Branch development in Lupinus angustifolius L.#II. Relationship with endogenous ABA, IAA and cytokinins in axillary and main stem buds

The concentrations of indole-3-acetic acid (IAA), cytokinins (CK) and abscisic acid (ABA) were measured in buds of different regions (main stem and lateral branches) of Lupinus angustifolius L. (cv. Merrit) and at different stages in the development of branches. In lupin, branching patterns are the result of discrete regions of axillary branches (upper, middle and basal) which elongate at much different rates. Early in development only the main shoot elongates, followed usually by basal branch growth and then rapid upper branch growth. Branches in the middle of the main stem grow only weakly or fail to develop. Levels of IAA were generally high in the apical buds of slowly growing branches and low in buds from strongly growing branches, whereas CK levels showed the opposite relationship. CK:IAA ratio showed a closer relationship with the rate of growth of a particular branch better than the levels of either CK or IAA alone. During early stages of growth ABA concentration did not follow the rate of branch growth. However, later in development, where growth did not closely match the ratio of CK:IAA, ABA level showed a strong negative relationship with growth. A significant decrease in ABA was associated with continued strong growth of the main stem apex following a decline in CK:IAA ratio. Overall, the best relationship between the level of growth factors in apical buds and branching pattern in lupin was the ratio of CK:IAA, implying that high CK:IAA at a given bud would promote growth. ABA level appeared to play a secondary role, as a growth inhibitor.     

DETERMINATE BRANCH DEVELOPMENT IN ALSTONIA SCHOLARIS (APOCYNACEAE): THE PLAGIOTROPIC MODULE

The development of the vegetative lateral branches in Alstonia scholaris (L.) R. Br. was examined. The overall architecture conforms to Prévost's model and the branches are sympodial complexes of plagiotropic modules. Each module consists of two whorls of 6–11 foliage leaves and a whorl of four scale leaves. The apex is parenchymatized just distal to the scale leaves. Renewal branches grow from buds in the axils of the scale leaves. These large buds are initiated simultaneously with the scale leaves and “use up” a large portion of the original apex. Parenchymatization of the central region of the apex occurs after a period of lateral growth and development that separates and vascularizes the renewal branches. Branch extension occurs sympodially by substitution. More typical buds develop in the axils of the foliage leaves but grow out only in response to injury or pruning. They are smaller than the renewal buds and, unlike them, are delimited by a shell zone during early development.     

Floral determination in the terminal and axillary buds of Nicotiana tabacum L

The terminal and axillary buds of the day-neutral plant, Nicotiana tabacum cv. Wisconsin 38, become determined for floral development during the growth of the plant. This state of determination can be demonstrated with a simple experiment: buds determined for floral development produce the same number of nodes in situ and if rooted. After several months of growth and the production of many leaves, the terminal bud became determined for floral development within a period of about 2 days. After the terminal bud became florally determined, it produced four nodes and a terminal flower. The buds located in the axils of leaves borne just below the floral branches became florally determined 5 to 9 days after the terminal bud became florally determined. Since florally-determined axillary buds were not clonally derived from a florally-determined terminal meristem, axillary buds and the terminal bud acquired the state of floral determination independently. These data indicate that a pervasive signal induced a state of floral determination in competent terminal and axillary buds.     

