A brief evolutionary excursion comes to an end: the genetic relationship of British species of Gentianella sect. Gentianella (Gentianaceae)

 There is much taxonomic confusion in the genus Gentianella section Gentianella, five species of which are found in Britain. Gentianella anglica is a British endemic restricted in its distribution to the chalk downland of southern England. It is considered to be threatened because of habitat loss, and due to hybridisation with the closely related, widely distributed G. amarella. The Red Data Book species, G. uliginosa, shares morphological similarities with the other two species but has a very restricted distribution. Individual plants from populations across the range of these three species were analysed using AFLPs and universal cpSSRs to determine the degree of genetic variability within and between them, and to look for evidence of hybridisation. Samples of the two other Gentianella section Gentianella species found in Britain, G. campestris and G. germanica, were also included in the study. The analysis of chloroplast SSRs was not informative for G. anglica, G. amarella and G. uliginosa, while G. campestris and G. germanica differed from each other and the other three species at a single locus. Principal co-ordinate analysis of the AFLP data revealed only three distinct groups: one group contained G. campestris samples, another contained all samples of G. germanica, and a third contained all individuals from the other three species. In mixed populations of G. anglica and G. amarella, individuals of the two species were genetically more similar to each other than they were to individuals of the same species from other populations. It is proposed that G. anglica may be an early flowering form of G. amarella that has been created and maintained as a consequence of former grassland management practices. Received May 20, 2002; accepted October 28, 2002 Published online: March 31, 2003     

Seasonal differentiation — a conservative reproductive barrier in two grasslandGentianella (Gentianaceae) species

18 populations of the grassland biennialsGentianella amarella andG. campestris were cultivated to clarify the genetical vs. environmental components of the flowering phenology, and the reproductive isolation caused by seasonal differentiation. The influence of some environmental factors was tested. The seasonal variation persisted in cultivation, and the plants could normally be assigned to distinct aestival or autumnal groups, with no reproductive contact. Flowering phenology was affected by environmental factors, but not to such an extent that the reproductive isolation was broken. The observed phenological variation was not reflected by a corresponding variation in present management practices. Management history and possible non-anthropogenic factors are discussed as alternative explanations.     

Grazing tolerance of Gentianella amarella and other monocarpic herbs: why is tolerance highest at low damage levels?

Plants have adapted to compensate for the loss of vegetative biomass and reproductive potential caused by grazing. Shoot damage breaks down the correlative inhibition maintained by apical dominance. The consequent increased branching may lead to increased production of flowers and fruits in damaged plants, provided that enough resources, both in terms of meristems and nutrients, are available. In Gentianella amarella, the removal of the apex of the main stem (10% clipping) had no pronounced effect on branching and plant performance. In one of the two study populations, however, apically damaged plants produced more fruits than undamaged control plants. The plants also fully compensated for 50% removal of the main stem in terms of above-ground biomass, but their fruit production was reduced compared to control and apically damaged plants. After 75% clipping, fruit production was not significantly reduced compared to 50% clipping. Consequently, G. amarella showed highest tolerance in the presence of minor shoot damage. The pattern is qualitatively similar in some other monocarpic species (Gentianella campestris, Erysimum strictum and Rhinanthus minor). Multiple constraints as well as selective forces may shape these compensatory responses: (1) A lack of basal meristems may constrain tolerance of high damage levels. (2) Species with basal meristems may have a potential to tolerate major damage, but a shortage of resources or otherwise unfavourable growth conditions may constrain their compensatory ability. (3) It may be adaptive to have maximum tolerance of low and moderate damage levels if chemical defences reduce the risk of extensive shoot damage as well as the risk of repeated grazing. (4) The compensatory ability of monocarpic species may be affected by selective forces that favour fast vertical growth early in the season and unbranched architecture in undamaged conditions. Therefore, it is not the mere grazing history, but also other factors associated with growth conditions that are required to explain the variation in grazing tolerance.     

