Responses of Bunias orientalis to Short-term Fungal Infection and Insect Herbivory are Independent of Nutrient Supply.

Plants have to allocate their resources in both growth and defense under different environmental challenges. Several plant species have become invasive particularly in disturbed fertile habitats, which may influence their resource allocation. We studied the effects of nitrate fertilization (low versus high) on various plant responses towards a pathogenic fungus, Alternaria brassicae, and a herbivorous insect species, Mamestra brassicae, in a population of Bunias orientalis, which is invasive in parts of central Europe. Aboveground biomass and leaf trichome density were enhanced in plants under high fertilization. In contrast, the short-term fungal infection and herbivory had no effect on aboveground biomass. Leaf water, nitrogen content and glucosinolate concentrations were neither affected by fertilization nor in response to antagonist attack. The total soluble sugar content, especially fructose, as well as leaf peroxidase activity increased significantly in leaves upon fungal infection, but independent of fertilization. Larval biomass gain and herbivore survival were likewise unaffected by fertilization. Our findings highlight that under conditions of high fertilization, B. orientalis plants allocate more resources into growth and morphological defenses than chemical defenses. In contrast, induced responses to short-term antagonist attack seem independent of nitrate availability in this population.

The large genome size variation in the Hesperis clade was shaped by the prevalent proliferation of DNA repeats and rarer genome downsizing.

BACKGROUND AND AIMS: Most crucifer species (Brassicaceae) have small nuclear genomes (mean 1C-value 617 Mb). The species with the largest genomes occur within the monophyletic Hesperis clade (Mandáková et al., Plant Physiology174: 2062-2071; also known as Clade E or Lineage III). Whereas most chromosome numbers in the clade are 6 or 7, monoploid genome sizes vary 16-fold (256-4264 Mb). To get an insight into genome size evolution in the Hesperis clade (~350 species in ~48 genera), we aimed to identify, quantify and localize in situ the repeats from which these genomes are built. We analysed nuclear repeatomes in seven species, covering the phylogenetic and genome size breadth of the clade, by low-pass whole-genome sequencing. METHODS: Genome size was estimated by flow cytometry. Genomic DNA was sequenced on an Illumina sequencer and DNA repeats were identified and quantified using RepeatExplorer; the most abundant repeats were localized on chromosomes by fluorescence in situ hybridization. To evaluate the feasibility of bacterial artificial chromosome (BAC)-based comparative chromosome painting in Hesperis-clade species, BACs of arabidopsis were used as painting probes. KEY RESULTS: Most biennial and perennial species of the Hesperis clade possess unusually large nuclear genomes due to the proliferation of long terminal repeat retrotransposons. The prevalent genome expansion was rarely, but repeatedly, counteracted by purging of transposable elements in ephemeral and annual species. CONCLUSIONS: The most common ancestor of the Hesperis clade has experienced genome upsizing due to transposable element amplification. Further genome size increases, dominating diversification of all Hesperis-clade tribes, contrast with the overall stability of chromosome numbers. In some subclades and species genome downsizing occurred, presumably as an adaptive transition to an annual life cycle. The amplification versus purging of transposable elements and tandem repeats impacted the chromosomal architecture of the Hesperis-clade species.

Bunias erucago L.: Glucosinolate Profile and In Vitro Biological Potential.