SCLEREID DISTRIBUTION IN THE LEAVES OF PSEUDOTSUGA UNDER NATURAL AND EXPERIMENTAL CONDITIONS

Al -talib , Khalil H., and John G. Torrey . (U. California, Berkeley.) Sclereid distribution in the leaves of Pseudotsuga under natural and experimental conditions. Amer. Jour. Bot. 48(1): 71–79. Illus. 1961.—A study of the distribution of sclereids in cleared leaves taken from 1-, 2-, and 4-year-old shoots of an adult tree of Pseudotsuga menziesii (Mirb.) Franco showed a repeated pattern of sclereid distribution along the shoot axis with many sclereids in the basal leaves grading into few or no sclereids in the terminal leaves of each year's growth. Attempts were made to influence sclereid distribution by bud defoliation of attached branches with and without auxin treatment and by testing the effects of growth-regulating substances on sclereid formation in leaves of excised buds of Pseudotsuga cultured in vitro. Whereas removal of the basal ¾ of the leaves at the time of bud unfolding had no effect on bud, leaf or sclereid development, removal of the leaves of the upper half or complete defoliation led to premature expansion of next year's terminal bud with leaves developing in part from presumptive bud-scale primordia. Indoleacetic acid at 0.5% in lanolin paste applied to the defoliated region prevented this premature bud expansion. Defoliation of the basal half did not affect sclereid formation in the terminal leaves. Sclereid development in leaves of prematurely expanded buds on defoliated branches was normal except in the few cases where bud expansion occurred in the presence of low-auxin concentrations. Then, sclereid development was inhibited. Sclereid formation in leaves of excised buds grown in nutrient culture was generally much less frequent than in intact branches, and auxin treatment still further reduced the frequency of sclereids. It was concluded that sclereid initiation and differentiation in the intact plant may well be under the control of hormonal factors in the plant, one of which may be auxin.     

Correlative inhibition of lateral bud growth in Phaseolus vulgaris L. timing of bud growth following decapitation

Summary On intact, 3-week-old plants of Phaseolus the larger bud in the axils of the primary leaves shows slow, continuous elongation growth. Release from correlative inhibition can be detected within 30 min following decapitation. When 0.1% indoleacetic acid in lanolin is applied to the decapitated stem stump, the lateral bud shows slow growth during the first 7 h, then stops completely for a further 15 h but after 2 days a further gradual increase in length is observed.The movement of ¹⁴C-labelled assimilates from the subtending primary leaf into the lateral bud increases following removal of the shoot apex. When indole acetic acid is applied to decapitated plants the ability of the buds to import ¹⁴C increases for 5–7 h and then declines to a negligible amount. Little or no radioactivity from tritiated indoleacetic acid is transported into the lateral buds of decapitated plants during the first 48 h following removal of the apex and it appears that rapid metabolism of the compound occurs in the stem tissues.     

Survival and growth of eastern white pine shoot apical meristemsin vitro

Shoot apical meristems of seedling and mature eastern white pine trees were excised and grownin vitro. Placing the meristems on filters instead of directly on agarose-solidified nutrient medium enhanced survival of both juvenile and mature meristems. Applying forcing treatments to mature branches improved survival and growth of dissected meristems compared with meristems from non-forced branches in experiments conducted over two years. No consistent differences were observed among 2-, 4-, and 6-week forcing treatments. Including 5.37 nM (0.001 mg l^-1) l-naphthaleneacetic acid in the culture medium did not affect meristem survival or growth. Some meristems from seedlings grew rapidly, produced primary leaves, underwent internode elongation, and in three cases, produced adventitious roots. Meristems from mature trees did not grow as rapidly as seedling meristems. The leaves produced by mature meristems appeared to be scale leaves and a few of these had brachyblast primordia in the axils. The shoots derived from mature meristems did not produce adventitious roots.     

Shoot elongation,leaf demography and bud formation in relation to branch position on Larix laricina saplings

Summary Shoot development was investigated on branches of Larix laricina (Du Roi) K. Koch trees growing in their 8th year in two plantations and in a natural stand approximately 12 years old. Expansion of throughout-crown series of short and long shoots was measured weekly, and later colour change and natural fall of leaves were assessed. Similar shoots were collected at intervals and dissected, the long shoots by 25-leaf segments. Leaf area and weight, as well as time of bud formation, were determined. Increasing acropetal trends were evident in time to bud burst: duration of short-shoot leaf-cluster expansion; size of leaf clusters and number, area and weight of leaves per cluster; duration and rate of long-shoot elongation; number, area and weight of leaves on long shoots; time to terminal-bud formation on long shoots. Along each long shoot, stem and leaf elongation and lateral-axis formation progressed acropetally. Lateral axes were most numerous on second to fourth 25-leaf segments. On longer shoots, some axes in middle segments developed as sylleptic short shoots rather than as lateral buds. Leaves of short shoots and basal leaves on long shoots turned yellow and abscissed sooner than axial leaves on long shoots. Colour change and loss among axial leaves were acropetal along shoots and up the crown. Thus, last-formed leaves, in axils of some of which lastformed lateral buds occurred, were held longest.     

