Phylogenomic analyses based on genome-skimming data reveal cyto-nuclear discordance in the evolutionary history of Cotoneaster (Rosaceae).

As a consequence of hybridization, polyploidization, and apomixis, the genus Cotoneaster (Rosaceae) represents one of the most complicated and controversial lineages in Rosaceae, with ca. 370 species which have been classified into two subgenera and several sections, and is notorious for its taxonomic difficulty. The infrageneric relationships and taxonomy of Cotoneaster have remained poorly understood. Previous studies have focused mainly on natural hybridization involving only several species, and phylogeny based on very limited markers. In the present study, the sequences of complete chloroplast genomes and 204 low-copy nuclear genes of 72 accessions, representing 69 species as ingroups, were used to conduct the most comprehensive phylogenetic analysis so far for Cotoneaster. Based on the sequences of complete chloroplast genomes and many nuclear genes, our analyses yield two robust phylogenetic trees respectively. Chloroplast genome and nuclear data confidently resolved relationships of this genus into two major clades which largely supported current classification based on morphological evidence. However, conflicts between the chloroplast genome and low-copy nuclear phylogenies were observed in both the species level and clade level. Cyto-nuclear discordance in the phylogeny could be caused by frequent hybridization events and incomplete sorting lineage (ILS). In addition, our divergence-time analysis revealed an evolutionary radiation of the genus from late Miocene to date.

Phylogenetic relationships and chloroplast capture in the Amelanchier-Malacomeles-Peraphyllum clade (Maleae, Rosaceae): Evidence from chloroplast genome and nuclear ribosomal DNA data using genome skimming.

The Amelanchier-Malacomeles-Peraphyllum (AMP) clade consists of ca. 26 species distributed in North and Central America, Europe, Asia, and northwestern Africa. While molecular and morphological data strongly support this clade, relationships of its genera are uncertain. Support for the monophyly of Amelanchier and for the phylogenetic positions of Malacomeles and Peraphyllum has varied between studies. Our goals were to reconstruct a robust phylogeny of the AMP clade in the framework of Maleae and clarify the phylogenetic placements of Malacomeles and Peraphyllum. This study employs sequences of the whole plastome and nuclear ribosomal DNA (nrDNA) repeats assembled using genome skimming with 131 samples representing 115 species in 31 genera of Rosaceae, especially Maleae. Maximum likelihood (ML) and Bayesian analysis (BI) of whole plastome datasets strongly supported Amelanchier as not monophyletic, with Peraphyllum sister to eastern North American Amelanchier and Malacomeles sister to the western North American-Eurasian Amelanchier. In contrast, nrDNA recovered the monophyly of Amelanchier, with Peraphyllum sister to Amelanchier and Malacomeles sister to the Amelanchier-Peraphyllum clade. The strong topological conflicts between plastome and nrDNA phylogenies of Peraphyllum and of Malacomeles are best explained by ancient chloroplast capture that occurred in SW North America.

Pollen morphology and variability of invasive Spiraea tomentosa L. (Rosaceae) from populations in Poland.

The aim of this study was to investigate the pollen morphology and the ranges of intraspecific and interindividual variability of the North American steeplebush-Spiraea tomentosa L., an invasive species in Poland. Steeplebush inflorescences were collected randomly from 30 localities of S. tomentosa in Poland. In total, 900 pollen grains were analysed with both a light and a scanning electron microscope. Nine quantitative and three qualitative pollen features were studied. The diagnostic features were: exine ornamentation (size and direction of the muri), operculum and perforation size. For the first time, the intraspecific and interindividual variability of the pollen grains of the highly invasive S. tomentosa were investigated. Pollen grain features were so similar, that they did not allow to differentiate individual samples of S. tomentosa and only groups of samples were recognized.

Convergence in leaf size versus twig leaf area scaling: do plants optimize leaf area partitioning?

