Petiole Bases Research Articles

Ecotypical characterization of genetic variation of beech provenances from south-eastern Europe based on the morphometric characteristics of leaves

The research was conducted on a provenance test of beech established in the Educational-research centre ?Majdanpecka domena? - Faculty of Forestry, University of Belgrade. This paper presents the results of an analysis of the morphometric characteristics of leaves, at the level of 10 provenances in the juvenile developmental stage, originating from South-Eastern Europe. Herbaria material was used to measure the following parameters: leaf length, leaf width, petiole length, leaf base width at 1 cm (from petiole base), the number of veins -on the left, the number of veins - on the right, and distance between the 3rd and 4th vein - on the left. Based on research results, it can be concluded that the obtained differences between the mean values of all measured foliar characteristics of the analyzed provenances are statistically significant, and that there is significant correlation between the length and width of leaves and the Ellenberg?s quotient (EQ). The relationship between the adaptive traits of beech from different provenances and ecological parameters of their seed source stands indicates genetic differentiation of beech, as a consequence of the population adaptation to local environmental conditions. Therefore, in the future, ecological criteria must be a priority in the selection of seed sources and planting materials, with special consideration of the global climate change.

Generic status of <i>Quisqualis</i> (Combretaceae), with notes on the taxonomy and distribution of <i>Q. parviflora</i>

The taxonomic status of Quisqualis L., a genus closely related to and sometimes considered congeneric with Combretum Loefl., is discussed. The genus Quisqualis is maintained to accommodate selected African, Indian, Asian and Malesian species (including Q. indica L. and Q. parviflora Sond.). Diagnostic characters for Quisqualis include: leaves with abundant subepidermal crystalliferous idioblasts, each containing a large druse of calcium oxalate; leaves, stems and flowers with stalked glands but no scales; persistent petiole bases that develop into curved spines; petals well developed; hypanthium tubular or cylindrical, usually longer than 20 mm; stamens and style not or scarcely exserted; style adnate to hypanthium for more than half its length. Quisqualis shares a number of morphological similarities with Combretum Loefl. subgen. Cacoucia (Aubl.) Exell Stace sect. Poivrea (Comm. ex DC.) G.Don. Some species of Combretaceae from West, West Central and East Africa have the style adnate to the upper hypanthium and display features reminiscent of both Quisqualis and Combretum. These species also have characters of their own and in the past were placed in different sections under Combretum. It is suggested that at least some of these species may be best classified in genera distinct from Combretum and Quisqualis, one of which is Campylogyne Hemsley. Combretum s.str. is defined on the basis of a combination of characters and includes species of which the upper hypanthium is variable in shape, but when tubular or cylindrical, then always shorter than 20 mm. Other diagnostic characters include: stamens exserted well beyond petals; style exserted and free, but when shortly adnate to upper hypanthium (only at the base or for a short distance), then stamens long-exserted. It is suggested that different pollination strategies have developed independently in the Combretum–Quisqualis clade, resulting in convergent morphological trends in floral morphology. These homoplasious similarities in floral morphology are at the root of the difficulties experienced to demarcate genera. An alternative classification is provided for those preferring to include the southern African Quisqualis parviflora under Combretum s. l. For this purpose, a new combination and name, Combretum sylvicola O.Maurin is provided. Quisqualis parviflora is confined to the Eastern Cape and KwaZulu-Natal coastal regions and does not extend beyond this area as has been claimed by some. A comparative table to differentiate among four groups in Quisqualis and Combretum in Africa, as well as a photo of a herbarium specimen and a distribution map of Quisqualis parviflora, are provided.

First record of paternal care in the family Stygnidae (Opiliones: Laniatores)

Abstract Two cases of paternal care are described for species of the genus Stenostygnellus (Stygnidae), S. flavolimbatus Roewer 1913 and S. aff. flavolimbatus, both from Venezuela. Males of both species guard multiple clutches containing a large number of eggs, which are laid under rotting logs (S. flavolimbatus) or in the base of palm petioles (S. aff. flavolimbatus). These records probably represent a new and independently evolved case of paternal care in harvestmen.

