Propagule pressure from historic U.S. plant sales explains establishment but not invasion.

Introduction history, including propagule pressure and residence time, has been proposed as a primary driver of biological invasions. However, it is unclear whether introduction history increases the likelihood that a species will be invasive or only the likelihood that it will be established. Using a dataset of non-native species historically available as ornamental plants in the conterminous United States, we investigated how introduction history relates to these stages of invasion. Introduction history was highly significant and a strong predictor of establishment, but only marginally significant and a poor predictor of invasive success. Propagule pressure predicted establishment better than residence time, with species likely to be established if they were introduced to only eight locations. These findings suggest that ongoing plant introductions will lead to widespread establishment but may not directly increase invasive success. Instead, other characteristics, like plant traits and local scale processes, may better predict whether a species becomes invasive.

Biological effects of Bougainvillea glabra, Delonix regia, Lantana camara, and Platycladus orientalis extracts and their possible metabolomics therapeutics against the West Nile virus vector, Culex pipiens (Diptera: Culicidae).

Plants are a treasure trove of biological materials containing a wide range of potential phytochemicals that are target-specific, rapidly biodegradable, and environmentally friendly, with multiple medicinal effects. Unfortunately, the development of resistance to synthetic pesticides and antibiotics led to the discovery of new antibiotics, antioxidants, and biopesticides. This has also led to the creation of new medications that work very well. The current study aimed to prove that ornamental plants contain specialized active substances that are used in several biological processes. Mosquitoes, one of the deadliest animals on the planet, cause millions of fatalities each year by transmitting several human illnesses. Phytochemicals are possible biological agents for controlling pests that are harmful. The potential of leaf extracts of Bougainvillea glabra, Delonix regia, Lantana camara, and Platycladus orientalis against Culex pipiens and microbial agents was evaluated. Acetone extracts had more toxic effects against Cx. pipiens larvae (99.0-100 %, 72 h post-treatment), and the LC50 values were 142.8, 189.5, 95.4, and 71.1 ppm for B. glabra, D. regia, L. camara, and P. orientalis, respectively. Plant extracts tested in this study showed high insecticidal, antimicrobial, and antioxidant potential. GC-MS and HPLC analyses showed a higher number of terpenes, flavonoids, and phenolic compounds. The ADME analysis of element, caryophyllene oxide, caryophyllene, and copaene showed that they were similar to drugs and that they were better absorbed by the body and able to pass through the blood-brain barrier. Our results confirm the ability of ornamental plants to have promising larvicidal and antimicrobial activity and biotechnology.

Discovery and Characterization of Two Highly Divergent Variants of a Novel Potyvirus Species Infecting Madagascar Periwinkle (Catharanthus roseus).

During the summer of 2022, a cluster of Madagascar periwinkle plants with white and mauve flowers were observed with foliar mild yellow mosaic symptoms on a private property in Harlingen, Cameron County, Texas. The symptoms were reproduced on mechanically inoculated periwinkle and Nicotiana benthamiana plants. Virions of 776 to 849 nm in length and 11.7 to 14.8 nm in width were observed in transmission electron microscopy of leaf dip preparations made from symptomatic periwinkle leaves. High-throughput sequencing (HTS) analysis of total RNA extracts from symptomatic leaves revealed the occurrence of two highly divergent variants of a novel Potyvirus species as the only virus-like sequences present in the sample. The complete genomes of both variants were independently amplified via reverse transcriptase PCR, cloned, and Sanger sequenced. The 5' and 3' of the genomes were acquired using random amplification of cDNA ends methodology. The assembled virus genomes were 9,936 and 9,944 nucleotides (nt) long, and they shared 99.9 to 100% identities with the respective HTS-derived genomes. Each genome encoded hypothetical polyprotein of 3,171 amino acids (aa) (362.6 kilodaltons [kDa]) and 3,173 aa (362.7 kDa), respectively, and they shared 77.3/84.4% nt/aa polyprotein identities, indicating that they represent highly divergent variants of the same Potyvirus species. Both genomes also shared below-species-threshold polyprotein identity levels with the most closely phylogenetically related known potyviruses, thus indicating that they belong to a novel species. The name periwinkle mild yellow mosaic virus (PwMYMV) is given to the potyvirus with complete genomes of 9,936 nt for variant 1 (PwMYMV-1) and 9,944 nt for variant 2 (PwMYMV-2). We propose that PwMYMV be assigned into the genus Potyvirus (family Potyviridae).

