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Aim: Diversification of obligate parasites is often closely associated with historical shifts among host species. This phenomenon is well‐documented in animal parasites but still poorly understood for parasitic plants. We studied the associations between host shifts, biogeography and diversification in Cytinus, a genus of endophytic holoparasitic plants which show a remarkable disjunct distribution. Location: Mediterranean Basin, southern Africa, Madagascar. Taxon: Cytinus. Methods: We sampled numerous populations in South Africa and the western Mediterranean Basin, as well as a few populations in Madagascar where the genus is rare. We amplified two nuclear (ITS and SSU) and two mitochondrial (matR and nad1) loci, to infer its evolutionary history using maximum likelihood and time‐calibrated Bayesian analyses, to elucidate the factors responsible for its current distribution and to assess whether host switching is a main driver of speciation. Results: All genes recover lineages corresponding to the three geographic areas of Cytinus and sublineages associated with specific host plants, although they disagree on their deep‐level relationships. Ribosomal nuclear genes support an initial split of the Malagasy lineage and an Afrotropical origin of Cytinus before colonization of warm temperate latitudes. Mitochondrial genes support an initial split of the Mediterranean and Afro‐Malagasy lineages and a later split between the South African and Malagasy clades. Introgressive hybridization is the most likely explanation for this discrepancy, while horizontal gene transfers from hosts is less likely. We found strong support for cryptic host‐specific diversity, with five and eight host races in the Mediterranean and South Africa respectively, and a strong phylogenetic signal in the host–parasite associations suggestive of parasite diversification via phylogenetic host tracking. Main Conclusions: These dated phylogenies indicate that radiation through long‐distance dispersal events and adaptation to new hosts best explain the disjunct distribution of Cytinus. We emphasize the importance of host specificity and host‐switching in the diversification and biogeography of plant endoparasites. [ABSTRACT FROM AUTHOR]

• Sympatric, host-driven divergence in parasitic plants has rarely been explored. • Co-occurring host-specific races of Cytinus, an endophytic holoparasite, differ in flowering time, reproductive output, floral biometry and rewards. • Host races are interfertile yet appear to remain genetically isolated by restricted gene flow and host-driven selection pressures. • Host-driven sympatric diversification challenges our application of species concepts to cryptic parasitic plant races. Host specificity is a key factor influencing the ecology and evolutionary diversification of parasitic organisms. Host specialisation and geographic isolation are known to lead to the genetic differentiation of allopatric races in parasitic plants. However, how divergence can co-occur in sympatry remains largely unknown. We investigated phenological and phenotypic differentiation and potential reproductive isolation among three sympatric genetic races of Cytinus hypocistis (Cytinaceae) - an extreme endophytic holoparasite with a high degree of host specialisation. We compared spatio-temporal variations in flowering phenology, flower production, floral longevity, floral rewards, and morphology, and conducted inter-race pollinations among three races parasitising Cistus ladanifer, C. salviifolius , and Halimium halimifolium (Cistaceae) in six co-occurring populations. We found that host-defined genetic races differed significantly across multiple phenotypic and phenological aspects – a phenomenon previously overlooked due to the plants' cryptic morphology. The race parasitising H. halimifolium showed earlier blooming, higher floral display, longer flowers, and higher pollen production and nectar concentration; the race on C. salviifolius showed later flowering, significantly lower floral display and smaller flowers with lower floral rewards; the race on C. ladanifer had intermediate characteristics. Genetic races were interfertile yet may remain differentiated by restricted gene flow and host-driven selection pressures. Together, our data point to a rare case of sympatric divergent evolution hiding in plain sight: apparently morphologically similar co-occurring parasite races can be genetically, phenotypically, and phenologically distinct. This hitherto unreported example of host-driven sympatric diversification challenges how species concepts are applied to cryptic parasitic plant races. [ABSTRACT FROM AUTHOR]

Pollen limitation, resource limitation, fruit abortion, and predation have all been proposed as factors explaining low fruit set in hermaphroditic plants. We conducted a 5-year study combining field observations and pollination experiments to determine the causes of the low fruit set in Aristolochia paucinervis, a Mediterranean species with a specialized pollination system in two populations in SW Spain. Fruit initiation was markedly low, and between 28.6 and 75.0% of the flowering stems did not initiate any fruit. In most flowers, the number of germinated pollen grains was less than the number of ovules, and supplemental pollination significantly increased fruiting, indicating deficient pollination. In A. paucinervis, autonomous self- pollination seems to be a decisive factor in fruit production because the number of germinated pollen and the fruit set from flowers bagged before anthesis were similar to those in free-pollinated flowers. Only in 2005 did flowers that were successfully pollinated outnumber ripened fruits, suggesting that other factors limit fruiting. We found a significant positive correlation between tuber mass and fruit set. Deficient pollination and lack of resources could explain the low fruit set, but the relative consequences seem to vary spatially and temporarily. Key words: Aristolochia paucinervis; Aristolochiaceae; autonomous self-pollination; fruit set; multi-year study; pollen limitation; resource limitation; Spain.

