Basal Plate Tissue in Narcissus Bulbs and in Shoot Clump Cultures: Its Structure and Role in Organogenic Potential of Single Leaf Cultures

Light microscopy demonstrated that the apparently amorphous,achlorophyllous tissue at the base of in vitro shoot clump cultureof Narcissus was comparable in structure to the basal plateof Narcissus bulbs. Both had very complex vascularisation andsmall, densely packed parenchymatous cells. In shoot clump cultures, primordia were produced by meristematiczones at the surface of this achlorophyllous tissue, very closeto the base of leaves. Single leaf units excised from the invitro shoot clump cultures with a wedge of basal achlorophylloustissue were highly organogenic when used as secondary explantsfor in vitro culture of Narcissus. No organogenesis occurredin the absence of the leaf base and achlorophyllous (basal plate)tissue and little organogenesis occurred unless the leaf baseand basal plate tissue were immersed in the culture medium (i.e.explants inoculated into liquid medium or upright in agar-solidifiedmedium). After two 5-week culture passages in liquid medium, more thanfive leaves were produced per leaf base inoculated. Thus rapidmicropropagation of Narcissus can be achieved using only thebase of single leaf units excised from shoot clump cultures.Copyright1993, 1999 Academic Press Anatomy, basal plate, bulb, in vitro, leaf culture, Narcissus, organogenesis     

Some aspects of daughter bulb growth and development and apical dominance in bulbous Iris

Apical dominance appears to have minimal direct involvementin daughter bulb formation in the bulbous Iris cultivar Ideal.Daughter bulb number and growth relate to the size and reproductivestate of the mother bulb and are not markedly influenced bymeristem destruction. In contrast, destruction or removal ofthe apical meristem promotes lateral bud sprouting in intactbulbs, and lateral bud elongation in Iris meristem explants.These results show that, in contrast to certain other bulbousplants, apical dominance does not direcdy limit daughter bulbnumber in bulbous Iris, but does prevent lateral bud sprouting. (Received September 6, 1978; )     

Factors Affecting the Growth of Daughter Bulbs in the Tulip

The relative growth rate (R_w) of daughter bulbs of the tulipcultivar Rose Copland was remarkably constant during the springperiod of growth in four seasons at two sites. The Q₁₀ of R_wwas 2.2, and the long period of constant R_w is attributed tocompensation of a fall with age by increasing temperatures inthe spring. Final bulb weight differed among four cultivarsbecause of differences in R_w and in initial daughter bulb weights. Partial defoliation reduced R_w roughly in proportion to theleaf area removed, and removal of mother bulb scales resultedin reduced leaf area, fewer daughter bulbs, and a lower daughterbulb R_w. Heat-treatment of mother bulbs before planting (blindstoken)killed the flower within the bulb, inactivated the apical dominanceexerted by the flower, and resulted in a higher initial daughter-bulbweight at the start of the spring period of exponential growth.The R_w of heat-treated and control daughter bulbs were not different,neither were the leaf areas, so it is assumed that final daughter-bulbweights were higher following treatment because of increasedsink strength. The economic implications of these findings arediscussed.     

The Shoot Apex and its Dichotomous Branching in the Nypa Palm

Seedlings of the palm Nypa fruticans van Wurmb are viviparous,the plumule becoming exserted before the fruit is ripe and possiblyassisting in fruit detachment. Established seedlings have horizontalaxes, this growth orientation being maintained throughout thelife of the palm which may be described as ‘rhizomatous’.Inflorescences are axillary in adult plants, but their distributionis irregular. The shoot apex is small and very asymmetricalsince it is more or less displaced into a lateral position byprogressive enlargement of each leaf primordium during thisleaf's first plastochrone. The plastochrone interval is apparentlya long one so that leaves have a wide developmental gap betweenthem. This results in a leaf base which is more or less cylindricalbut with a groove to accommodate the next youngest leaf. All the available evidence suggests that vegetative branchingis by equal dichotomy of the shoot apex at wide intervals. Thedichotomy is marked superficially by a leaf, enclosing the twonew shoots, which has two grooves. The twin shoots are insertedin the lateral, not the dorsiventral plane of this enclosingleaf. The daughter shoots are always at precisely the same stageof development and they always have mirror-image symmetry withrelation to each other, the phyllotaxis of the parent shootbeing maintained without obvious interruption. There is no anatomicalevidence for abortion of the original apex and its replacementby two new ones. The vascular system is divided equally betweeneach daughter shoot without interruption, suggesting stronglythat there is continuity of growth from the undivided to thedivided condition.     