Modified basal elements in Dicroidium fronds (Corystospermales)

We describe a distinct type of heteromorphic basal frond element in four species of the seed-fern foliage Dicroidium, based principally on a survey of plant-fossil collections from the Triassic of Antarctica. The modified foliar elements are conspicuously enlarged, and arise at wide angles and obliquely to the frond plane. Those of D. elongatum and D. crassinerve arise more or less directly from the petiole base; they are overall wedge- to fan-shaped with variably dissected margins and fan-shaped venation. Those of D. odontopteroides and D. dubium are (sub)circular, reniform, or obcordate, also with fan-shaped venation, or divided into narrow tongue-shaped segments with alethopteroid venation. The basal elements of some species commonly occur isolated. By analogy with comparable structures among other plant groups, we conclude that the basal elements represent a distinct, early leaf-ontogenetic architectural unit in the frond bauplan of Dicroidium, which provides an important additional character for a more accurate delimitation and systematic classification. Similar structures also occur on the corystosperm reproductive organs Umkomasia and Pteruchus. It appears that the basal elements were particularly common among high-latitude Dicroidium trees that flourished in a strongly seasonal light regime. We hypothesize that the modified elements may represent the initial foliar outgrowths during spring flush, ensuring a rapid re-initiation of sap flow and metabolic activity after the extended period of winter dormancy.

Morphological variability in 17 wild elephant foot yam (Amorphophallus paeoniifolius) collections from southwest India

Amorphophallus paeoniifolius (Dennst.) Nicolson is a tuberous herb occurring in the wild and cultivated state. Vegetative morphological characters were studied at full foliage stage in 17 accessions of A. paeoniifolius which include two cultivars, 15 wild accessions and a related species, A. dubius Blume. The first principal component (PC) accounted for 42.32% of phenotypic variance followed by second for another 18.38%. Major traits that accounted for more variability in both PC1 and PC2 include offset shape, cormel weight per corm, corm fresh weight, petiole surface pattern and canopy spread. The unweighted pair- group method with mathematical averaging (UPGMA) clustering method revealed three principal clusters which separated all the accessions between Euclidean distances of 0.3–1.6. Both cluster analysis and principal co-ordinate analysis revealed T10, a morphotype of A. paeoniifolius var. campanulatus (Decne.) Sivad. cultivated in Tamil Nadu and P19 accession of A. paeoniifolius var. paeoniifolius from Karnataka as morphologically distinct, which needs further validation on the basis of floral characters or molecular markers and G3 from Gujarat as an immediate ancestor of cultivated elephant foot yam. The genotypic (GCV) and phenotypic (PCV) coefficients of variation, broad sense heritability (h2B) and genetic advance (GA) as a percent of the mean assessed for 18 accessions revealed high heritability estimates. A highly significant (P < 0.01) correlation coefficient between circumference of petiole base and corm diameter, corm height, corm weight, east west spread and north south spread suggests that circumference of petiole and canopy spread are indicators to corm weight and size.

Indirect organogenesis from leaf explants of Eucalyptus benthamii x Eucalyptus dunniiand shoot multiplication

