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Background and Aims The reliance on external support by lianas has been hypothesized to imply a reduction in the biomass cost of stem construction and root anchorage, and an increased investment in leaves, relative to self-supporting plants. These evolutionary trade-offs have not been adequately tested in an ontogenetic context and on the whole-plant scale. Moreover, the hypothesis may be extended to other potentially limiting resources, such as nitrogen (N.) Methods Plants belonging to five con-familiar pairs of temperate liana/shrub species were cultivated in 120 L barrels and sequentially harvested over up to three growing seasons. To account for the ontogenetic drift, organ biomass and nitrogen fractions were adjusted for plant biomass and N pool, respectively. Key Results Lianas invested, on average, relatively less biomass in the root fraction in comparison with shrubs. This was offset by only insignificant increases in leaf or stem investment. Even though liana stems and roots showed higher N concentration in comparison with shrubs, plant N distribution was mostly driven by, and largely matched, the pattern of biomass distribution. Lianas also showed a greater relative growth rate than shrubs. The differences between the growth forms became apparent only when ontogenetic drift was controlled for. These results were confirmed regardless of whether reproductive biomass was included in the analysis. Conclusions Our results suggest that temperate lianas, in spite of their diverse, species-specific resource distribution patterns, preferentially allocate resources to above-ground organs at the expense of roots. By identifying this trade-off and demonstrating the lack of a general trend for reduction in stem investment in lianas, we significantly modify the prevailing view of liana allocation strategies and evolutionary advantages. Such a resource distribution pattern, along with the cheap unit leaf area and stem unit length construction, situates lianas as a group close to the fast acquisition/rapid growth end of the life strategy spectrum.

Harsh environmental conditions affect both leaf structure and root traits. However, shoot growth in high-latitude systems is predominately under photoperiod control while root growth may occur for as long as thermal conditions are favorable. The different sensitivities of these organs may alter functional relationships above- and belowground along environmental gradients. We examined the relationship between absorptive root and foliar traits of Scots pine trees growing in situ along a temperate-boreal transect and in trees grown in a long-term common garden at a temperate latitude. We related changes in foliar nitrogen, phosphorus, specific leaf area, needle mass and 13 C signatures to geographic trends in absorptive root biomass to better understand patterns of altered tree nutrition and water balance. Increased allocation to absorptive fine roots was associated with greater uptake of soil nutrients and subsequently higher needle nutrient contents in the northern provenances compared with more southern provenances when grown together in a common garden setting. In contrast, the leaf δ13 C in northern and southern provenances were similar within the common garden suggesting that higher absorptive root biomass fractions could not adequately increase water supply in warmer climates. These results highlight the importance of allocation within the fine-root system and its impacts on needle nutrition while also suggesting increasing stomatal limitation of photosynthesis in the context of anticipated climatic changes.

In some lianas the use of trellis modifies within-plant biomass allocation and stimulates growth, however in other species trellis use may negatively affect growth indicating a cost associated with climbing. In order to improve access to light, lianas use other plants as climbing trellises. Whereas in shaded lianas climbing a trellis may enhance biomass gain by increasing leaf-level irradiance, we suspected that trellis use may also stimulate growth by triggering modifications in whole-plant allocation of biomass and nitrogen. We evaluated responses to trellis in three temperate lianas: Hedera helix, Celastrus orbiculatus and Wisteria floribunda. Lianas were grown outdoors in 120-L barrels and with ample space, with and without trellises. Biomass and nitrogen accumulation, distribution patterns and total stem length were determined after three and four seasons. Responses were adjusted for individual plant biomass. Liana responses to trellises were species-specific. In W. floribunda trellis use enhanced growth, consistently with the increased leaf mass fraction and leaf area ratio while biomass distribution to roots was reduced. Biomass distribution to stems and total stem length were increased by trellis use. In contrast, growth and biomass distribution in C. orbiculatus were not altered by trellis use. In H. helix growth was reduced in plants climbing on trellises in comparison with plants creeping on the ground, but biomass distribution pattern was not altered. Moreover, supported H. helix plants accumulated less nitrogen than did unsupported plants, suggesting a less efficient uptake of this nutrient. The ability to plastically modify growth and allocation patterns in response to trellis found in some lianas may constitute an important aspect of their ecological strategy. In other species, however, the switch to climbing may incur physiological costs resulting in lower growth.