Effect of monocultures and polycultures of Typha latifolia and Heliconia psittacorum on the treatment of river waters contaminated with landfill leachate/domestic wastewater in partially saturated vertical constructed wetlands.

Partially Saturated Vertical Constructed Wetlands (PSV-CWs) are novel wastewater treatment systems that work through aerobic and anaerobic conditions that favor the removal of pollutants found in high concentrations, such as rivers contaminated with domestic wastewater and landfill leachate. The objective of the study was to evaluate the efficiency of PSV-CWs using monocultures and polycultures of Typha latifolia and Heliconia psittacorum to treat river waters contaminated with leachates from open dumps and domestic wastewater. Six experimental units of PSV-CWs were used; two were planted with Typha latifolia monoculture, two with Heliconia psittacorum monoculture and two with polycultures of both plants. The results indicated better organic matter and nitrogen removal efficiencies (p < 0.05) in systems with polycultures (TSS:95%, BOD5:83%, COD:89%, TN:82% and NH4+:99%). In general, the whole system showed high average removal efficiencies (TSS:93%, BOD5:79%, COD:85%, TN:79%, NH4+:98% and TP:85%). Regarding vegetation, both species developed better in units with monocultures, being Typha latifolia the one that reached a more remarkable development. However, both species showed high resistance to the contaminated environment. These results showed higher removals than those reported in the literature with conventional Free Flow Vertical Constructed Wetlands (FFV-CWs), so PSV-CWs could be a suitable option to treat this type of effluent.

The research addresses the contamination of water resources in developing countries by landfill leachate and domestic wastewater discharges. It proposes treatment through Partially Saturated Vertical Constructed Wetlands (PSV-CWs), which, despite the limited information available, have been shown to be effective in removing pollutants in effluents with high concentrations. In addition to evaluating PSV-CWs, the study examines the impact of different types of vegetation on pollutant removal efficiency, concluding that PSV-CWs are a promising and viable option for the treatment of these effluents.

Methylation Modification in Ornamental Plants: Impact on Floral Aroma and Color.

Methylation represents a crucial class of modification that orchestrates a spectrum of regulatory roles in plants, impacting ornamental characteristics, growth, development, and responses to abiotic stress. The establishment and maintenance of methylation involve the coordinated actions of multiple regulatory factors. Methyltransferases play a pivotal role by specifically recognizing and methylating targeted sites, which induces alterations in chromatin structure and gene expression, subsequently influencing the release of volatile aromatic substances and the accumulation of pigments in plant petals. In this paper, we review the regulatory mechanisms of methylation modification reactions and their effects on the changes in aromatic substances and pigments in plant petals. We also explore the potential of methylation modifications to unravel the regulatory mechanisms underlying aroma and color in plant petals. This aims to further elucidate the synthesis, metabolism, and regulatory mechanisms of various methylation modifications related to the aroma and color substances in plant petals, thereby providing a theoretical reference for improving the aroma and color of plant petals.

Microbial perspective on restoration of degraded urban soil using ornamental plants.

