity in bud tissues continually increased during frozen storage. Within 10 months of frozen storage the content of starch and sugars in resting buds changed. It may be concluded that changes in composition of non-structural sugars in pine buds after five months of frozen storage are part of metabolic changes leading to loss of morphogenic capacity.     

Endorhythmic development in Choisya ternata Kunth (Rutaceae), with a further elucidation of lammas shoots, as well as sylleptic and proleptic shoots

Most apical resting buds of Choisya tenata include inflorescence buds in the axils of their lower consecutive paired scales. These inflorescences develop as apical buds which burst in spring. The whole of the lateral inflorescence system on a shoot originating from an apical bud may be viewed as a single, proliferous inflorescence. After the spring flush there are usually two other flushes of the same shoot within the same season, each of which may be accompanied by the development of lateral inflorescences as in the spring flush. Each further flush produces an apical 'lammas shoot'. As an apical lammas shoot elongates, lateral lammas shoots may also develop from upper, previously resting, axillary buds on the underlying stem segment of the preceding flush. Lateral inflorescences on apical lammas shoots arise from axillary buds preformed within the briefly-dormant apical buds terminating the preceding flush. These inflorescences, as well as the spring ones, represent proleptic shoots. The production of resting apical buds between two intra-season flushes of a shoot may be fugacous, without the differentiation of perfect bud-scales, and with curtailmenl ol internode elongation. As no environmental influence seems to be responsible for intra-season rhythmicity in development, this is said to be endorhythmic. The interrelations of proleptic to sylleptic shoots are discussed.     

The influence of cytokinin pulse treatments on adventitious bud formation on vegetative buds of Picea abies

Resting vegetative buds of Picea abies collected from phytotron-grown rooted cuttings of 24-year-old trees or a 12-year-old hedge were tested for their capacity to form adventitious buds after various cytokinin treatments. The most effective method for obtaining a high yield of adventitious buds within 8 weeks was to pulse treat the buds in 250 M BA for 3 h and then culture them on medium containing 5 M each of BA and kinetin for 1 week. The developmental pattern for adventitious bud production, with the formation of 10 to 20 adventitious buds per bud, was similar for all tested genotypes, although the number of buds giving rise to adventitious buds varied significantly. The capability of some clones to form adventitious buds was correlated to endogenous cytokinin content. The clone which contained most endogenous cytokinin in its resting bud had the highest potential for adventitious bud formation.     

Bud Structure and Shoot Architecture of Canopy and Understorey Evergreen Broad-leaved Trees at their Northern Limit in East Asia

The morphology of winter buds, shoot growth and branching architecturewas studied in evergreen broad-leaved trees of subtropical/warm-temperaterain forests of southern and central Japan. Winter buds werecategorized into three types based on external morphology anddevelopmental processes: naked, hypsophyllary and scaled buds.Each shoot tip with intermittent growth was covered with a smallnumber of immature leaves or hypsophylls when growth ceased.Hypsophylls protect the apical meristem during its resting period,hence we termed them hypsophyllary buds. In trees with nakedbuds, immature leaves resumed their growth and developed tomature leaves the following spring; thus these trees had nospecial organs to cover shoot tips during winter. In trees withhypsophyllary buds, some hypsophylls covering the shoot tipsthrough the year were shed without further growth when new shootsstarted to grow in the spring. In trees with scaled buds, newlygrowing shoots had hypsophyllary buds at their tips in spring.After the completion of stem elongation, the buds were replacedby scaled buds (often covered with more than 30 scales) in summer.These scaled buds grew during autumn and winter until a newflush of growth the following spring. The three bud types correspondedto forest stratification in the northern-limit forest: the nakedbuds of Rubiaceae and Myrsinaceae in the ground layer; the hypsophyllarybuds of various families (e.g. Symplocaceae, Myrsinaceae) inthe understorey; and the scaled buds of Fagaceae and Lauraceaein the forest canopy. The position and activity of buds on abranch were reflected in the architectural patterns of the treesin different layers of the forest. The scaled-bud trees hadwell-protected, abundant axillary buds and are probably suitedto survive in the forest canopy (with frequent disturbances),whereas the single terminal bud of hypsophyllary-bud trees cansurvive in the less disturbed, resource-limited understoreyof the forest.Copyright 1998 Annals of Botany Company Bud structural type; bud formation; bud growth; shoot elongation; shoot-growth cycle; branching architecture; forest stratification.     

