Floral ontogeny of Tachigali (Caesalpinioideae, Fabaceae) species.

Background: The present ontogenetic study reveals variations throughout floral development in three morphologically representative species from the genus Tachigali, allowing a better understanding of floral organs diversity, flower symmetry and their homologies, especially in Fabaceae, a diverse family that exhibits a wide variation in floral architecture. Tachigali (Caesalpinioideae) corresponds to an important Neotropical legumes tree genus with 58 species in Brazil. Species of the genus Sclerolobium Vogel were incorporated in its circumscription, increasing the diversity of its floral morphology. Methods: This work aims to perform an ontogenetic study of T. denudata, T. paratyensis and T. spathulipetala, morphologically representative species of Tachigali, in order to describe the floral development and to better comprehend the floral morphology varieties among the species, using scanning electron microscopy. Results: We found the studied species to have floral buds with acropetal and helical development along the inflorescence axis; sepals and petals with helical development, varying the position of the primordia in the bud, according to the different species; stamens with unilateral development and carpel with adaxial curvature. These data correspond to original records of Tachigali ontogeny and contribute to an improved understanding of floral morphology and symmetry with data related to the zygomorphic and early development of the sepals and petals.

Reconstructing an historical pollination syndrome: keel flowers.

BACKGROUND: Keel flowers are bilaterally symmetrical, pentamerous flowers with three different petal types and reproductive organs enclosed by keel petals; generally there is also connation of floral parts such as stamens and keel petals. In this study, the evolution of keel flowers within the order Fabales is explored to investigate whether the establishment of this flower type within one of the species-rich families, the Fabaceae (Leguminosae), preceded and could have influenced the evolution of keel flowers in the Polygalaceae. We conducted molecular dating, and ancestral area and ancestral state analyses for a phylogeny constructed for 678 taxa using published matK, rbcL and trnL plastid gene regions. RESULTS: We reveal the temporal and spatial origins of keel flowers and traits associated with pollinators, specifically floral symmetry, the presence or absence of a pentamerous corolla and three distinct petal types, the presence or absence of enclosed reproductive organs, androecium types, inflorescence types, inflorescence size, flower size, plant height and habit. Ancestral area reconstructions show that at the time keel flowers appeared in the Polygaleae, subfamily Papilionoideae of the Fabaceae was already distributed almost globally; at least eight clades of the Papilionoideae had keel flowers with a functional morphology broadly similar to the morphology of the first evolving Polygaleae flowers. CONCLUSIONS: The multiple origins of keel flowers within angiosperms likely represent convergence due to bee specialization, and therefore pollinator pressure. In the case of the Fabales, the first evolving keel flowers of Polygaleae have a functional morphology that corresponds with keel flowers of species of the Papilionoideae already present in the environment. These findings are consistent with the keel-flowered Polygaleae exploiting pollinators of keel-flowered Papilionoideae. The current study is the first to use ancestral reconstructions of traits associated with pollination to demonstrate that the multiple evolutionary origins of the keel flower pollinator syndrome in Fabales are consistent with, though do not prove, mimicry.

Soil fertility interactions with Sinorhizobium-legume symbiosis in a simulated Martian regolith; effects on nitrogen content and plant health.

Due to increasing population growth and declining arable land on Earth, astroagriculture will be vital to terraform Martian regolith for settlement. Nodulating plants and their N-fixing symbionts may play a role in increasing Martian soil fertility. On Earth, clover (Melilotus officinalis) forms a symbiotic relationship with the N-fixing bacteria Sinorhizobium meliloti; clover has been previously grown in simulated regolith yet without bacterial inoculation. In this study, we inoculated clover with S. meliloti grown in potting soil and regolith to test the hypothesis that plants grown in regolith can form the same symbiotic associations as in soils and to determine if greater plant biomass occurs in the presence of S. meliloti regardless of growth media. We also examined soil NH4 concentrations to evaluate soil augmentation properties of nodulating plants and symbionts. Greater biomass occurred in inoculated compared to uninoculated groups; the inoculated average biomass in potting mix and regolith (2.23 and 0.29 g, respectively) was greater than the uninoculated group (0.11 and 0.01 g, respectively). However, no significant differences existed in NH4 composition between potting mix and regolith simulant. Linear regression analysis results showed that: i) symbiotic plant-bacteria relationships differed between regolith and potting mix, with plant biomass positively correlated to regolith-bacteria interactions; and, ii) NH4 production was limited to plant uptake yet the relationships in regolith and potting mix were similar. It is promising that plant-legume symbiosis is a possibility for Martian soil colonization.

