Leaf anatomy for delimiting Atlantic Forest species of Psidium (Myrtaceae)

Abstract Leaf anatomical features are widely used to better understand angiosperm taxonomy. However, such information is scarce for the family Myrtaceae. Aiming to fill this knowledge gap, we studied anatomical and micromorphological leaf characters of ten species of Psidium: P. cattleyanum, P. cauliflorum, P. corynanthum, P. guajava, P. guineense, P. macahense, P. myrtoides, P. oligospermum, P. ovale and P. sartorianum. Uniseriate epidermis, paracytic stomata, secretory cavities, and adaxial hypodermis are common among the studied species and are typical characteristics of Myrtaceae. The presence of three or more layers of palisade parenchyma and the absence of sclerenchyma are diagnostic characters of P. guajava. The abaxial epidermis of Psidium cattleyanum and P. macahense possess curved walls. Psidium corynanthum and P. macahense are the only species with sinuous anticlinal walls on both sides of the epidermis, with all other species having straight or curved walls. Open bicollateral vascular bundles are present in all the studied species except P. guineense. With the exception of P. cauliflorum, all the studied species possess druses. The absence of collenchyma in the adaxial face is exclusive to P. ovale. The leaf anatomy of P. macahense, P. corynanthum, P. oligospermum and P. ovale are described for the first time here

DIVERSIDADE GENÉTICA DE Psidium guineense EM DUAS LOCALIDADES NO ESPÍRITO SANTO

Resumo: Psidium guineense Swartz pertence à família Myrtaceae, oferece potencial para exploração comercial e em virtude das propriedades nutricionais e farmacêuticas desperta a atenção da indústria. Entretanto, por ser uma espécie poliplóide, estudos de diversidade genética são escassos, dado a dificuldade das análises. O objetivo deste estudo foi avaliar a diversidade genética de duas populações P. guineense em dois municípios do estado do Espírito Santo, utilizando sete marcadores microssatélites. Todos os locos analisados foram polimórficos com média de 11,14 por locus. O método UPGMA agrupou os genótipos em dois grupos principais, diferenciando as populações das duas localidades. Dois índividuos de Águia Branca alocaram-se separadamente dos demais, demonstrando divergência genética. Os marcadores SSR utilizados neste estudo demonstraram eficiência na detecção de polimorfismos moleculares, revelando que houve grande diversidade genética entre os indivíduos das duas populações amostradas, sendo importantes para o melhoramento e conservação da espécie

Nomenclatural and taxonomic changes in tribe Myrteae (Myrtaceae) spurred by molecular phylogenies

Phylogenetic studies have highlighted incongruous generic placement and the usage of inappropriate names for species within tribe Myrteae (Myrtaceae). The genera affected are Calycolpus, Eugenia, Myrcia and Psidium. Eugenia aubletiana is legitimized by the designation of a lectotype and its usage proposed instead of Calycorectes bergii. Two generic transfers are proposed: Psidium sessiliflorum based on Calycolpus sessiliflorus and Myrcia neosericea, based on Eugenia neosericea. The re-instatement of Psidium cupreum, currently a synonym of Psidium rufum as an accepted species is proposed. Illustrations of the four affected species are furnished, as well as a map of occurrences of Psidium sessiliflorum. Tetramery associated to inflorescences reduced to 1(-3) flowers, an unusual combination of characters in Myrcia sect. Gomidesia, is identified in both Myrcia glaziovii and Myrcia neosericea, and a key to distinguish them is provided

A list of land plants of Parque Nacional do Caparaó, Brazil, highlights the presence of sampling gaps within this protected area

Brazilian protected areas are essential for plant conservation in the Atlantic Forest domain, one of the 36 global biodiversity hotspots. A major challenge for improving conservation actions is to know the plant richness, protected by these areas. Online databases offer an accessible way to build plant species lists and to provide relevant information about biodiversity. A list of land plants of “Parque Nacional do Caparaó” (PNC) was previously built using online databases and published on the website "Catálogo de Plantas das Unidades de Conservação do Brasil." Here, we provide and discuss additional information about plant species richness, endemism and conservation in the PNC that could not be included in the List. We documented 1,791 species of land plants as occurring in PNC, of which 63 are cited as threatened (CR, EN or VU) by the Brazilian National Red List, seven as data deficient (DD) and five as priorities for conservation. Fifity-one species were possible new ocurrences for ES and MG states

Refinement of the karyological aspects of Psidium guineense (Swartz, 1788): a comparison with Psidium guajava (Linnaeus, 1753)

Euploidy plays an important role in the evolution and diversification of Psidium Linnaeus, 1753. However, few data about the nuclear DNA content, chromosome characterization (morphometry and class) and molecular markers have been reported for this genus. In this context, the present study aims to shed light on the genome of Psidium guineense Swartz, 1788, comparing it with Psidium guajava Linnaeus, 1753. Using flow cytometry, the nuclear 2C value of P. guineense was 2C = 1.85 picograms (pg), and the karyotype showed 2n = 4x = 44 chromosomes. Thus, P. guineense has four chromosome sets, in accordance with the basic chromosome number of Psidium (x = 11). In addition, karyomorphometric analysis revealed morphologically identical chromosome groups in the karyotype of P. guineense. The high transferability of microsatellites (98.6%) further corroborates with phylogenetic relationship between P. guajava and P. guineense. Based on the data regarding nuclear genome size, karyotype morphometry and molecular markers of P. guineense and P. guajava (2C = 0.95 pg, 2n = 2x = 22 chromosomes), P. guineense is a tetraploid species. These data reveal the role of euploidy in the diversification of the genus Psidium

