Effect of Sucrose on Starch Accumulation in and Adventitious Bud Formation on Embryos of Picea abies

Adventitious buds were initiated on embryos of Picea abies (L.)Karst. after a pulse treatment with cytokinin. The initial stagesof bud formation could take place on culture medium lackingsucrose, but sucrose was required for further development ofmeristematic centres into bud primordia and buds. Sucrose atone per cent was optimal for adventitious bud formation. Embryoscultured on media containing sucrose started to accumulate starchduring the first day. Starch accumulation occurred especiallyin the cortex cells where starch grains were frequently presentin the chloroplasts. The starch accumulation increased withhigher sucrose concentrations in the culture medium. Embryoscultured on medium lacking sucrose did not accumulate starchbefore the formation of meristematic centres. Starch accumulationwas never observed in meristematic cells from which adventitiousbud primordia developed. Picea abies (L.) Karst., Norway spruce, adventitious bud, starch accumulation, sucrose concentration     

Changes in Protein Synthesis upon Cytokinin-Mediated Adventitious Bud Induction and during Seedling Development in Norway Spruce, Picea abies

A pulse-treatment of embryos of Picea abies (L.) Karst with cytokinin efficiently and reproducibly induces the coordinate de novo formation of bud primordia from subepidermal cells. The cytokinin treatment also affects the germinative development of the embryo; chloroplast maturation is delayed, and cell elongation is completely suppressed. We have analyzed the protein patterns in developing spruce embryos with the aim of identifying proteins which are differentially synthesized during early bud-differentiation and germination. In addition to a set of major seed storage proteins and a large set of constitutively synthesized proteins, we distinguish two sets of proteins that showed different patterns of synthesis in relation to germination. One was synthesized at high rates during germination, and the second set during post-germinative seedling development. Twenty-two proteins were differentially synthesized in the bud-induced versus the germinating embryos. Interestingly, all 22 belonged to either the germination phase-abundant or the seedling protein sets, whereas the constitutively synthesized proteins were unaffected by the treatment. Proteins synthesized exclusively in bud-induced embryos were not found. In total, the bud-induction treatment caused a maintenance of a protein synthesis pattern typical for the germination phase in the nontreated embryos, and the de novo formation of buds was not preceded by a major change in gene expression in the tissue.     

Induction of Adventitious Buds on Embryos of Norway Spruce Grown in vitro

Adventitious buds were induced when isolated embryos of Norway spruce (Picea abies L.) were cultured on a defined medium containing 2iP. Anatomically different bud primordia were formed at high and low cytoldnin concentrations. The highest percentage of embryos forming bud primordia was obtained after 4–5 weeks on 2iP medium. Buds developed after transfer of the induced embryos to medium without growth regulators. Many of the buds developed into elongated shoots. No root primordia were observed in any of the induced embryos.     

The Relationship between Species Diversity and Genetic Structure in the Rare Picea chihuahuana Tree Species Community,Mexico

Species diversity and genetic diversity, the most basic elements of biodiversity, have long been treated as separate topics, although populations evolve within a community context. Recent studies on community genetics and ecology have suggested that genetic diversity is not completely independent of species diversity. The Mexican Picea chihuahuana Martínez is an endemic species listed as “Endangered” on the Red List. Forty populations of Chihuahua spruce have been identified. This species is often associated with tree species of eight genera in gallery forests. This rare Picea chihuahuana tree community covers an area no more than 300 ha and has been subject of several studies involving different topics such as ecology, genetic structure and climate change. The overall aim of these studies was to obtain a dataset for developing management tools to help decision makers implement preservation and conservation strategies. However, this unique forest tree community may also represent an excellent subject for helping us to understand the interplay between ecological and evolutionary processes in determining community structure and dynamics. The AFLP technique and species composition data were used together to test the hypothesis that species diversity is related to the adaptive genetic structure of some dominant tree species (Picea chihuahuana, Pinus strobiformis, Pseudotsuga menziesii and Populus tremuloides) of the Picea chihuahuana tree community at fourteen locations. The Hill numbers were used as a diversity measure. The results revealed a significant correlation between tree species diversity and genetic structure in Populus tremuloides. Because the relationship between the two levels of diversity was found to be positive for the putative adaptive AFLP detected, genetic and species structures of the tree community were possibly simultaneously adapted to a combination of ecological or environmental factors. The present findings indicate that interactions between genetic variants and species diversity may be crucial in shaping tree communities.     