Background In Brazil, especially in the Southern region, stresses caused by cold and eventual frost are those that exert the most negative effect on the productivity of Eucalyptus spp. The genetic transformation techniques may contribute to forestry improvement programs in order to obtain genotypes expressing new interesting characteristics. They allow shortening the long breeding cycles and avoiding manipulation of adult trees. Their efficiency depends on establishment of regeneration procedures that allow the development of shoots from the transformed tissues. E. benthamiix E. dunnii hybrids have shown superiority to their parents concerning growth and frost tolerance [1], but no information about their in vitro organogenesis has been reported in the literature. The objective of this study was to evaluate the effect of some factors of culture medium on indirect organogenesis and shoot multiplication of anE. benthammi x E. dunnii clone. Methods In vitroestablished shoots,provided by EMBRAPA-Florestas (Colombo, PR, Brazil), were used as explant source. Cultures were maintained under white fluorescent tubes providing a photon flux density (PFD) of approximately 20 μmol m -2 s -1 , a 16-h photoperiod and a temperature of 25±2 °C. The cultures were performed in glass flasks containing 25 mL MS [2] medium supplemented with 1.11µM BA and sealed with rigid polypropylene caps. For the indirect organogenesis, leaves were excised from shoots at the petiole base, split into two halves and inoculated in culture media. The cultures were done in Petri dishes kept in a growth chamber in the dark throughout the experiment. The statistical design was performed in a factorial scheme (2:2:2) and a comparison was done between two culture media (MS-N/2, with half concentration of potassium and ammonium nitrates, and JADS [3] with 0.1 µM NAA, with and without PVP-40 (250 mg L -1 ) and two TDZ concentrations (0.1 and 0.5 µM). After 70 days, the percentages of explants forming callus, oxidized explants, explants producing anthocyanin, explants forming buds and shoots, and the number of shoots per explant were evaluated. For the multiplication test, the statistical design was performed in a factorial scheme (3:2) with three culture media (MS, WPM [4] and JADS, with 1.11µM BA) and two subcultures (28 and 56 days after the initial culture period). The analyzed variables for each subculture were: percentage of oxidation, of explants showing chlorosis, fresh weight and number of shoots. Results and discussion Regarding the oxidation, the higher rates (100%) were observed on JADS medium in presence or absence of PVP-40 and on MS-N/2 medium (68.3%) in presence of PVP-40. However, the JADS medium showed the highest percentage of callus formation (83.3%). In MS-N/2 medium the highest percentage of callus formation (55%) was found in the presence of PVP-40 and 0.5µM

Bud and Root Rot of Windmill Palm (Trachycarpus fortunei) Caused by Simultaneous Infections of Phytophthora palmivora and P. nicotianae in Sicily.

In June 2009 in a commercial nursery in eastern Sicily (Italy), 3-year-old potted windmill palms (Trachycarpus fortunei (Hooker) H. Wendl.) showed a decline in growth, wilt, droop, and basal rot of the youngest leaves. The rot progressed inward and killed the bud. Initially, older leaves remained green but eventually the entire plant collapsed. Root rot was consistently associated with aboveground symptoms. Two Phytophthora species were consistently isolated from the petiole base, heart, roots, and rhizosphere soil of symptomatic plants on a selective medium (2) and occasionally recovered from roots and rhizosphere soil of asymptomatic plants. Pure cultures were obtained by single-hypha transfers and the two species were identified on the basis of morphological and molecular characters as Phytophthora palmivora and P. nicotianae. Both species were recovered from all symptomatic plants. From multiple tissue samples per plant, we recovered either or both species. On potato dextrose agar (PDA), P. palmivora isolates grew between 10 and 35°C, with the optimum at 27°C. On V8 juice agar, they produced elliptical to ovoid, papillate, caducous sporangia (32 to 78 × 23 to 39 μm) with a mean length/breadth (l/b) ratio of 1.8:1 and a short pedicel (mean pedicel length = 5 μm). Isolates of P. nicotianae produced arachnoid colonies on PDA, grew at 37°C but did not grow at 40°C. Sporangia (29 to 55 × 23 to 45 μm) were spherical to ovoid (l/b ratio 1.3:1), papillate and often bipapillate, and noncaducous. Isolates of both species produced amphigynous antheridia and oogonia only when paired with reference isolates of P. nicotianae of the A2 mating type. The internal transcribed spacer (ITS) region of rDNA of two isolates of P. palmivora (IMI 398987 and IMI 398988) and an isolate of P. nicotianae (IMI 398989) from T. fortunei was amplified with primers ITS6/ITS4 and sequenced (1). Blast analysis of the sequences of isolates IMI 398987 and IMI 398988 (GenBank Accession Nos. HQ596556 and HQ596558) showed 99% homology with the sequence of two reference isolates of P. palmivora (GQ398157.1 and GU258862), while the sequence of isolate IMI 398989 (HQ596557) showed 99% homology with a reference isolate of P. nicotianae (EU331089.1). Pathogenicity of isolates IMI 398987 and IMI 398989 was proved by inoculating separately each isolate on 1-year-old potted plants of T. fortunei (10 plants per isolate). A zoospores suspension (2 × 104 zoospores/ml) was pipetted onto the petiole base of the three central leaves (200 μl per leaf) of each plant. Sterile water was used for control plants. All plants were incubated at 25 ± 2°C with 100% humidity for 48 h and then maintained in a greenhouse at 24 to 28°C. Within 3 weeks, all inoculated plants showed symptoms of bud rot. Control plants remained healthy. P. palmivora and P. nicotianae were reisolated only from inoculated plants. Bud rot of palms caused by P. palmivora was reported previously in Italy (3). However, to our knowledge, this is the first report of simultaneous infections of P. palmivora and P. nicotianae as causal agents of this disease. Outbreak of bud rot may have been favored by overhead sprinkler irrigation. The recovery of P. palmivora and P. nicotianae from rhizosphere soil and roots of asymptomatic plants suggests infested soil was the primary inoculum source.