The urban soil where abandoned buildings are demolished is barren and structurally poor, and this degraded soil requires restoration. Ornamental plants enhance the urban environment, increase biodiversity, and affect soil physicochemical properties, microbial diversity; however, their effects remain unclear. Thus, in this study, a mixed-planting meadow consisting of 14 perennial ornamental flower species, including Iris tectorum, Iris lacteal, and Patrinia scabiosaefolia, etc. Was planted at a demolition site with sewage-contaminated soil in Beijing. Simultaneously, a single-planting lawn of I. tectorum was established in a nearby park. We aimed to examine soil physicochemical properties, sequence soil bacterial 16S rRNA and fungal ITS amplicons, and analyze soil microbial diversity and community structure at both sites at five time points in the year after planting, To explore the effect of herbaceous ornamental plants on degraded urban soil, we used FAPROTAX and FUNGuild to predict bacterial and fungal functions, the bin-based null model to evaluate the soil microbial community, and random matrix theory to construct soil microbial molecular networks. The mixed-planting meadow produced a visually appealing landscape and dynamic seasonal enrichment, significantly increasing soil total nitrogen (TN) and organic matter (SOM) contents by 1.99 and 1.21 times, respectively. TN had a positive correlation with soil microbial α diversity and community structure. Dominant phyla at both sites included Proteobacteria, Actinobacteria, and Ascomycota. Although soil microorganisms were primarily influenced by stochastic processes, stochasticity was notably higher in the mixed-planting meadow than in the single-planting lawn. The mixed-planting meadow significantly increased the relative abundance of beneficial microorganisms, improving nitrification and aerobic ammonium oxidation of soil bacteria, as well as symbiotroph of fungi. No significant changes were observed in the single-planting lawn. The mixed-planting meadow established a complex soil microbial molecular network, enhancing the correlation between bacteria and fungi and increasing the number of key microorganisms. Our findings suggest the potential of mixed-planting meadow in restoring degraded urban soils by influencing the soil microbial community and enhancing the ecological service function. Our study provides theoretical support for applying mixed-planting meadow communities to improve the soil environment of urban green spaces.

Uromyces savulescui on statice (Limonium sinuatum) in the Americas and reevaluation of its reported geographic range.

Limonium sinuatum (Plumbaginaceae) is the most commonly cultivated recognizable cut flower crop in the genus Limonium. It is known by several common names including statice and sea lavender, due to its lilac-colored flowers and the fact that it naturally inhabits mainly coastal areas (Mellesse et al, 2013). Limonium sinuatum is native to the Mediterranean, although as a popular garden plant, has been naturalized in other parts of the world including coastal areas of California (USDA NRCS 2020). Cultivated L. sinuatum is used in fresh and dry flower arrangements in the Americas, comprising approximately 20% of the floriculture cultivated area in Ecuador (Vega and Morales 2011; Abascal Cañas 2017). In December 2014, L. sinuatum plants in the public park "Baños del Inca" in Cajamarca, Peru (S 7 9'46"; W 78 27'53"), were found infected with a rust disease. The plants were scattered in the park but infection incidence was 100% as individual plants were all found to be infected (Fig 1). Based on the percentage of symptomatic areas, including the yellow halos around pustules, calculated with ImageJ (Collins, 2007) from field photographs, the disease severity was estimated to be 58.9% in average, ranging from 19.8% up to 90.0%. Uredinia were present on both sides of the leaves as well as on stems and were roundish, oblong, pulverulent, and cinnamon brown in color; urediniospores 25.5 to 35.0 × 22.5 to 31.0 µm, were globoid to ellipsoid; urediniospore walls were cinnamon-brown, 2.5 to 3.0 µm thick, densely verrucose, with 2 to 3 equatorial germ pores. Few telia were present on leaves; these were scattered roundish or oblong, and greyish in color; teliospores 26.5 to 41.0 × 16.0 to 25.0 µm, were ellipsoid to obovoid, mostly attenuated at the apex; teliospore walls were colorless, 2-3 µm thick at sides, and up to 10 µm thick at apex. Teliospores readily germinated in sori producing basidia and basidiospores (Fig. 2). The rust features and dimensions of rust spores are consistent with available descriptions of Uromyces savulescui Rayss (Guyot 1951; Vakalounakis and Malathrakis 1987). To confirm identity, a 576 bp region of the 28S subunit of the ribosomal DNA repeat was sequenced following previously published protocols and primers (Aime 2006, Aime et al. 2018). The resulting sequence (GenBank Accession No. OR291160) shared 99.83% (573/574 bp) identity with a sequence deposited as Uromyces limonii (DC.) Lev. (accession KY764194, BPI910295, Demers et al. unpublished) from L. sinuatum in Ethiopia. However, U. limonii produces orange uredinia, thin-walled yellow-orange urediniospores, teliospores with mostly light chestnut brown wall and infects different hosts (Savile and Conners 1951). It is likely that KY764194 represents a misannotated record of U. savulescui. While Koch's postulates can be a useful tool for establishing causality in certain infectious diseases, their use may be limited when it comes to rust diseases based on old herbarium specimens. In our case, due to the age of the specimen, which is almost nine years old, various other methods were employed to identify the pathogen. These methods included microscopic examination for morphological criteria of the urediniospores and teliospores, as well as molecular techniques like 28S rDNA sequencing. Rust disease on L. sinuatum has been previously reported in Ecuador but the causal agent was identified as a Puccinia sp. and reported that the rust was able to destroy entire plots in humid conditions (Vega and Morales 2011). Whether this report also represent U. savulescui is not certain, but given that the urediniospores of Puccinia species are generally 2-celled, it is unlikely. García-Hernández et al. (2008) reported U. limonii on Limonium spp. from Chile, and Coca (2020) also reported U. limonii on Limonium sp., from Bolivia. However, judging from the photomicrographs (Coca 2020), the rust in the latter report is definitely U. savulescui and not U. limonii. Uromyces savulescui has been previously reported from the Mediterranean region and the Canary Islands (Vakalounakis and Malathrakis 1987). To our knowledge there is no report of this rust in the Americas, excepting the probable misidentifications already listed herein. The specimen has been deposited in the Arthur Fungarium at Purdue University as PURN15037.

