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The study of pollen morphology has historically allowed evolutionary biologists to assess phylogenetic relationships among Angiosperms, as well as to better understand the fossil record. During this process, pollen has mainly been studied by discretizing some of its main characteristics such as size, shape, and exine ornamentation. One large plant clade in which pollen has been used this way for phylogenetic inference and character mapping is the order Myrtales, composed by the small families Alzateaceae, Crypteroniaceae, and Penaeaceae (collectively the \"CAP clade\"), as well as the large families Combretaceae, Lythraceae, Melastomataceae, Myrtaceae, Onagraceae and Vochysiaceae. In this study, we present a novel way to study pollen evolution by using quantitative size and shape variables. We use morphometric and morphospace methods to evaluate pollen change in the order Myrtales using a time-calibrated, supermatrix phylogeny. We then test for conservatism, divergence, and morphological convergence of pollen and for correlation between the latitudinal gradient and pollen size and shape. To obtain an estimate of shape, Myrtales pollen images were extracted from the literature, and their outlines analyzed using elliptic Fourier methods. Shape and size variables were then analyzed in a phylogenetic framework under an Ornstein-Uhlenbeck process to test for shifts in size and shape during the evolutionary history of Myrtales. Few shifts in Myrtales pollen morphology were found which indicates morphological conservatism. Heterocolpate, small pollen is ancestral with largest pollen in Onagraceae. Convergent shifts in shape but not size occurred in Myrtaceae and Onagraceae and are correlated to shifts in latitude and biogeography. A quantitative approach was applied for the first time to examine pollen evolution across a large time scale. Using phylogenetic based morphometrics and an OU process, hypotheses of pollen size and shape were tested across Myrtales. Convergent pollen shifts and position in the latitudinal gradient support the selective role of harmomegathy, the mechanism by which pollen grains accommodate their volume in response to water loss.

Abstract Sympatry and evolution in Myrcia Myrcia spectabilis DC. has a wide distribution in the south and southeast Brazilian regions. M. guarujana Sobral, Magenta & Caliari is known from the few collections in submontane ombrophilous forest and a transitional site between restinga and ombrophilous forest in São Paulo state. These species are morphologically similar and occur in sympatry, which prompted us to investigate the morphological aspects, sequence the genomes and consider the effects of such sympatry. In a fragment of Brasilian Atlantic rainforest, we collected leaves from individuals of M. guarujana and M. spectabilis. Morphological analysis and DNA extraction were performed for sequencing and construction of the GBS library. A total of 3,429 loci containing neutral SNP markers were identified, and 446 represented outlier loci. The fixation index (FST) had a high value (0.735; p < 0.05). By AMOVA, the highest variance percentage found was 73.54% (P = 0.0079) between the species. Principal component analysis presented two clusters referring to the species, with the MS1 (M. spectabilis- 1) sample isolated from both. On the neighbour-joining dendrogram, both species presented strongly sustained branches (100 and 99, respectively), and MS1 emerged as an intermediate. Among the outlier loci, we have LNG1, which promotes foliar elongation, and MYB82, a transcription activator functionally equivalent to GL1, in which high levels of expression result in decreased trichome abundance. Studies with more representative samples, together with the discovery of the SNPs found here, will constitute a powerful tool to understand the evolution, diversification, and conservation of these two species. Resumo Simpatria e evolução em Myrcia Myrcia spectabilis DC. tem ampla distribuição nas regiões sul e sudeste do Brasil. M. guarujana Sobral, Magenta & Caliari é conhecida das poucas coletas em floresta ombrófila submontana e em um local de transição entre restinga e floresta ombrófila do estado de São Paulo. Essas espécies são morfologicamente semelhantes e ocorrem em simpatria, o que nos levou a investigar os aspectos morfológicos, sequenciar os genomas e considerar os efeitos dessa simpatria. Em um fragmento de floresta atlântica brasileira, coletamos folhas de indivíduos de M. guarujana e M. spectabilis. Análise morfológica e extração de DNA foram realizadas para sequenciamento e construção da biblioteca GBS. Um total de 3.429 loci contendo marcadores SNP neutros foram identificados e 446 representaram loci outliers. O índice de fixação (FST) teve um valor alto (0,735; P < 0,05). Por AMOVA, o maior percentual de variância entre as espécies encontrado foi de 73,54% (P = 0,0079). A análise de PCA apresentou dois clusters referentes às espécies, com a amostra MS1 (M. spectabilis 1) isolada de ambos. No dendrograma neighbor-joining, ambas as espécies apresentaram ramificações fortemente sustentadas (100 e 99, respectivamente) e MS1 emergiu como um táxon intermediário. Entre os loci outliers, temos LNG1, que promove alongamento foliar, e MYB82, um ativador de transcrição funcionalmente equivalente a GL1, no qual altos níveis de expressão resultam em diminuição da abundância de tricomas. Estudos com amostras mais representativas, juntamente com a descoberta dos SNPs encontrados aqui, constituirão uma ferramenta poderosa para entender a evolução, diversificação e conservação dessas duas espécies.

