Myrtaceae Species Research Articles

Gap-free genome assembly and comparative analysis reveal the evolution and anthocyanin accumulation mechanism of Rhodomyrtus tomentosa.

Rhodomyrtus tomentosa is an important fleshy-fruited tree and a well-known medicinal plant of the Myrtaceae family that is widely cultivated in tropical and subtropical areas of the world. However, studies on the evolution and genomic breeding of R. tomentosa were hindered by the lack of a reference genome. Here, we presented a chromosome-level gap-free T2T genome assembly of R. tomentosa using PacBio and ONT long read sequencing. We assembled the genome with size of 470.35Mb and contig N50 of ~43.80Mb with 11 pseudochromosomes. A total of 33 382 genes and 239.31Mb of repetitive sequences were annotated in this genome. Phylogenetic analysis elucidated the independent evolution of R. tomentosa starting from 14.37MYA and shared a recent WGD event with other Myrtaceae species. We identified four major compounds of anthocyanins and their synthetic pathways in R. tomentosa. Comparative genomic and gene expression analysis suggested the coloring and high anthocyanin accumulation in R. tomentosa tends to be determined by the activation of anthocyanin synthesis pathway. The positive selection and up-regulation of MYB transcription factors were the implicit factors in this process. The copy number increase of downstream anthocyanin transport-related OMT and GST gene were also detected in R. tomentosa. Expression analysis and pathway identification enriched the importance of starch degradation, response to stimuli, effect of hormones, and cell wall metabolism during the fleshy fruit development in Myrtaceae. Our genome assembly provided a foundation for investigating the origins and differentiation of Myrtaceae species and accelerated the genetic improvement of R. tomentosa.

The complete chloroplast genome of a fast-growing tree Lophostemon confertus (Myrtaceae)

Lophostemon confertus (Myrtaceae), a fast-growing ornamental tree, is widely cultivated in tropical and subtropical regions. To determine its phylogenetic position within Myrtaceae, here we report its complete chloroplast (cp) genome, which is 160,297 bp long and contains two inverted repeats (IRs) of 26,490 bp each, separated by a small single-copy region of 18,826 bp and a large single-copy region of 88,491 bp. The cp genome contains 123 genes, including 73 unique protein-coding genes (six duplicated in the IR regions), 29 unique tRNA genes (seven duplicated in the IR regions), and four unique rRNA genes (all located in the IR regions). Phylogenetic analysis of 18 species of Myrtaceae showed that L. confertus is sister to Xanthostemon chrysanthus. The complete cp genome of L. confertus provides a valuable genetic resource for further phylogenetic studies.

Natural parasitism in fruit fly (Diptera: Tephritidae) and interaction with wild hosts surrounding apple orchards adjacent to Atlantic Forest fragments in Paraná State, Brazil.

The South American fruit fly, Anastrepha fraterculus (Wiedemann, 1830) (Diptera: Tephritidae), is an important pest in the subtropical region of Brazil. This insect has tritrophic relation between wild fruits and parasitoids and is associated with apple (Malus domestica Borkh.) orchards adjacent to the Atlantic Forest in Paraná. We thus investigated the degree of infestation of the fruit fly and natural parasitism in wild and cultivated fruits surrounding apple orchards. For this purpose, we collected fruits of Acca sellowiana (Berg.) Burret, Campomanesia xanthocarpa (Mart), Eugenia uniflora L., Eugenia pyriformis Cambessèdes, Psidium cattleianum Sabine, Psidium guajava (L.), Annona neosericea Rainer and Eriobotrya japonica (Thumb) in apple orchards adjacent to the Atlantic Forest located in Campo do Tenente, Lapa and Porto Amazonas counties. In total, we collected 18,289 fruits during four growing years. The occurrence of A. fraterculus depends on the susceptible period of apple fruits. A. sellowiana and P. cattleianum were considered primary fruit fly multipliers and P. guajava was secondary, all occurring after the apple harvest (IS period). The group of parasitoids with A. fraterculus was Aganaspis pelleranoi (Brèthes, 1924) (Hymenoptera: Figitidae), Opius bellus (Gahan, 1930), Doryctobracon areolatus (Szépligeti, 1911) and Doryctobracon brasiliensis (Szépligeti, 1911) (Hymenoptera: Braconidae) all of which are first records in the Atlantic Forest in Paraná. First record of O. bellus occurring in the State of Paraná, as well as, first record of the tritrophic association between host plant A. neosericea, parasitoids D. areolatus and O. bellus and fruit fly A. fraterculus. The host P. cattleianum stood out among the Myrtaceae species in regard to the high diversity of parasitoid species (81% of parasitoids). The total number of Figitidae species (76.5%) was higher than that of Braconidae species. The influence of climatic events in southern Brazil on wild fruit production should be further studied to understand the association of A. fraterculus with the tritrophic relationship.

