Quantitative description of the process of architecture formation inViburnum dilatatum andV. wrightii (Caprifoliaceae)

Process of architecture formation was comparatively analyzed usingViburnum dilatatum andV. wrightii (Caprifoliaceae). In both species, orthotropic primary axes emerge from the basal parts of mother plants near the ground level. The primary axes grow vigorously in the first and the subsequent few years of their development. Later on, they decrease their elongation rates gradually and many axillary buds stay in dormancy. A few of the axillary buds emerge after several years' dormancy and elongate vigorously forming orthotropic secondary axes. inViburnum dilatatum, nearly 50% of the primary axes develop the secondary axes. The secondary axes elongate as vigorous as the primary axes. Furthermore, more than 20% of the secondary axes form the tertiary axes, and only 10% of the tertiary axes form the quarternary axes. In contrast, inViburnum wrightii only less than 25% of the primary axes form the secondary axes, and there is no tertiary or quarternary axis. The secondary axes of this species elongate less vigorously than the primary axes. As the result of those differences in the axis formation,Viburnum wrightii forms a simpler architecture thanV. dilatatum.     

Sympodial and monopodial branching inAcer (Aceraceae): Evolutionary trend and ecological implications

The evolutionary trend and its ecological implications in sympodial and monopodial branching patterns has been investigated in 20 JapaneseAcer spp. through comparison of shoot tip abortion and terminal bud formation. The genus is divided into two species groups according to its branching pattern, one (6 species) predominantly exhibiting sympodial branching with frequent monopodial branching in short shoots (sympodial species), and the other (14 species) exhibiting only monopodial branching (monopodial species). The early ontogeny of leaf and bud scales is described. Despite the difference in branching patterns, the bud scales of terminal buds are essentially the same in having a leaf base developed to function as a protecting organ. In all the sympodial species, during the abortion of a sympodium shoot tip, one or two pairs of primordia were found to occur on the apex, and later wither. These primordia resemble bud scales of terminal buds in their ontogeny and morphology, and appear to be rudimentary. It is suggested that a rudimentary terminal bud develops together with the establishment of sympodial branching, and that sympodial branching has originated from monopodial branching. Based on this proposed evolutionary trend, it is suggested thatAcer has moved from less shady habitats into shady habitats with monopodial branching (advantageous for vertical growth) changing into sympodial branching (advantageous for lateral spread).     

All in the timing: how fruit nutritional content influences the timing of fruit consumption of two invasive shrubs

The functional role that invasive species occupy within their new range is of significant interest for those concerned about invasive species management. Of particular importance is the distribution mechanisms of invasive plants. Viburnum dilatatum and Viburnum sieboldii are considered invasive species in New Jersey forest understories. We have observed that while the fruit of both species ripens at the same time, there is a difference in how long fruit persists. To better understand the temporal pattern, we examine fruit phenology and consumption, as well as energy density, percentage crude fat, and antioxidant capacity. We hypothesized that the difference in the timing of fruit consumption in these species is largely driven by nutritional content and that fruit with higher energy and fat content are eaten during migration. Our results indicate that V. sieboldii fruit is depleted in the fall, while V. dilatatum fruit persists into winter. In addition, we found that V. sieboldii fruit had higher energy density and 4.4 times as much crude fat compared to that of V. dilatatum fruit. However, V. dilatatum fruit had 9.5 times greater antioxidant capacity than V. sieboldii fruit. We also found that V. sieboldii fruit is mainly consumed by gray catbirds (Dumetella carolinensis) during the fall migration and the primary avian consumer of V. dilatatum fruit are American robins (Turdus migratorius) in the winter when birds are more sedentary. We suspect a mutualistic relationship has developed between these two invasive viburnum species and native avian frugivores. What remains to be seen is what effect different fruiting strategies have on seed dispersal.