BACKGROUND AND AIMS: Corner's rule states that thicker twigs bear larger leaves. The exact nature of this relationship and why it should occur has been the subject of numerous studies. It is obvious that thicker twigs should support greater total leaf area ([Formula: see text]) for hydraulical and mechanical reasons. But it is not obvious why mean leaf size ([Formula: see text]) should scale positively with [Formula: see text] We asked what this scaling relationship is within species and how variable it is across species. We then developed a model to explain why these relationships exist. METHODS: To minimize potential sources of variability, we compared twig properties from six co-occurring and functionally similar species: Acer grandidentatum, Amelanchier alnifolia, Betula occidentalis, Cornus sericea, Populus fremontii and Symphoricarpos oreophilus We modelled the economics of leaf display, weighing the benefit from light absorption against the cost of leaf tissue, to predict the optimal [Formula: see text] combinations under different canopy openings. KEY RESULTS: We observed a common [Formula: see text] by [Formula: see text] exponent of 0.6, meaning that [Formula: see text]and leaf number on twigs increased in a specific coordination. Common scaling exponents were not supported for relationships between any other measured twig properties. The model consistently predicted positive [Formula: see text] by [Formula: see text] scaling when twigs optimally filled canopy openings. The observed 0·6 exponent was predicted when self-shading decreased with larger canopy opening. CONCLUSIONS: Our results suggest Corner's rule may be better understood when recast as positive [Formula: see text] by [Formula: see text] scaling. Our model provides a tentative explanation of observed [Formula: see text] by [Formula: see text] scaling and suggests different scaling may exist in different environments.

Networks of plants: how to measure similarity in vegetable species.

Despite the common misconception of nearly static organisms, plants do interact continuously with the environment and with each other. It is fair to assume that during their evolution they developed particular features to overcome similar problems and to exploit possibilities from environment. In this paper we introduce various quantitative measures based on recent advancements in complex network theory that allow to measure the effective similarities of various species. By using this approach on the similarity in fruit-typology ecological traits we obtain a clear plant classification in a way similar to traditional taxonomic classification. This result is not trivial, since a similar analysis done on the basis of diaspore morphological properties do not provide any clear parameter to classify plants species. Complex network theory can then be used in order to determine which feature amongst many can be used to distinguish scope and possibly evolution of plants. Future uses of this approach range from functional classification to quantitative determination of plant communities in nature.

[Environmental variability and physiological responses from Polylepis cuadrijuga (Rosaceae) in a fragmented environment in the Páramo de la Rusia (Colombia]. / Variabilidad ambiental y respuestas fisiológicas de Polylepis cuadrijuga (Rosaceae) en un ambiente fragmentado en el Páramo de la Rusia (colombia).

Polylepis cuadrijuga is an endemic woody species from the Colombian Eastern range, being the only tree species with capacity to live on mountainous environments beyond 4 000m of altitude. Grazing and agriculture have transformed at least 30% of the Guantiva-La Rusia region, turning continuous extensions of high Andean forest in a fragmented landscape, and P cuadrijuga remnants have become smaller and more isolated. The aim of this study was to establish the environmental differences between a matrix of grazing pastures and the interior of fragments, to evaluate the physiological responses of P cuadrijuga and determining the edge effect. Air temperature and humidity, soil water holding capacity and photosynthetic active radiation, were measured along two 50X2m transects from the matrix toward the center of fragment. Six trees inside the transects were chosen in each one of three sites (matrix, edge and interior) to measure the index chlorophyll content and to sample leaves to assess the leaf area, leaf biomass, specific leaf area, anatomy, health condition and pubescence. Results showed significantly differences between the matrix and the interior and intermediate conditions in the edge. Radiation, temperature and air desiccation were higher in the matrix than in the interior, submitting P cuadrijuga trees to a stressing environment, where they presented stratification of epidermis and palisade parenchyma, and a higher leaf area, leaf thickness, chlorophyll content and pubescence than in the interior of fragments. All these physiological traits allow avoiding the photoxidation and damages by freezing or desiccation to which trees are exposed in a grazing pasture matrix. Nevertheless, there was a higher frequency of healthy leaves in the interior of fragments, showing that high irradiations and extreme air temperature and humidity reach adversely affect to P cuadrijuga. Individuals in the edge had ecophysiological traits similar to the matrix ones, which confirm an edge effect that could penetrate 17m inside the fragments. We conclude that P cuadrijuga is a plastic species, able to overcome the stress conditions from anthropogenic transformations, species able to be used in high Andean forest restoration programs

Functional morphology underlies performance differences among invasive and non-invasive ruderal Rubus species.