濒危植物庙台槭生殖生物学研究1.花序和花的形态及发育

庙台械的花序为有限花序,由一顶花和6—9枝侧花枝组成,属圆锥状聚伞花序。一个花序共有14—29朵花,包括两性花、雄花和无性花三类花。根据花在花序上着生的位置,可分为三级。7月初,花序原基形成,在花序轴伸长的同时,侧面形成侧花枝轴原基。花序的顶花最早进行个体发育,随后是侧花枝顶花;侧花枝上同一级花的发育顺序则是从花序的下面向上进行。花器官发生时,花萼原基最先形成,然后是花瓣、雄蕊、心皮和胚珠。     

Bulbil production in Narcissus: the effect of temperature and duration of storage on bulb unit development and subsequent propagation by twin-scaling

The growth of bulb components and carbohydrate content of Narcissus bulbs was followed during storage at 5–30 ^oC, and the productivity of twin-scale propagules cut from bulbs after these storage treatments was studied. Growth of daughter bulb unit components was greatest during storage at 9–15 ^oC, and greatly inhibited at 30 ^oC. Concentrations of soluble sugars were highest following 30 ^oC storage, and higher in intermediate bulb scales than in outer or inner scales. Bulbil production on twin-scales was greatest on propagules cut from the intermediate scales, and in bulbs previously stored at 15 or 30 ^oC.     

Development of Meristems of Weigela florida Variety 'Bristol Ruby' Following Reproductive Induction in Long Days

Weigela florida variety ‘Bristol Ruby’ has longday requirements for its growth and, in general, for its flowering.Vegetative development, floral initiation and floral organogenesisare described using scanning electron microscopy during photoperiodictreatment in long days, under controlled conditions. Flowering of axillary buds of cuttings has been studied. Theapex of Weigela at the vegetative phase is characterized bya very small hollow meristem. After 9 long days, the meristemenlarges and, after 12 long days, early axillary buds are initiatedin the axils of the leaves, which become bracts. When the numberof long days was increased, flowers were initiated in the budson the induced branches; first at the proximal part of the branchwhere development afterwards slowed down, then on the medianparts of the branch where development was accelerated. Two bracteoles are differentiated soon after floral initiation;first initiation of the calyx required 18 long days. Petals,stamens and ovary were rapidly initiated after that. Weigelaflowers are clustered; the inflorescence ceased growth by abortionof the terminal meristem or by formation of a terminal flower.In axillary buds of the fifth node the formation of the clusterwas completed about 20 days after the beginning of floral induction. Weigela florida ‘Bristol Ruby’, scanning electron microscopic analysis, vegetative meristem, floral development stages, long days induction     

Effect of Bulb Size on the Growth of Tulips

A study of the growth in the field of tulip plants from bulbsof four different sizes showed marked differences of leaf areaand shoot dry weight, those produced by larger bulbs being thegreater. Relative growth rates of the smaller plants were higherthan those of the large ones; this was due to different proportionsof total plant weight being non-growing mother bulb, as therelative growth rates of the shoots were not affected by bulbsize. The relative growth rates of daughter bulbs were alsounaffected by the mother bulb size, being very similar to previouslydetermined values in other sites and seasons. The final bulbyield was proportional to daughter bulb weight early in theseason. It is suggested that daughter bulb weight, shoot weight,and leaf area are directly related to the size of the motherbulb, and controlled by the factors determining mother bulbsize during its development.     

Branching Principles Governing the Architecture of Cornus kousa (Cornaceae)

The complex structure of the crown of Cornus kousa, generallyfive-forked in vegetative branching and two-forked in reproductivebranching, is analysed quantitatively and described by two basicbranching principles: decussate phyllotaxy and the resettingrule for planes of branching. Most Cornus species have opposite,decussate phyllotaxis. The leaf pair (with axillary buds) definesthe branching plane of a node. Because of regular phyllotaxis,the fundamental branching pattern is that every branching planealong an axis is perpendicular to the preceding one. However,the first node of a lateral horizontal shoot always has a horizontalbranching plane; we term this the resetting rule. We observedthat resetting occurs when the first nodes initiated in thevertical plane are repositioned by a twisting of their firstinternodes. All later nodes alternate directions, i.e. showusual decussate alternation. Foliage leaf nodes usually producethree-forked branchings. When vegetative winter buds are formed,a foliar node and adjacent scale leaf node produce a five-forkedbranching. When reproductive winter buds with a terminal inflorescenceare formed, the last foliar node and two adjacent scale leafnodes can produce a variety of branchings but usually producean equal two-forked branching. To understand better the architecturein C. kousa, we contrast it with C. capitata which does notproduce buds with scale leaves and whose vegetative nodes areclearly separated. Copyright 1999 Annals of Botany Company Branching pattern, Cornaceae, Cornus kousa, decussate branching, dogwood, Japanese strawberry tree, tree architecture, tree geometry.     