Characterization of constricted fruit (ctf) mutant uncovers a role for AtMYB117/LOF1 in ovule and fruit development in Arabidopsis thaliana.

Pistil and fruit morphogenesis is the result of a complex gene network that is not yet fully understood. A search for novel genes is needed to make a more comprehensive model of pistil and fruit development. Screening for mutants with alterations in fruit morphology generated by an activation tagging strategy resulted in the isolation of the ctf (constricted fruit) mutant. It is characterized by a) small and wrinkled fruits, with an enlarged replum, an amorphous structure of the septum and an irregular distribution of ovules and seeds; b) ectopic carpelloid structures in sepals bearing ovule-like structures and c) dwarf plants with curled rosette leaves. The overexpressed gene in ctf was AtMYB117, also named LOF1 (LATERAL ORGAN FUSION1). AtMYB117/LOF1 transcripts were localized in boundary regions of the vegetative shoot apical meristem and leaf primordia and in a group of cells in the adaxial base of petioles and bracts. Transcripts were also detected in the boundaries between each of the four floral whorls and during pistil development in the inner of the medial ridges, the placenta, the base of the ovule primordia, the epidermis of the developing septum and the outer cell layers of the ovule funiculi. Analysis of changes of expression of pistil-related genes in the ctf mutant showed an enhancement of SHATTERPROOF1 (SHP1) and SHP2 expression. All these results suggest that AtMYB117/LOF1 is recruited by a variety of developmental programs for the establishment of boundary regions, including the development of floral organs and the initiation of ovule outgrowth.

Glyphosate reduces urediniospore development and Puccinia psidii disease severity on Eucalyptus grandis

Recent studies have shown the effects of glyphosate drift on decreasing rust intensity on Eucalyptus grandis plants. However, the effects of the herbicide on Puccinia psidii initial development are unknown. In this study the systemic action of glyphosate on rust severity was evaluated on Eucalyptus plants maintained under greenhouse conditions. Urediniospore germination and apressorium formation on detached leaves and on water agar medium, previously treated with glyphosate, were also evaluated. Rust severity and the number of urediniospores per leaf area were significantly reduced with increasing glyphosate doses, even on branches not directly treated with the herbicide, indicating a systemic effect of glyphosate on pathogen development. Similarly, higher glyphosate doses also reduced germination and apressorium formation on detached Eucalyptus leaves, regardless of the direct application of the product on the leaf limb or on the petiole base. Puccinia psidii urediniospore germination in water agar medium also decreased with increasing herbicide doses. Reductions in germination and apressorium formation of P. psidii urediniospores with increasing glyphosate dose indicate that a lower severity and intensity of the disease may perhaps be due to blockage of the shikimic acid pathway in the fungal metabolic system.

A new species of Ashicaulis (Osmundaceae) from the Mesozoic of China: A close relative of living Osmunda claystoniana L.