Floristic inventory of Myrtaceae of Parque Nacional do Iguaçu, Paraná, Brazil

Abstract Myrtaceae is a diverse family in Brazil and the sixth most representative family in the Atlantic Forest. In Paraná, the Parque Nacional do Iguaçu (ParNa Iguaçu) is a large National Park and also one of the largest remnants of this phytogeographic domain. The objective of the present study was to carry out a floristic inventory of the Myrtaceae of the ParNa Iguaçu, presenting an identification key to the species, illustrations, conservation status evaluation, and comments on geographic distribution and phenology. The collections were carried out between May 2019 and March 2020 in two areas composed of Seasonal Semideciduous Forest and a transitional area to Mixed Ombrophilous Forest. In addition to the samples collected by us, material from other herbaria were also examined. Twenty-five native species and one exotic species of Myrtaceae were found, distributed in seven genera. Eugenia was the most representative genus with 11 species. Of the 26 species, seven are new occurrences for ParNa Iguaçu. From the samples collected in this research and other records in the northwest and west regions of the state of Paraná, the presence of Psidium striatulum in Seasonal Semideciduous Forest is confirmed. Eugenia myrciariifolia was the only species on Brazil’s endangered species list, the IUCN conservation status of which is Endangered (EN). The other species were considered as Least Concern (LC), but some of these species are restricted to certain areas or types of vegetation. Therefore, we conclude that ParNa Iguaçu contributes to the maintenance of these species in their natural environment.

Transferability of SSR markers from Eugenia uniflora L. to Myrtaceae species of the Atlantic Forest

Transferability of SSR markers from Eugenia uniflora L. to Myrtaceae species of the Atlantic Forest

Isolamento, identificação molecular e controle in vitro de bacterias endógenas de Campomanesia rufa (O. Berg) Nied.

ABSTRACT Campomanesia rufa (O. Berg) Nied. is a Myrtaceae species native to the Brazilian Cerrado. As C. rufa is considered endangered, in vitro propagation is an alternative for its conservation. However, the lack of effective disinfection protocols for endophytic microorganisms naturally present in plant tissues hinders the success of micropropagation. In this context, the objective of this study was to isolate, molecular identify, and control endogenous occurring bacteria of C. rufa propagated in vitro. Purified PCR products of bacterial isolates were sequenced by the Sanger method and aligned with homologous sequences using the Basic Local Alignment Search Tool (BLAST) available in National Centre for Biotechnology Information (NCBI) database. MEGA7 software was used to align all sequences and to draw phylogenetic trees. Survival, shoot height, and efficiency of antibiotics (streptomycin, ampicillin, and chloramphenicol) at different concentrations in the culture medium were evaluated. Different Bacillus sp. strains were observed in the plant tissues. When testing the control of Bacillus sp. with antibiotics, 32 mg L-1 ampicillin caused a significant reduction in bacterial contamination with no effect on explant survival. On the other hand, 256 mg L-1 streptomycin caused the greatest reduction in contamination but was lethal to over 90% of the explants. This study is the first report on the occurrence of endogenous bacteria and their control in the context of in vitro native species conservation.