     

Crown hollowing as a consequence of early shedding of leaves and shoots

Leafing pattern has long been considered as an important element characterizing the growth strategy of tree species; however, the consequences of leafing pattern for tree-crown formation have not been fully understood. To address this issue, the dynamic events (growth, birth, and death) of current-year shoots and leaves were investigated together with their location in saplings of a pioneer tree, Alnus sieboldiana. The leafing pattern was characterized by successive emergence and shedding of short-lived leaves. The combination of successive leafing and within-crown variation in leaf production brought about characteristic outcomes in crown morphology. In the outer crown, because of continuous leaf production, the shoots achieved great extension and enormous daughter shoot production, resulting in rapid expansion of the crown. In contrast, in the inner crown, due to early termination of leaf production, the shoots completely lost their leaves early in the growing season and consequently themselves died and were shed within the season. Such quick shedding of shoots caused “crown hollowing”, i.e., the interior crown consisted of primary branches with little secondary development or foliage. These dynamic features are an effective adaptive strategy in early succession but also may be a disadvantage to maintaining foliage for longer period. Crown maintenance associated with the longevity of structural components is thought to play an important role in survival strategy of tree species.     

A Developmental Pattern of Flowering in Colored <Emphasis Type="Italic">Zantedeschia</Emphasis> spp.: Effects of Bud Position and Gibberellin

The restricted flowering of colored cultivars ofZantedeschia is a consequence of developmental constraints imposed by apical dominance of the primary bud on secondary buds in the tuber, and by the sympodial growth of individual shoots. GA₃ enhances flowering inZantedeschia by increasing the number of flowering shoots per tuber and inflorescences per shoot. The effects of gibberellin on the pattern of flowering and on the developmental fate of differentiated inflorescences along the tuber axis and individual shoot axes were studied in GA₃ and Uniconazole-treated tubers. Inflorescence primordia and fully developed (emerged) floral stems produced during tuber storage and the plant growth period were recorded. Days to flowering, percent of flowering shoots and floral stem length decreased basipetally along the shoot and tuber axes. GA₃ prolonged the flowering period and increased both the number of flowering shoots per tuber and the differentiated inflorescences per shoot. Activated buds were GA₃ responsive regardless of meristem size or age. Uniconazole did not inhibit inflorescence differentiation but inhibited floral stem elongation. The results suggest that GA₃ has a dual action in the flowering process: induction of inflorescence differentiation and promotion of floral stem elongation. The flowering pattern could be a result of a gradient in the distribution of endogenous factors involved in inflorescence differentialtion (possibly GAs) and in floral stem growth. This gradient along the tuber and shoot axes is probably controlled by apical dominance of the primary bud. Online publication: 7 April 2005     

<Emphasis Type="Italic">SINGLE FLOWER TRUSS</Emphasis> regulates the transition and maintenance of flowering in tomato

The characterisation of the single flower truss ( sft) mutant phenotype of tomato ( Lycopersicon esculentum Mill.), as well as its genetic interactions with other mutations affecting FALSIFLORA ( FA) and SELF PRUNING ( SP) genes, has revealed that SFT is a key gene in the control of floral transition and floral meristem identity. The single sft mutation produces a late-flowering phenotype in both long-day and short-day conditions. In combination with fa, a mutation affecting the tomato gene orthologous to LFY, sft completely blocks the transition to flowering in this species. Thus, the phenotype of the sft fa double mutants indicates that SFT and FA participate in two parallel pathways that regulate the switch from vegetative to reproductive phase in tomato, and that both genes are indispensable for flowering. On the other hand, the replacement of flowers by vegetative shoots observed in the sft inflorescence suggests that SFT regulates flower meristem identity during inflorescence development of tomato. In addition to these two main functions, SFT is involved in the development of both flowers and sympodial shoots of tomato. First, the mutation produces a partial conversion of sepals into leaves in the first floral whorl, and a reduction in the number of floral organs, particularly carpels. Secondly, the sympodial development in the mutant plants is altered, which can be related to the interaction between SFT and SP, a gene controlling the number of nodes in sympodial shoots. In fact, we have found that the sft phenotype is epistatic to that of sp, and that the level of SP mRNA in the apical buds of sft around flowering is reduced. SFT can therefore co-ordinate the regulation of two simultaneous developmental processes in the tomato apical shoot, the promotion of flowering in one sympodial segment and the vegetative development of the next segment.     

Somatic embryogenesis and shoot regeneration from intact seedlings of Phaseolus acutifolius A., P. aureus (L.) Wilczek,P. coccineus L., and P. wrightii L.

