Morphoanatomy of nectaries of Chamaecrista (L.) Moench sections Chamaecrista, Caliciopsis and Xerocalyx (Leguminosae: Caesalpinioideae)

Nectaries are specialized structures that secrete nectar. Several species of Chamaecrista possess nectaries on the petiole, which have been shown to vary widely in morphology and the chemical nature of their secretion. However, a comprehensive investigation of the nectaries of the clade formed by sect. Chamaecrista, Caliciopsis and Xerocalyx has yet to be performed. Our study aimed to confirm whether or not the leaf glands of species of this clade are in fact nectaries, determine the chemical nature of their secretion and expand the morphoanatomical database on leaf nectaries in Chamaecrista with the intention of contributing to the taxonomy and phylogeny of the genus. Samples from herbarium and field-collected material were subjected to standard methods for light and scanning electron microscopy. Four different forms of nectaries were observed: urceolate, patelliform, verruciform and cupuliform. The nectaries were found to comprise a single-layered epidermis, nectary parenchyma, subnectary parenchyma and vascularization. Polysaccharides, lipids, phenolic compounds and proteins were detected in secretions. Although anatomical similarities were observed among the studied species, their morphology differed. Moreover, the glands are indeed nectaries and are similar to those observed in other species of the genus Chamaecrista. These data hold potential taxonomic usefulness for the studied sections

Environmental drivers of water use for Caatinga woody plant species: combining remote sensing phenology and sap flow measurements

Abstract: We investigated the water use of Caatinga vegetation, the largest seasonally dry forest in South America. We identified and analysed the environmental drivers of phenology in woody species and their relationship with transpiration. To monitor the phenological evolution we used remote sensing indices at different spatial and temporal scales: normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), and green chromatic coordinate (GCC). To represent the phenology we used the GCC extracted from in-situ automated digital camera images; indices calculated based on sensors included NDVI, SAVI and GCC from Sentinel-2A and B satellites images, and NDVI products MYD13Q1 and MOD13Q1 from moderate-resolution imaging spectroradiometer (MODIS). Environmental drivers included continuously monitored rainfall, air temperature, soil moisture, net radiation, and vapour pressure deficit. To monitor soil water status and vegetation water use we installed soil moisture sensors along three soil profiles and sap flow sensors for five plant species. Our study demonstrated that the near-surface GCC data played an important role in allowing individual monitoring of species whereas the species’ sap flow data correlated better with NDVI, SAVI and GCC than with species’ near-surface GCC. The wood density appeared to affect the transpiration cessation times in the dry season given species with the lowest wood density reach negligible values of transpiration earlier in the season than those with high woody density. Our results show that soil water availability is the main limiting factor for transpiration during more than 80 % of the year, and that both the phenological response and water use are directly related to water availability when relative saturation of the soil profile falls below 0.25

Expanding tropical forest monitoring into Dry Forests: The DRYFLOR protocol for permanent plots

This is the final version. Available on open access from Wiley via the DOI in this recordSocietal Impact Statement Understanding of tropical forests has been revolutionized by monitoring in permanent plots. Data from global plot networks have transformed our knowledge of forests’ diversity, function, contribution to global biogeochemical cycles, and sensitivity to climate change. Monitoring has thus far been concentrated in rain forests. Despite increasing appreciation of their threatened status, biodiversity, and importance to the global carbon cycle, monitoring in tropical dry forests is still in its infancy. We provide a protocol for permanent monitoring plots in tropical dry forests. Expanding monitoring into dry biomes is critical for overcoming the linked challenges of climate change, land use change, and the biodiversity crisis.Newton FundNatural Environment Research Council (NERC)Fundação de Amparo à Pesquisa do Estado de São PauloCYTE

Leaf anatomy as an additional tool to the taxonomy of Chamaecrista Moench with emphasis on section Apoucouita (Leguminosae - Caesalpinioideae)