Intraspecific variability of anatomical leaf traits is usually determined on the basis of median sections and interpreted as adaptive. We hypothesized that anatomical traits may relate to the position within the leaf, reflecting functional coordination e.g., between transport and gas exchange capacities and between supporting tissue and the supported leaf weight. Anatomical variation may thus be partly controlled by leaf size. We examined variability of transverse anatomical traits and stomata at different positions along the leaf axis using Scots pine (Pinus sylvestris L.) needles collected from three geographical locations with contrasting climate (Poland, Southern and Northern Sweden) and differing in length. Transverse xylem and phloem area, and the number of tracheids at a given cross-section scaled positively with length of the distal needle part and the number of distal stomata. Similarly, the number of vascular sclerenchyma fibers in a cross-section scaled with the length and volume of the distal needle part. Allometric slopes were less steep in the longer, southern-sites needles. Additionally, our study revealed an increased sclerification of epidermis towards the needle apex, the occurrence of widest tracheids in central or subapical regions, a reduced number of resin ducts in basal and apical parts, as well as overall basipetal decreases in duct diameter, the number of stomatal files and stomatal density. These results show that allometry accounts for significant amount of intraspecific variability in xylem, phloem and fibers, and that environmental adaptation involves also modification of the within-needle allometric relationships. The allometric component of variability, together with the nonlinear distribution of certain traits along needle length, should be considered when designing comparative studies of foliar phenotypes and scaling up from transverse sections to entire needles.

AtDeg2 is a chloroplast protein with dual protease/chaperone activity. Since data on how the individual activities of AtDeg2 affect growth and development of Arabidopsis thaliana plants is missing, two transgenic lines were prepared that express mutated AtDeg2 versions that have either only protease or chaperone activity and a comprehensive ontogenesis stage-based study was performed comprising wild type (WT) plants and insertional mutants that do not express AtDeg2, as well as the two transgenic lines. The repression of both AtDeg2 activities in deg2-3 mutants altered just a few phenotypic traits including the time when cotyledons were fully opened, the time when 10% flowers were open as well as the number of inflorescence branches and seed length in plants which have completed their generative development. It was demonstrated that complete opening of cotyledons as well as the number of inflorescence branches and seed length in plants which have completed their generative development required involvement of both AtDeg2 activities, whereas the time when 10% of flowers were open was controlled by AtDeg2 protease activity. These results show for the first time that the chaperone activity of AtDeg2 is needed for some elements of generative development of A. thaliana plants to proceed normally. So far, the chaperone activity of AtDeg2 was confirmed based on in vitro assays only.

In evergreen plants, old leaves may contribute photosynthate to initiation of shoot growth in the spring. They might also function as storage sites for carbohydrates and nitrogen (N). We hence hypothesized that whole-plant allocation of carbohydrates and N to storage in stems and roots may be lower in evergreen than in deciduous species. We selected three species pairs consisting of an evergreen and a related deciduous species: Mahonia aquifolium (Pursh) Nutt. and Berberis vulgaris L. (Berberidaceae), Prunus laurocerasus L. and Prunus serotina Ehrh. (Rosaceae), and Viburnum rhytidophyllum Hemsl. and Viburnum lantana L. (Adoxaceae). Seedlings were grown outdoors in pots and harvested on two dates during the growing season for the determination of biomass, carbohydrate and N allocation ratios. Plant size-adjusted pools of nonstructural carbohydrates in stems and roots were lower in the evergreen species of Berberidaceae and Adoxaceae, and the slope of the carbohydrate pool vs plant biomass relationship was lower in the evergreen species of Rosaceae compared with the respective deciduous species, consistent with the leading hypothesis. Pools of N in stems and roots, however, did not vary with leaf habit. In all species, foliage contained more than half of the plant’s nonstructural carbohydrate pool and, in late summer, also more than half of the plant’s N pool, suggesting that in juvenile individuals of evergreen species, leaves may be a major storage site. Additionally, we hypothesized that concentration of defensive phenolic compounds in leaves should be higher in evergreen than in deciduous species, because the lower carbohydrate pool in stems and roots of the former restricts their capacity for regrowth following herbivory and also because of the need to protect their longer-living foliage. Our results did not support this hypothesis, suggesting that evergreen plants may rely predominantly on structural defenses. In summary, our study indicates that leaf habit has consequences for storage economics at the whole-plant level, with evergreen shrub species storing less carbohydrates (but not N) per unit plant biomass than deciduous species.