Anatomical characterization and technological properties of Pterogyne nitens wood, a very interesting species of the Brazilian Caatinga biome.

Pterogyne nitens is commonly known in northeastern Brazil as a lesser-known fast-growing species in the Caatinga biome, which is a difficult place for tree development due to the low natural fertility soils and low availability of water. Due to the importance of expanding information about the anatomical wood properties of Caatinga native species, the aim of this work was to characterize the anatomical elements, to macroscopically describe the wood and make inferences about its possible end-uses. Maceration was performed which enabled measuring fiber dimensions, pore frequency and the following technological indexes: cell wall fraction, slenderness ratio, Runkel index and flexibility coefficient. Histological sections enabled describing the arrangements of the cellular elements in different observation sections and to determine the pore diameter. P. nitens wood has anatomical arrangements characterized by confluent axial parenchyma, being diffuse-porous with the presence of tylosis and heterogeneous/stratified rays (biseriate). The fibers were classified as very short (length 0.81 mm), not flexible and Runkel index 0.82. The pores were few in number with a frequency of 32.9 pores/mm2, distributed in a diffuse format and many were obstructed by tylosis. Based on the anatomical results and considering other technological studies, P. nitens wood is most suitable for charcoal production.

Morphology, germination, and geographic distribution of Pentaclethra macroloba (Fabaceae): a hyperdominant Amazonian tree / Morfología, germinación y distribución geográfica de Pentaclethra macroloba (Fabaceae): árbol amazónico hiperdominante

Introduction: Pentaclethra macroloba is a hyperdominant tree in the Amazon estuary of great socioeconomic importance for the region because the oil from its seeds is a powerful herbal medicine. Objective: We aimed to characterize the morphological structure, the morphological adaptations in response to the daily flooding of the Amazon estuary and the biogeographic area of P. macroloba. Methods: Detailed description of the external morphology, from germination to the adult tree, was obtained from individuals located in floodplain forest, Northeast Amazonia. The occupation area and the geographical extension of P. macroloba were determined from point of geographical coordinates of botanical samples deposited in the digital collections of Mobot and SpeciesLink. Results: Adult individuals have adapted structures in response to daily flooding, such as: adventitious roots to increase respiratory efficiency and lenticels in the trunk, serving as a connection point for oxygen transport between the root and the aerial part. Dried fruit favours the activation of the explosive dehiscence mechanism, allowing the seed to be expelled long distance. Deltoid shape of the seed allows water fluctuation and more efficient dispersal. Seedling is phanerocotylar hypogeal and with one pair of reserve cotyledons that provide the seedling an extra source of energy to escape the flood. Germination rate was 78 % and the speed was 0.2 seeds.day-1. Circular buffer method revealed the presence of 123 subpopulations of P. macroloba distributed in a radius of 5 699 943 km² across the Neotropical region. Conclusions: Much of the morphological structures of P. macroloba are adaptive and evolutionary responses to the periodically flooded environment of the Amazon estuary, showing that these environments select the trees, best adapted, to inhabit the flood. P. macroloba has a wide geographical area denotes the plasticity of adapting to different environments, which may justify its monodominance in some regions.