Chamaecrista Moench (Leguminosae, Caesalpinioideae, Cassieae, Cassiineae) inclui mais de 330 espécies. A presença de estruturas secretoras é um dos parâmetros utilizados para a circunscrição das seis seções do gênero, no entanto, tal circunscrição não é corroborada pelos estudos filogenéticos. A anatomia foliar de Chamaecrista tem se mostrado uma importante ferramenta, corroborando inclusive as novas circunscrições taxonômicas baseadas em dados moleculares. Dentre as várias estruturas secretoras descritas para o gênero Chamaecrista, coléteres foram mencionados em algumas das espécies estudadas. Entretanto um estudo comparativo da diversidade e importância taxonômica dessas estruturas no gênero Chamaecrista ainda não foi realizado. Dentre as seções de Chamaecrista, poucos estudos têm investigado a seção Apoucouita que inclui espécies com glândulas no pecíolo/raque e no racemo denominadas de nectários. No entanto, tal caracterização demanda estudos complementares como análise da presença de açúcar e análises histoquímicas. Embora estudos moleculares tenham se mostrado úteis para a separação e delimitação de grupos taxonômicos, caracteres morfológicos são necessários para reconhecimento das espécies tanto em campo quanto em herbário e nestes casos a morfoanatomia foliar é uma alternativa promissora. Os materiais foram processados conforme metodologia usual de microscopia de luz e varredura utilizados em estudos anatômicos. O trabalho foi organizado em três capítulos. No capítulo I a presença e a diversidade de coléteres em folhas e flores em desenvolvimento de espécies do gênero Chamaecrista, foram avaliadas. Foram descritos seis tipos de coléteres: “club-shaped”, “racket-shaped”, “long bottle-shaped”, “short bottle-shaped”, “long digitiform” e “short digitiform”. As análises histoquímicas confirmaram a presença de proteínas totais, polissacarídeos totais, mucilagens e lipídeos na secreção dos coléteres. O tipo e posição dos coléteres corroboram as novas circunscrições com base em estudos moleculares propostas para Chamaecrista. No capítulo II procedeu-se o estudo anatômico das glândulas do pecíolo/raque para verificar se tais estruturas correspondem a nectários como descrito na literatura. Foram observados 13 tipos de nectários extraflorais (NEF) para Chamaecrista, os quais podem ser impressos, sésseis ou pedunculados, com superfície secretora côncava, plano/truncada ou convexa. Embora variações morfológicas tenham sido observadas, a estrutura anatômica e a composição química da secreção foram similares para todos os tipos de NEF. A formação de periderme de cicatrização em NEFs mais velhos é um fato inédito para Chamaecrista, uma vez que não foi relatada para as outras seções do gênero. O capítulo III aborda a morfoanatomia das folhas de espécies de C. seção Apoucouita com vistas verificar a utilidade dessas características para fins taxonomicos. O arranjo do sistema vascular no pecíolo/raque, tipo de mesofilo, idioblastos mucilaginosos na face adaxial e abaxial da epiderme, contorno das paredes periclinais das células epidérmicas (reto na adaxial e sinuoso na abaxial) e posição e tipo de estômato, (hipoestomática e paracítico- laterocíclico, respectivamente) foram caracteres comuns a todas as espécies da seção Apoucouita. A presença e posição de papilas na epiderme e a posição e tipo de NEF são caracteres promissores quanto à taxonomia de algumas das espécies do gênero.Chamaecrista Moench (Leguminosae, Caesalpinioideae, Cassieae, Cassiineae) includes more than 330 species. The presence of secretory structures is one of the parameters used for the circumscription of the six sections of the genus. However, such circumscription is not supported by the phylogenetic studies. Leaf anatomy of Chamaecrista has proved an important tool to the new taxonomic circumscription based on molecular data. Among the secretory structures described for Chamaecrista, colleters have been mentioned in some species. However, a comparative study of the diversity and taxonomic importance of such structures for Chamaecrista has not yet been performed. Among the sections of Chamaecrista, few studies have focused on sect. Apoucouita, a section with species displaying glands on the petiole/rachis and on the raceme. Such glands have been called extrafloral nectaries (EFN), even though, no additional studies such as the analysis of the presence of sugars and histochemical tests have been performed to confirm if such glands are in fact EFNs. Although molecular studies have proved useful in the circumscription of taxonomic groups, morphological characters are necessary for recognizing species in the field and also when dried material is analyzed and in both cases, leaf anatomy is a promising alternative for the recognition of species. For this study, standard anatomical techniques for light and scanning electron microscopy were carried out. The present study is organized in three chapters. The presence and diversity of colleters on developing leaves and flowers of Chamaecrista is described in Chapter I. Six types of colleters were described: “club- shaped”, “racket-shaped”, “long bottle-shaped”, “short bottle-shaped”, “long digitiform” and “short digitiform”. The histochemical analyses confirmed the presence of total proteins, total polysaccharides, mucilage and lipids in the secretion of the colleters. The type and position of colleter supported new circumscriptions based on molecular studies proposed for the Chamaecrista. The anatomical study of the petiole/rachis glands in order to verify if such structures are in fact nectaries, as described in the literature, is given in Chapter II. It was observed 13 types of ENFs for Chamaecrista. Such EFNs may be impressed, sessile or stalked, with secretory surface concave, flat/truncate or convex. Although morphological variations were observed, the anatomical structure and chemical composition of the secretion was similar to all types of EFNs. The formation of a wound-healing periderm in older EFNs is a novelty for Chamaecrista, as such was not reported for the other sections of the genus. The leaf morphoanatomy of C. sect. Apoucouita with the intent of using such characters in the taxonomy is given in Chapter III. The arrangement of the vascular system in the petiole/rachis, type of mesophyll, mucilage idioblasts in the adaxial and abaxial epidermis, outline of the anticlinal walls of the epidermal cells (straight on the adaxial side and sinuous on the abaxial side) and the position and type of stomata (hipostomatic leaves and paracytic laterocyclic, respectively) were characters common to all species from sect. Apoucouita. The presence of papillae on the epidermis as well as the position and type of extrafloral nectaries are promising characters regarding the taxonomy of some species of Chamaecrista.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Leaf anatomy as an additional taxonomy tool for Chamaecrista species (section Absus, subsection Baseophyllum (Leguminosae - Caesalpinioideae)