Collateral damage: epiphytic orchids at risk from myrtle rust

Epiphytic orchids rely on the habitat provided by their plant hosts to survive. The naturalisation of Austropuccinia psidii (G. Winter) Beenken (the causal agent for myrtle rust) in Australia means that some of these plant hosts, from the family Myrtaceae, are at risk of serious decline. We aimed to identify orchid species that associate with myrtaceous host plants and determine which, if any, might be susceptible to loss of habitat as a result of myrtle rust. We reviewed species descriptions and herbarium records and identified 73 epiphytic orchid species that are commonly found growing on myrtaceous hosts. At least seven orchid species are predominantly reliant on myrtaceous hosts, are distributed predominantly in the myrtle rust zone, and have host species that are highly or extremely susceptible to myrtle rust. Four of these orchid species are already listed as threatened. The impact of myrtle rust is broader than causing decline of Myrtaceae species, with knock-on effects on other biota, including epiphytic orchids. Moreover, there is the potential for further impact on these orchids through fragmentation (e.g. affecting pollination) and interactive effects with fire. Increased effort is required to identify the relative frequency of myrtaceous and non-myrtaceous hosts for these epiphytic orchid species, especially in relation to the compound effects of myrtle rust and other perturbations, such as fire and climate change. Where this is not possible, ex situ conservation may be required.

Are the anatomical traits of stems and leaves good indicators of habitat specificity in closely related Myrtaceae species from Patagonia?

Are the anatomical traits of stems and leaves good indicators of habitat specificity in closely related Myrtaceae species from Patagonia?

Characterization of Nitrogen Use by Neotropical Myrtaceae in Dry and Wet Forests of Southeast Brazil

We hypothesized that neotropical Myrtaceae could be organized into groups that are naturally less or non-responsive to NO3−, and that use other N forms, such as amino acids, for internal N transport. Ecophysiological tests were conducted to measure nitrate reductase activity (NRA), NO3− content, total N, δ15N natural abundance, the C:N ratio in leaves, free amino acid, and NO3− transport via xylem sap. We showed that Myrtaceae tree species have a relatively low NRA, in addition to little NO3− in leaves and free NO3− in the xylem sap during the wet and dry seasons. We suggested a possible compartmentalization of N use, wherein plants derive their internal N from and use their transport mechanism to move N between below-ground and above-ground parts, assimilating and transporting more N and C through amino acids such as glutamine, arginine, and citrulline. Evidence of low NO3− availability in tropical soils is important when trying to understand forest species’ N-use strategies, given their importance to plant nutrition. Differences in the responses of some Myrtaceae species to the seasonality of environmental factors suggest the need for further studies concerning N in natural forests, for example, to help understand the problem of N deposition ecosystems.

Environmental monitoring for invasive fungal pathogens of ʽŌhiʽa (Metrosideros polymorpha) on the Island of Hawaiʽi

The invasive rust Austropuccina psidii was detected in the Hawaiian Islands in 2005 and has become widely established throughout the archipelago in both native and introduced species of Myrtaceae. Initial predictions about the impacts of the fungus on native ʽōhiʽa lehua (Metrosideros polymorpha), a keystone native tree, have not materialized, but there is ongoing concern that introductions of new genotypes of the fungus could lead to widespread mortality with catastrophic effects on native ecosystems. By contrast, two recently emergent Ascomycete pathogens, Ceratocystis lukuohia (Ceratocystis wilt of ‘ōhi‘a) and C. huliohia (Ceratocystis canker of ‘ōhi‘a), collectively known to cause Rapid ʽŌhiʽa Death (ROD), are causing significant mortality in native forests on Hawaiʻi and Kauaʻi Islands, but pathways of spread are still incompletely understood. We used a network of passive environmental samplers for collecting windblown urediniospores of Austropuccina to evaluate the effectiveness of environmental monitoring to detect seasonal and landscape-scale differences in airborne propagules of this rust on Hawai`i Island. The samplers were also used to determine if windborn ambrosia beetle frass or spores of Ceratocystis can spread long distances. We found frequent detections and regional and seasonal differences in numbers of samplers that were positive for urediniospores of Austropuccinia, but little evidence of long-distance airborne dispersal of the ROD-causing fungi. The simple, inexpensive platform for sampling airborne fungal spores that we used may have value as a monitoring tool for detecting spread of airborne fungal pathogens, evaluating habitats for suitability for restoration efforts, and for detecting new pathogen introductions, particularly new Austropuccinia genotypes both in Hawaiʻi and other parts of the world.