Introducción: Pentaclethra macroloba es un árbol hiperdominante en el estuario del Amazonas, de gran importancia socioeconómica para la región, pues el aceite de sus semillas es un poderoso medicamento natural. Objetivo: Nuestro objetivo fue caracterizar la estructura morfológica, las adaptaciones morfológicas en respuesta a las inundaciones diarias del estuario del Amazonas y el área biogeográfica de P. macroloba. Métodos: Una descripción detallada de la morfología externa, desde la germinación hasta el árbol adulto, se obtuvo de individuos ubicados en el bosque periódicamente inundado, al noreste de la Amazonia. El área de ocupación y la extensión geográfica de P. macroloba se determinaron a partir del punto de coordenadas geográficas de muestras botánicas depositadas en las colecciones digitales de Mobot y SpeciesLink. Resultados: Los individuos adultos tienen estructuras adaptadas en respuesta a las inundaciones diarias, tales como: raíces adventicias para aumentar la eficiencia respiratoria y lenticelas en el tronco, que sirven como punto de conexión para el transporte de oxígeno entre la raíz y la parte aérea. Los frutos secos favorecen la activación del mecanismo de dehiscencia explosiva, permitiendo que la semilla sea expulsada a larga distancia. La forma deltoidea de la semilla permite la fluctuación en el agua y una dispersión más eficiente. La plántula es hipogel fanerocotiledones y con un par de cotiledones de reserva que proporcionan a la plántula una fuente extra de energía para escapar de la inundación. La tasa de germinación fue del 78 % y la velocidad fue de 0.2 semillas día-1. El método Circular buffer reveló la presencia de 123 subpoblaciones de P. macroloba distribuidas en un radio de 5 699 943 km² a lo largo de la región neotropical. Conclusiones: Gran parte de las estructuras morfológicas de P. macroloba son respuestas adaptativas y evolutivas al ambiente periódicamente inundado del estuario del Amazonas, lo que demuestra que estos ambientes actúan como filtro ambiental seleccionado las especies mejor adaptadas al medio. Su amplia área geográfica denota la plasticidad de adaptarse a diferentes ambientes, lo que puede justificar su monodominancia en algunas regiones.

Albinism in plants - far beyond the loss of chlorophyll: Structural and physiological aspects of wild-type and albino royal poinciana (Delonix regia) seedlings.

The partial or complete loss of chlorophylls, or albinism, is a rare phenomenon in plants. In the present study, we provide the first report of the occurrence in albino Delonix regia seedlings and describe the morpho-physiological changes associated with albinism. Wild-type (WT) and albino seedlings were characterized. Leaflets samples were processed following common procedures for analysis with light, scanning and transmission electron microscopy. The chlorophyll a fluorescence parameters and the carbohydrate, lipid and soluble protein content were also determined in leaf and cotyledon samples of both albino and WT seedlings. Albino seedlings showed reduced growth. They also had lower chlorophyll and protein content in foliar tissues than WT seedlings, in addition to lower concentrations of lipids and carbohydrates stored in cotyledons. The chloroplasts of albino seedlings were poorly developed, with an undefined internal membrane system and the presence of plastoglobules. Wild-type seedlings had a uniseriate and hypoestomatic epidermis. The mesophyll was dorsiventral, consisting of a layer of palisade parenchyma and two to four layers of spongy parenchyma. In albino seedlings, the spongy parenchyma was compact, with few intercellular spaces, and the thickness of the mesophyll was larger, resulting in increased thickness of the leaf blade. Albino seedlings had higher stomatal density and number of pavement cells, although the stomata had smaller dimensions. In addition to the partial loss of chlorophylls, albino D. regia showed changes at physiological and structural levels, demonstrating the crucial nature of photosynthetic pigments during the development and differentiation of plant leaf tissues/cells.

Palynological investigation of some selected species of family Fabaceae from Pakistan, using light and scanning electron microscopy techniques.