Evergreen plants are an important component of many ecosystems of the world and occur in nu- merous evolutionary lineages. In this article we review phenotypic traits of evergreen woody angiosperms occurring in habitats that regularly experience frost. Leaf anatomical traits such as sclerenchymatic tissues or prominent cuticles ensure mechanical strength while often enhancing tolerance of water deficit. The low ratio of photosynthetic to nonphotosynthetic tissues as well as modified cell wall structure and nitrogen allocation patterns in evergreen leaves result in lower mass-based photosynthetic rate and photosynthetic nitrogen use efficiency in comparison with deciduous leaves. Their photosynthetic apparatus is adapted for the survival of frost in a down-regulated state with potential for photosynthetic activity in winter during periods of permissive temperatures. Leaf structure interacts with the mechanisms of frost survival. Stem xylem in evergreen plants tends to contain smaller diameter conduits incurring greater resistance to freeze/ thaw induced cavitation than in deciduous plants, although at the cost of reduced hydraulic efficiency. In contrast, no such differences in hydraulic conductivity have been documented at the leaf level. There is ev- idence for reduced structural plasticity of evergreen leaves in response to variability in irradiance, however photosynthetic downregulation occurs in mature leaves in response to self shading. Some evergreen species exhibit slow leaf development and "delayed greening", while in many species aging is also a very protracted process. Finally, evergreen leaves may participate in carbohydrate and, less obviously, in nitrogen storage for the support of spring shoot and foliage growth, although the importance of this function is under debate. In conclusion, the evergreen leaf habit is correlated with numerous structural and functional traits at the leaf and also at the stem level. These correlations may generate trade-offs that shape the ecological strategies of evergreen plants.

Xeromorphism is a set of structural traits facilitating plant functioning under the conditions of water deficit. While leaf xeromorphic traits have been widely described in a variety of species, much less is known about the ability of plants to acclimate to drought by plastically modifying their leaf structure. We hypothesized that such modification would recapitulate the xeromophic syndrome. We conducted a greenhouse experiment in which a genetically and phenotypically diverse population of barley (Hordeum vulgare L.) cultivars and hybrid lines were subjected to controlled drought followed by re-watering. Leaves produced after the onset of drought were sampled for determination of lamina length and 18 anatomical traits of adaxial epidermis and central transverse lamina sections. Across all studied genotypes, mean leaf length, width, and dimensions of all internal structures were reduced by drought, whereas the density of veins, stomata, and trichomes increased. However, since anatomical traits were commonly correlated with leaf length and following drought the leaves became shorter, we statistically controlled for the leaf size-related variation. Although leaf shortening explained much anatomical response to drought, several traits exhibited additional, leaf-length independent modification. For example, vein and stomatal density increased and xylem area and vessel diameter decreased to a greater extent than expected from leaf size reduction. These results confirm the occurrence of modest facultative xeromorphism in barley but also emphasize the need to use allometric analysis to uncouple the true plasticity of traits from changes attributable to altered plant and organ size.

Background As proposed by Darwin, climbers have been assumed to allocate a smaller fraction of biomass to support organs in comparison with self-supporting plants. They have also been hypothesized to possess a set of traits associated with fast growth, resource uptake and high productivity. Scope In this review, these hypotheses are evaluated by assembling and synthesizing published and unpublished data sets from across the globe concerning resource allocation, growth rates and traits of leaves, stems and roots of climbers and self-supporting species. Conclusions The majority of studies offer little support for the smaller allocation of biomass to stems or greater relative growth rates in climbers; however, these results are based on small sized (

Semidwarf barley cultivars have been created in the past decades featuring shortened straw length. The semidwarfness trait is desirable because plants with reduced height are more resistant to lodging and, as a consequence, have an improved harvest index. Accordingly, both breeding and molecular mapping experiments were undertaken to enhance and evaluate the performance of semidwarf barley lines. To study the morpho-anatomical effects of the denso locus twenty barley lines developed by single seed descent technique were analysed. We measured several macro and microscopic traits of aboveground organs. We detected reduction in leaf size, which at tillering stage was also reflected by smaller sizes of some, but not all, categories of epidermal cells. Lower cell division frequencies were deduced for cell files with unchanged cell lengths. Denso leaf blades were thinner and had smaller vascular bundles and narrower tracheal elements compared to the wild type. On the other hand, a lack of effect was noted e.g. for sizes of stomata and size of spike. Denso gene thus exerted a multilevel dwarfing effect on cells, tissues and organs although not all organs and cells were affected to the same extent, and cell size or division frequency were modified depending on cell type.