Bunias erucago belongs to the Brassicaceae family, which represents a forgotten crop of the Euro-Mediterranean area. The aim of the present study was to determine the glucosinolate profile in different plant parts and biological properties (antioxidant, anticholinesterase, and cytotoxic activities) of the isolates containing glucosinolate breakdown products. The chemical profiles were determined by using HPLC-PDA-MS/MS of desulfoglucosinolates and GC-MS of glucosinolate degradation products. The analysis of B. erucago showed the presence of seven glucosinolates: gluconapin (1), glucoraphasatin (2), glucoraphenin (3), glucoerucin (4), glucoraphanin (5), glucotropaeolin (6), and glucosinalbin (7). The total glucosinolate content ranged from 7.0 to 14.6 µmol/g of dry weight, with the major glucosinolate glucosinalbin in all parts. The antioxidant activity of all volatile isolates was not notable. At a tested concentration of 227 µg/mL, flower hydro-distillate (FH) showed good AChE inhibition, i.e., 40.9%, while root hydro-distillate (RH) had good activity against BChE, i.e., 54.3%. FH showed the best activity against both tested human bladder cancer cell lines, i.e., against T24 after 72 h, which have IC50 of 16.0 µg/mL, and against TCCSUP after 48 h with IC50 of 7.8 µg/mL, and can be considered as highly active. On the other hand, RH showed weak activity against tested cancer cells.

Variation in plant defences among populations of a range-expanding plant: consequences for trophic interactions.

Although plant-herbivore-enemy interactions have been studied extensively in cross-continental plant invasions, little is known about intra-continental range expanders, despite their rapid spread globally. Using an ecological and metabolomics approach, we compared the insect performance of a generalist and specialist herbivore and a parasitoid, as well as plant defence traits, among native, exotic invasive and exotic non-invasive populations of the Turkish rocket, Bunias orientalis, a range-expanding species across parts of Eurasia. In the glasshouse, the generalist herbivore, Mamestra brassicae, and its parasitoid, Microplitis mediator, performed better on non-native than on native plant populations. Insect performance did not differ between the two non-native origins. By contrast, the specialist herbivore, Pieris brassicae, developed poorly on all populations. Differences in trichome densities and in the metabolome, particularly in the family-specific secondary metabolites (i.e. glucosinolates), may explain population-related variation in the performance of the generalist herbivore and its parasitoid. Total glucosinolate concentrations were significantly induced by herbivory, particularly in native populations. Native populations of B. orientalis are generally better defended than non-native populations. The role of insect herbivores and dietary specialization as a selection force on defence traits in the range-expanding B. orientalis is discussed.

Differences in growth and competition between plants of a naturalized and an invasive population of Bunias orientalis.

The global shift of species' distributions has led to high numbers of noninvasive naturalized plants and the accumulation of invasive species within ecosystems. Competition between species may influence population dynamics, but little is known about the impacts of competition between conspecifics of naturalized and invasive populations. We investigated several plant traits at initial growth and regrowth following artificial defoliation in intra and interpopulation competition. Therefore, we used plants of Bunias orientalis from one noninvasive naturalized and one invasive population grown alone or in competition of two or three. Plants from the naturalized population were expected to be less competitive than plants from the invasive population, reflecting their differential impact in the introduced range. Independent of status, intrapopulation competition was expected to have less negative impacts on plants than interpopulation competition. Our results show that competition impacted mostly growth- rather than physiology-related traits. The relative magnitude of intra and interpopulation competition differed among plant traits at the first and second harvest. Plants of the invasive population outperformed the naturalized population by allocating relatively more resources to the aboveground biomass and producing more and longer leaves particularly when grown in competition against two plants. Moreover, plants of the invasive population were more competitive, which may influence their successful establishment and range expansion in the introduced range, but growth patterns differed after artificial defoliation. Although evolution of intrapopulation competition in naturalized and invasive ranges may be expected, interpopulation competition seems to adversely impact the performance of the naturalized plant population of B. orientalis studied here. Apart from the status (naturalized vs. invasive), other factors may have had an influence on plant performance. Thus, further research is needed with more naturalized and invasive populations to test the generality of our findings and to isolate the specific mechanisms driving differences in competitiveness.

The first checklist of alien vascular plants of Kyrgyzstan, with new records and critical evaluation of earlier data. Contribution 1.