Pollen morphology of 11 species of family Fabaceae that is, Trifolium alexandrinum, Trifolium resupinatum, Arachis hypogaea, Lathyrus aphaca, Medicago lupulina, Vicia sativa, Lathyrus odoratus, Pongamia pinnata, Melilotus indicus, Medicago polymorpha, Medicago sativa from Pakistan has been investigated by light and scanning electron microscopy. Pollen were generally tricolporate, radially symmetrical, isopolar, elliptic in equatorial view and triangular in polar view under LM. Results showed that pollens were per-prolate (T. alexandrinum), prolate (T. resupinatum, V. sativa, L. odoratus, Melilotus indicus, M. polymorpha, M. sativa) and sub-prolate (A. hypogaea, L. aphaca, M. lupulina, P. pinnata). The larger polar/equatorial (P/E) ratio was found in T. alexandrinum (2.26 µm) and the smallest was found in M. lupulina (1.21 µm). The exine of T. resupinatum was 3.00 µm in thickness while others posses smaller exine thickness. The larger pore diameter was found in P. pinnata (16.01 µm) while others have smaller. The length of colpi was larger in Arachis hypogaea (32.24) while others posses smaller. Eight types of surface ornamentation (Psilate, faintly rugulate). Perforate and rugulate to verrucate have been observed under SEM. The pollens were europalynous type. Pollen morphology proved to be useful for the specific delimitation and serve as a tool for the identification and classification of taxa at specific and generic levels and can also be used as a key for the taxonomic features. Diversity in exine sculpture is helpful indicative characters for the isolation of closely related species. Hence, it is clear that both qualitative and quantitative characters of pollen can be useful for differentiating between taxa at specific level.

Mapping the habitat suitability of Andira humilis Mart. ex Benth. (Fabaceae) as a means to detect its associated galling species in Brazil

Host plant species have very specific interconnection with galling species. Here, we estimate the potential distribution of the host plant species Andira humilis Mart. ex Benth. (Fabaceae) to consequently locate the potential distribution ranges of its galling species Lopesia andirae Garcia, Lima, Calado, and Guimarães (2017) based on ecological requirements. The ecological niche model was built using Maxent v.3.4.1k, an algorithm that estimates species’ distributions. We found suitable habitats for L. andirae encompassing areas of the Cerrado, Caatinga and Atlantic Forest. Annual mean temperature (70.2%) and temperature annual range (13.9%) were the most critical factors shaping A. humilis and necessarily L. andirae. Our results can guide taxonomists and ecologists regarding the delineation of sampling areas as well as conservation strategies for this ecological interaction.

Seed vigor of Piptadenia moniliformis Benth. subjected to thermal stress

The objective of this work is to evaluate the influence of accelerated aging test at 41ºC on the germination and seed vigor of Piptadenia moniliformisBenth. Two experiments were conducted. Experiment 1: seeds were submitted to dormancy overcoming treatments. They were immersed into sulfuric acid for 0 (intact seeds), 5, 10, 15, 20 and 25 minutes. Experiment 2: two methods were evaluated for the accelerated aging test at 41ºC, that is, the traditional method and the saturated NaCl solution method with exposure periods of 0, 24, 48, 72 and 96 hours. After each treatment, the seeds were subjected to electrical conductivity and germination tests. Seeds overcame their dormancy when immersed into concentrated sulfuric acid for 5, 10, 15, 20 or 25 minutes, but thegermination was faster when immersed for 20 minutes. The different methods for the accelerated aging test, decreased the germination potential and seed vigor of P. moniliformisafter 24 hours of exposure. Regarding the method used, the saturated solution provided, in general, the best results since the seed water content was lower, thus reducing the proliferation of fungi. The electrical conductivity test showed that, by increasing the aging period regardless of the method, there is an increase in seed deterioration, corroborating with germination results, which showed that the correlation was moderate and negative and indicated that the higher the conductivity, the lower the percentage and the germination speed index. The immersion of seeds of P. moniliformisinto concentrated sulfuric acid for 20 minutes provides a fast and increased germination. The methods for accelerated agingat 41ºC, traditional and saturated solution, can be used as vigor tests to evaluate the physiological quality of seeds.

Phylogenomic analyses reveal an exceptionally high number of evolutionary shifts in a florally diverse clade of African legumes.