植物生长调节剂对黑木相思优树腋芽增殖及生根的影响

为建立黑木相思(Acacia melanoxylon)快繁技术体系,以含1个腋芽的无菌茎段为材料,研究了植物生长调节剂对其增殖和生根的影响。结果表明,6-BA 极易诱导黑木相思愈伤组织形成,但芽长势较差,不利于腋芽增殖体系的建立。而生长素既能诱导黑木相思生根,又能诱导腋芽增殖;将无菌茎段接入MS+IAA 0.5 mg L^-1+IBA 0.5 mg L^-1培养基中培养20 d的生根率为98.41%,培养40 d的腋芽增殖倍数为2.36,单株繁殖系数为6.57。这是首次成功建立高效、简便的生根和增殖同步发生的黑木相思直接器官发生途径的组培技术体系。     

Analysis of Branching in Spring-sown White Lupins (Lupinus albusL.): The Significance of the Number of Axillary Buds

Plant density and sowing date were shown to affect branchingin spring-sown white lupin (Lupinus albusL.), but the responsevaried among environments. The patterns of primary and secondarybranching in the cv. Lublanc were studied as a function of boththe number of axillary buds and the plant growth rate. Fieldexperiments that used a wide range of sowing dates and plantdensities to alter plant architecture were conducted over 5years, and these were supplemented with data from additionalglasshouse and growth cabinet experiments. The number of axillary buds on the main stem or primary branches,which determined the potential number of branches, increasedlinearly with the number of nodes. In situations where all axillarybuds did not produce branches, it was found that the numberof primary and secondary branches produced was related to theplant growth rate at the beginning of branch elongation. Knowledgeof the number of axillary buds improved the analysis of theinteraction between cultural practices and environmental conditionson plant architecture. The variability of branching potentialamong genotypes was discussed. Lupinus albus; branches; axillary buds; growth; sowing date; plant density     

Evaluation of Lupinus Species to Accumulate Heavy Metals From W aste Waters

Several Lupinus species, for example, Lupinus albus, Lupinus luteus, Lupinus angustifolius, and Lupinus hispanicus were used to accumulate Mn(II), Cd(II), Pb(II), Cr(III), Cr(VI), Hg²⁺, and CH₃Hg⁺ from waste waters. The influence of different species concentrations (50 and 100 mg L^-1) and pH on growing behavior as well as the resulting distribution of metals in the plants were investigated. The results obtained showed that lupins were able to germinate and to grow in the presence of the metals mentioned above, even when they were present at levels as high as 50 mg L^-1. Accumulation of Pb(II), Cr(III), and Cd(II) was higher in roots than in shoots. As far as mercury is concerned, the highest CH₃Hg and Hg²⁺ accumulation was detected in roots, but fast transport toward the leaves was noticed. In contrast to mercury, the uptake of chromium seems to be influenced by the chemical form of the analyte, remaining Cr(VI) in solution. No differences in growing behavior and accumulation were observed for the four Lupinus species studied. Even though plants were exposed only a relatively short time to the metal solutions, metal concentrations of approximately 2 g/kg of dry matter were detected in the young lupins plants. The feasibility of utilizing Lupinus plants for the removal of heavy metals from wastewater was also investigated. Lupins were able to grow under extreme conditions (wastewater, pH lower than 2) and to remove 98% of the initial amount of toxic metals present in the sample.     

Development and Growth Potential of Axillary Buds in Roses as Affected by Bud Age