The Rest Period of RhododendronFlower Buds I. EFFECT OF THE BUD SCALES ON THE ONSET AND DURATION OF REST

Shortly after flower differentiation, Rhododendron flower developmentis interrupted by a rest period. The results reported here showthat the onset and duration of rest depended upon the presenceof the flower bud scales. When the scales were removed beforethe onset of rest, the flowers continued to elongate and attainedanthesis. Intact buds stopped growing and remained in rest forat least four months. Scale removal after the onset of restterminated the rest period, though there was a lag phase beforethe flowers began to elongate. The duration of the lag phasewas related to the time of scale removal. The scales preventedflower development in situ, on detached stems and in vitro.Theresults further show that the rest period of each flower budwas independent of the rest period of adjacent flower buds andthat the resting terminal flower buds correlatively inhibitedthe growth of the lateral vegetative apices. The correlativeinhibition was eliminated by removing the terminal flower budor by breaking the rest period of the flower bud.     

Carbohydrate,metabolic, and osmotic changes in scaled-up liquid cultures of <Emphasis Type="Italic">Narcissus</Emphasis> leaves

Summary The use of scaled-up liquid cultures could be an efficient system for mass propagation of Narcissus, as it can greatly reduce the costs involved with manual handling. Induction of hyperhydric meristematic leaf section clusters and proliferation were carried out in an ancymidol (ANC)-containing liquid medium in flasks and disposable presterilized plastic bioreactors. Non-hyperhydric bulblets started to develop from hyperhydric meristematic leaf section clusters after subculture on a 0.8% agar strength medium, and young bulbs formed after 10 mo. in vivo acclimatization with a 98% survival rate. The present study reveals that in Narcissus leaf sections cultured in liquid medium, morphogenetic changes in leaf sections were associated with metabolic changes. The changes in carbohydrate, protein, and water potential of the liquid media and leaf sections were found to be closely related to meristematic center initiation on Narcissus hyperhydric leaf sections. Starch, sucrose, and glucose were significantly higher in the hyperhydric leaf sections cultured in ANC medium. The water potential was signifieantly higher in ANC-treated leaf sections and significantly lower in the medium containing ANC, at the stage shortly before or after hyperhydricity and meristematic centers hegan forming on the leaf sections. A 30kDa protein was found to be present in the hyperhydric leaf sections. Based on the present study, a largescale micropropagation protocol of Narcissus in agar and liquid cultures is proposed.     

Bud Structure in Relation to Shoot Morphology and Position on the Vegetative Annual Shoots of Juglans regia L. (Juglandaceae)

The length and basal diameter of all lateral and terminal budsof vegetative annual shoots of 7-year-oldJuglans regia treeswere measured. All buds were dissected and numbers of cataphylls,embryonic leaves and leaf primordia were recorded. Each axillarybud was ranked according to the position of its associated leaffrom the apex to the base of its parent shoot. Bud size andcontent were analysed in relation to bud position and were comparedwith the size and number of leaves of shoots in equivalent positionswhich extended during the following growing season. Length andbasal diameter of axillary buds varied according to their positionon the parent shoot. Terminal buds contained more embryonicleaves than any axillary bud. The number of leaves was smallerfor apical and basal axillary buds than for buds in intermediatepositions on the parent shoot only. All new extended shootswere entirely preformed in the buds that gave rise to them.Lateral shoots were formed in the median part of the parentshoot. These lateral shoots derived from buds which were largerthan both apical and basal ones. Copyright 2001 Annals of BotanyCompany Juglans regia L., Persian walnut tree, branching pattern, preformation, bud content, shoot morphology     

In vitro Propagation of Narcissus

Adventitious shoots were induced on leaf, scale and stem explantstaken from the basal plate region of flowering-size bulbs onmedia containing 2–16 mg l^–1 6-benzylaminopurineand 0·25–4·0 mg 1^–1 1-naphthal-eneacetic acid (NAA). Only the levels of NAA had a significanteffect on the numbers of shoots produced. When trimmed and splitin half, 6 mm or more diameter in vitro shoots regenerated furtheradventitious shoots which in turn grew in size suitable forsplitting within 16 weeks. The vigour of the first generation of shoots was proportionalto the hormone levels used for their initiation. All shootseventually declined in vigour, senesced and formed dormant bulbils.Split senescent shoots regenerated only a few secondary shootswhich quickly became senescent. A total of 500–2000 bulbilscould be obtained from each initial bulb within 18 months. Bulbilsrequired 10 weeks at low temperature before planting to breakdormancy. Histological observations showed that in twin scales and splitshoots, adventitious shoots were regenerated from at least twosuperficial layers of menstematic cells near to the basal plate.This multicellular mode of origin suggests that plants multipliedfrom in vitro adventitious shoots could be as genetically uniformas those from natural vegetative increase. Narcissus, tissue culture, propagation, adventitious shoots, histology     

Ontogeny of Tendrils in Antigonon leptopus H. & Arn.