Herbaceous ornamental plants with conspicuous aesthetic traits contribute to plant invasion risk in subtropical urban parks.

Global ornamental horticulture is a major pathway for plant invasions, while urban parks are key areas for introducing non-native ornamental plants. To react appropriately to the challenges (e.g., biological invasion issues) and opportunities (e.g., urban ecosystem services) of herbaceous ornamentals in urban parks, we conducted a comprehensive invasive risk assessment in 363 urban parks in Chongqing, a subtropical city in China. The results found more than 1/3 of the 119 non-native species recorded in urban parks had a high invasion risk, and more than five species had potential invasion risk in 96.29% of the study area, indicating herbaceous ornamentals in urban parks are potentially a pool of invasive species that deserves attention. Moreover, humans have chosen herbaceous ornamentals with more aesthetic characteristics in urban parks, where exotic species were more prominent than native species in floral traits, such as more conspicuous flowers and longer flowering periods. The findings can inform urban plant management, provide an integrated approach to assessing herbaceous ornamentals' invasion risk, and offer insights into understanding the filtering effects of human aesthetic preferences.

Cadmium Uptake From Soil by Ornamental Metallophytes: A Meta-analytical Approach.

Soil pollution by cadmium (Cd) is a serious issue worldwide affecting environmental and human health. Conventional chemical and physical methods of treating contaminated soil are costly, time-consuming, and less effective. Phytoremediation using ornamental plants is a safe and effective method for the treatment of heavy metal-polluted soil due to their rapid growth and accumulation of biomass, high heavy metal tolerance, and non-edible nature. The present study is the first attempt for the meta-analysis of existing literature on Cd accumulation and translocation by ornamental plants. The uptake and transfer capacity of ornamental plants was measured using the bio-concentration factor (BCF) and translocation factor (TF). The results indicate that ornamental plants have varying Cd-absorption capacities. Among the 49 plant species identified from 31 articles, Helianthus annuus (BCF = 5.785), Impatiens glandulifera (BCF = 4.722), and Crassocephalum crepidioides (BCF = 3.623) represented higher accumulation capacity, whereas Rorippa globosa (TF = 1.653) and Sedum spectabile Boreau (TF = 1.579) represented significantly higher translocation capacity for Cd. The contribution of various environmental factors in influencing BCF was obtained through multiple linear regression analysis. Results showed that soil pH was the major factor influencing the BCF. To further explain the influence of four main factors that are soil pH, soil organic matter (SOM), cation exchange capacity (CEC), and soil Cd concentration on the accumulation efficiency of ornamental plants, a subgroup meta-analysis was performed. Results of the subgroup meta-analysis revealed that the BCF is negatively correlated with the soil pH and SOM, while the estimated limit of soil Cd concentration for growing ornamental plants was up to 50 mg/kg. Results of this study indicate that choosing a native hyperaccumulator is not the sole key to the success of a phytoremediation design, rather the conditions of the pedosphere will determine the regulating factor for efficient removal. In order to overcome the issue of recirculation and gradual release in the rhizosphere, it is important to match the type of hyperaccumulators to the soil environment (pH, CEC, SOM, etc.) to achieve maximum translocation and desired removal. This study will help researchers to pair the right plant with environmental conditions and customize more efficient phytoremediation systems.