The ability of some introduced plant species to outperform native species under altered resource conditions makes them highly productive in ecosystems with surplus resources. However, ruderal native species are also productive when resources are available. The differences in abundance among invasive and non-invasive ruderal plants may be related to differences in ability to maintain access to or store resources for continual use. For a group of ruderal species in the Pacific Northwest of North America (invasive Rubus armeniacus; non-invasive R. ursinus, R. parviflorus, R. spectabilis, and Rosa nutkana), we sought to determine whether differences in functional morphological traits, especially metrics of water access and storage, were consistent with differences in water conductance and growth rate. We also investigated the changes in these traits in response to abundant vs. limited water availability. Rubus armeniacus had among the largest root systems and cane cross-sectional areas, the lowest cane tissue densities, and the most plastic ratios of leaf area to plant mass and of xylem area to leaf area, often sharing its rank with R. ursinus or Rosa nutkana. These three species had the highest water conductance and relative growth rates, though Rubus armeniacus grew the most rapidly when water was not limited. Our results suggest that water access and storage abilities vary with morphology among the ruderal species investigated, and that these abilities, in combination, are greatest in the invasive. In turn, functional morphological traits allow R. armeniacus to maintain rapid gas exchange rates during the dry summers in its invaded range, conferring on it high productivity.

Variabilidad ambiental y respuestas fisiológicas de Polylepis cuadrijuga (Rosaceae) en un ambiente fragmentado en el Páramo de la Rusia (Colombia) / Environmental variability and physiological responses from Polylepis cuadrijuga (Rosaceae) in a fragmented environment in the Páramo de la Rusia (Colombia)

Polylepis cuadrijuga is an endemic woody species from the Colombian Eastern range, being the only tree species with capacity to live on mountainous environments beyond 4 000m of altitude. Grazing and agriculture have transformed at least 30% of the Guantiva-La Rusia region, turning continuous extensions of high Andean forest in a fragmented landscape, and P. cuadrijuga remnants have become smaller and more isolated. The aim of this study was to establish the environmental differences between a matrix of grazing pastures and the interior of fragments, to evaluate the physiological responses of P. cuadrijuga and determining the edge effect. Air temperature and humidity, soil water holding capacity and photosynthetic active radiation, were measured along two 50X2m transects from the matrix toward the center of fragment. Six trees inside the transects were chosen in each one of three sites (matrix, edge and interior) to measure the index chlorophyll content and to sample leaves to assess the leaf area, leaf biomass, specific leaf area, anatomy, health condition and pubescence. Results showed significantly differences between the matrix and the interior and intermediate conditions in the edge. Radiation, temperature and air desiccation were higher in the matrix than in the interior, submitting P. cuadrijuga trees to a stressing environment, where they presented stratification of epidermis and palisade parenchyma, and a higher leaf area, leaf thickness, chlorophyll content and pubescence than in the interior of fragments. All these physiological traits allow avoiding the photoxidation and damages by freezing or desiccation to which trees are exposed in a grazing pasture matrix. Nevertheless, there was a higher frequency of healthy leaves in the interior of fragments, showing that high irradiations and extreme air temperature and humidity reach adversely affect to P. cuadrijuga. Individuals in the edge had ecophysiological traits similar to the matrix ones, which confirm an edge effect that could penetrate 17m inside the fragments. We conclude that P. cuadrijuga is a plastic species, able to overcome the stress conditions from anthropogenic transformations, species able to be used in high Andean forest restoration programs.

Polylepis cuadrijuga es una especie leñosa endémica de la cordillera oriental de Colombia, donde la agricultura y el pastoreo han generado la fragmentación de sus bosques. Para determinar si existe un efecto borde en fragmentos ubicados en el Páramo de la Rusia, se establecieron diferencias ambientales y se evaluó las respuestas ecofisiológicas de P. cuadrijuga entre matriz de pastura, borde e interior de los fragmentos, a través de la medición de temperatura ambiental, humedad relativa, capacidad de retención de agua del suelo y radiación fotosintéticamente activa, a lo largo de dos transectos de 50m desde la matriz hacia el interior. En cada sitio se escogieron seis árboles para evaluar el contenido de clorofila, área foliar, biomasa foliar, área foliar específica, anatomía foliar, sanidad y pubescencia. En matriz fue mayor la temperatura y la radiación, condiciones relacionadas con la disminución del AFE y el aumento del contenido de clorofilas, evidenciado por la presencia de un parénquima en empalizada biestratificado. Características ecofisiológicas similares a las expuestas en borde, confirman un efecto de borde que podría penetra unos 17m en el interior de los fragmentos. Se concluye que P. cuadrijuga es una especie plástica, capaz de enfrentar condiciones de estrés generadas por actividades antropogénicas.

