A Revised Phylogenetic Classification for Viola (Violaceae)

The challenging biogeography of the Juan Fernández Islands and Coast Range of central Chile explained by new models of East Pacific tectonics

Biogeographers have often been puzzled by several unusual features in the Juan Fernández Islands (JFI) biota. These include the very high endemism density, multiple endemics that are older than the current islands, close biogeographic affinities with the central and West Pacific, and affinities with the diverse Coast Range of central Chile. We review aspects of biogeography in the JFI and the Coast Range in light of recent geological studies. These have examined the mantle below the East Pacific and South America, and have produced radical, new ideas on tectonic history. A long-lived, intraoceanic archipelago ~9000 km long is now thought to have existed in the East Pacific (passing between the JFI hotspot and mainland Chile) until the mid-Cretaceous. At this time, South America, which was moving westward with the opening of the Atlantic, collided with the archipelago. The assumption that the JFI biota is no older than its current islands is questionable, as taxa would have survived on prior islands produced at the JFI hotspot. We propose a new interpretation of evolution in the region based on tectonics rather than on island age and incorporating the following factors: the newly described East Pacific Archipelago; a long history for the JFI hotspot; metapopulation dynamics, including metapopulation vicariance; and formation of the Humboldt Current in the Cretaceous. The model accounts for many distinctive features of the JFI and Coast Range biota.

Cyclotides: The next generation in biopesticide development for eco-friendly agriculture

Chemical pesticides remain the predominant method for pest management in numerous countries. Given the current landscape of agriculture, the development of biopesticides has become increasingly crucial. The strategy empowers farmers to efficiently manage pests and diseases, while prioritizing minimal adverse effects on the environment and human health, hence fostering sustainable management. In recent years, there has been a growing interest and optimism surrounding the utilization of peptide biopesticides for crop protection. These sustainable and environmentally friendly substances have been recognized as viable alternatives to synthetic pesticides due to their outstanding environmental compatibility and efficacy. Numerous studies have been conducted to synthesize and identify peptides that exhibit activity against significant plant pathogens. One of the peptide classes is cyclotides, which are cyclic cysteine-rich peptides renowned for their wide range of sequences and functions. In this review, we conducted a comprehensive analysis of cyclotides, focusing on their structural attributes, developmental history, significant biological functions in crop protection, techniques for identification and investigation, and the application of biotechnology to enhance cyclotide synthesis. The objective is to emphasize the considerable potential of cyclotides as the next generation of plant protection agents on the global scale.

Violasuavis var. pannonica (Violaceae), a new white-flowered violet from central Europe

Violasuavisvar.pannonica (Violaceae) from central Europe is described here as a new variety to science. It is most similar to the blue-flowered V.suavisvar.suavis and the white-flowered V.suavisvar.catalonica and V.suavissubsp.naqshii, but exhibits differences in several characters, such as petal colour, spur shape, fimbriae length on the stipules, bracteoles position on the peduncle and lamina sinus shape. Although the new taxon is often considered a colour mutation of V.suavisvar.suavis, previous genetic analyses revealed that these white-flowered plants do not arise recurrently at different locations (having multiple origins), but rather form a monophyletic evolutionary lineage. To date, the occurrence of V.suavisvar.pannonica has been reported in the Slovak Republic, the Czech Republic and western Ukraine. In this paper, we report its occurrence in Austria and Hungary. Notes on its etymology, distribution, ecology, origin and hybridization, as well as photographs of the new variety (including the holotype) are also provided.

Cyclotides derived from Viola dalatensis Gagnep: A novel approach for enrichment and evaluation of antimicrobial activity