ORIGIN AND EARLY MORPHOGENESIS OF LATERAL BUDS IN THE FERN DAVALLIA

The general organography, vascular organization, and leaf and bud development in Davallia solida and D. trichomanoides are described. These epiphytic species have creeping shoots with dorsally-borne leaves in a distichous phyllotaxis and the buds occur near each leaf base. Roots are borne on the ventral and flanking surfaces of the rhizome, but only at bud positions. The vascular pattern of these species is a perforated solenostele. Leaf and bud traces have distinctly different origins. While the proximity of buds to leaves has suggested that bud origin is axillary, observations show that the origin of buds is cauline and that their position is extra-axillary from inception. The stages of structural morphogenesis in Davallia buds differ significantly from the scheme proposed by Wardlaw. The principal difference is the absence of a resting period occurring between the origin and continued development of buds in Davallia. The elongated internodes which separate leaf-bud pairs from one another, the topographically distinct and predictable positions of leaves and buds, the structural equivalence of unexpanded buds, and vascular differences in leaves and buds make Davallia an useful species for physiological studies of differential bud expansion.     

Multiplication of Eucalyptus citriodora (L) Hook Through Shoot Bud Induction on the Internodal Portions of Mature Tree Explants

Nodal explants of Eucalyptus citriodora responded better for high frequency bud break and fast growth in liquid agitated cultures with 4.4 μM benzyladenine (BA) and 5.37 μM α-naphthalene acetic acid (NAA) rather than on semisolid medium. On transfer to MS medium with 1.11 μM BA and 5.37 μM NAA the sprouted axillary buds showed further elongation growth alongwith a slight callus and formation of globular structures on the internodal regions. The anatomy of these globular structures revealed that they are shoot buds. These buds elongated into shoots on MS medium with low levels of BA.     

REPRODUCTIVE DEVELOPMENT IN LOBLOLLY PINE. II. THE EFFECT OF AGE,GIBBERELLIN PLUS WATER STRESS AND OUT-OF-PHASE DORMANCY ON LONG SHOOT GROWTH BEHAVIOR

The effects of age from seed, out-of-phase dormancy, and gibberellin treatment with water stress on the reproductive and vegetative development of the long shoot terminal bud were observed. Scions of different ages were grafted onto 1-yr-old rootstocks, and the younger scions grew more and produced fewer strobili than older ones. Out-of-phase dormancy promoted both male and female flowering at all ages, but the older scions responded better. Gibberellin_4/7 plus water stress promoted development of female strobili only. Treatments that promote flowering also increase the size of the resting bud. It is proposed that treatment effects promoting flowering appear to fall into two categories: 1) Those which promote the formation of a resting bud, and 2) those which affect the subsequent development of resting buds which have the potential to develop strobili.     

In Vitro Multiplication of Sesame (Sesamum indicum) through Tissue Culture

Tissue cultures were established from different parts of sesame(Sesamum indicum L. cv. PT) seedlings. A callus tissue derivedfrom hypocotyl segments produced embryo like structures. Shoottips with cotyledons excised from 8 to 10-d-old seedlings producedmultiple shoot buds on a cytokinin-enriched medium. Presoakingand germination of seeds in BA or 2iP (8 mg l–1) enhancedthe development of shoot buds. Upon isolation and culture theshoots buds formed rooted plantlets in a charcoal-enriched medium. Sesamum, multiple buds, plantlets     

A cold environment is a prerequisite for formation of "plastid initials" in winter buds of poplar

The “plastid initial,” the presumed precursor of eoplasts and proplastids, is present in the cells of the apical meristem of winter buds of poplar (Populus euramericana). The formation of the plastid initial in the cells of winter buds is initiated soon after the breaking of the innate or resting stage of dormancy, even in winter under nongrowing conditions in mid-January or early February. From this stage to March, the conglomeration of the plastid initial and the formation of prolamellar bodies is evident. In contrast to the poplar samples kept outdoors, the cells of the apical meristem of the indoor winter buds did not show any indication of the formation of the plastid initial and the buds of the latter sample did not flush even at the end of May. These results suggest that the sequence of reactions involved in the onset of regrowth may be closely related to the formation of the plastid initial.     

Fine structure and distribution of epidermal projections associated with taste buds on the oral papillae in some loricariid catfishes (Siluroidei: Loricariidae)

Two morphologically distinct structures occur on the surfaces of the oral papillae in several loricariid catfish species; namely, (1) typical vertebrate taste buds composed of receptor and sustentacular cells and (2) brushlike projections, termed epidermal brushes, that represent specialized epidermal cells containing keratin. Both of these structures were studied with the combined use of light microscopy and scanning and transmission electron microscopy. The general body surface, fins, and rostral cutaneous processes of some loricariid catfishes are covered with taste or terminal buds but lack the epidermal brushes. It is suggested that the epidermal brushes found on the oral papillae serve as protective devices for the taste buds and as abrasive surfaces for substrate scraping during feeding. The taste buds on the oral papillae may detect any gustatory stimuli from the resulting substrate disturbance. Comparative studies reveal many differences in the number and spatial arrangement of these two structures on the oral papillae among the several species of the Loricariidae examined. These differences may represent functional adaptations to the various modes of life in the Loricariidae.