Mechanics of plant fruit hooks.

Hook-like surface structures, observed in some plant species, play an important role in the process of plant growth and seed dispersal. In this study, we developed an elastic model and further used it to investigate the mechanical behaviour of fruit hooks in four plant species, previously measured in an experimental study. Based on Euler-Bernoulli beam theory, the force-displacement relationship is derived, and its Young's modulus is obtained. The result agrees well with the experimental data. The model aids in understanding the mechanics of hooks, and could be used in the development of new bioinspired Velcro-like materials.

Xylem vulnerability to cavitation can be accurately characterised in species with long vessels using a centrifuge method.

Vulnerability to cavitation curves describe the decrease in xylem hydraulic conductivity as xylem pressure declines. Several techniques for constructing vulnerability curves use centrifugal force to induce negative xylem pressure in stem or root segments. Centrifuge vulnerability curves constructed for long-vesselled species have been hypothesised to overestimate xylem vulnerability to cavitation due to increased vulnerability of vessels cut open at stem ends that extend to the middle or entirely through segments. We tested two key predictions of this hypothesis: (i) centrifugation induces greater embolism than dehydration in long-vesselled species, and (ii) the proportion of open vessels changes centrifuge vulnerability curves. Centrifuge and dehydration vulnerability curves were compared for a long- and short-vesselled species. The effect of open vessels was tested in four species by comparing centrifuge vulnerability curves for stems of two lengths. Centrifuge and dehydration vulnerability curves agreed well for the long- and short-vesselled species. Centrifuge vulnerability curves constructed using two stem lengths were similar. Also, the distribution of embolism along the length of centrifuged stems matched the theoretical pressure profile induced by centrifugation. We conclude that vulnerability to cavitation can be accurately characterised with vulnerability curves constructed using a centrifuge technique, even in long-vesselled species.

White-fruited Duchesnea indica (Rosaceae) is impaired in ANS gene expression.

PREMISE OF THE STUDY: Duchesnea indica is a wild strawberry-like species that has red fruits. In a recent survey in the highlands of Tucumán (Argentina), a plant of D. indica with white fruits was discovered. The aim of this study was to investigate whether the white-fruited character was due to a phenotypic or genotypic change. The stability and heritability of the character and the expression of genes involved in anthocyanins synthesis were studied and compared with red-fruited genotypes. This study contributes to understanding the molecular basis of some factors involved in fruit pigmentation, a horticulturally and taxonomically important trait. METHODS: Stability and heritability of the white-fruited character were evaluated in plants obtained by asexual propagation or by sexual crosses between the white- and red-fruited genotypes. Asexual multiplications were carried out by stolon rooting and sexual multiplications by germination of achenes obtained from crosses. The expression level of the genes involved in the synthesis and regulation of the anthocyanins pathway (CHS, F3H, DFR, ANS, and MYB10) were evaluated by RT-PCR using specific primers. KEY RESULTS: Plants with the white-fruited character always yielded white-fruited progeny when propagated asexually, whereas in sexually propagated plants fruit color depended on the mother. Red-fruited mothers yielded red-fruited progeny, and white-fruited mothers yielded fruits ranging from dark pink to white. Molecular analysis suggested that the white-fruited character was due to the low expression of the ANS gene. CONCLUSIONS: Results obtained indicate that the white-fruited character was stable. Mother progenitors exert a strong influence on the expression of the white-fruited character. The white-fruited phenotype is due to the impairment or downregulation of the ANS gene.

[Development and structure defense strategies on the fruit of Chaenomeles speciosa].