SummaryFlowers and floral parts have seldom been used successfully as explants to initiate tissue culture. Flower buds of Mammillaria albicoma, M. carmenae, and M. schiedeana (Cactaceae) were cultured on solid Murashige and Skoog medium containing 0.1 mg l−1 -naphthaleneacetic acid (NAA) and 5.0 mg l−1 6-benzylaminopurine. The formation of vegetative buds (areoles) and the development of shoots were observed in all three species. Both direct and indirect mechanisms of shoot morphogenesis were observed. Direct shoot morphogenesis from the perianth (especially from the axils of the perianth segments) in M. albicoma and M. carmenae was confirmed by microscopic examination. Shoots that formed on explants were isolated and used to establish proliferating cultures. Finally, proliferated shoots were rooted in vitro on MS medium containing 0.01 mg l−1 NAA and acclimated to ex vitro conditions. M. carmenae shoots were also rooted non-aseptically in horticultural substrate. This is the first report of the complete ...

In several genera of Cactaceae flowers are produced by a specialized, nonphotosynthetic portion of the stem known as the cephalium. The objective of this study is to test if cephalial tissue can be induced to revert to vegetative growth under in vitro conditions. Segments excised from the surface of Melocactus matanzanus cephalium and placed on Murashige and Skoog medium supplemented with 0.1 mg l−1 1-napthaleneacetic acid (NAA) and 1.0 or 5.0 mg l−1 6-benzyloaminopurine (BAP) regularly produced vegetative shoots. Shoots were also obtained when kinetin was used instead of BAP, although the frequency of their formation was then lower. One of the reverted shoots was successfully established as a rooted plant ex vitro.

We tested the organogenetic capacity of floral buds of Mammillaria albicoma Boed. (Cactaceae). Buds were incubated on solid MS medium supplemented with 0.1 mg l−1 α-naphthaleneacetic acid (NAA) and 5.0 mg l−1 6-benzylaminopurine (BA). Callus growth was observed from the cut explant base and from within the perianth. These calli during subsequent subcultures to the same medium gave rise to adventitious shoots. Shoots formed also directly from the perianth, as confirmed by observations in the light microscope and scanning electron microscope (SEM). On transfer to a fresh medium, the shoots produced proliferating cultures. This is the first report of regeneration of cactus shoots from floral explants.

In continuous light, the Crassulacean acid metabolism plant Kalanchoe daigremontiana Hamet et Perrier has a circadian rhythm of gas exchange with peaks occurring during the subjective night. The rhythm of gas exchange is coupled to a weak, reverse phased rhythm of quantum yield of photosystem II (Phi (PSII)). To test if the rhythm of Phi (PSII) persists in the absence of stomatal control, leaves were coated with a thin layer of translucent silicone grease which prevented CO2 and H2O exchange. In spite of this treatment, the rhythm of Phi (PSII) occurred with close to normal phase timing and with a much larger amplitude than in uncoated leaves. The mechanism underlying the Phi (PSII) rhythm in coated leaves can be explained by a circadian activity of phosphoenolpyruvate carboxylase (PEPC). At peaks of PEPC activity, the small amount of CO2 contained in the coated leaf could have become depleted, preventing the carboxylase activity of Rubisco and causing decreases in electron transport rates (observed as deep troughs of Phi (PSII) at 23-h in LL and at ca. 24-h intervals afterwards). Peaks of Phi (PSII) would be caused by a downregulation of PEPC leading to improved supply of CO2 to Rubisco. Substrate limitation of photochemistry at 23 h (trough of Phi (PSII)) was also suggested by the weak response of ETR in coated leaves to stepwise light enhancement. These results show that photosynthetic rhythmicity in K. daigremontiana is independent of stomatal regulation and may originate in the mesophyll.