Induction of Adventitious Buds on Buds of Norway Spruce (Picea abies) Grown in vitro

Resting vegetative buds of Norway spruce, Picea abies (L.) Karst., were induced to form adventitious bud primordia when cultured on medium -containing cytokinin. After transfer of the induced buds to medium lacking cytokinin, adventitious buds developed. The adventitious buds arose from meristems formed de novo in the needle primordia. No differences were found in the ability to form adventitious buds among buds collected from trees ranging from 5–50 years old.     

Effects of Auxins and 2,3,5-Triiodobenzoic Acid on Somatic Embryo Initiation from Norway Spruce Zygotic Embryos (Picea abies)

Embryonal-suspensor mass (ESM) initiation from zygotic embryo sections was not affected by explant orientation whatever the type of external auxin used. Thus, polar auxin transport might not be directly involved in the control of somatic embryo formation. Application of 40 µM 2,3,5-triiodobenzoic acid (TIBA) suppressed ESM initiation in hypocotyl sections. This effect of TIBA mimicked that of a supraoptimal dose of -naphtaleneacetic acid suggesting a detrimental effect of fast internal auxin accumulation on ESM initiation.     

Polarity in Adventitious Bud Formation on Excised Leaves of Heloniopsis orientalis (Liliaceae)

The position of adventitious bud formation on isolated leavesfrom young, green and etiolated plants of Heloniopsis orientaliswas considerably influenced by their orientation on the medium.Homogeneous distribution of buds over the whole surface of theleaves was observed in darkness, however, irrespective of theirorientation. The polarity of the bud regeneration was influencedby the application of various growth regulators, such as fusicoccin,cytokinins or abscisic acid. All attempts to induce the formationof adventitious buds on the abaxial side of the leaves wereunsuccessful. From the present and previous results, three polarityaxes (longitudinal, transverse and dorsiventral axes) in thesiting of bud formation on leaves are described. The gradientin the quantity and relative position of vascular bundles andchanges in the stomatal density of a leaf are discussed in termsof their possible roles in the determination of the sites ofbudding on isolated leaves. (Received March 9, 1981; Accepted August 28, 1981)     

Effects of Wounding on Adventitious Bud Formation in Torenia Stem Segments Cultured In Vitro

In in vitro cultured stem segments of Torenia fournieri Lind.,the formation of adventitious buds can be induced when the culturemedium contains cytokinin. When long stem segments (2.0 cm ormore) were cultured with cytokinin, a large number of buds wereformed in the marginal regions, namely, within the limits of0.5 cm from the cut ends of explants, while only a few budswere initiated in the middle part of the explants. If a slightinjury was made transversely with a scalpel in the central partof an explant, a significant increase in the number of budswas noted within the limits of 0.5 cm from the wound site. Whena wounding treatment was given lengthwise to an explant, a largenumber of adventitious buds were formed over the entire surfaceof the explant compared to the control. Excision itself of explantsfrom mother plants and the additional wounding given to theexplants seemed to trigger the induction of adventitious buddifferentiation in Torenia stem segments. These wounding treatmentsdid not affect the uptake into explants and/or the distributionpattern of radioactive benzyladenine applied to the culturemedium. Key words: Torenia fournieri, Adventitious bud formation, Cytokinin, Wounding     

Polyamines and Adventitious Root Formation in the Juvenile and Mature Phase of English Ivy

The involvement of polyamines during adventitious root formationwas evaluated using a de-bladed petiole rooting assay for theeasy-to-root juvenile and difficult-to-root mature phase ofEnglish ivy (Hedera helix L.). Auxin (NAA 0.1 mM) stimulatedroot formation in juvenile phase cuttings, but failed to promoterooting in the mature phase. The addition of putrescine, spermineor spennidine (1.0 mM) with or without NAA (0.1 mM) did notaffect the rooting response in either the juvenile or maturephase cuttings. There was a significant increase in endogenouslevels of putrescine and spermidine in NAA-treated cuttings,but the only significant difference between the root formingjuvenile and the non-root forming mature phase cuttings wasan increase in putrescine levels. In NAA-treated juvenile cuttings,the polyamine biosynthesis inhibitor DFMA (1.0 mM) promotedroot formation from 9.2 to 14.5 roots per cutting, while DFMO(1.0 mM) reduced root formation from 9.1 to 1.4 roots per cutting.The promotion of rooting by DFMA was completely reversed byputrescine (1.0 mM), but putrescine, spermine or spermidine(1.0 mM) could not reverse the inhibitory effect of DFMO. NeitherDFMA nor DFMO promoted root formation in mature phase cuttings.DFMA was also added to NAA-treated juvenile petioles at variousstages during the root formation process. DFMA promoted rootingwhen applied during the early stages of root induction (0–3d), but became inhibitory to root formation when applied duringthe organization (6–9 d) or root elongation stages (9–12d). Key words: Hedera helix, organogenesis, root initiation, polyamines, DFMA, DFMO     