Plant-Parasitic Nematodes and their Effects on Ornamental Plants: A Review.

Worldwide, the ornamental plant industry is estimated to be valued at $70 billion, with the United States' ornamental plant industry valued at $4.8 billion in 2020. Ornamental plants are cultivated for numerous reasons worldwide, such as decorative, medicinal, social, and utility purposes, making the ornamental field a high growth industry. One of the main pathogen groups affecting the yield and growth of the ornamental plant industry is plant-parasitic nematodes, which are microscopic roundworms that feed on plant parts causing significant yield loss. There are many kinds of plant-parasitic nematodes that affect ornamental plants, with the main genera being Meloidogyne spp., Aphelenchoides spp., Paratylenchus spp., Pratylenchus spp., Helicotylenchus spp., Radopholus spp., Xiphinema spp., Trichodorus spp., Paratrichodorus spp., Rotylenchulus spp., and Longidorus spp. The aim of this review is to focus on the effects, hosts, and symptoms of these major plant-parasitic nematodes on ornamental plants and synthesize current management strategies in the ornamental plant industry.

Physiological and metabolomics responses of Hydrangea macrophylla (Thunb.) Ser. and Hydrangea strigosa Rehd. to lead exposure.

Hydrangea is a potential remediation plant for lead (Pb) pollution. Plant roots communicate with soil through the release of root exudates. It is crucial to study rhizoremediation mechanisms to understand the response of root exudates to contamination stress. Here, we investigated the physiological responses and metabolomic profiling of two Hydrangea species, a horticultural cultivar (Hydrangea macrophylla (Thunb.) Ser.) and a wild type (Hydrangea strigosa Rehd.), under Pb-free and Pb-stressed conditions for 50 days. The results showed that Pb treatment adversely affected the biomass and root growth of the two species. H. strigosa was a Pb-tolerant species with higher superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and more ascorbic acid (AsA) content in roots. Metabolomic profiling showed that 181 and 169 compounds were identified in H. macrophylla and H. strigosa root exudates, respectively, among which 18 showed significant differences between H. macrophylla and H. strigosa under Pb exposure. H. strigosa showed significantly (P < 0.05) higher secretion of sucrose, glycolic acid, and nonanoic acid than H. macrophylla after Pb treatment. Pb stress promoted fatty acid metabolism in H. strigosa, suppressed amino acid metabolism in H. macrophylla, and promoted a higher carbohydrate metabolism in H. strigosa compared with H. macrophylla. This study provides a possible mechanism for the high Pb absorption potential of Hydrangea.

Trichoderma spp. Improves Flowering, Quality, and Nutritional Status of Ornamental Plants.

Scientists all over the world conduct research to determine the influence of Trichoderma spp. on various groups of plants, mostly crops. However, there is little information on the influence of these fungi on ornamental plants. Therefore, the authors of this study analyzed the influence of Trichoderma spp. on the growth, flowering, quality, and nutritional status of ornamental plants. The research showed that Trichoderma spp. in this group of plants stimulate the elongation and thickening of shoots and the formation of leaves. These fungi also stimulate or inhibit leaf elongation. They also accelerate the flowering of plants, stimulate the elongation of inflorescence shoots and inflorescences, and the development of flowers. Apart from that, Trichoderma spp. positively influence the content of chlorophyll and carotenoids in leaves, and they stimulate the uptake of micro- and macroelements.

Towards the Improvement of Ornamental Attributes in Chrysanthemum: Recent Progress in Biotechnological Advances.