The effect of axillary bud age on the development and potentialfor growth of the bud into a shoot was studied in roses. Ageof the buds occupying a similar position on the plant variedfrom 'subtending leaf just unfolded' up to 1 year later. Withincreasing age of the axillary bud its dry mass, dry-matterpercentage and number of leaves, including leaf primordia, increased.The apical meristem of the axillary bud remained vegetativeas long as subjected to apical dominance, even for 1 year. The potential for growth of buds was studied either by pruningthe parent shoot above the bud, by grafting the bud or by culturingthe bud in vitro. When the correlative inhibition (i.e. dominationof the apical region over the axillary buds) was released, additionalleaves and eventually a flower formed. The number of additionalleaves decreased with increasing bud age and became more orless constant for axillary buds of shoots beyond the harvestablestage, while the total number of leaves preceding the flowerincreased. An increase in bud age was reflected in a greaternumber of scales, including transitional leaves, and in a greaternumber of non-elongated internodes of the subsequent shoot.Time until bud break slightly decreased with increasing budage; it was long, relatively, for 1 year old buds, when theysprouted attached to the parent shoot. Shoot length, mass andleaf area were not clearly affected by the age of the bud thatdeveloped into the shoot. With increasing bud age the numberof pith cells in the subsequent shoot increased, indicatinga greater potential diameter of the shoot. However, final diameterwas dependent on the assimilate supply after bud break. Axillarybuds obviously need a certain developmental stage to be ableto break. When released from correlative inhibition at an earlierstage, increased leaf initiation occurs before bud break.Copyright1994, 1999 Academic Press Age, axillary bud, cell number, cell size, pith, shoot growth, Rosa hybrida, rose     

AXILLARY AND DICHOTOMOUS BRANCHING IN THE PALM CHAMAEDOREA

In both Chamaedorea seifrizii Burret and C. cataractarum Martius each adult foliage leaf subtends one axillary bud. The proximal buds in C. seifrizii are always vegetative, producing branches (= new shoots or suckers); and the distal buds on a shoot are always reproductive, producing inflorescences. The prophyll and first few scale leaves of a vegetative branch lack buds. Transitional leaves subtend vegetative buds and adult leaves subtend reproductive buds. Both types of buds are first initiated in the axil of the second or third leaf primordia from the apex, P2 or P3. Later development of both types of bud tends to be more on the adaxial surface of the subtending leaf base than on the shoot axis. Axillary buds of C. cataractarum are similarly initiated in the axil of P2 or P3 and also have an insertion that is more foliar than cauline. However, all buds develop as inflorescences. Vegetative branches arise irregularly by a division of the apex within an enclosing leaf (= P1). A typical inflorescence bud is initiated in the axil of the enclosing leaf when it is in the position of P2 and when each new branch has initiated its own P1. No scale leaves are produced by either branch and the morphological relationship among branches and the enclosing leaf varies. Often the branches are unequal and the enclosing leaf is fasciated. The vegetative branching in C. cataractarum is considered to be developmentally a true dichotomy and is compared with other examples of dichotomous (= terminal) branching in the Angiospermae.     

Flowering Habit and Vegetative Behaviour in Tea (Camellia sinensis L) Seed Trees in North-East India

Apical growth of a tea shoot occurs by a succession of flushesseparated by short periods of rest. This paper describes theexternal morphology of flowering, fruiting, and abscission ofleaves of the tea plant in north-east India in relation to thephasic activity of shoot apices. All shoots on a tree make leafy growth when a new cycle of growthbegins in the spring, but terminal buds apparently become dormantas the season advances. Apparently dormant terminal buds shedbud scales, leaving on the stem a considerable number of scars,representing leafless cataphyllary flushes. These cataphyllaryflushes are produced at the same time as the leafy flushes onother shoots. A flower is formed only in the axil of a bud scale. Flowerswhich appear to develop in leaf axils are in fact inserted inthe axils of bud scales of the axillary buds. A distal leafy flush is without flowers. Flowers appear in itsleaf axils only when the terminal bud starts growth for thenext higher flush. A distal floriferous cataphyllary flush appearsas a terminal cluster of flowers. Thus, there is an acropetalsuccession of flowers, flush by flush on a caulome, determinedby the phasic activity of the apical bud. The main crop of flowers exposes anthers from the end of thethird flush (late September to early October) until the endof the winter period of growth (late January to early February).In some plants a second, minor crop of flowers appears in thespring between the end of the first and beginning of the secondflushes. In spite of considerable time lag between anthesis,the fruits produced by these two crops of flowers mature anddehisce at the same time during October to November. Abscission of leaves is also dependent upon the phasic activityof the apical buds. Only the top two flushes of a shoot possessleaves. Resumption of apical growth for a third flush, leafyor cataphyllary, causes the abscission of leaves on the lowermostof the three flushes. Two cataphyllary flushes therefore resultin the loss of all leaves on a shoot.     

