Transformation of Liquidambar styraciflua using Agrobacterium tumefaciens

Summary We describe the molecular transformation of Liquidambar styraciflua using Agrobacterium tumefaciens. A binary TI-plasmid vector containing a chimeric neomycin phosphotransferagene which confers resistance to kanamycin and either a chimeric Bacillus thuringiensis toxin gene, a chimeric E. coli -glucuronida(GUS), or a chimeric tobacco anionic peroxidase gene was introduced into sweetgum by co-cultivation with Agrobacterium tumefaciens. Sweetgum shoots regenerated in the presence of kanamycin were confirmed to be transformed by genomic DNA blots or the presence of GUS activity. The optimization of the transformation protocol and the incorporation of molecular transformation into a rapid germplasm improvement protocol are discussed.     

In vitro propagation of mature Liquidambar styraciflua

Mature specimens of liquidambar styraciflua were propagated in vitro. Components of the nutrient medium and culture conditions were first determined for one-year-old seedling material. Mature material responded similarly to seedling material in culture, but alterations in frequency of early transfers and components of the medium were required. Explants responded best to Woody Plant Medium of Lloyd and McCown supplemented with 0.2 mg l^-1 BA and 0.05 mg l^-1 NAA. Root formation occurred on shoots placed on media containing 0.5–1.0 mg l^-1 IBA. Growth in culture and percentage of rooting of mature explants were markedly affected by the individual selection, with rooting percentages varying from 33–100% among selections.     

Water source utilization under differing surface flow regimes in the riparian species Liquidambar styraciflua,in the southern Appalachian foothills,USA

Plant Ecology - Studies across the United States and globally have revealed that mature riparian trees often utilize little streamwater, relying on soil moisture and groundwater instead....     

北美枫香的离体培养和植株再生

1植物名称北美枫香(Liquidambar styraciflua L.). 2材料类别幼嫩枝条. 3培养条件(1)腋芽诱导培养基:MS 6-BA 0.2mg·L-1(单位下同);(2)不定芽增殖培养基:MS 6-BA 0.2,0.5,1.0,2.0 NAA 0.2;(3)壮苗培养基:MS 6-BA 0.2 NAA 0.02;(4)生根培养基:1/2MS IBA 0.2 NAA 0.2.以上培养基pH为5.7～5.8,加入3%蔗糖和0.48%琼脂.培养温度为25℃,光照时间为12 h·d-1,光照度为2 000 1x.     

Micropropagation with a novel pattern of adventitious rooting in American sweetgum (Liquidambar styraciflua L.)

Liquidambar styraciflua L. has great potential not only as an ornamental, but also for its commercial importance in pulp and paper production or biomass energy. This study was designed to evaluate the influence of plant growth regulators on adventitious shoot multiplication from shoot tips, and in vitro adventitious rooting. The morphogenic capacity of intact leaves grown in vitro was also assayed for adventitious shoot formation and aerial root development. The highest shoot multiplication rate of 5.9 shoots per explant was achieved with 0.7 mg l⁻¹ 6-benzylaminopurine plus 0.01 mg l⁻¹ indole-3-butyric acid. Thidiazuron, alone or in combination with 6-benzylaminopurine, did not significantly support higher shoot multiplication rates. The organogenic ability of the in vitro grown leaves was significantly lower and slower in comparison with shoot tips. Microshoots rooted readily after transfer to a half-strength woody plant medium supplemented with 0.5–0.7 mg l⁻¹ 1-naphthaleneacetic acid, and were then successfully acclimatised to an ex vitro environment. A novel pattern of adventitious rooting was observed from the aerial parts of microshoots which were not in contact with the medium, including the parenchyma cells of the leaf blades as well as stem nodes and internodes. The regenerated plants established in soil did not show any detectable morphological variation.     