A new species, Ashicaulis claytoniites, is established based on two specimens collected from Middle Jurassic sediments near Duanmugou, Changgao Village, Beipiao County, west Liaoning Province of China. The specimens represent stems surrounded by a mantle of stipular petiole bases and adventitious roots. The stems, 6–8 mm in diameter, consist of an ectophloic dictyoxylic stele and a two-layered cortex containing 31–37 leaf traces. When departing from the stele, the leaf traces are a flattened C-shaped, with an endarch protoxylem which bifurcates at the base of petiole. The sclerenchyma ring is heterogeneous with an arch of stipular petiole base at the base that are divided into two lateral strands at the top. A big mass heterogeneous sclerenchyma is present in the stipular wing. In the ectophloic dictyoxylic stele and arrangement of sclerenchyma of the petiole base, Ashicaulis claytoniites shares smiliarities with Osmunda claytoniana L. of Osmunda subg. Osmunda, but not with other subgenera of Osmunda subg. Plenasium, Osmundastrum, the genera Todea, and Leptopteris in the extant Osmundaceae. According to the similarities of these features, a distinct relationship is suggested between Ashicaulis claytoniites and Osmunda claytoniana. The new species could be a close Mesozoic relative of O. claytoniana. This new species shows the similar arrangement of the sclerenchyma of the petiole base with the Mesozoic species, Millerocaulis preosmunda, suggesting that the morphogenera Millerocaulis and Ashicaulis are closely related, and the new species may be a transitional form between the Mesozoic M. preosmunda and Osmunda claytoniana of extant subgenus Osmunda.

Vegetative and Reproductive Morphology of an Extinct Early Cretaceous Member of Platanaceae from the Braun’s Ranch Locality, Kansas, U.S.A.

Abstract Early Cretaceous platanoid species are presented, based on observations of isolated organs from the Braun Ranch locality, Kansas, and the Yankee Hill I locality, Nebraska. Approximately 500 leaf specimens and 238 infructescence specimens have been studied in detail. The reproductive axis may contain up to 37 sessile, globose infructescences. Fruits are small achenes and lack dispersal hairs. The leaves are typically three-lobed, with basal or suprabasal actinodromous or palinactinodromous venation. Secondary venation is dominantly craspedodromous. Typically, one secondary vein extends into each tooth and is accompanied by tertiary or higher-order veins, which form a series of ascending loops. Tertiary veins are percurrent, with those in the axils of primary-primary and primary-secondary veins forming a V-shaped pattern. Conically inflated petiole bases are hollow and enclose axillary buds. Stipules are triangular and small and are observed only on immature leaves. The repeated and common co-occur...

Infection and colonization of strawberry by Gnomonia fragariae strain expressing green fluorescent protein

Gnomonia fragariae is a poorly studied ascomycete, which was recently demonstrated to be a cause of severe root rot and petiole blight of strawberry. The pathogen was genetically transformed with the GFP as a vital marker and hygromycin resistance gene. Several stable transformants were obtained, which did not differ in their phenotype from the wild type isolate. Using one of the GFP-tagged isolates the infection process and colonization of roots and petioles of host plant by the pathogen were studied. Fluorescence microscopy examinations of the inoculated plants at different time points showed that plant infection occurs 24 h after inoculation and intensively continues during first 3 days. The specific penetration sites on epidermal cells and preferences in colonization for certain root and petiole tissues were observed. The pathogen intensively colonized and destroyed cortex of roots and petioles and spread rapidly longitudinally within intercellular spaces. The petioles were colonized by the hyphae, which grew mostly in the intracellular spaces of the cortical cells while in the roots the intracellular growth of hyphae occurred only in the later stages of infection. The fungus was also capable to infect the vascular tissues of petioles although these were not the primary tissues colonized by the pathogen. The mature ascomata were formed on the infected petiole bases several weeks after the inoculation. This study presents a genetic transformation method for Gnomonia fragariae and it demonstrates details on infection process and colonization of root, crown and petiole tissues of strawberry by the pathogen.