Detarioideae is well known for its high diversity of floral traits, including flower symmetry, number of organs, and petal size and morphology. This diversity has been characterized and studied at higher taxonomic levels, but limited analyses have been performed among closely related genera with contrasting floral traits due to the lack of fully resolved phylogenetic relationships. Here, we used four representative transcriptomes to develop an exome capture (target enrichment) bait for the entire subfamily and applied it to the Anthonotha clade using a complete data set (61 specimens) representing all extant floral diversity. Our phylogenetic analyses recovered congruent topologies using ML and Bayesian methods. Anthonotha was recovered as monophyletic contrary to the remaining three genera (Englerodendron, Isomacrolobium and Pseudomacrolobium), which form a monophyletic group sister to Anthonotha. We inferred a total of 35 transitions for the seven floral traits (pertaining to flower symmetry, petals, stamens and staminodes) that we analyzed, suggesting that at least 30% of the species in this group display transitions from the ancestral condition reconstructed for the Anthonotha clade. The main transitions were towards a reduction in the number of organs (petals, stamens and staminodes). Despite the high number of transitions, our analyses indicate that the seven characters are evolving independently in these lineages. Petal morphology is the most labile floral trait with a total of seven independent transitions in number and seven independent transitions to modification in petal types. The diverse petal morphology along the dorsoventral axis of symmetry within the flower is not associated with differences at the micromorphology of petal surface, suggesting that in this group all petals within the flower might possess the same petal identity at the molecular level. Our results provide a solid evolutionary framework for further detailed analyses of the molecular basis of petal identity.

Thigmomorphogenesis and biomechanical responses of shade-grown Serianthes nelsonii plants to stem flexure.

The influences of stem flexure on shade-grown Serianthes nelsonii Merr. stem growth and strength were determined in a container nursery setting. Treated stems were bent 90° two times daily for a 14 wk nursery production period. Plant height, internode length, and slenderness were decreased by stem flexure when compared with control plants that received no flexure. Two force-displacement tests revealed stem strength was increased by the flexure treatment. Control plants exhibited undesirable lean of the main stem, and 1 hr of wind stress further increased the angle of lean. Treated plants were close to orthotropic and the wind stress did not change the stem lean. Results indicate stem flexure is a reliable method for increasing the quality of shade-grown S. nelsonii plants and some form of mechanical stimulation should be added to nursery production protocols for the species.

Phenotypic and genetic characterisation revealed the existence of several biotypes within the Neorautanenia brachypus (Harms) C.A. wild accessions in South East Lowveld, Zimbabwe.

BACKGROUND: Local communities in the South Eastern Lowveld of Zimbabwe have adopted the feeding of livestock with Neorautanenia brachypus (Harms) C.A. tuber to mitigate against climate change. Differences within Neorautanenia brachypus (Harms) tuber flesh colour and preferences by cattle have been observed, suggesting possible diversity within the N. brachypus plant community. This study aimed at distinguishing the N. brachypus wild plant species through phenotypic and genetic characterization using morphological descriptors and random amplified polymorphic (RAPD) markers respectively. Leaf samples were selected using judgmental sampling techniques from wards 11-15 in Sengwe (Chiredzi district) for leaf morphology and molecular characterization. RAPD-PCR analysis was done using 18-screened random decamer primers to confirm the diversity in the plant population. The similarity of the biotypes was evaluated using binary coding on the basis of the presence or absence of a morphological indicator as well as distinct DNA amplicon fragments. Primer 7.0.13 was used to estimate morphological and genetic similarities using the unweighted pair group method with arithmetic average (UPGMA). The cluster number was estimated using the Elbow method part of the R package. RESULTS: Initially, 14 biotype groups were identified from 96 accessions visually characterized basing of leaf characteristics. All the leaf biotypes displayed arcuate venation with differences observed for leaf shape, tip shape and leaf margins. The 14 biotypes clustered into six groups based on the binary data of the morphological characteristics. RAPD primers generated three hundred and sixty eight distinct amplicons with 77.5% being polymorphic from the 14 biotypes. The number of bands produced per primer ranged from four (OPF-02) to 44 (UBC-746). The PIC value ranged from 0.1327 to 0.1873 for the RAPD primers. Use of molecular markers collapsed the biotypes into five clusters. Both the leaf descriptors and RAPD markers showed the existence of genetic diversity within the wild accessions of N. brachypus. CONCLUSIONS: A combination of morphological and RAPD markers effectively refined the resolution of the genetic diversity within the N. brachypus wild accessions to nine biotypes. These findings have indicated to the existence of more than one biotype of N. brachypus with potentially different properties. The favorable biotypes can further be promoted through incorporation in pastures as alternative feed or complementary feed to livestock. As such the output of this study will serve as a guide for N. brachypus germplasm management and improvement.