A new C-methyl-flavone and other compounds from Myrcia guianensis

This study reports the isolation of one new C-methyl-flavone (6,8-dimethyl-4′,5-dihydroxy-3′,7-dimethoxyflavone, 1), along with one C-methyl-flavone (sideroxylin, 2), one known C-methyl-flavonol (quercetin, 3), two C-methyl-flavonol glycosides [(quercitrin, 4) and (guaijaverin, 5)], one lignan (9′,9′-O-feruloyl-(−)-seco-isolaricinresinol, 6) and gallic acid (7) from Myrcia guianensis (Aubl.) DC. The structural elucidation of compounds 1–7 was performed based on the detailed analysis of their NMR spectra and the comparison with the literature. This is the first report of compound 2 in the genus Myrcia and of compounds 3, 4, and 5 in M. guianensis, whereas compound 6 has not been isolated from any species of the Myrtaceae family. C-methyl-flavonoids are frequently isolated from Myrtaceae species; thus, the occurrence of C-methyl-flavones and C-methyl-flavonols in M. guianensis may present chemophenetics relevance to the consolidation of the genus Myrcia within the Myrtaceae family.

Glimpsing the chemical composition and the potential of Myrtaceae plant extracts against the food spoilage fungus Thielaviopsis ethacetica

• Native Brazilian Myrtaceae species are promising against Thielaviopsis ethacetica fungus. • Percentages of mycelial inhibition above 80% were observed. • Two Myrtaceae extracts showed fungistatic action. • Promising Myrtaceae extracts inhibited conidial germination. • 13 metabolites are annotated in the polar extract of Myrcia amazonica. • Flavonoids are predominant in Myrciaria floribunda extract according to LC-HRMS/MS analysis.

Meta-analysis of the influence of seasonality on the chemical composition of essential oils from Myrtaceae species

Myrtaceae is one of the most important families in the Neotropics, with 23 genera and 990 species occurring in Brazil. Seasonal environmental changes can cause alterations in the secondary metabolism of plants and, consequently, in the chemical composition, yield and biological activity of essential oils. The aim of the present study was to determine the influence of seasonality on the chemical composition of essential oils from Myrtaceae species through the technique of meta-analysis. The articles were obtained from searches carried out in Journal Databases (Web Of Science, Scorpus and Science Direct) following the PRISMA protocol. The data that composed this study were binary data (presence or absence) of the influence of seasonality on the composition of essential oils of Myrtaceae species. The meta-analysis effect size was derived from the observational comparison of data obtained from the primary articles available in the literature, which was statistically relevant. The conclusion of the meta-analysis was that seasonality significantly influences the chemical composition of essential oils from Myrtaceae species. The heterogeneity test corroborate the results obtained in the meta-analysis. Determination of the influence of seasonality on the chemical composition of essential oils of Myrtaceae species, through the meta-analysis technique according to the PRISMA protocol for a systematic literature review. • The influence of seasonality on the chemical composition of essential oils from Myrtaceae species was investigated. • The PRISMA protocol methodology was used in the Systematic Literature Review to apply the meta-analysis technique. • Meta-analysis indicated that seasonality significantly influences the chemical composition of the oil of Myrtaceae species.