OBJECTIVE: To study the development rule and structure defense strategies on the fruit of Chaenomeles speciosa. METHODS: Anatomical and histochemical methods were used to investigate the structure and localization of tannin of the fruit of Chaenomeles speciosa. RESULTS: The development of the fruit of Chaenomeles speciosa were divided into two periods: cells reproduced rapidly from fluorescence to 40 - 50 days after fluorescence, and cells augmented after this. The pericarp and seeds were protected by beceptacle which was formed by cuticle, epidermis, taniniferous cells layer, parenchyma cells which contained tannin and stone cells zones. Tannin was distributed in parenchyma cells of beceptacle mostly and in pericarp barely. CONCLUSION: The development and structure of fruit of were related with its defense strategies.

Mapping QTLs for developmental traits in raspberry from bud break to ripe fruit.

Protected cropping systems have been adopted by the UK industry to improve fruit quality and extend the current season. Further manipulation of season, alongside consideration of climate change scenarios, requires an understanding of the processes controlling fruit ripening. Ripening stages were scored from May to July across different years and environments from a raspberry mapping population. Here the interest was in identifying QTLs for the overall ripening process as well as for the time to reach each stage, and principal coordinate analysis was used to summarise the ripening process. Linear interpolation was also used to estimate the time (in days) taken for each plot to reach each of the stages assessed. QTLs were identified across four chromosomes for ripening and the time to reach each stage. A MADS-box gene, Gene H and several raspberry ESTs were associated with the QTLs and markers associated with plant height have also been identified, paving the way for marker assisted selection in Rubus idaeus.

The adaptive value of phenotypic floral integration.

Floral integration has been deemed an adaptation to increase the benefits of animal pollination, yet no attempts have been made to estimate its adaptive value under natural conditions. Here, the variation in the magnitude and pattern of phenotypic floral integration and the variance-covariance structure of floral traits in four species of Rosaceae were examined. The intensity of natural selection acting on floral phenotypic integration was also estimated and the available evidence regarding the magnitude of floral integration reviewed. The species studied had similar degrees of floral integration, although significant differences were observed in their variance-covariance structure. Selection acted on subsets of floral traits (i.e. selection on intrafloral integration) rather than on the integration of the whole flower. Average integration was 20% and similar to the estimated mean value of flowering plants. The review indicated that flowering plants present lower integration than expected by chance. Numerical simulations suggest that this pattern may result from selection favouring intrafloral integration. Phenotypic integration at the flower level seems to have a low adaptive value among the species surveyed. Moreover, it is proposed that pollinator-mediated selection promotes the evolution of intrafloral integration.

[Study on quality control of Rubus suavissimus].

OBJECTIVE: To control the quality of Rubus suavissimus. METHODS: We inspected the character observation, microscopic, physical and chemical identification, TLC, the examination of water and extraction of Rubus suavissimus, then used HPLC to assay the contents of the principal sweet taste component. RESULTS: The quality control indexes of Rubus suavissimus were founded. CONCLUSIONS: The method is feasible and can control the quality of Rubus suavissimus.

Plant biological warfare: thorns inject pathogenic bacteria into herbivores.

Thorns, spines and prickles are among the rich arsenal of antiherbivore defence mechanisms that plants have evolved. Many of these thorns are aposematic, that is, marked by various types of warning coloration. This coloration was recently proposed to deter large herbivores. Yet, the mechanical defence provided by thorns against large herbivores might be only the tip of the iceberg in a much more complicated story. Here we present evidence that thorns harbour an array of pathogenic bacteria that are much more dangerous to herbivores than the painful mechanical wounding by the thorns. Pathogenic bacteria like Clostridium perfringens, the causative agent of the life-threatening gas gangrene, and others, were isolated and identified from date palm (with green-yellow-black aposematic spines) and common hawthorn (with red aposematic thorns). These thorn-inhabiting bacteria have a considerable potential role in antiherbivory, and may have uniquely contributed to the common evolution of aposematism (warning coloration) in thorny plants.

Shifts from competition to facilitation between a foundation tree and a pioneer shrub across spatial and temporal scales in a semiarid woodland.