Microscopic investigations of some selected species of Papilionaceae through SEM and LM from Skardu valley, northern Pakistan.

Pollen morphology of 10 species and foliar epidermal anatomy of eight species of Papilionaceae from Skardu valley, northern Pakistan has been estimated for the first time. The present study was commenced with an aim to provide a detailed account of the pollen morphology by scanning electron microscopy and foliar epidermal anatomy by light microscopy. The pollen aperture was tricolporate with reticulate exine in the selected species. Stomata types are actinocytic, paracytic, and anomocytic. Irregular or polygonal with undulate or straight walls, epidermal cells were reported. A unique diversity was observed in the foliar trichomes that show the taxonomic significance of the discrimination of taxa. Non-glandular trichomes were observed in the selected species which are unicellular with thin, long and pointed apical cells. Pollen and foliar micro morphological characters proved to be helpful for the identification of taxa at a specific level.

Leaf adaptations and species boundaries in North American Cercis: implications for the evolution of dry floras.

PREMISE OF THE STUDY: The North American Cercis clade spans dry to mesic climates and exhibits complex morphological variation. We tested various proposed species classifications of this group and whether aspects of leaf morphology, particularly the "drip-tip" in some regional populations, are adaptive and/or linked with phylogeny. METHODS: We made measurements on over 1100 herbarium specimens from throughout North America and analyzed the data with univariate and multivariate approaches. We analyzed phylogenetically DNA sequence data from nuclear ITS and three plastid regions from 40 samples, and estimated divergence times with a relaxed-clock Bayesian analysis. We used climate and geographic position data to predict the variation observed in leaf size and shape by using stepwise multiple linear regressions. KEY RESULTS: Morphometric analyses yielded a pattern of continuous and often clinal character variation across North America, without correlated gaps in character states. Conversely, phylogenetic and divergence time analyses yielded distinct clades from California, the interior west, and eastern North America separated by between ~12 and 16 million years. Multiple regressions yielded highly significant correlations between leaf apex shape and precipitation of the warmest quarter. CONCLUSIONS: Despite a pattern of continuous morphological character variation, the long period of geographic and presumably genetic isolation warrants the delimitation of three species. Predictive modeling supports the adaptive value of acuminate apices or "drip-tips" in mesic habitats. This suggests that Cercis leaves change more rapidly than inferred from parsimony reconstruction, which has implications for the evolution of the dry floras of North America and Eurasia.

Efecto del origen geográfico en la calidad morfológica de plantas de Prosopis alba (Fabaceae) / Effect of geographic origin on morphological qualities of the plant Prosopis alba (Fabaceae)

Resumen El origen geográfico de la semilla ejerce un control genético sobre los caracteres de comportamiento de las plantas por lo cual su selección es una herramienta útil para lograr la máxima adaptación de la especie al medio. En este sentido, la caracterización de materiales de diferentes procedencias brinda información para la elección de las fuentes de semilla utilizables en programas de mejora, así como en proyectos de forestación y/o repoblación. El presente trabajo tuvo como objetivo establecer el efecto de la procedencia sobre las variables morfológicas que constituyen parámetros de calidad en plantines de Prosopis alba provenientes de tres áreas geográficas. Se midieron variables morfológicas de las plantas hasta los 150 días posteriores a la siembra. El efecto de la procedencia resultó significativo para la mayoría de las variables medidas: altura de las plantas y diámetro a la altura del cuello (al menos durante los primeros 3 meses de viverización), volumen de raíz, peso foliar específico y área foliar específica. Así mismo algunos de los índices y cocientes morfológicos considerados como variables para determinar la calidad de plantas resultan afectados por el origen geográfico del material: relación longitud parte aérea/parte radical, coeficiente de esbeltez e índice de esbeltez. Los resultados permiten afirmar que en P. alba la procedencia influye sobre la morfología de las plantas y determina la existencia de dos grupos diferentes: por un lado, las procedencias santiagueña y chaqueña y, por otro, la procedencia Salta Norte.