Cyclotides, plant-derived cysteine-rich peptides, exhibit a wide range of beneficial biological activities and possess exceptional structural stability. Cyclotides are commonly distributed throughout the Violaceae family. Viola dalatensis Gagnep, a Vietnamese species, has not been well studied, especially for cyclotides. This pioneering research explores cyclotides from V. dalatensis as antimicrobials. This study used a novel approach to enhance cyclotides after extraction. The approach combined 30% ammonium sulfate salt precipitation and RP-HPLC. A comprehensive analysis was performed to ascertain the overall protein content, flavonoids content, polyphenol content, and free radical scavenging capacity of compounds derived from V. dalatensis. Six known cyclotides were sequenced utilizing MS tandem. Semi-purified cyclotide mixtures (M1, M2, and M3) exhibited antibacterial efficacy against Bacillus subtilis (inhibitory diameters: 19.67-23.50 mm), Pseudomonas aeruginosa (22.17-23.50 mm), and Aspergillus flavus (14.67-21.33 mm). The enriched cyclotide precipitate from the stem extract demonstrated a minimum inhibitory concentration (MIC) of 0.08 mg/mL against P. aeruginosa, showcasing significant antibacterial effectiveness compared to the stem extract (MIC: 12.50 mg/mL). Considerable advancements have been achieved in the realm of cyclotides, specifically in their application as antimicrobial agents.

Species-specific effects of production practices on genetic diversity in plant reintroduction programs

Plant production practices can influence the genetic diversity of cultivated plant materials and, ultimately, their potential to adapt to a reintroduction site. A common step in the plant production process is the application of seed pretreatment to alleviate physiological seed dormancy and successfully germinate seeds. In production settings, the seeds that germinate more rapidly may be favored in order to fill plant quotas. In this study, we investigated how the application of cold-moist stratification treatments with different durations can lead to differences in the genetic diversity of the propagated plant materials. Specifically, we exposed seeds of three Viola species to two different cold stratification durations, and then we analyzed the genetic diversity of the resulting subpopulations through double-digestion restriction site-associated sequencing (ddRADseq). Our results show that, in two out of three species, utilizing a short stratification period will decrease the genetic diversity of neutral and expressed loci, likely due to the imposition of a genetic bottleneck and artificial selection. We conclude that, in some species, the use of minimal stratification practices in production may jeopardize the adaptive potential and long-term persistence of reintroduced populations and suggest that practitioners carefully consider the evolutionary implications of their production protocols. We highlight the need to consider the germination ecology of target species when selecting the length of dormancy-breaking pretreatments.

Thallium hyperaccumulation status of the violets of the Allchar arsenic-thallium deposit (North Macedonia) confirmed through synchrotron µXRF imaging

The abandoned Allchar Mine in the Republic of North Macedonia is a globally unique deposit with the highest known grades of thallium (Tl) and arsenic (As) mineralization. We aimed to determine the distribution of As and Tl in whole dehydrated shoots of the three Viola taxa using synchrotron micro-X-ray fluorescence analysis. Additionally, soil and plant organ samples were collected from all three Viola taxa at the Allchar site and analysed using inductively coupled plasma-atomic emission spectrometry. Concentrations of Tl were extremely high in all three Viola taxa (up to 58 900 mg kg-1), but concentrations of As were highly variable with V. tricolor subsp. macedonica and V. allchariensis having low As (up to 20.2 and 26.3 mg kg-1, respectively) and V. arsenica having the highest concentrations (up to 381 mg kg-1). The extremely high Tl in all three species is endogenous and not a result of contamination. Arsenic in V. tricolor subsp. macedonica and V. allcharensis is strongly affected by contamination, but not in V. arsenica where it appears to be endogenous. The pattern of As enrichment in V. arsenica is very unusual and coincides with Ca-oxalate deposits and Br hotspots. The results of this study could form the basis for more detailed investigations under controlled conditions, including plant dosing experiments.

Effect of environmental factors on seed germination and seedling emergence of Viola prionantha, a cleistogamous plant