Floral nectar harbours a diverse microbiome of yeasts and bacteria that depend predominantly on animal visitors for their dispersal. Since pollinators visit specific sets of flowers and carry their own unique microbiota, we hypothesize that plant species visited by the same set of pollinators may support non‐random nectar microbial communities linked together by the type of pollinator.Here we explore the importance of plant–pollinator interactions in the assembly of nectar microbiome and study the role of plant geographic location as a determinant of microbial community composition. We intensively sampled the nectar of 282 flowers of 48 plant species with beetles, birds, long‐tongued and short‐tongued insects as pollinators in wild populations in South Africa, one of the world's biodiversity hotspots, and using molecular techniques we identified nectar yeast and bacteria taxa. The analyses provided new insights into the richness, geographic structure and phylogenetic characterization of nectar microbiome, and compared patterns of composition of bacteria and yeast communities in relation to plant and pollinator guild.Our results showed that plant–pollinator interactions played a crucial role in shaping nectar microbial communities. Plants visited by different pollinator guilds supported significantly different yeast and bacterial communities. The pollinator guild also contributed to the maintenance of beta diversity and phylogenetic microbial segregation. The results revealed different patterns for yeast and bacteria; whereas plants visited by beetles supported the highest richness and phylogenetic diversity of yeasts, bacteria communities were significantly more diverse in plants visited by other insect groups. We found no clear microbial spatial segregation at different geographical scales for bacteria, and only the phylogenetic similarity of yeast composition was correlated significantly with geography.Synthesis. Interactions of animal vector, plant host traits and microbe physiology contribute to microbial community assemblages in nectar. Our results suggest that plants visited by the same pollinator guild have a characteristic nectar microbiota signature that may transcends the geographic region they are in. Contrasted patterns for yeast and bacteria stress the need for future work aimed at better understanding the causes and consequences of the importance of plants and pollinators in shaping nectar microbial communities in nature. [ABSTRACT FROM AUTHOR]

Mycorrhizae are widespread mutualistic symbioses crucial for the functioning of terrestial ecosystems. Not all plants associate with mycorrhizae; most parasitic plants have been siggested to be nonmycorrhizal because they have developed alterantive strategies to obtain nutrients. In endophytiv parasitic plants, whose vegetative bodies grow completely inside their mycorrhizal host roots, the opportunity for establishing a tripartite association seems evident, but information on these systems is lacking. In studying natural associationc among hte endophytic holoparasite Cytinud hypocistis, their Cistaceae host species, and associated mycorhizal fungi, we found that mycorrhizae were associated wiht the hosts and the parasires, reaching high frequencies of colonization. In parasitic and host root tissues, mycorrhizal fungi spread in the parenchymatic cells by intracellular growth and formed hyphal coils and vesicles, while the cambium and the vascular tissues were never colonized. This report is the first on a tripatite association of an endophytic parasitic plant, its host, and nycorrhizae in natural conditions, representing a novel trophic interaction not previously reported within the angiosperms. Additional studies on the interactions occuring among these three players are needed because they may be crucial to our understanding of how this mutualistic – antagonistic system is functioning and evolving. [ABSTRACT FROM AUTHOR]

Mycorrhizae are widespread mutualistic symbioses crucial for the functioning of terrestial ecosystems. Not all plants associate with mycorrhizae; most parasitic plants have been siggested to be nonmycorrhizal because they have developed alterantive strategies to obtain nutrients. In endophytiv parasitic plants, whose vegetative bodies grow completely inside their mycorrhizal host roots, the opportunity for establishing a tripartite association seems evident, but information on these systems is lacking. In studying natural associationc among hte endophytic holoparasite Cytinud hypocistis, their Cistaceae host species, and associated mycorhizal fungi, we found that mycorrhizae were associated wiht the hosts and the parasires, reaching high frequencies of colonization. In parasitic and host root tissues, mycorrhizal fungi spread in the parenchymatic cells by intracellular growth and formed hyphal coils and vesicles, while the cambium and the vascular tissues were never colonized. This report is the first on a tripatite association of an endophytic parasitic plant, its host, and nycorrhizae in natural conditions, representing a novel trophic interaction not previously reported within the angiosperms. Additional studies on the interactions occuring among these three players are needed because they may be crucial to our understanding of how this mutualistic – antagonistic system is functioning and evolving. [ABSTRACT FROM AUTHOR]