Incessant development and introduction of novel cultivars with improved floral attributes are vital in the dynamic ornamental industry. Chrysanthemum (Chrysanthemum morifolium) is a highly favored ornamental plant, ranking second globally in the cut flower trade, after rose. Development of new chrysanthemum cultivars with improved and innovative modifications in ornamental attributes, including floral color, shape, plant architecture, flowering time, enhanced shelf life, and biotic and abiotic stress tolerance, is a major goal in chrysanthemum breeding. Despite being an economically important ornamental plant, the application of conventional and molecular breeding approaches to various key traits of chrysanthemum is hindered owing to its genomic complexity, heterozygosity, and limited gene pool availability. Although classical breeding of chrysanthemum has resulted in the development of several hundreds of cultivars with various morphological variations, the genetic and transcriptional control of various important ornamental traits remains unclear. The coveted blue colored flowers of chrysanthemums cannot be achieved through conventional breeding and mutation breeding due to technical limitations. However, blue-hued flower has been developed by genetic engineering, and transgenic molecular breeding has been successfully employed, leading to substantial progress in improving various traits. The recent availability of whole-genome sequences of chrysanthemum offers a platform to extensively employ MAS to identify a large number of markers for QTL mapping, and GWAS to dissect the genetic control of complex traits. The combination of NGS, multi-omic platforms, and genome editing technologies has provided a tremendous scope to decipher the molecular and regulatory mechanisms. However, the application and integration of these technologies remain inadequate for chrysanthemum. This review, therefore, details the significance of floral attributes, describes the efforts of recent advancements, and highlights the possibilities for future application towards the improvement of crucial ornamental traits in the globally popular chrysanthemum plant.

Flower Extracts from Ornamental Plants as Sources of Sunscreen Ingredients: Determination by In Vitro Methods of Photoprotective Efficacy, Antigenotoxicity and Safety.

Plants are sources of sunscreen ingredients that prevent cellular mutations involved in skin cancer and aging. This study investigated the sunscreen properties of the extracts from some ornamental plants growing in Colombia. The UV filter capability of the flower extracts obtained from Rosa centifolia L., Posoqueria latifolia (Rudge) Schult, and Ipomoea horsfalliae Hook. was examined. Photoprotection efficacies were evaluated using in vitro indices such as sun protection factor and critical wavelength. UVB antigenotoxicity estimates measured with the SOS Chromotest were also obtained. Extract cytotoxicity and genotoxicity were studied in human fibroblasts using the trypan blue exclusion and Comet assays, respectively. Major compounds of the promising flower extracts were identified by UHPLC-ESI+-Orbitrap-MS. The studied extracts showed high photoprotection efficacy and antigenotoxicity against UVB radiation, but only the P. latifolia extract showed broad-spectrum photoprotection at non-cytotoxic concentrations. The P. latifolia extract appeared to be safer for human fibroblast cells and the R. centifolia extract was shown to be moderately cytotoxic and genotoxic at the highest assayed concentrations. The I. horsfalliae extract was unequivocally cytotoxic and genotoxic. The major constituents of the promising extracts were as follows: chlorogenic acid, ecdysterone 20E, rhamnetin-rutinoside, cis-resveratrol-diglucoside, trans-resveratrol-diglucoside in P. latifolia; quercetin, quercetin-glucoside, quercetin-3-rhamnoside, kaempferol, kaempferol-3-glucoside, and kaempferol-rhamnoside in R. centifolia. The potential of the ornamental plants as sources of sunscreen ingredients was discussed.

Iconic but Invasive: The Public Perception of the Chinese Windmill Palm (Trachycarpus fortunei) in Switzerland.

Biological invasions strongly increased during the last centuries and are challenging environmental managers worldwide. In this context, public acceptance of management measures is a key factor determining the long-term success of the control of invasive species. However, in the case of charismatic and iconic invasive species, the public has often been unwilling to accept strict management measures. Here, we studied the public perception of the Chinese windmill palm (Trachycarpus fortunei) in Switzerland, which is declared as invasive in southern Switzerland but also recognized as iconic. We conducted a nation-wide online survey in the multilingual and multicultural context of Switzerland, investigating the influence of social and cultural factors on the knowledge of, the attitude toward, and the willingness to control the invasive T. fortunei. Results confirm that the knowledge and perception of invasive plants have a strong social and cultural component and may vary greatly as a function of the cultural background, education level, age, and other social characteristics. Furthermore, information on the invasiveness of the focal species provided during the survey significantly affected informants' perceptions, which are closely related to the acceptance of possible management and control measures. This allows us to highlight the importance of a holistic approach that includes targeted public information when dealing with biological invasions, especially in the case of charismatic and iconic species. Based on the obtained results, we suggest avenues for refining management and control strategies of T. fortunei in Switzerland, many of which generally applicable to other cases of invasive species.

Time lags and the invasion debt in plant naturalisations.