The leaves of Myrcia DC. ex Guill species are used in traditional medicine and are also exploited commercially as herbal drugs for the treatment of diabetes mellitus. The present work aimed to assess the qualitative and quantitative profiles of M. bella hydroalcoholic extract, due to these uses, since the existing legislation in Brazil determines that a standard method must be developed in order to be used for quality control of raw plant materials. The current study identified eleven known flavonoid-O-glycosides and six acylated flavonoid derivatives of myricetin and quercetin, together with two kaempferol glycosides and phenolic acids such as caffeic acid, ethil galate, gallic acid and quinic acid. In total, 24 constituents were characterized, by means of extensive preparative chromatographic analyses, along with MS and NMR techniques. An HPLC-PAD-ESI-IT-MS and FIA-ESI-IT-MS(n) method were developed for rapid identification of acylated flavonoids, flavonoid-O-glycosides derivatives of myricetin and quercetin and phenolic acids in the hydroalcoholic M. bella leaves extract. The FIA-ESI-IT-MS techinique is a powerful tool for direct and rapid identification of the constituents after isolation and NMR characterization. Thus, it could be used as an initial method for identification of authentic samples concerning quality control of Myrcia spp extracts.

Previous molecular phylogenetic analyses have resolved the Australian bloodwood eucalypt genus Corymbia (~100 species) as either monophyletic or paraphyletic with respect to Angophora (9-10 species). Here we assess relationships of Corymbia and Angophora using a large dataset of chloroplast DNA sequences (121,016 base pairs; from 90 accessions representing 55 Corymbia and 8 Angophora species, plus 33 accessions of related genera), skimmed from high throughput sequencing of genomic DNA, and compare results with new analyses of nuclear ITS sequences (119 accessions) from previous studies. Maximum likelihood and maximum parsimony analyses of cpDNA resolve well supported trees with most nodes having >95% bootstrap support. These trees strongly reject monophyly of Corymbia, its two subgenera (Corymbia and Blakella), most taxonomic sections (Abbreviatae, Maculatae, Naviculares, Septentrionales), and several species. ITS trees weakly indicate paraphyly of Corymbia (bootstrap support <50% for maximum likelihood, and 71% for parsimony), but are highly incongruent with the cpDNA analyses, in that they support monophyly of both subgenera and some taxonomic sections of Corymbia. The striking incongruence between cpDNA trees and both morphological taxonomy and ITS trees is attributed largely to chloroplast introgression between taxa, because of geographic sharing of chloroplast clades across taxonomic groups. Such introgression has been widely inferred in studies of the related genus Eucalyptus. This is the first report of its likely prevalence in Corymbia and Angophora, but this is consistent with previous morphological inferences of hybridisation between species. Our findings (based on continent-wide sampling) highlight a need for more focussed studies to assess the extent of hybridisation and introgression in the evolutionary history of these genera, and that critical testing of the classification of Corymbia and Angophora requires additional sequence data from nuclear genomes.

Fire is a major modifier of communities, but the evolutionary origins of its prevalent role in shaping current biomes are uncertain. Australia is among the most fire-prone continents, with most of the landmass occupied by the fire-dependent sclerophyll and savanna biomes. In contrast to biomes with similar climates in other continents, Australia has a tree flora dominated by a single genus, Eucalyptus , and related Myrtaceae. A unique mechanism in Myrtaceae for enduring and recovering from fire damage likely resulted in this dominance. Here, we find a conserved phylogenetic relationship between post-fire resprouting (epicormic) anatomy and biome evolution, dating from 60 to 62 Ma, in the earliest Palaeogene. Thus, fire-dependent communities likely existed 50 million years earlier than previously thought. We predict that epicormic resprouting could make eucalypt forests and woodlands an excellent long-term carbon bank for reducing atmospheric CO 2 compared with biomes with similar fire regimes in other continents. Trees of the genus Eucalyptus dominate the flora in Australia and can undergo resprouting after fire. Here, fossils and DNA of eucalypts reveal that the resprouting feature of the trees can be linked to the evolution of fire biomes, and that this likely began 60 million years ago.