Growth and water relations of Liquidambar styraciflua L. in an urban park and plaza

Summary Growth and water relations of 10-year-old sweet gum (Liquidambar styraciflua L.) street trees were studied in sites with low and high potential evapotranspiration to determine how these differences are integrated by growth and water relations over time. The trees were located in the parking strip between the curb and sidewalk at a partially vegetated urban park and an urban plaza in Seattle, Washington. Crown size, and seasonal and diurnal stomatal conductance and water potential, as well as diurnal air temperature and humidity, were measured over 2 growing seasons. Yearly trunk growth since transplanting was measured from increment cores. Vapor pressure deficits and air temperatures averaged 18% greater at the plaza, but whole-tree water loss appeared to be much lower than the park trees due to more restricted stomatal conductance and crown size. In addition, yearly diameter increment declined progressively once the plaza trees were established in the existing soil several years after transplanting. Lower water potential in the plaza trees indicated greater internal moisture deficits than the park trees, and tissue analysis revealed lower nutritional status, particularly nitrogen. A manipulative study of water and fertilizer to several additional plaza trees showed an interaction between water and nutrient deficiencies in the coarse and shallow soil that apparently limited growth. Furthermore, soil limitations probably interacted with paved surface conditions over time by reducing nutrient recycling from leaf litter, and generating higher vapor pressure deficits that would contribute to prolonged stomatal closure. Restricted growth and water relations status of the plaza trees represented an equilibrium between chronic high-resource demand above ground and limited below ground.     

Phylogeographical structure and temporal complexity in American sweetgum (Liquidambar styraciflua; Altingiaceae)

Eastern North American plant biogeography has traditionally focused on two primary issues: (i) the location of temperate Pleistocene refugia and their proximity to the southern margin of the ice sheet during the last glacial maximum, and (ii) the origin of the temperate element of northern Latin America. While numerous population genetic and phylogeographical studies have focused on the first issue, few (if any) have considered the second. We addressed these issues by surveying 117 individuals from 24 populations of Liquidambar styraciflua (American sweetgum; Altingiaceae) across the southeastern USA, eastern Mexico, and Guatemala, using more than 2200 bp of chloroplast DNA sequence data. To specifically address the issue of timing, we estimated intraspecific divergence times on the basis of multiple fossil-based calibration points, using taxa from Altingiaceae ( Liquidambar and Altingia ) and Hammamelidaceae ( Hamamelis ) as outgroups. More than half of the sampled localities exhibited multiple haplotypes. Remarkably, the greatest variation was observed within the USA, with Mexico and Guatemala sharing widespread haplotypes with Texas, Mississippi, Kentucky, Ohio, and northern Virginia. This lack of differentiation suggests shared ancestral polymorphisms, and that the genetic signal we observed is older than the disjunction itself. Our data provide support for previously proposed hypotheses of Pleistocene refugia in peninsular Florida and along the eastern Atlantic, but also for deeper divergences (~8 million years ago) within the USA. These patterns reflect a dynamic biogeographical history for eastern North American trees, and emphasize the importance of the inclusion of a temporal component in any phylogeographical study.     

Photosynthetic and biomass allocation responses of Liquidambar styraciflua (Hamamelidaceae) to vine competition

This 2-year field study examined stomatal conductance, photosynthesis, and biomass allocation of Liquidambar styraciflua saplings in response to below- and aboveground competition with the vines Lonicera japonica and Parthenocissus quinquefolia. Vine competition did not affect stomatal conductance of the host trees. The leaf photosynthetic capacity and photosynthetic nitrogen-use efficiency were significantly reduced by root competition with vines, either singly or in combination with aboveground competition, early in the second growing season. However, such differences disappeared by the end of the second growing season. Trees competing below ground with vines also had lower allocation to leaves compared with steins. Aboveground competition with vines resulted in reduced photosynthetic capacity per unit leaf area, but not per unit leaf weight, in trees. No correlation was found between single leaf photosynthetic capacity and tree growth. In contrast, a high positive correlation existed between allocation to leaves and diameter growth. Results from this study suggest that allocation patterns are more affected than leaf photosynthesis in trees competing with vines.     