A rapid, one-step procedure has been developed for inducing direct organogenesis and somatic embryogenesis in cultures of Phaseolus coccineus L., P. acutifolius A., P. aureus L. [Vigna radiata L. Wilczek] and P. wrightii L. Development of somatic embryos and shoot buds occurred within 6–8 weeks of culture from intact seedlings raised on MS (Murashige and Skoog 1962) medium supplemented with N⁶-benzylaminopurine (BAP). Shoot buds or embryoids originated from subepidermal tissue of the regions adjacent to the shoot apex, hypocotyl and cotyledonary axils. While P. acutifolius and P. aureus were regenerated via shoot formation and P. wrightii by somatic embryogenesis, both embryogenesis and shoot regeneration were observed in P. coccineus. Relatively higher levels of BAP, 50–80 M, were found to be optimal for inducing regeneration while lower concentrations were ineffective. About 40–70 shoots and 70–250 somatic embryos were produced per responding seedling. Regenerated shoots and somatic embryos developed into whole plants on a basal medium or the one supplemented with 1 M naphthaleneacetic acid.     

Morphogenic response of the alginate-encapsulated axillary buds from in vitro shoot cultures of six mulberries

Axillary buds obtained from in vitro shoot cultures of six mulberries (Morus alba L., M. australis Poir., M. bombycis Koidz., M. cathyana Hemsl., M. latifolia Poir., and M. nigra L.) were encapsulated in calcium alginate hydrogel containing Murashige and Skoog (1962) nutrients (MS) and 4.4 μM benzyladenine (BA). Morphogenic response of encapsulated buds to various planting media such as MS medium + 4.4 μM BA, MS basal medium, soilrite mix + half-strength MS medium, garden soil + half-strength MS medium, soilrite mix + tap water and garden soil + tap water was evaluated. Encapsulated buds of M. alba, M. bombycis, M. latifolia and M. nigra exhibited shoot development in each of the six media tested whereas that of M. australis and M. cathyana responded only to the first four media. Analysis of variance revealed that the planting medium exhibited the greatest influence on shoot development. Of the six planting media evaluated, shoot development was highest in MS medium containing 4.4 μM BA and lowest in garden soil moistened with water. Of the six Morus species studied, one-step regeneration, i.e. both shoot and root formation, was recorded in M. alba, M. bombycis and M. latifolia. Rooted shoots were retrieved from encapsulated buds of these species on all planting media tested except the one that contained BA. Root development was significantly affected by the planting medium and the plant species with planting medium contributing the maximum amount (82%) of the total variation observed. Of the five planting media tested, the percentage of root development was highest in MS basal medium. Of the six Morus species studied, the best shoot and root development was observed in M. alba. Encapsulated buds of M. bombycis, M. latifolia and M. nigra stored for 90 days and those of M. alba, M. australis and M. cathyana for 60 days at 4 °C still regenerated shoots. Plants regenerated from the encapsulated buds were hardened off and transferred to soil. This revised version was published online in June 2006 with corrections to the Cover Date.     

High-frequency<Emphasis Type="Italic">in vitro</Emphasis> flowering in six species of<Emphasis Type="Italic">ceropegia</Emphasis>

High-frequencyin vitro flowering is reported here fromin vitro regenerated shoots ofin vitro-raised seedlings of rare and endemicCeropegia lawii, Ceropegia maccannii, Ceropegia oculata, andCeropegia sahyadrica, as well as the widely distributedCeropegia bulbosa var.bulbosa andCeropegia hirsuta. In our first set of experiments, the MS medium contained 87 mM sucrose and was supplemented with varying concentrations of BAP (4.4 to 26.6 μM). For the second set of trials, varying concentrations of sucrose (87 to 233 mM) were tested in MS media containing a constant 4.4 p.M BAP. Sub-cultured apical as well as axillary buds flowered with similar frequencies after 30 d of incubation. For all six species, the highest percentage of flowering shoots was obtained with either 26.6 μM BAP or 175 mM sucrose. Although smaller in size, theirin vitro flowers were morphologically comparable within wVo-derived flowers. Variations among species were noted for the number of flower buds per shoot and the percentage of flower formation. Because all six species showed similar responses in both experiments, we can suggest that this protocol is applicable across the wide range ofCeropegia species.     