Background Rose myrtle ( Rhodomyrtus tomentosa (Ait.) Hassk), is an evergreen shrub species belonging to the family Myrtaceae, which is enriched with bioactive volatiles (α-pinene and β-caryophyllene) with medicinal and industrial applications. However, the mechanism underlying the volatile accumulation in the rose myrtle is still unclear. Results Here, we present a chromosome-level genomic assembly of rose myrtle (genome size = 466 Mb, scaffold N50 = 43.7 Mb) with 35,554 protein-coding genes predicted. Through comparative genomic analysis, we found that gene expansion and duplication had a potential contribution to the accumulation of volatile substances. We proposed that the action of positive selection was significantly involved in volatile accumulation. We identified 43 TPS genes in R. tomentosa . Further transcriptomic and TPS gene family analyses demonstrated that the distinct gene subgroups of TPS may contribute greatly to the biosynthesis and accumulation of different volatiles in the Myrtle family of shrubs and trees. The results suggested that the diversity of TPS-a subgroups led to the accumulation of special sesquiterpenes in different plants of the Myrtaceae family. Conclusions The high quality chromosome-level rose myrtle genome and the comparative analysis of TPS gene family open new avenues for obtaining a higher commercial value of essential oils in medical plants.

Myrcia genus plants, like Myrcia pubipetala, traditionally used as hypoglycemic agents, hold promise for Type 1 Diabetes Mellitus (DM1) research but need more comprehensive chemical and pharmacological investigation. This is an experimental study involving controlled administration of treatments to a group of rats to assess their effects compared with a control group, investigating the effects of M. pubipetala on alloxan-induced Type 1 Diabetes Mellitus in rats. After the induction of diabetes, the rats received the hydroalcoholic extract (HAE) or aqueous fraction (AF) (25, 50, 100, or 150 mg kg-1) of M. pubipetala, or water. The results showed that diabetic rats presented cell damage in kidneys, oxidative stress, and high levels of glucose and triglycerides in their plasma and erythrocytes. The HAE (150 mg kg-1), per se, reduced lipid and protein oxidation, and the AF (150 mg kg-1) decreased lipoperoxidation. AF (150 mg kg-1), per se, decreased triglyceride levels. Conclusion: treatment with HAE and AF reduced oxidative damage, positively modulated antioxidant defenses, and exerted hypoglycemic and hypolipidemic effects, representing a potential adjuvant treatment for diabetes.

The Surinam cherry tree is a native Brazilian fruit tree with potential for use in several segments. Normally, it is propagated by seeds, but its biggest obstacle is the fact that it is recalcitrant, making its germination capacity unviable if stored in an unsuitable environment. The objective of this work was to evaluate the viability of Surinam cherry seeds stored under natural environmental conditions and freezing and cooling temperatures, in three different packages (ziplock, kraft paper and vacuum) during nine periods (0, 5, 10, 15, 20, 25, 30, 60 and 90 days). The study was carried out at UTFPR - Campus Dois Vizinhos. The experimental design used was completely randomized, adopting analysis for each type of packaging in a 3 x 9 factorial scheme (storage temperature x period), with four replications of 50 seeds per experimental unit. The germination, germination speed index and average germination time were analyzed. According to the results, the Surinam cherry seeds lost their viability in Kraft paper, vacuum and ziplock packaging from the thirtieth day onwards when kept in natural and cooling conditions. The seeds did not tolerate the use of freezing temperatures, regardless of the maintenance period. Under natural conditions, using Kraft paper packaging, germination remained above 40% up to five days, different from other environments, in which vacuum and ziplock remained up to 15 days in natural conditions and, from 25 to 30 days under cooling, respectively. The Surinam cherry tree is a native Brazilian fruit tree with potential for use in several segments. Normally, it is propagated by seeds, but its biggest obstacle is the fact that it is recalcitrant, making its germination capacity unviable if stored in an unsuitable environment. The objective of this work was to evaluate the viability of Surinam cherry seeds stored under natural environmental conditions and freezing and cooling temperatures, in three different packages (ziplock, kraft paper and vacuum) during nine periods (0, 5, 10, 15, 20, 25, 30, 60 and 90 days). The study was carried out at UTFPR - Campus Dois Vizinhos. The experimental design used was completely randomized, adopting analysis for each type of packaging in a 3 x 9 factorial scheme (storage temperature x period), with four replications of 50 seeds per experimental unit. The germination, germination speed index and average germination time were analyzed. According to the results, the Surinam cherry seeds lost their viability in Kraft paper, vacuum and ziplock packaging from the thirtieth day onwards when kept in natural and cooling conditions. The seeds did not tolerate the use of freezing temperatures, regardless of the maintenance period. Under natural conditions, using Kraft paper packaging, germination remained above 40% up to five days, different from other environments, in which vacuum and ziplock remained up to 15 days in natural conditions and, from 25 to 30 days under cooling, respectively.