Modeling flow in collecting lymphatic vessels: one-dimensional flow through a series of contractile elements

The lymphatic system comprises a series of elements, lymphangions, separated by valves and possessed of active, contractile walls to pump interstitial fluid from its collection in the terminal lymphatics back to the main circulation. Despite its importance, there is a dearth of information on the fluid dynamics of the lymphatic system. In this article, we describe linked experimental and computational work aimed at elucidating the biomechanical properties of the individual lymphangions. We measure the static and dynamic mechanical properties of excised bovine collecting lymphatics and develop a one-dimensional computational model of the coupled fluid flow/wall motion. The computational model is able to reproduce the pumping behavior of the real vessel using a simple contraction function producing fast contraction pulses traveling in the retrograde direction to the flow.     

In vitro adventitious shoot formation on mature-phase leaves and petioles of Liquidambar styraciflua L.

Adventitious shoots were induced to form on leaves and petiole segments of mature-phase Liquidambar styraciflua L. Shoot organogenesis occurred directly, without the formation of a distinct callus stage, and well-defined shoots were visible in 6–9 weeks. Prolific shoot production was supported by Woody Plant Medium supplemented with relatively high levels of benzyladenine (2.5 mg/l). Changes in benzyladenine concentration and the addition of 0.1 mg/l naphthaleneacetic acid to the medium altered the relative abundance of shoots on various parts of a leaf. Shoot formation occurred most frequently at or near breaks in major vasculature. Wounding of the leaves by slashing across the lamina and vasculature significantly increased the total number of shoots formed per explant and also altered the pattern of organogenesis. Differences in organogenic response were seen between the cultivars ‘Moraine’ and ‘Variegata’. Shoots derived from leaves were easily rooted and acclimated to greenhouse conditions. Three new variegation types arose in vitro as a result of adventitious shoot formation on ‘Variegata’ leaves.     

Evaporation of intercepted precipitation from fruit litter of Liquidambar styraciflua L. (sweetgum) in a clearing as a function of meteorological conditions

Interception of precipitation by fruit litter is a poorly understood component of the hydrologic cycle in forested ecosystems. Even less well understood is the effect of meteorological conditions on the evaporation of precipitation intercepted by forest litter. This study sought to examine the influence of meteorological conditions on the evaporation of intercepted precipitation by fruit litter from Liquidambar styraciflua L. (sweetgum) by deriving and calibrating a regression model to estimate evaporation from the fruit litter that may be of potential use to forest and watershed managers. Data on evaporative losses from the fruit litter used to derive and calibrate the statistical model were acquired through a larger field experiment conducted from mid November 2002 through April 2003. Results from the forward stepwise least squares multiple regression model demonstrated that evaporative losses from the fruit litter were estimated with a high degree of accuracy based on the amount of water stored, solar radiation inputs, and vapor pressure deficit (adjusted R²=0.836, F=82.28, P<0.00001). The amount of water stored in the fruit litter explained the highest proportion of variance in the regression model. Storm to storm comparisons also highlighted the importance of solar radiation and wind speed in determining evaporation from the fruit litter. The regression model potentially may be used in conjunction with a canopy interception model to predict interception losses from L. styraciflua dominated forests and plantations.     

Growth and photosynthetic responses of field-grown sweetgum (Liquidambar styraciflua; Hamamelidaceae) seedlings to UV-B radiation

Very few studies have evaluated the effects of UV-B radiation on trees. especially deciduous species. In this study we evaluate the effects of supplemental UV-B radiation on the growth and photosynthetic capacity of sweetgum (Liquidambar styraciflua L.). Sweetgum seedlings were grown for 2 years in the field under either ambient or supplemental UV-B radiation. Artificial UV-B radiation was supplied by fluorescent lamps at a maximum daily supplementation of either 3.1 or 5.0 kJ of biologically effective UV-B radiation. Over the 2-year period, supplemental UV-B radiation had little effect on total plant biomass or photosynthetic capacity. However, subtle changes in leaf physiology, carbon allocation, and growth were observed. Supplemental UV-B radiation reduced photosynthetic capacity only during the first year, while leaf area and biomass were reduced in the second year. Alterations in carbon allocation included an increase in branch number and root to shoot ratio. While these data do not indicate that the productivity of sweetgum would likely be compromised by an increase in solar UV-B radiation, they do suggest that the UV-B portion of the solar spectrum contributes to the regulation of sweetgum growth and development. Therefore the possibility of significant consequences to sweetgum due to possible increases in UV-B radiation cannot be ruled out.     