BACKGROUND: National checklists of alien plants and detailed databases of non-native plant occurrences are required to study and control regional and global plant invasions. No country in Central Asia has a national checklist of alien plants. A recent inventory counted 183 alien plant species in Kyrgyzstan, including archaeophytes and neophytes, established and casual. This preliminary checklist, which was developed for the Global Register of Introduced and Invasive Species in 2018, served as a starting point for the present study. NEW INFORMATION: A complete inventory of Xanthium in Kyrgyzstan has revealed that three alien species are resident in the country. Their correct nomenclature is X.orientale (syn. X.albinum, X.californicum, X.sibiricum auct.; invasive neophyle of the period of extensive grain import to the USSR after the Second World War), X.spinosum (invasive neophyte of the period of the Second World War, which arrived as a contaminant on the relocated livestock) and X.strumarium (syn. X.chinense, X.sibiricum; archaeophyte of the Neolithic period, introduced with wheat cultivation, which had lost its invasive status and appeared on the verge of extinction when its pool was no longer renewed by contaminated grain). A history of introduction to Central Asia is uncovered for all the species of Xanthium. A further spread is documented for Buniasorientalis, with a new record extending its distribution to the Eastern Tian-Shan; a complex history of its introduction to Europe and Central Asia is inferred from the archaeological data and its recent dispersal, and the pathways of its introduction to Kyrgyzstan are established. Erigeronannuus s.str. is reported as new to Kyrgyzstan and Uzbekistan, and E.lilacinus as new to Kyrgyzstan, Uzbekistan, Kazakhstan, Nepal and Tajikistan (it was previously recorded as E.annuus s.l. from the three latter countries, in which the presence of E.annuus s.str. is not confirmed). These closely related species differ in their pathways of introduction and invasion status: E.annuus s.str. is an invasive established alien which was imported as a contaminant of forage, whereas E.lilacinus is mostly a casual (locally persisting) alien introduced with contaminated seed of ornamental plants or nursery material, and also intentionally introduced and locally established in the Botanical Garden in Bishkek. Bidenstinctoria (syn. Coreopsistinctoria) is newly recorded as a casual alien from a single locality in Kyrgyzstan; this species name is validly published here in conformity with the phylogeny of Coreopsideae.Point maps of species distributions in Kyrgyzstan are provided on the basis of a complete inventory of the literature data, herbarium specimens and documented observations, and our recent fieldwork. The maps are documented with a dataset of herbarium specimens and observations. Period and pathways of introduction, vectors of dispersal, current and historical invasion status, evidence of impact and distributional trend are established or inferred for each species. Each species is discussed in the context of plant invasions in Central Asia as a whole.These species accounts are part of the national database of alien plants which aims at producing a comprehensive overview and analysis of plant invasions in Kyrgyzstan.

Floral nectar production and carbohydrate composition and the structure of receptacular nectaries in the invasive plant Bunias orientalis L. (Brassicaceae).

The data relating to the nectaries and nectar secretion in invasive Brassicacean taxa are scarce. In the present paper, the nectar production and nectar carbohydrate composition as well as the morphology, anatomy and ultrastructure of the floral nectaries in Bunias orientalis were investigated. Nectary glands were examined using light, fluorescence, scanning electron and transmission electron microscopy. The quantities of nectar produced by flowers and total sugar mass in nectar were relatively low. Total nectar carbohydrate production per 10 flowers averaged 0.3 mg. Nectar contained exclusively glucose (G) and fructose (F) with overall G/F ratio greater than 1. The flowers of B. orientalis have four nectaries placed at the base of the ovary. The nectarium is intermediate between two nectary types: the lateral and median nectary type (lateral and median glands stay separated) and the annular nectary type (both nectaries are united into one). Both pairs of glands represent photosynthetic type and consist of epidermis and glandular tissue. However, they differ in their shape, size, secretory activity, dimensions of epidermal and parenchyma cells, thickness of secretory parenchyma, phloem supply, presence of modified stomata and cuticle ornamentation. The cells of nectaries contain dense cytoplasm, plastids with starch grains and numerous mitochondria. Companion cells of phloem lack cell wall ingrowths. The ultrastructure of secretory cells indicates an eccrine mechanism of secretion. Nectar is exuded throughout modified stomata.