Este trabalho tem por objetivo estudar as espécies de Chamaecrista circunscritas na seção Absus subseção Baseophyllum, fornecendo informações morfo-anatômicas da lâmina foliar, pecíolo/raque e glândulas encontradas no pecíolo/raque que possam ser úteis na separação das variedades circunscritas para Chamaecrista cytisoides (secção Absus subseção Baseophyllum) elevando-as ao nível de espécies, como definido por dados moleculares. A presença de glicose nos exsudados das glândulas presentes no pecíolo/raque confirmou que essas glândulas são de fato nectários extraflorais (NEF). Os NEFs são originados da protoderme, parênquima fundamental e procâmbio. Testes histoquímicos detectaram a presença de polissacarídeos neutros, muco-polissacarídeos ácidos, pectinas, mucilagens, proteínas totais e compostos fenólicos no tecido secretor dos NEFs, o que pode ser um indicativo da presença de tais substâncias no néctar. As oito espécies de Chamaecrista seção Absus subseção Baseophyllum apresentam epiderme unisseriada, venação do tipo actinódromo-camptódromo-broquidódromo, feixes vasculares colaterais em arco aberto, camadas de fibras e bainha cristalífera ao redor dos feixes vasculares, traqueídes alargados nas terminações das vênulas, NEFs, coléteres e tricomas tectores. Essas características foram consideradas como caracteres unificadores para esta subseção. A posição dos estômatos na folha, o tipo de mesofilo, o número de camadas tanto do parênquima paliçádico quanto lacunoso, a presença de hipoderme, a posição dos idioblastos mucilaginosos nos folíolos e o número de feixes acessórios foram considerados caracteres úteis na distinção das espécies. A análise de componente principal (PCA) baseada e, caracteres morfo- anatômicos mostrou a separação clara entre as oito espécies incluídas na seção Absus subseção Baseophyllum.This paper aims at studying Chamaecrista species included in the sect. Absus subsect. Baseophyllum providing information on the morphology and anatomy of the leaflet blades, petiole/rachis, and glands found on the petiole/rachis which may be used on the separation of the varieties of Chamaecrista cytisoides (section Absus subsection Baseophyllum) into species, as defined by the molecular studies. The presence of glucose in the exudates of the glands confirmed that the petiolar/rachis glands are in fact EFNs. The EFNs arise from the protodermis, ground meristem and procambium. Histochemical tests detected the presence of neutral, acid muco- polysaccharides, pectins, mucilages, total proteins, and phenolic compounds in the EFN which may be indications of the presence of these substances in the nectar. All eight species of Chamaecrista sect. Absus subsect. Baseophyllum displayed a single- layered epidermis. Actinodromous-camptodromous-brochidodromous venation type, collateral vascular bundles arranged in open arc, layers of fibres and a sheath of cells containing prismatic crystals surrounding the vascular bundles, enlarged tracheids at the vein endings, vascular tissue of petiole/rachis with a pith parenchyma, accessory bundles, extrafloral nectaries, colleters, and non-secretory trichomes were observed in all the species studied and considered as unifying characters for this subsection. Position and type of stomata on leaves, type of mesophyll, number of both palisade and spongy parenchyma layers, presence of hypodermis, position of mucilage idioblasts in the leaflets, and number of accessory bundles were used to make distinction among the species. Principal component analysis (PCA) based on morphological and anatomical characters showed the clear separation of the eight species included within sect. Absus subsect. Baseophyllum.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Structural diversity of extrafloral nectaries in Chamaecrista sect. Apoucouita