Ecological studies on the plants of fagaceae V. Growth in the sapling stage and minimal participation of reserve materials in the formation of annual new shoots of the evergreenQuercus glauca thunb

The growth in the sapling stage and participation of reserve materials in the formation of annual new shoots were studied in the evergreen treeQuercus glauca. The growth and some allometric relationship were analyzed for 1-to 4-year-oldQ. glauca plants. Each individual was felled at the foot, or all the leaves were removed at the end of the growth season (December). Sprouts were formed on the remaining stump and new shoots were formed from winter buds under dark or light conditions. The dry weight of each plant part was measured before and afte,, the formation of these new shoots. The amount of reserve materials in each plant part was estimated from the difference in allometric relatationships before and after the formation of new shoots. Although the results showed that a small amount of reserve material existed in roots, the participation of reserve materials in the formation of annual new shoots was negligible inQ. glauca growing under usual conditions, and substrates for the formation of new shoots were derived from the products of photosynthesis in old leaves and developing new leaves. Some of the growth characteristics ofQ. glauca were compared with those of the deciduous speciesQuercus variabilis to explain ecological behavior of the two species in warmtemperate secondary forests.     

SYMMETRY AND DEVELOPMENT OF LIMNOBIUM SPONGIA (HYDROCHARITACEAE)

Limnobium spongia produces upright vegetative axes and prostrate stolons. The upright axes bear new stolons, whereas the stolons bear new upright axes and fertile and sterile branching systems. Upright axes and fertile and sterile branching systems are all interpreted to have sympodial growth. However, it was not determined whether growth of stolons is monopodial or sympodial. Both stolons and upright axes branch in alternate plastochrons, and branching is achieved solely by the bifurcation of apical meristems. Each meristematic bifurcation is interpreted to represent the formation of a precocious lateral bud. The upright axes develop from presumed precocious lateral buds on stolons, whereas such buds on upright axes produce renewal shoots. Limnobium spongia exhibits a marked degree of mirror-image symmetry.     

Rapid clonal propagation of three mulberries,Morus cathayana HemsL,M. lhou Koiz. andM. serrata Roxb., through in vitro culture of apical shoot buds and nodal explants from mature trees

High-frequency bud break and multiple shoots were induced in apical shoot buds and nodal explants ofMorus cathayana, M. lhou andM. serrata on Murashige and Skoog (MS) medium containing 0.5–1.0 mg/l 6-benzylaminopurine (BAP). Addition of gibberellic acid (0.4 mg/l) along with BAP induced faster bud break both in apical shoot buds and nodal explants and also enhanced the frequency of bud break in all three species. Shoot culture initiation was greatly influenced by explant type, explant age and explanting season. The shoots were successfully rooted on half-strength MS medium containing a combination of indole-3-acetic acid, indole-3-butyric acid and indole-3-propionic acid, each at 1.0 mg/l. The plantlets were successfully acclimated and eventually established in soil.Abbreviations BAP 6-Benzylaminopurine - GA ₃ Gibberellic acid - IAA Indole-3-acetic acid - IBA Indole-3-butyric acid - IPA Indole-3-propionic acid - Kn Kinetin - MS Murashige and Skoog (1962) medium - NAA 1-Naphthalene acetic acid     

Morphogenesis in Sitka spruce (<Emphasis Type="Italic">Picea sitchensis</Emphasis> (Bong.) Carr.) bud cultures – tree maturation and explants from epicormic shoots

The adventitious bud forming ability of Sitka spruce (Picea sitchensis (Bong.) Carr.) buds in vitro was found to be dependent upon the age of tree from which the explants were taken. Bud formation declined exponentially with increasing tree age when 1.0 and 10 μM 6-benzylaminopurine (BA) were used to induce adventitious buds. When less BA was used (0.1 μM) bud production was much lower with all ages of tree and no mathematical relationship between declining bud production and tree age was found. By a tree age of 6 years bud-forming ability had declined severely. Even the few buds that developed on older tree tissues failed to elongate into shoots, became necrotic and eventually died, indicating that adventitious bud induction in this species is not a rejuvenative process. Callusing of bud explants also declined with increasing tree age when 0.1 μM BA was used whilst very little callusing occurred at the higher cytokinin concentrations (1.0 and 10 μM BA). Tissue necrosis in vitro increased with tree age, whilst the ability of BA to retard necrosis declined with increasing tree age. Buds from epicormic shoots, formed on the lower trunks of 20-year-old trees when these were exposed to light, were not significantly better at forming adventitious buds in vitro than buds taken from the lower branches of the crown.     