Phytochemical Profile, Preliminary Toxicity, and Antioxidant Capacity of the Essential Oils of Myrciaria floribunda (H. West ex Willd.) O. Berg. and Myrcia sylvatica (G. Mey) DC. (Myrtaceae).

The essential oils (EOs) of Myrciaria floribunda (Mflo) and Myrcia sylvatica (Msyl) (Myrtaceae) were obtained by hydrodistillation. The analysis of volatile constituents was performed by GC/MS. Preliminary toxicity was assessed on Artemia salina Leach. The antioxidant capacity was measured by the ABTS•+ and DPPH• radical inhibitory activities. The results indicate that the Mflo EO had the highest yield (1.02%), and its chemical profile was characterized by high levels of hydrocarbon (65.83%) and oxygenated (25.74%) monoterpenes, especially 1,8-cineole (23.30%), terpinolene (22.23%) and α-phellandrene (22.19%). Regarding the Msyl EO, only hydrocarbon (51.60%) and oxygenated (46.52%) sesquiterpenes were identified in the sample, with (Z)-α-trans-bergamotene (24.57%), α-sinensal (13.44%), and (Z)-α-bisabolene (8.33%) at higher levels. The EO of Mflo exhibited moderate toxicity against A. salina (LC50 = 82.96 ± 5.20 µg.mL-1), while the EO of Msyl was classified as highly toxic (LC50 = 2.74 ± 0.50 µg.mL-1). In addition, relative to Trolox, the EOs of Mflo and Msyl showed significant inhibitory effects (p < 0.0001) against the DPPH• radical. This study contributes to the expansion of chemical and biological knowledge on the EOs of Myrtaceae species from the Amazon region.

Two new species of Myrtaceae from the western Caribbean forests of Panama

Two previously unrecognized species of Myrtaceae, Myrcia damaniensis and Eugenia tain, from the Western Caribbean coastal and swamp forests of Panama are named and described. Their conservation status is evaluated based on the categories and criteria of the IUCN.

Myrcia paivae O.Berg (Myrtaceae) Essential Oil, First Study of the Chemical Composition and Antioxidant Potential.

The Myrtaceae family is one of the most representative in the Amazon. Several species have high added-value pharmacological potential. In order to contribute to the knowledge of the aromatic profile of Myrtaceae species from the Amazon, the present study presents the first report on the productivity, chemical composition, and antioxidant profile of the essential oil (EO) of Myrcia paivae. Dry leaves of the species were submitted to hydrodistillation to obtain their EO. The EO performance was calculated on a moisture-free basis and the analysis of the chemical profile was carried out by GC/MS. The determination of the antioxidant capacity was assessed by means of the antioxidant capacity equivalent to the inhibition Trolox of the ABTS•+ and DPPH• radicals. The results indicate that EO performance was equivalent to 1.69%. As for the chemical composition, hydrocarbon monoterpenes were predominant in the sample (>77%); terpinolene (14.70%), α-phellandrene (14.69%), γ-terpinene (9.64%), sylvestrene (7.62%), α-thujene (6.46%), and α-pinene (6.39%) were the constituents with higher content. Regarding the antioxidant capacity, the results show that the EO presented good results in the inhibition of ABTS•+ (0.886 ± 0.226 mM L−1) and DPPH• (2.90 ± 0.083 mM L−1), which can be attributed to the high monoterpene content in the sample.

Phloroglucinols with hAChE and α-glucosidase inhibitory activities from the leaves of tropic Rhodomyrtus tomentosa

Four undescribed phloroglucinol meroterpenoids, rhodotomentodiones A–D, and one undescribed phloroglucinol dimer, rhodotomentodimer A, were obtained and structurally established from tropic Rhodomyrtus tomentosa leaves. Their structures were unambiguously elucidated based on the comprehensive analyses of the NMR and MS spectroscopic data, electronic circular dichroism (ECD) calculation, and single-crystal X-ray diffraction. In particular, rhodotomentodiones A and B represent the first examples of phloroglucinol meroterpenoids featuring a unique γ-pyranoid moiety. More importantly, rhodotomentodimer A exhibited the most potential human acetylcholinesterase (hAChE) and α-glucosidase inhibitory effects with IC50 values of 7.5 μM and 5.6 μM, respectively. The possible interaction sites of the above potential hAChE and α-glucosidase inhibitor were achieved by molecular docking studies. These findings greatly enrich the diversity of natural products from Myrtaceae species, and provide potential candidates for the further development of anti-Alzheimer and antidiabetic diseases.

