Larger Rosettes Research Articles

Agave infiernilloensis (sect. Choritepalae, Asparagaceae), a gigantic new species from the Balsas Basin in Western Mexico

We describe and illustrate Agave infiernilloensis, a new species of the section Choritepalae (Agavoideae, Asparagaceae). It is morphologically similar to A. gypsicola from which it differs by having larger rosettes and leaves, shorter terminal spine, shorter and recurving inflorescence, more flowers per node, as well as longer flowers, ovary, and filaments. We assessed the species as Endangered (EN) according to the IUCN criteria. We provide a distribution map and a key to the choritepalous species of Agave.

<p><strong>A new natural hybrid in <em>Saxifraga</em> sect. <em>Porphyrion</em> Tausch (Saxifragaceae)</strong></p>

A new natural hybrid Saxifraga ×klimesii Hajman, Horák & Hroneš from Ladakh (NW India) is described and illustrated. This hybrid resulted from cross between Saxifraga meeboldii Engler & Irmscher and Saxifraga pulvinaria Harry Smith. The morphology of the hybrid plants and its parental taxa was evaluated using morphometric analysis of both living plants and herbarium specimens. An artificial cross was also made to compare its morphology with spontaneous hybrids. Ploidy level and relative genome size was established using flow cytometry. Saxifraga ×klimesii is intermediate in morphology and relative genome size between both parents. It differs from S. meeboldii by shorter and wider rosette leaves and lighter yellow, larger and wider petals and from S. pulvinaria by larger rosettes, often more than one pore on leaves and usually yellow coloured petals. A lectotype is selected for S. pulvinaria.

The Effect of Red & Blue Rich LEDs vs Fluorescent Light on Lollo Rosso Lettuce Morphology and Physiology.

The challenges of feeding an increasing population, an increasingly urban population and within an increasingly challenging global environment have focused ideas on new ways to grow food. Growing food in a controlled environment (CE) is not new but new technologies such as broad-spectrum LEDs and robotics are generating new opportunities. Growth recipes can be tailored to plant species in a CE and plasticity in plant responses to the environment may be utilized to make growth systems more efficient for improved yield and crop quality. Light use efficiency within CE must consider energy requirements, yield and impacts on quality. We hypothesized that understanding how plants change their morphology and physiology in response to light will allow us to identify routes to make light more efficient for delivery of high-quality produce. We focused on responses to light in Lollo rosso lettuce which produces compact, crinkly and highly pigmented leaves. We compared the spectra of the commonly used artificial light sources in indoor farming (compact fluorescence tubes, FL, and broad-spectrum light-emitting diodes, LEDs) at two irradiance levels (270 and 570 μmol m–2 s–1). We discovered LEDs (λP: 451, 634, and 665 nm) produced the same amount of produce for half the incident energy of FL (T5). At higher irradiances LEDs produced 9% thicker leaves, 13% larger rosettes and 15% greater carotenoid content. Leaves differed in light absorptance with plants grown under lower FL absorbing 30% less of mid-range wavelengths. We show that the relative efficiencies of LED and FL is a function of the irradiances compared and demonstrate the importance of understanding the asymptotes of yield and quality traits. Increasing our understanding of structural and biochemical changes that occur under different combination of wavelengths may allow us to better optimize light delivery, select for different ranges of plasticity in crop plants and further optimize light recipes.

Biogeographic differences in plant-soil biota relationships contribute to the exotic range expansion of Verbascum thapsus.

Exotic plant species can evolve adaptations to environmental conditions in the exotic range. Furthermore, soil biota can foster exotic spread in the absence of negative soil pathogen–plant interactions or because of increased positive soil biota–plant feedbacks in the exotic range. Little is known, however, about the evolutionary dimension of plant–soil biota interactions when comparing native and introduced ranges.To assess the role of soil microbes for rapid evolution in plant invasion, we subjected Verbascum thapsus, a species native to Europe, to a reciprocal transplant experiment with soil and seed material originating from Germany (native) and New Zealand (exotic). Soil samples were treated with biocides to distinguish between effects of soil fungi and bacteria. Seedlings from each of five native and exotic populations were transplanted into soil biota communities originating from all populations and subjected to treatments of soil biota reduction: application of (a) fungicide, (b) biocide, (c) a combination of the two, and (d) control.For most of the investigated traits, native populations showed higher performance than exotic populations; there was no effect of soil biota origin. However, plants developed longer leaves and larger rosettes when treated with their respective home soil communities, indicating that native and exotic plant populations differed in their interaction with soil biota origin. The absence of fungi and bacteria resulted in a higher specific root length, suggesting that V. thapsus may compensate the absence of mutualistic microbes by increasing its root–soil surface contact. Synthesis. Introduced plants can evolve adaptations to soil biota in their new distribution range. This demonstrates the importance of biogeographic differences in plant–soil biota relationships and suggests that future studies addressing evolutionary divergence should account for differential effects of soil biota from the home and exotic range on native and exotic populations of successful plant invaders.