Variability of Xanthomonas Campestris pv. vasculorum From Sugarcane and Other Gramineae in Reunion Island. Characterization of a Different Xanthomonad

Strains presumed to be of Xanthomonas campestris pv. vasculorum (Cobb.) Dye, obtained from sugarcane and other gramineae in Réunion Island, were compared in terms of cultural aspects, pathogenic and physiological reactions, fatty acid profiles and restriction fragment length polymorphism (RFLP) of genomic DNA. The strains could be divided into two separate groups (G1 and G2). The G1 strains were identical to strains described as X. campestris pv. vasculorum; they showed an important variability in their cultural characteristics and in their aggressiveness. The G2 strains did not induce the usual symptoms of gumming disease on sugarcane cultivars infected under natural conditions or inoculated in the greenhouse. The G2 strains grew faster on agar medium, their colonies were more pigmented and less fluidal and had a different morphology on agar slant. Unlike the G1 strains, G2 strains hydrolyzed starch weakly and casein strongly; they utilized L-fucose and, to a lesser extent, melibioze. The fatty acid and genomic DNA profiles differed between the groups. Differences seemed large enough to support separation of G1 and G2 strains into distinct taxonomic entities, namely G1 as Xanthomonas campestris pv. vasculorum and G2 as a different pathovar of X. campestris. The taxonomic position of G2 strains is discussed.     

A re-evaluation of morphological characters in European Gentianella section Gentianella (Gentianaceae)

Morphological traits were investigated in Gentianella section Gentianella by morphometrics and Scanning Electronic Microscopy (SEM). Variation in vegetative measures and in calyx, corolla, ovary, and gynophor was analyzed in populational samples and herbarium material. Special emphasis was given to micro-morphology and variation of papillae on the calyx using SEM. Three types of papillae on the calyx lobes were found: (A) short conical (G. amarella-group, G. insubrica, G. germanica); (B) long conical often curved (G. campestris, G. anisodonta, G. engadinsesis, and G. liburnica; (C) long cylindrical (G. aspera and G. pilosa). G. austriaca, G. caucasea, G. crispata, G. fatrae, and G. ramosa usually lack any papillae. Plants without and with short conical papillae were found in G. bulgarica and G. lutescens as well as in the intermediate taxa G. bohemica and G. stiriaca. The different types of papillae together with other calyx characters (sinus, shape and margin of lobe) are of high systematic importance and provide more stable characters than morphometric flower measures. Principal component and correlation analysis revealed a strong response of nearly all morphometric traits to the environmental variable altitude. Adaptive and historical causes of morphological variation as well as taxonomical consequences are discussed and a determination key is provided.     

Variability of Xanthomonas Campestris pv. vasculorum From Sugarcane and Other Gramineae in Reunion Island. Characterization of a Different Xanthomonad

Stains presumed to be of Xanthomonas campestris pv. vasculorum (Cobb.) Dye, obtained from sugarcane and other gramineae in Réunion Island, were compared in terms of cultural aspects, pathogenic and physiological reactions, fatty acid profiles and restriction fragment length polymorphism (RFLP) of genomic DNA. The strains could be divided into two separate groups (G1 and G2). The G1 strains were identical to strains described as X. campestris pv. vasculorum; they showedan important variability in their cultural characteristics and in their aggressiveness. The G2 strains did not induce the usual symptoms of gumming disease on sugarcane cultivars infected under natural conditions or inoculated in the greenhouse. The G2 strains grew faster on agar medium, their colonies were more pigmented and less fluidal and had a different morphology on agar slant. Unlike the G1 strains, G2 strains hydrolyzed starch weakly and casein strongly; they utilized L-fucose and, to a lesser extent, melibioze. The fatty acid and genomic DNA profiles differed between the groups. Differences seemed large enough to support separation of G1 and G2 strains into distinct taxonomic entities, namely G1 as Xanthomonas campestris pv. vasculorum and G2 as a different pathovar of X. campestris. The taxonomic position of G2 strains is discussed.     

Morphological and genetic study of Prorocentrum donghaiense Lu from the East China Sea, and comparison with some related Prorocentrum species

In this paper, the detailed morphology of Prorocentrum donghaiense Lu from both field samples and cultures was examined, and a taxonomic comparison was made between P. donghaiense and some related Prorocentrum spp. using morphological and molecular data and other published information. There were distinct differences among these species in morphological characteristics that historically have been presented as conservative features. The discrepancies extended beyond that of individual variations within the same species due to environmental factors. Therefore, these morphological features may not be conservative but, rather, polymorphic depending on environmental conditions. Based on this analysis, we suggest that the high-biomass bloom-forming species in the East China Sea, previously reported as Prorocentrum dentatum Stein, is P. donghaiense Lu. The species reported from the East China Sea and Japanese and Korean waters appear to be the same species. Molecular data also suggest that P. dentatum (CCMP1517) and P. donghaiense are genetically identical. Therefore, the geographic distribution of P. donghaiense may be much wider than expected.     