Complete chloroplast genome sequence of Syzygium samarangense (Myrtaceae) and phylogenetic analysis

Syzygium samarangense (Blume) Merr. et Perry, 1938, commonly known as wax apple, is a Myrtaceae species that is known for its unique fruit shape, flavorful and colorful fruits, medicinal value and increasing economic relevance. In this study, we reported the complete chloroplast genome sequence of S. samarangense. The complete genome is 159,109 bp in length with a quadripartite structure containing two single copy regions, a Large Single Copy region (LSC, 88,155 bp) and a Small Single Copy region (SSC, 18,796 bp) separated by Inverted Repeat regions (IRs, 26,079 bp). The GC content was 37.0%. It encoded 126 genes, including 81 protein-coding genes, 37 transfer RNA genes, and 8 ribosomal RNA genes. The phylogenetic relationships of 20 species inferred that all Syzygium species formed a single cluster belonging to Syzygieae tribe. Our results offer insights into the evolutionary relationship of S. samarangense within Myrtaceae, indicating a closer relationship between S. samarangense and S. forrestii.

Essential Oils from Different Myrtaceae Species from Brazilian Atlantic Forest Biome - Chemical Dereplication and Evaluation of Antitrypanosomal Activity.

Chagas Disease (CD), caused by flagellate protozoan Trypanosoma cruzi, is a Neglected Tropical Diseases (NTD) that affect approximately seven million people worldwide with a restrict therapeutical arsenal. In the present study, the essential oils from 18 Myrtaceae species were extracted, chemically dereplicated, and evaluated in vitro against T. cruzi. From these, eight essential oils were considered promising (IC50 <10 μg/mL and SI>10) against the protozoan: Eugenia florida, E. acutata, E. widgrenii, Calyptranthes brasilienses, C. widgreniana, Plinia cauliflora, Campomanesia xanthocarpa, and Psidium guajava. Multivariate data analysis pointed out (E)-caryophyllene, α-humulene, limonene, caryophyllene oxide, and α-copaene playing an important role in the anti-T. cruzi activity. The obtained results demonstrated the potential of essential oils of Myrtaceae species as valuable sources of bioactive compounds against T. cruzi.

Myrtaceae in Australia: Use of Cryobiotechnologies for the Conservation of a Significant Plant Family under Threat.

The Myrtaceae is a very large and diverse family containing a number of economically and ecologically valuable species. In Australia, the family contains approximately 1700 species from 70 genera and is structurally and floristically dominant in many diverse ecosystems. In addition to threats from habitat fragmentation and increasing rates of natural disasters, infection by myrtle rust caused by Austropuccinia psidii is of significant concern to Australian Myrtaceae species. Repeated infections of new growth have caused host death and suppressed host populations by preventing seed set. Although most Myrtaceae species demonstrate orthodox seed storage behavior, exceptional species such as those with desiccation sensitive seed or from myrtle rust-suppressed populations require alternate conservation strategies such as those offered by cryobiotechnology. Targeting seven key Australian genera, we reviewed the available literature for examples of cryobiotechnology utilized for conservation of Myrtaceae. While there were only limited examples of successful cryopreservation for a few genera in this family, successful cryopreservation of both shoot tips and embryonic axes suggest that cryobiotechnology provides a viable alternative for the conservation of exceptional species and a potential safe storage method for the many Myrtaceae species under threat from A. psidii.