Section Apoucouita (Chamaecrista (L.) Moench – Caesalpinioideae) is an arboreal group that is most diverse in the Amazon and Brazilian Atlantic forests. These species typically bear petiolar and (or) rachis glands called extrafloral nectaries (EFNs). However, no detailed anatomical studies or histochemical analyses have been conducted to confirm nectar secretion. We aimed at describing the structure of such EFNs, as well as determining the chemical nature of the secretion. Eighteen species (23 taxa) were studied using standard light microscopy techniques. We describe 13 types of EFNs with variable morphology. Such EFNs may be impressed, sessile, or stalked; with concave, flat or truncate, or convex secretory surfaces. Cupuliform EFNs (stalked or not) were the most common type observed and patelliform the least common. Despite the morphological variation, differences in the anatomical structure of the EFNs and the chemical composition of the secretion were not observed. EFNs with concave secretory surfaces appear to be more effective as nectar may become accumulated in the concavity, increasing the volume of available nectar. Our results show that despite the variable morphology of the EFNs, such structures share similarities on the anatomy and composition of the secretion and development of a wound-healing periderm in older EFNs. We also indicate the importance of including the morphological variation observed in the EFNs in species of sect. Apoucouita in future taxonomic evaluations

Leaf anatomical studies of Chamaecrista subsect. Baseophyllum (Leguminosae, Caesalpinioideae): new evidence for the up-ranking of the varieties to the species level

This study aims to determine whether morphoanatomical characters of the leaves of the species of Chamaecrista sect. Absus subsection Baseophyllum could be used to support an up-ranking of C. cytisoides varieties to the species level as previously defined by molecular studies. The significance of anatomical adaptive strategies to arid environments is also discussed. Standard light microscopy techniques and histochemical tests were used for both morphoanatomical and histochemical characterization of the leaves. All the species studied share a single-layered epidermis, actinodromous–camptodromous–brochidodromous type of venation, vascular bundles surrounded by layers of fibers bounded externally by a sheath of cells containing solitary crystals, enlarged tracheids at the vein endings, vascular petiole/rachis tissue with a parenchymatous pith, accessory vascular bundles, mucilage idioblasts and hypodermis in the mesophyll, colleters, and non-secretory trichomes. The position and type of stomata, type of mesophyll, number of palisade and spongy parenchyma layers, position of mucilage idioblasts in the mesophyll, and the number of accessory vascular bundles of petiole/rachis provided useful characters for discriminating the eight species of the subsect. Baseophyllum. Histochemical tests reveal the presence of total polysaccharides, pectins, mucilage and phenolic compounds in the idioblasts. Other xeromorphic characters such as thickened outer periclinal cell walls, compact mesophyll, mucilage idioblasts and hypodermis in the mesophyll may help enable the studied species to survive in exposed sunny areas