In Antigonon leptopus the main tendrillar and axillary branchis a modified inflorescence axis. It usually bears 6–7lateral bracts out of which 3–4 lower ones are small andleaf-like while the upper 2–3 are tendrillar; 2–3tendrils are also present at its terminal end. The vegetativeshoot apex shows a single layer of tunica and an inner massof corpus without any cytohistological zonation. The earliestaxillary bud or tendril meristem arises at the second node andit elongates due to rib meristem activity. The bract primordiaarise in an acropetal succession. The initiation of the bract-tendriland the leafy bract is similar. In the development of the bract-tendril,marginal meristem activity is absent or reduced and the differentiationof the apical and subapical initials is absent. The terminalbract-tendrils arise as lateral appendages and the residuumof the apical meristem of the main axillary tendril persistsfor some time. In the flowering period the floral buds arisein the axils of the bracts and bract-tendrils. No flowers arepresent in the axils of terminal bract-tendrils.     

The Hexagonal Branching Pattern of Rhizomes of Alpinia speciosa L. (Zingiberaceae)

Alpinia speciosa L. (Zingiberaceae) is a striking example ofa plant in which an organized architectural structure fulfilsa basic functional requirement - the economical explorationand exploitation of the substrate. This rhizomatous plant spreadslaterally in a predictable manner by vegetative growth to forma clone of separated ramets. A morphological study establishes‘rules of growth’ governing the success and failureof lateral branches (sympodial units), their lengths, and theirrelative angles. The basic branching pattern of this rhizome system approximatesto that of a hexagonal grid - the most economical structuralshape that uniformly ‘samples’ a plane surface.It is shown that the significant deviation of branching anglefound in Alpinia from that required to develop an exact hexagonalnetwork will virtually eliminate aerial shoot ‘clashes’in which the placing of one aerial shoot coincides with thatof another aerial shoot, whilst at the same time enhancing thebenefits of the hexagonal system. The broader implications ofthe organised architecture of plants are emphasised. rhizome, branching pattern, architecture, productivity     

Developmental morphology of branching flowers in Nymphaea prolifera

Nymphaea and Nuphar (Nymphaeaceae) share an extra-axillary mode of floral inception in the shoot apical meristem (SAM). Some leaf sites along the ontogenetic spiral are occupied by floral primordia lacking a subtending bract. This pattern of flower initiation in leaf sites is repeated inside branching flowers of Nymphaea prolifera (Central and South America). Instead of fertile flowers this species usually produces sterile tuberiferous flowers that act as vegetative propagules. N. prolifera changes the meristem identity from reproductive to vegetative or vice versa repeatedly. Each branching flower first produces some perianth-like leaves, then it switches back to the vegetative meristem identity of the SAM with the formation of foliage leaves and another set of branching flowers. This process is repeated up to three times giving rise to more than 100 vegetative propagules. The developmental morphology of the branching flowers of N. prolifera is described using both microtome sections and scanning electron microscopy.     

The Influence of Genes for Vernalization Response on Development and Growth in Wheat

Studies were made of the influence of genes for vernalizationresponse on the growth and development of four near-isogeniclines of bread wheat (Triticum aestivum L.). The duration from sowing of flower initiation, terminal spikeletformation and ear emergence all increased with increasing vernalizationresponse. There was a close positive relationship between thedays from sowing to flower initiation and from sowing to earemergence, indicating that the duration of either phase of developmentis a useful measure of relative vernalization when daylengthdoes not limit the rate of development. Total spikelet number per ear and the duration of spikelet initationincreased with increasing vernalization response and there wasa correspondingly higher rate of spikelet initiation in thetwo lines with stronger vernalization response. Most of the differences in growth between the lines were associatedwith diferences in development caused by the vrn genes. Maximumtotal above-ground dry matter and total leaf area per plantincreased with increasing vernalization repsonse but relativegrowth rate and leaf area per plant were not significantly differentbetween the lines. There were no differences in net assimilationrate between the four lines until 40 d from sowing; thereafterit decreased, with the greatest decrease in the line with thestrongest vernalization response. Flower initiation, terminal spikelet formation, spikelet initiation, ear emergence, growth rate     