* Theoretical and empirical research has supported the hypothesis that plant-plant interactions change from competition to facilitation with increasing abiotic stress. However, the consistency of such changes has been questioned in arid and semiarid ecosystems. * During a drought in the semiarid south-western USA, we used observations and a field experiment to examine the interactions between juveniles of a foundation tree (Pinyon pine, Pinus edulis) and a common shrub (Apache plume, Fallugia paradoxa) in replicated areas of high and low stress. * The presence of F. paradoxa reduced P. edulis performance at low-stress sites, but had the opposite effect at high-stress sites. However, the intensity of the interactions depended on temporal variation in climate and age of P. edulis. Both above- and below-ground factors contributed to competition, while only above-ground factors contributed to facilitation. * These results support the hypothesis that interactions can change from competition to facilitation as abiotic stress increases in semiarid environments. A shift from competition to facilitation may be important for the recovery of P. edulis and other foundation species that have experienced large-scale mortality during recent droughts.

The construction of a genetic linkage map of red raspberry (Rubus idaeus subsp. idaeus) based on AFLPs, genomic-SSR and EST-SSR markers.

Breeding in raspberry is time-consuming due to the highly heterozygous nature of this perennial fruit crop, coupled with relatively long periods of juvenility. The speed and precision of raspberry breeding can be improved by genetic linkage maps, thus facilitating the development of diagnostic markers for polygenic traits and the identification of genes controlling complex phenotypes. A genetic linkage map (789 cM) of the red raspberry Rubus idaeus has been constructed from a cross between two phenotypically different cultivars; the recent European cultivar Glen Moy and the older North American cultivar Latham. SSR markers were developed from both genomic and cDNA libraries from Glen Moy. These SSRs, together with AFLP markers, were utilised to create a linkage map. In order to test the utility of the genetic linkage map for QTL analysis, morphological data based on easily scoreable phenotypic traits were collected. The segregation of cane spininess, and the root sucker traits of density and spread from the mother plant, was quantified in two different environments. These traits were analysed for significant linkages to mapped markers using MapQTL and were found to be located on linkage group 2 for spines and group 8 for density and diameter. The availability of co-dominant markers allowed heterozygosities to be calculated for both cultivars.

What can morphology and isozymes tell us about the history of the Dryas integrifolia-octopetala complex?

An earlier study of the morphological variation in the circumpolar genus Dryas in Greenland revealed that populations in east Greenland are highly variable and this variation was interpreted as a hybrid zone between D. octopetala and D. integrifolia. It was proposed that populations of Dryas in east Greenland immigrated postglacially from Svalbard. The purpose of our study was to investigate the population structure of the Dryas integrifolia-octopetala complex using a combination of morphological and genetic characters. Populations of Dryas were sampled in Greenland, Svalbard, Iceland and north Scandinavia (Sweden). The morphological traits clearly separated west Greenland from Svalbard, Iceland and north Scandinavia. A large number of individuals from east Greenland and some from north Greenland could be interpreted as hybrids between the morphs. The genetic pattern was, however, partly different as the greatest amount of differentiation among regions was found between west and north Greenland (FRT = 0.65). The highest degree of genetic variation appeared within east Greenland. This was in accordance with the putative hybrid origin of the populations, as concluded based on the morphological results. The total amount of genetic differentiation found among the six regions (FRT = 0.61) was larger than between the two species (FRT = 0.44). The genetic pattern matched the proposed postglacial migration routes.

Developmental patterns of the invasive bramble (Rubus alceifolius Poiret, Rosaceae) in Réunion island: an architectural and morphometric analysis.

The aim of this study was to identify the developmental stages of Rubus alceifolius and to determine one or more characteristic morphological markers for each stage. The developmental reconstitution method used involved a detailed description of many individuals throughout the different stages of growth, from germination to the development of an adult shoot capable of fruiting. Results revealed that R. alceifolius passes through five developmental stages that can be distinguished by changes in several morphological markers such as internode length and diameter, pith diameter and plant shape. This analysis indicated that R. alceifolius has a heteroblastic developmental pattern, midway between that of a bush and a liana. Moreover, results showed that this species taps environmental resources early in its development, i.e. foliarization is high (the foliar component overrides the caulinary component) and an autotrophic stage is rapidly reached, whereas it 'explores' the environment during the adult stage, i.e. axialization is substantial (the caulinary component overrides the foliar component) and autotrophy occurs at a later stage. The morphological markers identified could benefit land-use managers attempting to control this species before it reaches its optimum developmental stage.