Ecological processes often exhibit time lags. For plant invasions, lags of decades to centuries between species' introduction and establishment in the wild (naturalisation) are common, leading to the idea of an invasion debt: accelerating rates of introduction result in an expanding pool of introduced species that will naturalise in the future. Here, I show how a concept from survival analysis, the hazard function, provides an intuitive way to understand and forecast time lags. For plant naturalisation, theoretical arguments predict that lags between introduction and naturalisation will have a unimodal distribution, and that increasing horticultural activity will cause the mean and variance of lag times to decline over time. These predictions were supported by data on introduction and naturalisation dates for plant species introduced to Britain. While increasing trade and horticultural activity can generate an invasion debt by accelerating introductions, the same processes could lower that debt by reducing lag times.

Ornamental plants for the phytoremediation of heavy metals: Present knowledge and future perspectives.

Environmental matrices are polluted with the plethora of contaminants, and among these, the concerns related to heavy metals (HMs) are also included. Due to the low cost in a long-term application and environmental friendliness, the use of biological remediation has gained significant attention in recent decades. The use of ornamental plants (OPs) in the field of phytoremediation is scarcely reported, and the impacts of HMs on OPs have also not been investigated in great depth. The OPs mediated HMs remediation can simultaneously remove contaminants and bring improvement in aesthetics of the site. The biomass of OPs produced after such activities can be used and sold as pot plants, cut flowers, essential oils, perfumes, air fresheners production, metal phytomining, and feedstock in silk production. The OPs also present a lower risk of HMs bioaccumulation compared to crop plants. This review focuses on the current knowledge of HMs toxicity to OPs, their applicability advantages, methods to improve the tolerance of OPs with incremented HMs uptake, challenges in the field, and future application perspectives. The case studies realted to practical application of OPs, from China, Iran, India, Oman, Pakistan, and Turkey, were also discussed. This work fetches the inter-disciplinary features and understanding for the sustainable treatment of HMs in a new novel way, to which no previous review has focused.

Occurrence of Crown Gall Disease on Japanese Spindle (Euonymus japonicas var. Green Rocket) Caused by Agrobacterium rosae in Iran.

Crown gall disease caused by diverse Agrobacterium species is one of the main biotic constraints in the ornamental plants industry in Iran (Mafakheri et al. 2017). In August 2019, Japanese spindle (Euonymus japonicus var. Green Rocket) plants showing crown gall symptoms were observed in a commercial greenhouse in Tehran, Iran. Infected plants were characterized by a visible overgrowth on their stems and crown. Bacterial isolation from the gall tissues was performed on nutrient agar (NA) and 1A media as described by Moore et al. (2001). The six resulted bacterial strains (A.E1 to A.E6) were evaluated using PCR primer pair F8360/F8361 amplifying a 453 bp DNA fragment in recA gene and confirmed as Agrobacterium sp. (Shams et al. 2013). Pathogenicity of the strains was evaluated in two independent assays on Japanese spindle plantlets as well as 10-15 day old tomato (Solanum lycopersicum cv. Sunseed 6189) and sunflower (Helianthus annuus cv. Armavirski) plants in greenhouse conditions using the needle prick method as described previously (Mafakheri et al. 2019). The reference strain A. radiobacter ICMP 5856 and sterile distilled water were used as positive and negative controls, respectively. Crown gall symptoms appeared 20-25 days post inoculation on the Japanese spindle plantlets as well as tomato and sunflower plants inoculated with the strains isolated in this study, while the negative control plants remained asymptomatic. Koch's postulates were accomplished by re-isolating on NA medium and PCR-based identification of the inoculated strains from the symptomatic plants. The representative strain A.E1 was subjected to multilocus sequence analysis (MLSA) using the sequences of four housekeeping genes (i.e. atpD, gyrB, recA, and rpoB) as described previously (Mafakheri et al. 2019). MLSA results revealed that the strain A.E1 is phylogenetically closely related to A. rosae. The sequences were deposited into GenBank under the accession numbers MT007962 to MT007965 for atpD, gyrB, recA, and rpoB, respectively. Further, the strain A.E1 was subjected to whole genome sequencing using Illumina HiSeq X platform. DNA extraction was performed using NucleoSpin Microbial DNA kit (Macherey-Nagel, Germany), DNA libraries were obtained with Nextera XT DNA Library Prep Kit (Illumina, USA), and de novo sequence assembly was performed using SPAdes genome assembler. The resulting whole genome sequence was deposited into the GenBank database under the accession number JAFJZW000000000. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were calculated among all the type strains of Agrobacterium species/genomospecies using standard criteria as detailed previously (Osdaghi et al. 2020; Chen et al. 2021). The strain A.E1 had 97% ANI and 72% dDDH values with A. rosae strain NCPPB 1650, suggesting that the bacterial strains isolated from Japanese spindle in Iran belong to A. rosae. This is the first report of A. rosae causing crown gall disease on Japanese spindle in Iran. The new crown gall disease could negatively affect the ornamental shrub production industry in central Iran unless strict sanitary measures are taken into the account in the nurseries in these areas. Further nationwide surveys and samplings are warranted to elucidate the economic impact of the pathogen on ornamental plant industry in the country.