A COMPARATIVE DEVELOPMENTAL STUDY OF THE MUTANT SIDESHOOTLESS AND NORMAL TOMATO PLANTS

'Sideshootless,’ a mutant strain of tomato which does not produce axillary buds during vegetative growth, was compared with normally branching plants in order to study the nature of development particularly with regard to axillary buds. Sectioned material revealed no indication of axillary bud initiation in the sideshootless plant at any time during the vegetative phase of growth. In the normal plants, buds were noted to arise in the axil of the fifth youngest leaf. The buds take their origin in tissue which is in direct continuity with the apical meristem. The bud primordia later become set apart from the apex as vacuolation takes place in the surrounding tissue. At the time of floral initiation, the mutant and normal strains behave similarly. Axillary buds appear in the axils of the 2 leaves immediately below the floral apex. One of the buds elongates to overtop the existing plant axis; the other develops as a typical sidebranch. The inflorescence is pushed aside in the process. This pattern is repeated with each inflorescence; thus an axis composed of several superimposed laterals results.     

THE ORIGIN AND DEVELOPMENT OF INDUCED BRANCHES IN HELIANTHUS

The development of buds and their vascular connections are described for Helianthus annuus and H. bolanderi. Bud meristems of H. annuus usually become isolated by parenchymatization of the bud traces in the cortical zone. If the buds are induced to grow as a result of decapitation of the terminal meristem, a continuous range between typical primary connections and pseudo-adventitious connections are made between the main axis and the lateral buds. Considerable growth of the branches occurs within 48 hours after decapitation. Axillary buds of H. bolanderi grow continuously, and both the meristem and vascular system of the buds are derived directly from the apical meristem of the shoots.     

Lupinus species differ in their requirements for iron

The effect of iron supply on the growth and nodulation ofLupinus angustifolius L. (Gungurru),Lupinus luteus L. (R-1171) andLupinus pilosus Murr. (P20957) was studied in acid solutions. Plants of the three species were grown together in the same solution and inoculated withBradyrhizobium (Lupinus) WU 425. Plants were then grown with or without applied NH₄NO₃. The lupin species differed greatly in their sensitivity to low iron concentrations in solution withL. pilosus being most tolerant andL. luteus most sensitive.L. pilosus had the highest iron concentration in tissues and had a higher ratio of iron concentration in the youngest fully expanded leaf blades (YEB) to that in roots than the other two species.L. luteus had higher iron concentrations in roots but lower iron concentration in YEB and shoots than didL. angustifolius. The requirements of internal iron for the maximal chlorophyll synthesis in YEB were 65 μg g^-1 forL. angustifolius andL. luteus, and 52 μg g^-1 forL. pilosus. In contrast to effects on growth, the three species had similar external iron requirements for nodule formation in roots and for maximal nitrogen concentrations in shoots. The results indicate that iron tolerant lupin species require lower internal and external iron supply and have a greater ability than sensitive species to translocate iron from roots to shoots.     

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     

基于液—固交替培养的水曲柳快速微繁系统研究

以茎部木质化、叶片老化、顶芽休眠的水曲柳组培苗为材料,开发了一种液体—固体交替培养的水曲柳（Fraxinus mandshurica Rupr.）快速高效的再生系统,该技术通过液体悬浮培养在短时间内使腋芽萌发,并在固体培养中腋芽离体再生获得新的组培苗。在补充不同植物生长调节剂的WPM液体和固体培养基上,可以诱导水曲柳腋芽萌发并伸长成苗。发现在添加了0.6 mg·L^-1 TDZ的WPM液体培养基中暗培养,7~15 d之内可促使水曲柳腋芽100%萌发,将萌发的嫩芽切下后接种到0.05 mg·L^-1 TDZ和0.6 mg·L^-1 BA的WPM固体培养基中光照培养,腋芽在1~2个继代内可以伸长成苗,苗平均高为2.64 cm,增殖系数达到4.04。将生根的苗移栽,50 d后存活率为90%。该技术的建立有助于水曲柳的大规模繁殖,并且液体—固体交替循环培养,简单、可控、易操作,适用于不同的生产条件,减少成本。