Abstract Seed provenance has a genetic control over the behavioral characteristics of plants, whereby selection is an useful tool to achieve the maximum adaptation of the species to the environment. In this sense, different provenance materials characterization provides information for choosing seed sources used in breeding programs, as well as afforestation and/or reforestation projects. The aim of this work was established provenance´s effect on morphological variables that constitute quality parameters in Prosopis alba seedlings from three geographic areas. Morphological plants´ variables were measured up to 150 days after planting. Provenance effect was significant for most of measured variables: plant´s height, neck diameter (at least during the first 3 months of nursery), root volume, specific leaf weight and specific leaf area. Likewise, some of the morphological indices and quotients considered variables to determine plants´ quality are affected by material´s geographical origin: shoot length/ root length proportion, slenderness coefficient and index. Results allow affirming P. alba´s provenance influences plants´ morphology determining the existence of two different groups: on one hand Santiago del Estero and Chaco provenances, and on the other, Salta Norte origin. Rev. Biol. Trop. 66(2): 593-604. Epub 2018 June 01.

Strategies of leaf water uptake based on anatomical traits.

The ability of leaves to absorb fog water can positively contribute to the water and carbon balance of plants in montane ecosystems, especially in periods of soil water deficit. However, the ecophysiological traits and mechanisms responsible for variations in the speed and total water absorption capacity of leaves are still poorly known. This study investigated leaf anatomical attributes of seven species occurring in seasonal tropical high-altitude ecosystems (rocky outcrop and forest), which could explain differences in leaf water uptake (LWU) capacities. We tested the hypothesis that different sets of anatomical leaf attributes will be more marked in plant individuals living under these contrasting environmental conditions. Anatomical variations will affect the initial rate of water absorption and the total storage capacity, resulting in different strategies for using the water supplied by fog events. Water absorption by leaves was inferred indirectly, based on leaf anatomical structure and visual observation of the main access routes (using an apoplastic marker), the diffusion of water through the cuticle, and non-glandular or glandular trichomes in all species. The results suggest that three LWU strategies coexist in the species studied. The different anatomical patterns influenced the speed and maximum LWU capacity. The three LWU strategies can provide different adaptive advantages to adjust to temporal and spatial variations of water availability in these tropical high-altitude environments.

Functional dimorphic enantiostyly in monomorphic enantiostylous species of the subtribe Cassiinae (Fabaceae-Caesalpinioideae).

Monomorphic enantiostylous species produce flowers with a displacement of the style to the left (L) or right (R) on the same individual, and may exhibit different dynamics for the production of these floral types, which may influence levels of selfing. We investigated the production dynamics of L and R floral types in seven species and a variety of monomorphic enantiostylous species of the genera Senna and Chamaecrista. Our hypothesis was that most species present similar proportions of floral morphs each day. Individuals were classified daily over a period of 7 days according to the functional status, i.e. the proportion of floral morphs as functionally L, R or reciprocal (REC, i.e. similar proportions of the two floral morphs), and also according to the number of consecutive days in which they exhibited the same functional status. All species presented low daily flower production. Most species had individuals classified as functionally R, L and REC, and tend to repeat the same functional status over a few days, although they may change functional status during the flowering period. All species exhibited individuals that were classified as functionally reciprocal when both the daily and total number of flowers produced over 7 days was considered. The occurrence of different functional status has not yet been reported in the literature for enantiostylous species. The distinct strategies observed in the dynamics of floral morph production seemed likely to minimise geitonogamy and to favour cross-pollination between individuals (xenogamy).

Genetic diversity of root system architecture in response to drought stress in grain legumes.