Potential Susceptibility of Six Aquatic Plant Species to Infection by Five Species of Phytophthora.

Investigations of the susceptibility of aquatic plants to species of Phytophthora are limited. Therefore, the objective of this study was to assess the potential susceptibility of six aquatic plant species, frequently used in constructed wetlands or vegetated channels, to infection by five species of Phytophthora commonly found at nurseries in the southeastern United States. In a greenhouse experiment, roots of each plant species (Agrostis alba, Carex stricta, Iris ensata 'Rising Sun', Panicum virgatum, Pontederia cordata, and Typha latifolia) growing in aqueous solutions were exposed to zoospores of each of the species of Phytophthora (Phytophthora cinnamomi, Phytophthora citrophthora, Phytophthora cryptogea, Phytophthora nicotianae, and Phytophthora palmivora). Zoospore presence and activity in solution were monitored with a standard baiting bioassay with rhododendron leaf discs as baits. Experiments were initiated in 2016 and repeated in 2017 and 2018. During the 2016 trials, Phytophthora spp. were not isolated from the roots of any of the plants, but some roots of C. stricta, P. virgatum, and T. latifolia were infected with multiple species of Phytophthora during trials in 2017 and 2018. Presence of plant roots reduced the percentage of rhododendron leaf discs infected by zoospores of four of the species of Phytophthora but not those infected by P. cinnamomi, which suggested that roots of these plants negatively affected the presence or activity of zoospores of these four species of Phytophthora in the aqueous growing solution. Results from this study demonstrated that certain aquatic plant species may be sources of inoculum at ornamental plant nurseries if these plants are present naturally in waterways or used in constructed wetlands treating water flowing off production areas, which could be of concern to plant producers who recycle irrigation water.

Recent Progress in Enhancing Fungal Disease Resistance in Ornamental Plants.

Fungal diseases pose a major threat to ornamental plants, with an increasing percentage of pathogen-driven host losses. In ornamental plants, management of the majority of fungal diseases primarily depends upon chemical control methods that are often non-specific. Host basal resistance, which is deficient in many ornamental plants, plays a key role in combating diseases. Despite their economic importance, conventional and molecular breeding approaches in ornamental plants to facilitate disease resistance are lagging, and this is predominantly due to their complex genomes, limited availability of gene pools, and degree of heterozygosity. Although genetic engineering in ornamental plants offers feasible methods to overcome the intrinsic barriers of classical breeding, achievements have mainly been reported only in regard to the modification of floral attributes in ornamentals. The unavailability of transformation protocols and candidate gene resources for several ornamental crops presents an obstacle for tackling the functional studies on disease resistance. Recently, multiomics technologies, in combination with genome editing tools, have provided shortcuts to examine the molecular and genetic regulatory mechanisms underlying fungal disease resistance, ultimately leading to the subsequent advances in the development of novel cultivars with desired fungal disease-resistant traits, in ornamental crops. Although fungal diseases constitute the majority of ornamental plant diseases, a comprehensive overview of this highly important fungal disease resistance seems to be insufficient in the field of ornamental horticulture. Hence, in this review, we highlight the representative mechanisms of the fungal infection-related resistance to pathogens in plants, with a focus on ornamental crops. Recent progress in molecular breeding, genetic engineering strategies, and RNAi technologies, such as HIGS and SIGS for the enhancement of fungal disease resistance in various important ornamental crops, is also described.