Maize expressing the sunflower transcription factor HaHB11 has improved productivity in controlled and field conditions

HaHB11 is a sunflower transcription factor from the homeodomain-leucine zipper I family. Transgenic Arabidopsis plants expressing HaHB11 had larger rosettes and improved seed yield. In this work maize plants from hybrid HiII were transformed with 35S:HaHB11, ZmUBI:HaHB11 and ProHaHB11:HaHB11 and then backcrossed to B73 to obtain a more homozygous inbred phenotype. Transgene expression levels were stable at least during three generations. Greenhouse-grown HaHB11 transgenic lines had larger leaf area and delayed senescence than controls, together with increased total biomass (up to 25%) and seed yield (up to 28%). Field trials conducted with T2 and T4 generations indicated that enhanced leaf area (up to 18%), stem diameter (up to 28%) and total biomass (up to 40%) as well as delayed leaf senescence were maintained among transgenic individuals when upscaling from pots in the greenhouse to communal plants in the field. The T4 field-grown transgenic generation had increased light interception and radiation use efficiency as well as seed yield (43–47% for events driven by the 35S promoter). Results suggest that HaHB11 is a promising tool for crop improvement because differential traits observed in the Arabidopsis model plant were preserved in a crop like maize independently of growth conditions and backcross level.

The cytokinin response factors modulate root and shoot growth and promote leaf senescence in Arabidopsis.

The cytokinin response factors (CRFs) are a group of related AP2/ERF transcription factors that are transcriptionally induced by cytokinin. Here we explore the role of the CRFs in Arabidopsis thaliana growth and development by analyzing lines with decreased and increased CRF function. While single crf mutations have no appreciable phenotypes, disruption of multiple CRFs results in larger rosettes, delayed leaf senescence, a smaller root apical meristem (RAM), reduced primary and lateral root growth, and, in etiolated seedlings, shorter hypocotyls. In contrast, overexpression of CRFs generally results in the opposite phenotypes. The crf1,2,5,6 quadruple mutant is embryo lethal, indicating that CRF function is essential for embryo development. Disruption of the CRFs results in partially insensitivity to cytokinin in a root elongation assay and affects the basal expression of a significant number of cytokinin-regulated genes, including the type-A ARRs, although it does not impair the cytokinin induction of the type-A ARRs. Genes encoding homeobox transcription factors are mis-expressed in the crf1,3,5,6 mutant, including STIMPY/WOX9 that is required for root and shoot apical meristem maintenance roots and which has previously been linked to cytokinin. These results indicate that the CRF transcription factors play important roles in multiple aspects of plant growth and development, in part through a complex interaction with cytokinin signaling.

Rosettes and other white shiny structures in polarized dermoscopy: histological correlate and optical explanation

Rosettes are a specific form of a white shiny structure seen with polarized dermoscopy. The precise morphological correlate and optical explication are not known. To estimate the frequency of rosettes in ex vivo dermoscopy and to find explication and morphologic correlate of this dermoscopic feature. A series of 6108 consecutive skin biopsies were examined with ex vivo dermoscopy and when rosettes were present serial transverse sections with polarization were examined. In this series of 6108 consecutive skin biopsies, rosettes were found on ex vivo dermoscopy in 63 cases. When multiple we observed that they are always oriented at the same angle. Transverse sections with polarization of these lesions proved that smaller rosettes are mainly caused by polarizing horny material in adnexal openings, and larger rosettes by concentric perifollicular fibrosis. Rosettes are an optical effect of crossed polarization by concentric fibrosis or horny material and hence are not lesion-specific.

Pinguicula species (Lentibulariaceae) from the southeastern United States: observations of different habitats in Florida

During field observations mid to end of February 2003 different habitats of Pinguicula caerulea, P. ionantha, P. lutea, P. planifolia and P. pumila native to Florida were visited. A large variation of flower forms and coloration is described. At one location in Hernando county, much larger rosettes of P. pumila compared to normal sized plants were found and a new flower coloration is described.

Impact of the rosette crown weevil Trichosirocalus briesei on the growth and reproduction of Onopordum thistles

Summary Several European thistle species of the genus Onopordum have become naturalized in Australia and are considered serious pasture weeds, leading to a project aimed at their biological control. The population structure of a potential control agent, the crown weevil Trichosirocalus briesei, a newly described member of the Trichosirocalus horridus species group, was studied under natural conditions on its Onopordum spp. host‐plants in northern Spain. Trichosirocalus briesei was found to be the most abundant of three species of crown‐feeding insect utilizing these plants. Adults of this univoltine weevil began to lay eggs in mid‐autumn and larval population sizes increased over winter until pupation in early spring. The spatial distribution of the immobile larvae was not random, indicating that females were selective in their oviposition behaviour. Field data suggested that plants in dense patches were attacked less frequently, and larger rosettes were preferred for egg‐laying. A preliminary cage experiment indicated that feeding by T. briesei could damage Onopordum spp. thistles. A second experiment using plants in individual cages showed a clear relationship between the density of the weevils and the reduction in several growth parameters and seed production. At the highest densities, larval feeding could kill Onopordum rosettes before they produced flowering stems. These results indicated that T. briesei has the potential to contribute to the biological control of Onopordum spp. thistles in Australia. Following host‐specificity testing, the weevil was released in 1997.