Comparison of the physiology, morphology, and leaf demography of tropical saplings with different crown shapes

Branch architecture, leaf photosynthetic traits, and leaf demography were investigated in saplings of two woody species, Homolanthus caloneurus and Macaranga rostulata, co-occurring in the understory of a tropical mountain forest. M. rostulata saplings have cylindrical crowns, whereas H. caloneurus saplings have flat crowns. Saplings of the two species were found not to differ in area-based photosynthetic traits and in average light conditions in the understory of the studied site, but they do differ in internode length, leaf emergence rate, leaf lifespan, and total leaf area. Displayed leaf area of H. caloneurus saplings, which have the more rapid leaf emergence, was smaller than that of M. rostulata saplings, which have a longer leaf lifespan and larger total leaf area, although M. rostulata saplings showed a higher degree of leaf overlap. Short leaf lifespan and consequent small total leaf area would be linked to leaf overlap avoidance in the densely packed flat H. caloneurus crown. In contrast, M. rostulata saplings maintained a large total leaf area by producing leaves with a long leaf lifespan. In these understory saplings with a different crown architecture, we observed two contrasting adaptation strategies to shade which are achieved by adjusting a suite of morphological and leaf demographic characters. Each understory species has a suite of morphological traits and leaf demography specific to its architecture, thus attaining leaf overlap avoidance or large total leaf area.     

<Emphasis Type="Italic">In vitro</Emphasis> micropropagation of four lupin species

The complete protocols for long-term micropropagation of some cultivars of four lupin species: Lupinus luteus, L. albus, L. angustifolius and L. mutabilis were elaborated. The shoots were regenerated in vitro via induction of axillary buds development. Plantlets were multiplicated on lowered salts MS-derived media containing BAP in diverse and generally low concentrations. Significant differences in regeneration capacity between species and cultivars were observed. The highest multiplication ratio revealed L. mutabilis and L. luteus. Regenerated shoots were rooted in vitro on low-salts MS-derived media with B5 vitamins. Media were supplemented with different auxins that affected roots formation of particular species and cultivars. Rooting ability of regenerated shoots decreased rapidly through in vitro culture. For that reason, grafting was applied as an alternative method of transfer of shoots to in vivo conditions. This method turned out to be successful for the majority of studied species and cultivars. Complete rooted or grafted plantlets were cultivated in pots with perlit in greenhouse. An erratum to this article is available at .     

Induction of adventitious buds in cultured petal explants ofChelidonium majus L.

Petal explants ofChelidonium majus L. (Papaveraceae) formed noteworthy adventitious buds without any intermediate callus when cultured under appropriate conditions. Bud formation was favored by combinations of 1–2 mg/l indoleacetic acid (IAA) and/or 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.1–0.5 mg/l kinetin (K). In the present study, neither bud formation nor callus formation occurred in cultures of excised leaves. A histological study revealed that adventitious bud formation occurred only in single epidermal layers of petals, while several subepidermal parenchyma layers did not join in its formation. Activation zones arising from the epidermis underwent intense cell divisions to initiate buds on the epidermal surface. These buds later turned green in color, developing into shoots which eventually grew into plantlets after root formation.     

Observations on the life cycle and establishment ofCochylis atricapitana (Lep: Cochylidae), a moth used for biological control ofSenecio jacobaea in Australia

Larvae of the mothCochylis atricapitana (Stephens) are monophagous leaf, crown, stem or bud borers of ragwort,Senecio jacobaea L. (Asteraceae). In the present investigation, aspects of the life cycle ofC. atricapitana were determined. Moths ofC. atricapitana lay an average of 158 eggs/female with as many as 355 eggs being laid by a single female. The majority of eggs are laid individually along the primary and secondary veins on the underside of ragwort leaves. Egg incubation ranges from 4.2 days at 30°C to 14.4 days at 15°C. At a constant 23°C under a 16 hour photoperiod,C. atricapitana takes approximately 40 days to complete a generation. Caterpillars make their way to young, actively growing ragwort shoots or buds, and begin mining into the plant tissue, boring into the leaf, crown, stem or bud.C. atricapitana has five larval instars and enters diapause as a final instar larva. In southern Victoria, moths ofC. atricapitana fly from late September through to the beginning of February. Adults emerge after overwintering towards the end of spring or beginning of summer.C. atricapitana has established at two sites while larvae, or signs of damage have been observed at approximately 52% of release sites.      