Oligocene ferns from the Rancahué Formation (Aluminé, Neuquén, Argentina): Cuyenopteris patagoniensis nov. gen., nov. sp. (Polypodiales: Blechnaceae/Dryopteridaceae) and Alsophilocaulis calveloi Menéndez emend. Vera (Cyatheales: Cyatheaceae)

The study of abundant permineralized fern remains collected in the Oligocene Rancahué Formation (Neuquén Province, Argentina) allowed the identification of two different taxa. The name Cuyenopteris patagoniensis nov. gen., nov. sp. is proposed for several stems and fronds characterized by the presence of caulinar dictyosteles with root gaps, producing C-shaped leaf traces composed by two hippocampiform bundles flanked by eight to ten small round bundles, half of them diverging from cauline meristeles and the rest from the hippocampiform bundles. The presence of these features, along with frond bases with adaxial grooves and a pair of pneumatophores, suggest affinities with the Blechnaceae or Dryopteridaceae. The second identified taxon is Alsophilocaulis calveloi Menéndez. Based on features observed in these new materials, including characteristics of the mantle of adventitious roots and anatomy of the petiole bases, an emended diagnosis for this latter species is proposed.

Transcriptional regulation of aquaporins in accessions of Arabidopsis in response to drought stress

Aquaporins facilitate water transport over cellular membranes, and are therefore believed to play an important role in water homeostasis. In higher plants aquaporin-like proteins, also called major intrinsic proteins (MIPs), are divided into five subfamilies. We have previously shown that MIP transcription in Arabidopsis thaliana is generally downregulated in leaves upon drought stress, apart from two members of the plasma membrane intrinsic protein (PIP) subfamily, AtPIP1;4 and AtPIP2;5, which are upregulated. In order to assess whether this regulation is general or accession-specific we monitored the gene expression of all PIPs in five Arabidopsis accessions. The overall drought regulation of PIPs was well conserved for all five accessions tested, suggesting a general and fundamental physiological role of this drought response. In addition, significant differences among accessions were identified for transcripts of three PIP genes. Principal component analysis showed that most of the PIP transcriptional variation during drought stress could be explained by one variable linked to leaf water content. Promoter-GUS constructs of AtPIP1;4, AtPIP2;5 and also AtPIP2;6, which is unresponsive to drought stress, had distinct expression patterns concentrated in the base of the leaf petioles and parts of the flowers. The presence of drought stress response elements within the 1.6-kb promoter regions of AtPIP1;4 and AtPIP2;5 was demonstrated by comparing transcription of the promoter reporter construct and the endogenous gene upon drought stress. Analysis by ATTED-II and other web-based bioinformatical tools showed that several of the MIPs downregulated upon drought are strongly co-expressed, whereas AtPIP1;4, AtPIP2;5 and AtPIP2;6 are not co-expressed.

FLOWER BUD FORMATION IN SHORT-DAY STRAWBERRY CULTIVAR UNDER NON-PHOTO INDUCTIVE CONDITIONS

A scheme for producing short-day type strawberry cultivars that initiate flowers under long-day photoperiod was used to investigate the flower bud induction. When runner tips of short-day type 'Carmine' were started as plug plants in early July and field planted 1 September 86% of transplants flowered by mid October. When the July-plugged transplants were retained in tray flats at high plant density during July and August the leaves formed a full canopy or high leaf area index above the plant crowns and the crown near the base of leaf petioles was completely in the shade. A spectral analysis showed that wavelengths less than 700 nm did not reach the crown because of chlorophyll absorbance. Illuminating the crown for 16 h·day -1 for 4 weeks in August with 662 nm light decreased transplants that flowered by mid October. The results suggest that fall-flowering transplants of short-day strawberries were produced by rooting runner tips in early July and having a plant canopy that alters the quality of light that illuminates the crown.

First Report of Phytophthora nicotianae on German Statice in Bulgaria.