Bryophyte County Floras

Abstract

Experimental study of Pohlia populations that regularly produce axillary bulbils in Britain has shown that there are seven species present. The distinguishing bulbil characters of field populations of each species are retained when the plants are cultivated under uniform conditions, and can be used as a valid taxonomic criterion. Variation in bulbil morphology within and between populations of P. proligera is due to a combination of genetic, environmental and developmental variation. Bulbils show considerable phenotypic plasticity in P. drummondii but in the other five species studied variation is largely or entirely developmen tal.     

La distribuzione dell'acido l-ascorbico nelle foglie di piante officinali italiane. Aspetti quantitativi e tassonomici

Abstract

Distribution of l-ascorbic acid in leaves of Italian officinal plants. Quantitative and taxonomic aspects.—Fresh samples of 119 Italian officinal plants belonging to 41 families of Angiosperme were assayed for l-ascorbic acid content.

Estimation of data as reported by Seybold and Mehner indicates that relatively high contents are generally found among the Rosaceae, while low amounts are usual within Asteraceae. However, species with leaves rich in l-ascorbic acid may be found at widely different places of the taxonomic system.

Since the vitamin C is widespread in the plant kingdom it has been recommended the indication of the exact amount of vitamin C when a plant is reported as antiscorbutic.

Finally the knowledge of families whose species more frequently show large amounts of vitamin C may facilitate researches of edible wild plants with high content of vitamin C.     

Diverse reproductive barriers in hybridising crickets suggests extensive variation in the evolution and maintenance of isolation

Reproductive barriers reduce gene flow between populations and maintain species identities. A diversity of barriers exist, acting before, during and after mating. To understand speciation and coexistence, these barriers need to be quantified and their potential interactions revealed. We use the hybridising field crickets Gryllus bimaculatus and G. campestris as a model to understand the full compliment and relative strength of reproductive barriers. We find that males of both species prefer conspecific females, but the effect is probably too weak to represent a barrier. In contrast, prezygotic barriers caused by females being more attracted to conspecific male song and preferentially mounting and mating with conspecifics are strong and asymmetric. Postzygotic barriers vary in direction; reductions in fecundity and egg viability create selection against hybridisation, but hybrids live longer than pure-bred individuals. Hybrid females show a strong preference for G. bimaculatus songs, which together with a complete lack of hybridisation by G. campestris females, suggests that asymmetric gene flow is likely. For comparison, we review reproductive barriers that have been identified between other Gryllids and conclude that multiple barriers are common. Different species pairs are separated by qualitatively different combinations of barriers, suggesting that reproductive isolation and even the process of speciation itself may vary widely even within closely related groups.     

Two new species of Huberia (Melastomataceae: Merianieae) from Brazil

Two new Brazilian species of the genusHuberia,H. carvalhoi andH. consimilis, are described, discussed, and illustrated.Huberia carvalhoi is endemic to Bahia;H. consimilis has a wider distribution, with disjunct populations in Pernambuco, Bahia, and Rio de Janeiro. A key is provided to the three Bahia taxa with some comments on the taxonomic affinities of the two new species.     