Improved Regeneration Efficiency from Mature Embryos of Barley Cultivars

A reliable protocol for plant regeneration from mature embryo derived calli of nine barley (Hordeum vulgare) cultivars has been developed. The auxins 2,4-dichlorophenoxyacetic acid, picloram and dicamba proved effective in inducing callus from mature embryos of most of the barley cultivars. The induced primary callus was loose, friable and translucent. It ultimately yielded creamy white and compact callus after 2 - 3 transfers on fresh medium of the same composition. Callus induction and regeneration capacity were highly cultivar dependent. Addition of a high concentration of picloram (4 mg dm^-3) promoted regeneration in 3 cultivars (Tallon, Grimmett and Sloop). In cv. Arapiles, abscisic acid and betaine were crucial in generating morphogenic callus from the mature embryos. Plants regenerated from these calli were hardy and developed roots readily when transferred to hormone free medium. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spruce die-back: Isolation of p-hydroxyacetophenone from diseased shoots of Picea abies

p-Hydroxyacetophenone as a new growth substance exhibiting inhibitory activity was isolated from shoots of Picea abies damaged by die-back. Its identity was established by chromatographic and spectroscopic methods.     

几种木本植物插穗生根与内源IAA,ABA的关系

迄今为止,传统的插条繁殖仍是林业和园林工作者获得良种无性系和培育苗木的重要途径。在影响插穗不定根形成内外因素中,植物内源激素水平和生长调节剂应用占有重要地位。已知第一个根原基细胞的分裂依赖于内源生长素或外源的生长调节剂(Hartmann 1983,Haissig 1974),低浓度的ABA(1.26～20μg/ml)能促进     

Somatic Embryogenesis or Shoot Formation Following High 2,4-D Pulse-Treatment of Mature Embryos of Paspalum scrobiculatum

Mature zygotic embryos of Paspalum scrobiculatum L. cv. PSC 1 on MS or N₆ nutrient medium supplemented with various concentrations of 2,4-D (4.5 – 22.5 μM) formed embryogenic callus, which differentiated into somatic embryos within 5 weeks of culture. The somatic embryos after transfer to hormone-free regeneration medium germinated and formed plantlets. Of the two nutrient formulations, N₆ was relatively better than MS for somatic embryogenesis. A culture for 11 d on 100 μM 2,4-D was essential for the establishment of an embryogenic callus. Shorter duration, 4-d or 7-d culture on 2,4-D medium, supported some proliferation and subsequent differentiation into shoot-buds or multiple-shoots, in high-frequency cultures. This is first instance in monocots of a controlled regeneration response; either somatic embryogenesis or shoot formation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Adventitious Bud Formation from Bulb-scale Explants of Lilium speciosum Thunb. in vitro Effects of aminoethoxyvinyl-glycine, 1-aminocyclopropane-1-carboxylic acid,and ethylene

Several representatives of marine brown macroalgae (Phaeophyceae) including Fucus serratus L., Fucus spiralis L. and Fucus vesiculosus L. as well as Laminaria digitata (Huds.) Lamour., Laminaria hyperborea (Gunn.) Foslie and Laminaria saccharina (L.) Lamour. were investigated with particular regard to features of biosynthesis of the storage product mannitol. The respective catalytic system involved in the last step of mannitol formation, mannitol-1-phosphate dehydrogenase, appears to be a cytoplasmic enzyme as may be judged from the degree of correlation with the chloroplast key enzyme ribulose-1,5-bisphosphate carboxylase in different tissues of Laminaria digitata and Laminaria saccharina. Activity of mannitol-1-phosphate dehydrogenase in vitro is not affected by mannitol-l-phosphate or free mannitol, suggesting that mannitol biosynthesis in vivo) is mainly controlled by the environment and/or developmental stage. Certain inorganic ions such as NO₃^- (including K⁺) exert a strong influence on the activity of mannitol1-phosphate dehydrogenase thus suggesting that the intracellular pools of stored NO₃^- and mannitol are confined to spatially separated cellular compartments.     

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.