Myrcia section Aulomyrcia includes ∼120 species that are endemic to the Neotropics and disjunctly distributed in the moist Amazon and Atlantic coastal forests of Brazil. This paper presents the first comprehensive phylogenetic study of this group and this phylogeny is used as a basis to evaluate recent classification systems and to test alternative hypotheses associated with the history of this clade. Fifty-three taxa were sampled out of the 120 species currently recognized, plus 40 outgroup taxa, for one nuclear marker (ribosomal internal transcribed spacer) and four plastid markers (psbA-trnH, trnL-trnF, trnQ-rpS16 and ndhF). The relationships were reconstructed based on Bayesian and maximum likelihood analyses. Additionally, a likelihood approach, 'geographic state speciation and extinction', was used to estimate region- dependent rates of speciation, extinction and dispersal, comparing historically climatic stable areas (refugia) and unstable areas. Maximum likelihood and Bayesian inferences indicate that Myrcia and Marlierea are polyphyletic, and the internal groupings recovered are characterized by combinations of morphological characters. Phylogenetic relationships support a link between Amazonian and north-eastern species and between north-eastern and south-eastern species. Lower extinction rates within glacial refugia suggest that these areas were important in maintaining diversity in the Atlantic forest biodiversity hotspot. This study provides a robust phylogenetic framework to address important ecological questions for Myrcia s.l. within an evolutionary context, and supports the need to unite taxonomically the two traditional genera Myrcia and Marlierea in an expanded Myrcia s.l. Furthermore, this study offers valuable insights into the diversification of plant species in the highly impacted Atlantic forest of South America; evidence is presented that the lowest extinction rates are found inside refugia and that range expansion from unstable areas contributes to the highest levels of plant diversity in the Bahian refugium.

Some of the most spectacular adaptive radiations begin with founder populations on remote islands. How genetically limited founder populations give rise to the striking phenotypic and ecological diversity characteristic of adaptive radiations is a paradox of evolutionary biology. We conducted an evolutionary genomics analysis of genus Metrosideros, a landscape-dominant, incipient adaptive radiation of woody plants that spans a striking range of phenotypes and environments across the Hawaiian Islands. Using nanopore-sequencing, we created a chromosome-level genome assembly for Metrosideros polymorpha var. incana and analyzed whole-genome sequences of 131 individuals from 11 taxa sampled across the islands. Demographic modeling and population genomics analyses suggested that Hawaiian Metrosideros originated from a single colonization event and subsequently spread across the archipelago following the formation of new islands. The evolutionary history of Hawaiian Metrosideros shows evidence of extensive reticulation associated with significant sharing of ancestral variation between taxa and secondarily with admixture. Taking advantage of the highly contiguous genome assembly, we investigated the genomic architecture underlying the adaptive radiation and discovered that divergent selection drove the formation of differentiation outliers in paired taxa representing early stages of speciation/divergence. Analysis of the evolutionary origins of the outlier single nucleotide polymorphisms (SNPs) showed enrichment for ancestral variations under divergent selection. Our findings suggest that Hawaiian Metrosideros possesses an unexpectedly rich pool of ancestral genetic variation, and the reassortment of these variations has fueled the island adaptive radiation.