Reduced fecundity and offspring performance in small populations of the declining grassland plantsPrimula verisandGentiana lutea

Summary1 We studied reproduction and offspring performance in relation to population size in the declining self‐incompatible perennialsPrimula verisandGentiana lutea. In both species, reproduction was strongly reduced in small populations, where plants produced fewer seeds per fruit and per plant. Total seed mass per plant was higher in large populations, but individual seeds were smaller, indicating a trade‐off between seed number and size. Reproduction was depressed most strongly in populations consisting of less thanc.200 (P. veris) andc.500 plants (G. lutea), respectively.2 The inclusion of plant size (an integrated measure of habitat quality) in the statistical models did not change the relationships between fecundity and population size. Pollen limitation or inbreeding depression in small populations are therefore more likely explanations for these patterns than is habitat quality.3 Germination rate and survival of seedlings in a common environment was not related to population size in either species, althoughP. verisdeveloped into larger rosettes when seeds were derived from large populations. This suggests that inbreeding depression occurs in small populations ofP. veris.4 In a factorial fertilizer‐by‐competition experiment withP. veris, offspring from larger populations grew significantly larger and responded more strongly to fertilizer. For this declining species genetic deterioration as a result of habitat fragmentation may therefore aggravate the effects of environmental changes such as habitat eutrophication.5 Our results suggest that small populations may face an increased short‐term risk of extinction because of reduced reproduction, and an increased long‐term risk because they are less able to respond to environmental changes.

Plasmodium falciparum erythrocyte rosetting is mediated by promiscuous lectin-like interactions.

Herein we describe an assay that was developed to quantitate the binding of normal red blood cells (RBC), labeled with carboxy fluorescein diacetate (C-FDA), to rosetting Plasmodium falciparum-infected RBC. The binding of RBC obtained from various animal species or humans to different strains or clones of rosetting P. falciparum-infected RBC was studied. A strain-specific preference of rosetting was observed for either blood group A/AB or B/AB RBC for all parasites tested. The higher affinity of rosette binding of blood group A, B, or AB vs. O RBC was reflected in larger rosettes when a given parasite was grown in RBC of the preferred blood group. The small size of the rosettes formed when P. falciparum was grown in blood group O RBC may be the in vitro correlate of the relative protection against cerebral malaria afforded by belonging to blood group O rather than to blood group A or B. Rosettes of a blood group A-preferring parasite could be completely disrupted by heparin only when grown in blood group O or B RBC, but not when grown in blood group A RBC. Similarly, the rosettes of a blood group B-preferring parasite could be more easily disrupted by heparin when grown in blood group O or A RBC than when grown in blood group B RBC. Several different saccharides inhibited rosetting of group O RBC, including two monosaccharides that are basic components of heparin. The rosetting of the same parasites grown in blood group A or B RBC was less sensitive to heparin and was specifically inhibited only by the terminal mono- and trisaccharides of the A and the B blood group antigens, the H disaccharide, and fucose. Our results suggest that rosetting is mediated by multiple lectin-like interactions, the usage of which rely on the parasite phenotype and whether the receptors are present on the host cell or not.

Gypsum Nucleation and Crystal Morphology in Analog Saline Terrestrial Environments

ABSTRACT Gypsum crystals were grown in experimental conditions analogous to saline terrestrial environments within bentonite clay gels by diffusion control at three different temperatures, four brine salinities, and four tannic acid (a model terrestrial humic substance) concentrations. The resulting crystals correspond to natural gypsum formed in terrestrial environments. Prismatic gypsum typically grew at both high and low temperatures in the absence of the organic additive. With increasing organic acid concentrations, the prismatic crystals progressively became flattened perpendicular to [001], and two temperature-dependent trends developed. At low temperatures, a hemi-bipyramidal habit dominated by 1111 faces developed, whereas the lenticular e103 dominated habit forme at higher temperatures. With progressively greater concentrations of organic material a(100) penetration twinning developed, secondary complex nucleation occurred near the twin interfaces, and finally, rosette and rosette-like aggregates formed. Higher temperatures generally favored better-formed and larger rosettes. The presence of 5% and 15% NaCl greatly decreased nucleation density and resulted in larger single crystals and crystal aggregates. The a(100) penetation twins appear to be diagnostic of gypsum growth in natural terrestrial sediments at a pH greater than 7.5.