核桃黑斑病拮抗放线菌WMF106的筛选、鉴定及防效

【背景】核桃黑斑病是由2种病原菌引起的细菌性病害,目前缺乏有效的生物防治方法。【目的】从核桃树根际土壤中筛选对核桃黑斑病病原菌具有拮抗效果的放线菌菌株,为该病害生防菌剂的开发提供基础。【方法】采用稀释涂布法分离放线菌,并以病原菌野油菜黄单胞菌(Xanthomonas campestris pv. campestris)和成团泛菌(Pantoea agglomerans)作为指示菌,利用平板对峙法和改良牛津杯法筛选具有高拮抗活性的菌株,通过形态学特征、生理生化特性和16SrRNA基因序列分析确定其分类地位,并测定其无菌发酵液的抗菌谱和室内防效。【结果】筛选到一株对野油菜黄单胞菌和成团泛菌均有较强拮抗作用的放线菌菌株WMF106,该菌株对2种病原菌的抑菌圈直径分别为2.38 cm和1.82 cm,无菌发酵液对2种病原菌的抑菌圈直径分别为1.75 cm和1.55 cm。根据菌株形态学、生理生化特性及16SrRNA基因序列分析,将菌株WMF106鉴定为暗蓝色链霉菌(Streptomyces caeruleatus)。该菌株对尖孢镰刀菌、腐皮镰孢菌、辣椒刺盘孢菌、灰葡萄孢菌、胶孢炭疽菌5种植物病原菌及大肠杆菌、金黄色葡萄球菌、铜绿假单胞菌、白色念珠菌、黑曲霉5种指示菌均有抑制作用,抗菌性能广谱高效,其无菌发酵液原液对离体叶片上由野油菜黄单胞菌和成团泛菌造成的核桃黑斑病防效分别为77.44%和58.33%。【结论】菌株WMF106可作为防治核桃黑斑病的生防材料,具有良好的开发价值和应用前景。     

The taxonomic status and range extension of Grimmia exquisita J.Muñoz (Grimmiaceae,Bryophyta)

Introduction. We found an unusual specimen collected in 1975 from Xinjiang Province, China which may represent Grimmia exquisita J.Muñoz. However, this species is known only from the type localities and its taxonomic status is still controversial.

Methods. A voucher of the Chinese specimen is deposited in IFP herbarium. This specimen was studied with the typical anatomical and morphological methods applied within Grimmia (Maier, 2010).

Key Results. The Chinese species represents G. exquisita. After examining the type specimens of G. exquisita, we confirmed that it should be recognised as a distinct species.

Conclusions. This study expands the distribution area of G. exquisita to East Asia. The Chinese specimen was discovered in a rather different habitat to its types and consequently, G. exquisita may be a more widely distributed species. Evaluation of the Grimmia specimens in many different herbaria is needed.     

SINGLE LOCUS MICROSATELLITES IN GRACILARIALES (RHODOPHYTA): HIGH LEVEL OF GENETIC VARIABILITY WITHIN GRACILARIA GRACILIS AND CONSERVATION IN RELATED SPECIES1

Four single locus microsatellites identified in the red alga Gracilaria gracilis (Stackhouse) Steentoft, Irvine, et Farnham (Rhodophyta) were examined for allelic diversity at different spatial and taxonomic levels. First, because simple morphological diagnostic characters are often missing within the Gracilariaceae, we developed a simple and rapid method based on rDNA ITS size variation in order to verify the taxonomic status of the samples used in this study. All European (including Mediterranean samples), Argentinian, and Namibian samples used in our study were confirmed to be a homogenous G. gracilis group. By contrast, our results on rDNA ITS sizes showed that Gracilaria from Japan, initially identified as G. gracilis, was different from the rest of the G. gracilis group. Secondly, microsatellite polymorphism and conservation at the species level was tested on the worldwide collection of G. gracilis and within a single population. The loci Gv1AAG and Gv1AAC showed no allelic variation, whereas two others, Gv1CT and Gv2CT, were highly polymorphic. All microsatellite loci were conserved within G. gracilis, except in the sample from Japan. The taxonomic status of G. gracilis from Japan is thus questionable. This study revealed a high level of within-population polymorphism (52 alleles for Gv1CT and 12 for Gv2CT). Moreover, the combination of these two loci was shown to be very powerful for identifying individuals within a population, that is, 93% of the individuals were characterized by a unique genotype. Finally, conservation of the four loci was tested in taxonomically related species of Gracilaria (G. chilensis, G. pacifica, and G. tikvahiae) and two Gracilariopsis species (Gs. sp. and Gs. longissima). The results suggest that the polymorphic locus Gv2CT may provide a valuable genetic marker within the different species of the Gracilariaceae.     

Redefinition of the neotropical genus Anthopterus (Ericaceae: Vaccinieae), including one new species

The taxonomic history of Anthopterus as it relates to Themistoclesia is briefly reviewed. Anthopterus is redefined to include several species formerly placed in Themistoclesia. Two subgenera are established within Anthopterus. Anthopterus costaricensis Luteyn is described as new, and the new combination Anthopterus pterotus (A. C. Sm.) Luteyn is made. A key to the genus, a list of the species currently accepted, and brief notes on distribution and frequency are provided. Most species of Anthopterus are rare and their habitats are endangered.     