Environmental conditions during seed development and maturation can affect seed traits and germination behavior, yet systematic research on the effects of seed maturation time on seed traits, germination behavior and seedling emergence of cleistogamy plants is lacking. Here, we determined the difference in phenotypic characteristics of CH and CL (namely CL1, CL2 and CL3 based on maturation time, respectively) fruits/seeds that were collected from Viola prionantha Bunge, a cleistogamous perennial plant, and evaluated the effects of various environmental factors on seed germination and seedling emergence. The fruit mass, width, seed number per fruit and mean seed mass of CL1 and CL3 were greater than that of CH and CL2, while seed setting of CH was lower than that of CL1, CL2 and CL3. Germination of CH, CL1, CL2, and CL3 seeds was < 10% in the dark at 15/5 and 20/10 ℃, whereas germination (0%-99.2%) of CH, CL1, CL2, and CL3 seeds changed significantly under light conditions. In contrast, more than 71% (from 71.7 to 94.2%) germination of both CH, CL1, CL2 and CL3 seeds occurred under both light/dark conditions and continuous darkness at 30/20 ℃. Germination of CH, CL1, CL2 and CL3 seeds was sensitive to osmotic potential, but CL1 seeds were more resistant to osmotic stress, compared with CH, CL2 and CL3. Seedling emergence of CH seeds was more than 67% (from 67.8 to 73.3%) at a burial depth of 0 cm-2 cm, while all types of CL seeds were below 15% at a burial depth of 2 cm. Information gathered from this study indicates that CH and CL seeds of V. prionantha were different in fruit size, seed mass, thermoperiod and photoperiod sensitivity, osmotic potential tolerance and seedling emergence, especially, maturation time significantly affect phenotypic characteristics and germination behavior of CL seeds matured at different periods. These results indicate that V. prionantha adapts to unpredictable environmental conditions by developing a variety of adaptation strategies, and ensures the survival and reproduction of the populations.

An annotated nomenclatural checklist of endemic vascular plants distributed in the Ukrainian Carpathians

Background

The current paper presents a nomenclatural checklist for vascular plants validated being (sub)endemic to and present in the flora of the Ukrainian Carpathians. This checklist is a part of the work targeted on an inventory of endemic plants distributed in the Ukrainian Carpathians. It is mainly based on the analysis of primary sources (i.e. original protologues and monographic works), but also uses the data provided in the recent online taxonomic aggregators, such as the Global Biodiversity Information Facility (GBIF), Catalogue of Life (CoL), Plants of the World Online (POWO), Euro+Med PlantBase, World Flora Online (WFO) and others. Over 7,000 specimens deposited in the leading Ukrainian herbaria were also revised and used as a supporting data source during the work on the checklist.

New information

The checklist provides a revised nomenclature, including corrections on publication dates, rediscovered taxonomic protologues, corrected authorships and revised taxonomic status for (sub)endemic (sub)species of vascular plants occurring in the Ukrainian Carpathians. It contains 1,101 names, from which 78 species and subspecies have been accepted as valid and 1023 species and infraspecific taxa are provided as synonyms. It is completed with critical notes on the nomenclature of problematic taxa and brief annotations regarding their distribution in the Ukrainian Carpathians, indicating the endemicity range and sozological status for all analysed (sub)species.The current checklist is linked with the GBIF taxonomic backbone, provides notes on detected issues and primarily focuses on its update and correction of the nomenclatural issues and taxonomic inconsistencies, but also aims at discussing issues in other popular taxonomic databases.Sabulinapauciflora is proposed as a new combination to comply with a recent revision of the genus Sabulina.

A complete chloroplast genome sequence of Viola albida Palibin 1899 (Violaceae), a member of VIOLA ALBIDA complex

The VIOLA ALBIDA complex is a complicated group with taxonomic problems having continuous leaf variations and composed of taxa related to the following names: Viola albida, V. albida var. takahashii, and V. chaerophylloides. As a first step to understanding the genomic nature of this complex, this study identified the whole chloroplast genome of V. albida. The genome is 157,692 bp in length (36.3% of GC content) and contains four subregions: a large single copy region of 86,220 bp, a small single copy region of 17,248 bp, and a pair of inverted regions of 27,112 bp each. An annotation of the gene identifies 111 unique genes, including 77 protein-coding genes, four rRNA genes, and 30 tRNA genes. The phylogenetic analysis of this genome with selected cp genomes from Viola identifies the close relationship between V. albida and V. ulleungdoensis. It is noteworthy that V. chaerophylloides, traditionally recognized as a member of the VIOLA ALBIDA complex, is genetically distant from V. albida and forms a sister group of all other members of the subsection Patellares. Our genome report is expected to serve as a basis for understanding the identity of the VIOLA ALBIDA complex.