Nomenclatural and taxonomic changes in tribe Myrteae (Myrtaceae) spurred by molecular phylogenies

Phylogenetic studies have highlighted incongruous generic placement and the usage of inappropriate names for species within tribe Myrteae (Myrtaceae). The genera affected are Calycolpus, Eugenia, Myrcia and Psidium. Eugenia aubletiana is legitimized by the designation of a lectotype and its usage proposed instead of Calycorectes bergii. Two generic transfers are proposed: Psidium sessiliflorum based on Calycolpus sessiliflorus and Myrcia neosericea, based on Eugenia neosericea. The re-instatement of Psidium cupreum, currently a synonym of Psidium rufum as an accepted species is proposed. Illustrations of the four affected species are furnished, as well as a map of occurrences of Psidium sessiliflorum. Tetramery associated to inflorescences reduced to 1(-3) flowers, an unusual combination of characters in Myrcia sect. Gomidesia, is identified in both Myrcia glaziovii and Myrcia neosericea, and a key to distinguish them is provided

Phytochemical screening and phytocytotoxic effects of the tropical Myrcia vittoriana (Myrtaceae)

Abstract We investigated whether essential oil and aqueous and ethanolic extracts from M. vittoriana leaves have phytotoxic effects on the germination and initial development, and cytogenotoxic effects on the cell cycle, of model plants. The essential oil and extracts of M. vittoriana were characterized and used as treatments in phytotoxicity and cytotoxicity tests. The results indicated a reduction in germinative parameters and plant growth, with the higher concentrations of extracts and essential oil having the most evident effects. The cell cycle was also affected with a reduction of the mitotic index and the presence of chromosomal and nuclear alterations. All treatments showed clastogenic and aneugenic modes of action. The results can be associated with the synergistic effects of metabolites found in the extracts and essential oil, mainly the presence of the sesquiterpene germacrene D in the essential oil and of catechins, saponins, and tannins in the extracts. These substances inhibit plant germination and growth, confirming the phytotoxic effects of M. vittoriana in plant models, which should now be tested under field conditions

List of angiosperm species in an Atlantic Forest fragment reveals collection gaps in Espírito Santo state, Brazil

This study presents a list of angiosperm species in an Atlantic Forest fragment in the southern portion of Espírito Santo state, Brazil, a region that represents a collection gap within the Atlantic Forest. The studied site is a relatively small fragment of 144 ha located within a conservation unit, the Mata das Flores State Park. The site belongs to a conservation priority area for the Atlantic Forest in Espírito Santo, and is under strong anthropic pressure. Of the 239 species listed here, 21 are new records for the state, eight are endemic, and 20 figure either in the country’s or the state’s Red Lists of endangered species. Rubiaceae and Piperaceae were the families with the highest number of species. We show that small fragments that were never inventoried before can reveal a relatively large number of threatened species and that collection gaps need to be filled in order to refine our understanding about conservation priorities within the Atlantic Forest Biome

Diversity, phylogeny and evolution of the rapidly evolving genus Psidium L. (Myrtaceae, Myrteae).

BACKGROUND AND AIMS: Psidium is the fourthth largest genus of Myrtaceae in the Neotropics. Psidium guajava is widely cultivated in the tropics for its edible fruit. It is commercially under threat due to the disease guava decline. Psidium cattleyanum is one of the 100 most invasive organisms in the world. Knowledge of the phylogenetic relationships within Psidium is poor. We aim to provide a review of the biology, morphology and ecology of Psidium, a phylogenetic tree, an infrageneric classification and a list of species. METHODS: Morphological and geographic data were obtained by studying Psidium in herbaria and in the field between 1988 and 2020. Forty-six herbaria were visited personally. A database of approx. 6000 specimens was constructed, and the literature was reviewed. Thirty species (about a third of the species in the genus) were sampled for molecular phylogenetic inference. Two chloroplast (psbA–trnH and ndhF) and two nuclear (external transcribed spacer and internal transcribed spacer) regions were targeted. Phylogenetic trees were constructed using maximum likelihood (ML; RaxML) and Bayesian inference (BI; MrBayes). KEY RESULTS: Psidium is a monophyletic genus with four major clades recognized as sections. Section Psidium (ten species), to which P. guajava belongs, is sister to the rest of the genus; it is widespread across the Neotropics. Section Obversifolia (six species; restricted to the Brazilian Atlantic Forest), which includes P. cattleyanum, is sister to the innermost clade composed of sister sections Apertiflora (31 species; widespread but most diverse in the Brazilian Atlantic Forest) + Mitranthes (26 species; widespread in dry forests and probably diverse in the Caribbean). Characters associated with diversification within Psidium are discussed. CONCLUSIONS: Research on pre-foliation, colleters, leaf anatomy, leaf physiology, staminal development, placentation and germination associated with the anatomy of the opercular plug is desirable. Studies are biased towards sections Psidium and Obversifolia, with other sections poorly known