Utility of iPBS retrotransposons markers for molecular characterization of African Gnetum species

Abstract

Species of African Gnetum are lianas used as vegetables, medicines and for generating income. Despite the taxonomic confusion, identification of new species and diverse morphological characters in African Gnetum, molecular markers on these plants are lacking. However, the inter-primer binding site (iPBS) retrotransposons markers could be simple and excellent molecular markers for African Gnetum. The objective of this study was to determine the efficiency of iPBS markers in detecting genetic differentiation in African Gnetum species. A set of 21 iPBS markers were analysed on 14 accessions including G. africanum Welw., G. buchholzianum Engl. and the recently identified species G. latispicum. Six best selected primers generated 103 bands in G. africanum, 95 in G. buchholzianum and 24 in G. latispicum. Cluster analysis divided the accessions into two major groups. The first group contained all the accessions of G. africanum, whereas the second group was further divided in two subgroups representing accessions of G. buchholzianum and G. latispicum. Additionally, the Jaccard similarity coefficient indicated a close relationship between accessions of G. buchholzianum and G. latispicum. The iPBS marker system revealed genetic differentiation within African Gnetum and could be useful for evaluating genetic diversity, conservation, taxonomy and evolution studies.     

Isolating the role of soil resources,defoliation, and interspecific competition on early establishment of the late successional bunchgrass Festuca campestris

Native grasslands are valued for biodiversity and supporting dormant season grazing, but are prone to invasion. In western Canada, revegetation of Festuca campestris grasslands may be hindered by Poa pratensis, an invasive grass. To determine the competitive interaction of these species during establishment, two greenhouse experiments were conducted where F. campestris seedlings were planted in monocultures or mixtures with P. pratensis. The first experiment used equal‐aged (3‐month old) seedlings of both species, while the second experiment used unequal‐aged seedlings (4‐month‐old F. campestris and 2‐month‐old P. pratensis). Seedling performance was measured in response to manipulations of water and nitrogen, defoliation, and plant neighbor. While water and nitrogen reduced the biomass and vegetative reproduction (tillering) of F. campestris, exposure to P. pratensis most strongly limited the growth of F. campestris seedlings regardless of other treatments. More frequent and consistent decreases in F. campestris due to P. pratensis were observed in older F. campestris seedlings than younger seedlings. Defoliation also reduced the growth of F. campestris, and the added presence of P. pratensis during defoliation further enhanced these reductions in younger, equal‐aged bunchgrass seedlings. Overall, these results suggest that when restoring native F. campestris grasslands, early establishment may be improved by reducing the negative impacts of P. pratensis, and avoiding severe defoliation.     

Species pools along contemporary environmental gradients represent different levels of diversification

Aim Within a region, different habitat types are characterized by different species and some habitat types have higher species diversities than others. Different habitat types are also characterized by different phylogenetic clades. However, it is not known whether – within a given region – some habitat types have species pools that are more phylogenetically diversified than others. We investigated whether species pools in contemporary habitat types represent different levels of diversification of angiosperms and, if so, whether these differences correlate with particular environmental factors. We tested these relationships in a region of recent geological origin possessing a comparatively young flora, and compared the result with standard analyses of species diversity. Location The Netherlands. Methods We studied angiosperms across the full range of habitat types present in the Netherlands. We characterized levels of diversification represented in species pools within each of these habitat types with respect to (1) taxonomic diversification, i.e. the rate of increase of richness across taxonomic ranks (relative to a null expectation for a given species richness), and (2) cladogenic diversification, i.e. the average cladogenic distance of species from the root of a phylogenetic tree of the species pool within a given region. Results Species pools of different habitat types represented different levels of taxonomic and cladogenic diversification. These differences were strongly correlated with the environmental characteristics of the habitat type. Greater levels of taxonomic diversification were represented in the species pools of relatively dry and open habitat types. Greater levels of cladogenic diversification were represented in habitats with both dry and weakly acidic soils. The relationship between environmental factors and taxonomic and cladogenic diversification (r² = 0.88 and 0.76, respectively) was stronger than that between environmental factors and species richness (r² = 0.34). Main conclusions Within a region, species resulting from particularly high rates of diversification accumulated in particular habitat types. These habitat types represent specific contemporary abiotic environments and have a tighter relationship with levels of diversification than with species richness.