In June of 2008, rapidly developing necrotic symptoms were observed on 2-month-old seedlings of German statice (Goniolimon tataricum, synonym Limonium tataricum) that were started from field-collected seeds and grown in plastic pots under greenhouse conditions in the region of Plovdiv, Bulgaria. Initial symptoms were slight yellowing and wilting of single, lower leaves. Subsequently, necrosis affected several petioles and stem bases, which led to complete plant collapse. Isolations from symptomatic petioles, stem bases, and main roots were performed on potato dextrose agar (PDA) and corn meal agar (CMA). When incubated at 24 to 25°C, white, round, arachnoid colonies with fluffy aerial mycelium developed on the PDA isolation plates, whereas the mycelium was less dense on CMA. Sporangia were formed sporadically when cultures were maintained on V8 medium and formed abundantly in nonsterile soil extract after 1 to 2 days of incubation at 20°C. Sporangia were noncaducous, ovoid to spherical, semipapillate (sometimes with two papilla), measured 47.5 to 65 μm (average 53.6 μm) × 35 to 53.5 μm (average 42.9 μm) with an average length/width ratio of 1.25:1. Terminal and intercalary chlamydospores (25 to 48 μm in diameter; average 37 μm) and hyphal swellings were also present. Maximum temperature for growth was 36°C. Pathogenicity of the presumable Phytophthora nicotianae (1) isolate was proved by placing 5-mm-diameter mycelial plugs of 7-day-old cultures grown on V8 medium onto the petiole bases of three 3-month-old G. tataricum plantlets. Each inoculation site was first wiped with 70% ethanol and then scalpel wounded. Sterile V8 plugs were used as controls and all inoculated sites were wrapped with Parafilm. The plantlets were incubated at room temperature (22 to 26°C) and the first necrotic lesions around the mycelial plugs appeared 5 to 7 days after inoculation. Plantlets collapsed approximately 2 weeks later. Additionally, three plantlets were inoculated under the same conditions by watering their stem bases with a 15-ml suspension of mycelium and spores obtained by washing 2-week-old V8 cultures with sterile distilled water. Within a 4-week period, the plantlets died due to a stem base and petiole necrosis. Simultaneously, the pathogen was reisolated from all inoculated samples but not from any control plants that were symptomless. The internal transcribed spacer (ITS) region of mycelial DNA was amplified (ITS6 and ITS4 primers) and the PCR product was sequenced (GenBank Accession No. FJ410333). BLAST analysis showed 100% homology with P. nicotianae. To our knowledge, this is the first report of P. nicotianae on G. tataricum in Bulgaria and one of the few reports from Europe of Phytophthora invasion of related Limonium species (2,3).

Morphologic variation in the USDA/ARS rhubarb germplasm collection

Rhubarb includes approximately 60 species in the genusRheum. It has been utilized for thousands of years for medicinal purposes, but only recently identified for its culinary use. In the mid 1700s, edible petioles were discovered on seedlings from rhubarb species. Hundreds of cultivars have since been identified for a wide range of uses from tarts to wine. Unfortunately, propagation by seed and irregular naming has resulted in a plethora of similarly named cultivars and multitude of phenotypes. Fifteen morphological characters were evaluated to differentiate rhubarb cultivars in the USDA, ARSRheumcollection in Palmer, Alaska. Two years of morphological data, focusing on horticultural characteristics indicated variation between the years. To improve cultivar resolution, the results suggest using 1 year's data instead of combining data from different years. The mean °Brix observed was 3.8, with a range from 2.2 to 6.1. Flesh colour and basal skin colour were poorly correlated (R2 = 0.462); overall skin colour was more red at the base than in the middle of the petiole. Rhubarb character categories, in particular petiole number and petiole base thickness, need to be modified to better anticipate the range of expected values, and thereby contribute improved reproducibility and reliability to separate cultivars based on morphological characters.