In vitro micropropagation of the macarronesian evergreen treePersea indica (L.) K. Spreng

Summary Shoot propagation ofPersea indica (L.) K. Spreng was achieved using seedling axillary buds cultured on MS (Murashige and Skoog, 1962) medium with 1 mg/l (2.8 μM) N⁶-benzyladenine (BA). Forty percent of the obtained shoots did not elongate, but showed bud proliferation, which was maximal (three axillary buds per shoot) at the end of the seventh subculture. Sixty percent of the shoots elongated, did not show bud proliferation, and formed calluses at their base. Successful rooting (84.6%) was achieved dipping the base of each elongated shoot in 3 g/l (16.11 mM) indolebutyric acid (IBA) for 1–2 s, and transferring to half strength MS medium without growth regulators. These shoots presented an acclimatization success of 100%. Results suggest that micropropagated elongated shoots ofP. indica can be adequately used in reforestation programs.     

Shoot growth and tree architecture of saplings of the major canopy dominants in a warm-temperate rainforest

Sapling density, shoot growth, and sapling architecture were studied in five major canopy dominants both under closed canopy and gaps in a warm-temperate rainforest. The five species showed wide variations in distribution, shoot growth, and sapling architecture. Distylium racemosum and Quercus acuta had significantly higher sapling densities under closed canopy than in gaps. Castanopsis sieboldii and Machilus thunbergii had significantly higher sapling densities in gaps than under closed canopy. Quercus salicina showed no significant difference in sapling density between the two habitats. Under closed canopy, C. sieboldii and M. thunbergii had wider crowns than the other species. Distylium racemosum had the greatest number of terminal shoots among the species. Quercus acuta had a branchless small crown. Quercus salicina showed intermediate values in crown width, depth and the number of terminal shoots among the species. Distylium racemosum showed the greatest height-growth rate among the species under the closed canopy, but was the slowest in gaps. Castanopsis sieboldii and M. thunbergii showed the greatest height-growth rates among the species in gaps. Quercus salicina showed the slowest height-growth rates both under closed canopy and gaps. All of the five species showed low mortality under closed canopy. For the major canopy dominants: (i) sapling architecture may not be an important factor in determining mortality but it may be important for height-growth rate; and (ii) sprouting helps saplings to survive until gap formation and facilitates rapid growth in the gaps.     

羊草克隆种群的螺旋扩张规律

羊草是欧亚大陆草原东部区域的一个优势物种。其优势地位的取得是羊草种群年复一年不断克隆复制过程中进行螺旋扩张的结果,其中,每一个螺旋圆环代表一个生长季,进而每个生长季可再分为不同的种群成长阶段,执行不同的生存发展策略:5月下旬—7月下旬为成熟扩张期,羊草的成熟母株通过水平伸长根茎执行扩张策略;7月下旬—10月下旬为幼苗占领期,通过地下芽输出为地上子株执行占领策略;10月下旬—来年3月下旬为羊草的休眠期;3月下旬—4月下旬为它的生长准备期;4月下旬—5月下旬为生长巩固期,子株发育为成熟的母株,完成了领地的彻底控制,执行的是巩固策略。羊草的游击型分株和密集型分株源自于共同的母株,二者位置相互分开,不但可以避免内部竞争,而且通过根茎之间的连接进行资源共享,从而在对外竞争中始终处于优势地位,这是羊草的克隆区隔避险策略;羊草种群通过产生遗传异质性的种子来避免因外界环境条件巨变所造成的整体灭绝,执行的是一种有性繁殖避险策略。羊草在既定策略基础上也表现出明显的二八规律,即通过80%比例的密集型分株进行旧领地的巩固,以20%比例的游击型分株进行新领地的扩张。总之,羊草通过扩张,占领,巩固,再扩张,再占领,再巩固,这样的年复一年的螺旋扩张,成为了当地的优势物种。其研究结果能为提高羊草生产力和种子产量及恢复受损草原生态系统提供十分重要的科学支持。