Colleters in Chamaecrista (L.) Moench sect. Chamaecrista and sect. Caliciopsis (Leguminosae-Caesalpinioideae): anatomy and taxonomic implications

ABSTRACT The genus Chamaecrista contains ca. 330 species organized into six sections, of which section Chamaecrista is the second largest (ca.75 species) distributed among six series, while the section Caliciopsis contains only two species. Colleters have been described in the genus Chamaecrista and they show potential taxonomic and phylogenetic significance. They are associated with lubrication, desiccation prevention and protection from microbial attacks of young developing organs. Although six types of colleters have been described for the genus Chamaecrista, there have been no studies focusing on the diversity of colleters in the sections Chamaecrista and Caliciopsis. Samples from developing leaves and flowers of both sections were obtained from herbarium and field collections and subjected to standard methodologies for both light and scanning electron microscopy. Histochemical tests were also performed to determine the nature of the exudates. Five types of non-vascularized colleters were found: short digitiform, long digitiform, club-shaped, pyriform and short bottle-shaped. Polysaccharides, pectins, lipids and proteins were detected in the exudates of all types of colleters. Among the five types of colleters observed, pyriform is a novelty for Chamaecrista, reinforcing the significant morphological diversity of these secretory structures in this genus

A study of the morphoanatomical characters of the leaves of Chamaecrista (L.) Moench sect. Apoucouita (Leguminosae-Caesalpinioideae)

Little attention has been paid to species of Chamaecrista sect. Apoucouita (Leguminosae-Caesalpinioideae), especially regarding anatomical studies. When only vegetative material is available, the identification of such species may be difficult. Additionally, vegetative material of some species of C. sect. Apoucouita may be even harder to identify because they can resemble species of Inga Mill. (Leguminosae-Mimosoideae). The present study focused on recognizing morphoanatomical characters of leaves that are taxonomically useful for the species of C. sect. Apoucouita by employing standard anatomical techniques. The arrangement of the vascular system in the petiole/rachis, dorsiventral mesophyll, mucilage idioblasts in the epidermis of leaflets and hypostomatic leaves were some of the characters shared by all species studied. Length of the petiole, position and type of extrafloral nectaries, leaflet venation, presence and type of papillae on the epidermis of the leaflet blades and sclereids in the mesophyll were some of the characters useful in the distinction of taxa. The vascular arrangement of the petiole/rachis is a promising character in the distinction of species of C. sect. Apoucouita and Inga. Based on morphoanatomical data, the taxonomic revision of some species and varieties ascribed to C. sect. Apoucouita is suggested

Anatomy of the extrafloral nectaries in species of Chamaecrista section Absus subsection Baseophyllum (Leguminosae, Caesalpinioideae)

In this paper the ontogenesis and histochemistry of the petiolar glands found on the petiole/rachis of the eight Chamaecrista species of the section Absus, subsection Baseophyllum (Leguminosae, Caesalpinioideae) are studied by using light microscopy techniques, aiming to characterise these structures and to provide taxonomic characters which may be useful in phylogenetic approaches. Strips for glucose identification reacted positively with the exudates of the glands, confirming the presence of nectar in the secretion, characterising these glands as extrafloral nectaries (EFN). Histochemical tests also detected the presence of neutral and acid muco-polysaccharides, pectins, mucilages, total proteins, and phenolic compounds in the EFNs. The EFNs arise from a group of meristem cells (protodermis, ground meristem and procambium) in the petiole/rachis. All EFNs of the investigated taxa share some morpho-anatomical characters, so that their peculiarities are too weak to be used alone in the identification of particular species. Rather their similarities may be used to include these species into a single group, supporting the hypothesis of monophyly of the subsection Baseophyllum