Totipotency in Tissue Explants and Callus of Some Members of the Liliaceae, Iridaceae, and Amaryllidaceae

In vitro responses of twelve species of bulbs and conns werecompared. Plantlets could be induced directly without interveningcallus on stem tissue in nine species, on ovary tissue in fivespecies, and on leaf tissue in four species. In Gladiolus, Hyacinthus,Muscari, Ornithogahim, and Scilla plantlets were formed withoutgrowth factors added to the Murashige and Skoog medium. In Hippeastrum,Schizoslylis, Sparaxis, and Ipheion auxin was required. No plantletscould be induced directly on explants of growing tissue of Freesia,Tulipa, or Narcissus. Adventitious plantlets could be inducedon pieces of bulb or corm from ten species but such materialwas difficult to free from contamination. Callus was obtained from all species except Tulipa and Hippeastrum.Plantlets could be regenerated from callus except that of Gladiolus,Sparaxis, and Schizostylis. Differences in responses of the twelve species tend to cut acrossthe three families and no simple relation is evident betweenthe natural rate of vegetative increase and the in vitro behaviour.     

DOSAGE EFFECTS OF THE LANCEOLATE GENE IN TOMATO

In contrast to the odd-pinnately compound leaf of the normal (+/+) tomato plant (Lycopersicon esculentum), the single-gene mutant lanceolate (La/+) generally has a simple leaf. Lanceolate plants, also, have small fruits and flowers, weak apical dominance, and exhibit variation in the position and fusion of cotyledons. Homozygous mutants (La/La) appear in 3 different phenotypes, 1 of which, narrow, has narrow simple leaves, sterile inflorescences, and extremely weak apical dominance. The other 2, modified, and reduced, lack an organized shoot. After selfing La/ + plants for 9 generations, autotetraploids were produced with the aid of colchicine. In addition, several triploid plants arose spontaneously. The study of diploid, triploid, and tetraploid material with various proportions of the La allele revealed in many characters a graded series as a function of the La dosage. With increasing La dose, there was a gradual reduction in: (1) total leaf length; (2) the number and size of primary and secondary lateral leaflets; (3) the number and size of marginal lobes of the terminal leaflet, associated with an increase in the proportional length of the terminal leaflet. Many leaves were found with the basal lobes of the terminal leaflet resembling incompletely separated lateral leaflets. The differences in leaf shape between different genotypes came about before the leaf primordium was 3 mm long. There was a progressive delay in the initiation of lateral primordia with increasing La dosage. It is proposed that the gradual changes from compound to simple leaves with increasing La dosage are produced by successively greater restrictions of meristematic activity after the terminal leaflet is formed. With increasing proportion of La alleles, the reproductive structures showed: (1) a decrease in the number of flowers per inflorescence; (2) a decrease in the length of the sepals; (3) an increase in the proportion of flowers with dialytic anthers. Dialytic anthers had narrow adaxial lobes and were frequently twisted along their main axes. The common denominator for most trends affected by the La allele seems to be a general reduction of growth, but more so in lateral than in longitudinal growth. Histological data suggest that the reduction in lateral growth is mainly brought about by a reduction of cell division in lateral meristems.     

Narrow-leafed Lupins with Restricted Branching

Crop phenology is one of the most important characters influencingproductivity in a given environment. Narrow-leafed lupin (Lupinusangustifolius L.) is a major grain legume crop in southern Australiawith general phenological adaptation to this Mediterranean-typeenvironment. However, it is an indeterminate crop with severalassociated limitations to productivity, such as overlappingvegetative and reproductive growth, late grain filling and sometimesexcessive vegetative growth. Here we studied two novel typesof narrow-leafed lupin with restricted branching, which mightbe useful for overcoming these problems. These restricted branchinglupins arose spontaneously within a breeding population, inthe case of ‘Tallerack’, and within a farmer's cropin the case of ‘ Hurst’ and we compared them withthe ‘Merrit’, which is widely grown and has thenormal indeterminate branching habit. The morphology and developmentof the main shoot of these genotypes were similar. However,‘Hurst’ had much larger leaves. There were alsostriking differences in the lateral branches of the restrictedbranching types; they had fewer leaves than ‘Merrit’and flowered earlier. These differences were most marked in‘ Hurst’, where the upper main stem branches werereduced to a single floret in the axil of main stem leaves,and these flowers often exhibited abnormal morphology. Copyright2000 Annals of Botany Company Lupinus angustifolius L., narrow-leafed lupin, adaptation, development, morphology, branching, leaves, mutant, plastochron, phyllochron, floral initiation, flowering.