Climate change has increased the occurrence of extreme weather patterns globally, causing significant reductions in crop production, and hence threatening food security. In order to meet the food demand of the growing world population, a faster rate of genetic gains leading to productivity enhancement for major crops is required. Grain legumes are an essential commodity in optimal human diets and animal feed because of their unique nutritional composition. Currently, limited water is a major constraint in grain legume production. Root system architecture (RSA) is an important developmental and agronomic trait, which plays vital roles in plant adaptation and productivity under water-limited environments. A deep and proliferative root system helps extract sufficient water and nutrients under these stress conditions. The integrated genetics and genomics approach to dissect molecular processes from genome to phenome is key to achieve increased water capture and use efficiency through developing better root systems. Success in crop improvement under drought depends on discovery and utilization of genetic variations existing in the germplasm. In this review, we summarize current progress in the genetic diversity in major legume crops, quantitative trait loci (QTLs) associated with RSA, and the importance and applications of recent discoveries associated with the beneficial root traits towards better RSA for enhanced drought tolerance and yield.

DigR: a generic model and its open source simulation software to mimic three-dimensional root-system architecture diversity.

Background and Aims: Many studies exist in the literature dealing with mathematical representations of root systems, categorized, for example, as pure structure description, partial derivative equations or functional-structural plant models. However, in these studies, root architecture modelling has seldom been carried out at the organ level with the inclusion of environmental influences that can be integrated into a whole plant characterization. Methods: We have conducted a multidisciplinary study on root systems including field observations, architectural analysis, and formal and mathematical modelling. This integrative and coherent approach leads to a generic model (DigR) and its software simulator. Architecture analysis applied to root systems helps at root type classification and architectural unit design for each species. Roots belonging to a particular type share dynamic and morphological characteristics which consist of topological and geometric features. The DigR simulator is integrated into the Xplo environment, with a user interface to input parameter values and make output ready for dynamic 3-D visualization, statistical analysis and saving to standard formats. DigR is simulated in a quasi-parallel computing algorithm and may be used either as a standalone tool or integrated into other simulation platforms. The software is open-source and free to download at http://amapstudio.cirad.fr/soft/xplo/download. Key Results: DigR is based on three key points: (1) a root-system architectural analysis, (2) root type classification and modelling and (3) a restricted set of 23 root type parameters with flexible values indexed in terms of root position. Genericity and botanical accuracy of the model is demonstrated for growth, branching, mortality and reiteration processes, and for different root architectures. Plugin examples demonstrate the model's versatility at simulating plastic responses to environmental constraints. Outputs of the model include diverse root system structures such as tap-root, fasciculate, tuberous, nodulated and clustered root systems. Conclusions: DigR is based on plant architecture analysis which leads to specific root type classification and organization that are directly linked to field measurements. The open source simulator of the model has been included within a friendly user environment. DigR accuracy and versatility are demonstrated for growth simulations of complex root systems for both annual and perennial plants.

Chemocoding as an identification tool where morphological- and DNA-based methods fall short: Inga as a case study.

The need for species identification and taxonomic discovery has led to the development of innovative technologies for large-scale plant identification. DNA barcoding has been useful, but fails to distinguish among many species in species-rich plant genera, particularly in tropical regions. Here, we show that chemical fingerprinting, or 'chemocoding', has great potential for plant identification in challenging tropical biomes. Using untargeted metabolomics in combination with multivariate analysis, we constructed species-level fingerprints, which we define as chemocoding. We evaluated the utility of chemocoding with species that were defined morphologically and subject to next-generation DNA sequencing in the diverse and recently radiated neotropical genus Inga (Leguminosae), both at single study sites and across broad geographic scales. Our results show that chemocoding is a robust method for distinguishing morphologically similar species at a single site and for identifying widespread species across continental-scale ranges. Given that species are the fundamental unit of analysis for conservation and biodiversity research, the development of accurate identification methods is essential. We suggest that chemocoding will be a valuable additional source of data for a quick identification of plants, especially for groups where other methods fall short.