Changes in leaf expansion and epidermal screening effectiveness in Liquidambar styraciflua and Pinus taeda in response to UV-B radiation

Absorption or screening of ultraviolet-B (UV-B) radiation by the epidermis may be an important protective method by which plants avoid damage upon exposure to potentially harmful UV-B radiation. In the present study we examined the relationships among epidermal screening effectiveness, concentration of UV-absorbing compounds, epidermal anatomy and growth responses in seedlings of loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.). Seedlings of each species were grown in a greenhouse at the University of Maryland under either no UV-B radiation or daily supplemental UV-B radiation levels of 4, 8 or 11 kJ m^?2 of biologically effective UV-B (UV-B_BE) radiation. Loblolly pine seedlings were subsequently grown in the field under either ambient or supplemental levels of UV-B radiation. At the conclusion of the growing season, measurements of epidermal UV-B screening effectiveness were made with a fiber-optic microprobe. In loblolly pine, less than 0.5% of incident UV-B radiation was transmitted through the epidermis of fascicle needles and about 1% was transmitted in primary needles. In contrast, epidermal transmittance in sweetgum ranged from about 20% in leaves not preconditioned to UV-B exposure, to about 10% in leaves grown under UV-B radiation. The concentration of UV-absorbing compounds was unaffected by UV-B exposure, but generally increased with leaf age. Increases in epidermal thickness were observed in response to UV-B treatment in loblolly pine, and this accounted for over half of the variability in UV-B screening effectiveness. In spite of the low levels of UV-B penetration into the mesophyll, delays in leaf development (both species) and final needle size (loblolly pine) were observed. Seedling biomass was reduced by supplemental UV-B radiation in loblolly pine. We hypothesize that the UV-induced growth reductions were manifested by changes in either epidermal anatomy or epidermal secondary chemistry that might negatively impact cell elongation.     

Resistances to fluid flow of model xylem vessels with simple and scalariform perforation plates

The resistances of xylem vessel walls and perforation plates has been investigated using 18 large-scale physical models made of plastic tubing into which scale models of plates were inserted. Flow of water through vessels was modelled using glycerol instead of water to keep the Reynolds number below 0.1. The technique proved easy, cheap and reliable.Results showed that perforation plate resistance is low compared with the resistance of the walls, whatever the plate morphology; plates only provided 0.6-18.6% extra resistance. Simple plates provided less resistance than scalariform plates, but because they are arranged closer together in vessels, resistance values (1.7-5.1%) overlap with those of scalariform plates. The resistance of scalariform plates varied in a systematic way with their morphology. For a given plate angle, increasing the number of bars increased resistance. For a given bar number, increasing the angle of the plate to the vessel axis also increased the resistance. However, for a given gap between bars, increasing the angle of the plate to the vessel axis decreased resistance. These results are discussed in the light of theories about the function of perforation plates.Keywords: Flow, xylem vessel, perforation plate, models.      

Water flow through junctions in Douglas-fir roots

Roots are important conduits for the redistribution of water within the rooting zone. Root systems are often highly branched, and water flow between regions undoubtedly involves passage through junctions between individual roots. This study considered junctions in the roots of Douglas-fir with regard to the resistances encountered by water flow through the xylem. Flow into the root branch distally along the main root encountered much greater resistance than flow into the branch and proximally along the main root (toward the plant stem). When the main root proximal to the junction was gradually shortened, the resistance to flow in the branch root and distally along the main root increased dramatically. Thus, flow in this manner appears to depend on lateral flow within the root over many centimetres proximal to the junction and not just within the direct connection at the junction. These results suggest that the hydraulic nature of junctions is an important aspect of hydraulic redistribution of water within the soil utilizing flow through roots.