Révision synoptique du genreLastreopsisChing (Dryopteridaceae) à Madagascar

Rakotondrainibe F. & Tronchet F. 2009. — Révision synoptique du genre Lastreopsis Ching (Dryopteridaceae) à Madagascar. Adansonia, sér. 3, 31 (1): 7-24.Synoptic revision of the genus Lastreopsis Ching (Dryopteridaceae) in Madagascar. This paper presents a synoptic revision of the genus Lastreopsis Ching (Dryopteridaceae) in Madagascar. A new identification key is presented, along with new distribution maps. The presence of L. barteriana (Hook.) Tardieu, an African species, is indicated for the first time. Three new species are described: 1) L. coriaceosquamata Rakotondr. resembles L. boivinii (Baker) Tardieu but can be distinguished by differences in the morphology of the scales present on its rhizome and petiole base, which is brownish black, coriaceous, flat, and appressed; 2) L. manongarivensis Rakotondr. can be easily distinguished by its upright rhizome covered with red, membraneous scales; and 3) L. fidelei Rakotondr. has median sori similar to those of L. currorii (Mett. ex Kuhn) Tindale but can be distinguished by having non-gemmiferous fronds, median pinnae that are 1-pinnate-pinnatifid and indusia with entire margins. Two African species, L. currorii and L. subsimilis (Hook.) Tindale, have been cited in the literature as occurring in Madagascar, but the material from there differs clearly from the type specimens, and these taxa are no longer thought to occur in Madagascar. The type of Lastreopsis hornei (Baker) Tindale from the Seychelles, is fragmentary, and this name is treated as “insufficiently known”. Finally, a lectotype is designated for Nephrodium granulosum Baker, a synonym of L. boivinii.

Developmental plasticity and biomechanics of treelets and lianas in Manihot aff. quinquepartita (Euphorbiaceae): a branch-angle climber of French Guiana.

Most tropical lianas have specialized organs of attachment such as twining stems, hooks or tendrils but some do not. Many climbers also have an early self-supporting phase of growth and in some species this can produce treelet-sized individuals. This study focuses on how a liana can climb without specialized attachment organs and how biomechanical properties of the stem are modulated between self-supporting treelets and canopy-climbing lianas. Biomechanics and stem development were investigated in self-supporting to climbing individuals of Manihot aff. quinquepartita (Euphorbiaceae) from tropical rain forest at Saül, central French Guiana. Bending tests were carried out close to the site of growth. Mechanical properties, including Young's elastic modulus, were observed with reference to habit type and changes in stem anatomy during development. This liana species can show a remarkably long phase of self-supporting growth as treelets with stiff, juvenile wood characterizing the branches and main stem. During the early phase of climbing, stiff but unstable stem segments are loosely held in a vertical position to host plants via petiole bases. The stiffest stems--those having the highest values of Young's modulus measured in bending--belonged to young, leaning and climbing stems. Only when climbing stems are securely anchored into the surrounding vegetation by a system of wide-angled branches, does the plant develop highly flexible stem properties. As in many specialized lianas, the change in stiffness is linked to the development of wood with numerous large vessels and thin-walled fibres. Some angiosperms can develop highly effective climbing behaviour and specialized flexible stems without highly specialized organs of attachment. This is linked to a high degree of developmental plasticity in early stages of growth. Young individuals in either open or closed marginal forest conditions can grow as substantial treelets or as leaning/climbing plants, depending on the availability of host supports. The species of liana studied differs both in terms of development and biomechanics from many other lianas that climb via twining, tendrils or other specialized attachment organs.

Auritifolia gen. nov., Probable Seed Plant Foliage with Comioid Affinities from the Early Permian of Texas, U.S.A.

Auritifolia waggoneri gen. et sp. nov. has compound leaves and is possibly a peltasperm, with venation similar to Comia Zalessky. The frond is once pinnate, >40 cm in length, with a short petiole, subopposite pinnae, increasing in size distally, terminating in two elongate pinnae. The petiole base is swollen. Fronds probably abscised upon senescence. Venation is three ordered, each higher order of progressively smaller diameter. Pinna midveins arise from the main rachis and give rise to secondary veins. Two types of tertiary veins are present. One type arises from the secondaries and forms fascicles; the other type is interfascicular and arises directly from pinna midveins. All tertiaries are of the same diameter. Tertiary veins dichotomize, anastomose, and may terminate in blind endings, so not all extend to the laminar margin. Laminae are amphistomatic. Monocyclic stoma are surrounded by five to six subsidiary cells. Epidermis and palisade parenchyma are uniseriate. Auritifolia is most similar to Comia ...