An emerging focus of research at the intersection of botany, zoology, and microbiology is the study of floral nectar as a microbial habitat, referred to as the nectar microbiome, which can alter plant-pollinator interactions. Studies on these microbial communities have primarily focused on yeasts, and it was only about a decade ago that bacteria began to be studied as widespread inhabitants of floral nectar. This review aims to give an overview of the current knowledge on nectar bacteria, with emphasis on evolutionary origin, dispersal mode, effects on nectar chemistry and plant-animal interactions, community assembly, agricultural applications, and their use as model systems in ecological research. We further outline gaps in our understanding of the ecological significance of these microorganisms, their response to environmental changes, and the potential cascading effects., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

The genus Rosenbergiella is one of the most frequent bacterial inhabitants of flowers and a usual member of the insect microbiota worldwide. To date, there is only one publicly available Rosenbergiella genome, corresponding to the type strain of Rosenbergiella nectarea (8N4 T ), which precludes a detailed analysis of intra-genus phylogenetic relationships. In this study, we obtained draft genomes of the type strains of the other Rosenbergiella species validly published to date ( R. australiborealis , R. collisarenosi and R. epipactidis ) and 23 additional isolates of flower and insect origin. Isolate S61 T , retrieved from the nectar of an Antirrhinum sp. flower collected in southern Spain, displayed low average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values when compared with other Rosenbergiella members (≤86.5 and ≤29.8 %, respectively). Similarly, isolate JB07 T , which was obtained from the floral nectar of Metrosideros polymorpha plants in Hawaii (USA) had ≤95.7 % ANI and ≤64.1 % isDDH with other Rosenbergiella isolates. Therefore, our results support the description of two new Rosenbergiella species for which we propose the names Rosenbergiella gaditana sp. nov. (type strain: S61 T =NCCB 100789 T =DSM 111181 T ) and Rosenbergiella metrosideri sp. nov. (JB07 T =NCCB 100888 T =LMG 32616 T ). Additionally, some R. epipactidis and R. nectarea isolates showed isDDH values<79 % with other conspecific isolates, which suggests that these species include subspecies for which we propose the names Rosenbergiella epipactidis subsp. epipactidis subsp. nov. (S256 T =CECT 8502 T =LMG 27956 T ), Rosenbergiella epipactidis subsp. californiensis subsp. nov. (FR72 T =NCCB 100898 T =LMG 32786 T ), Rosenbergiella epipactidis subsp. japonicus subsp. nov. (K24 T =NCCB 100924 T =LMG 32785 T ), Rosenbergiella nectarea subsp. nectarea subsp. nov. (8N4 T = DSM 24150 T = LMG 26121 T ) and Rosenbergiella nectarea subsp. apis subsp. nov. (B1A T =NCCB 100810 T = DSM 111763 T ), respectively. Finally, we present the first phylogenomic analysis of the genus Rosenbergiella and update the formal description of the species R. australiborealis , R. collisarenosi , R. epipactidis and R. nectarea based on new genomic and phenotypic information.

This article documents the addition of 142 microsatellite marker loci to the Molecular Ecology Resources database. Loci were developed for the following species: Agriophyllum squarrosum, Amazilia cyanocephala, Batillaria attramentaria, Fungal strain CTeY1 (Ascomycota), Gadopsis marmoratus, Juniperus phoenicea subsp. turbinata, Liriomyza sativae, Lupinus polyphyllus, Metschnikowia reukaufii, Puccinia striiformis and Xylocopa grisescens. These loci were cross-tested on the following species: Amazilia beryllina, Amazilia candida, Amazilia rutila, Amazilia tzacatl, Amazilia violiceps, Amazilia yucatanensis, Campylopterus curvipennis, Cynanthus sordidus, Hylocharis leucotis, Juniperus brevifolia, Juniperus cedrus, Juniperus osteosperma, Juniperus oxycedrus, Juniperus thurifera, Liriomyza bryoniae, Liriomyza chinensis, Liriomyza huidobrensis and Liriomyza trifolii., (© 2013 John Wiley & Sons Ltd.)

This article documents the addition of 153 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Brassica oleracea, Brycon amazonicus, Dimorphandra wilsonii, Eupallasella percnurus, Helleborus foetidus, Ipomoea purpurea, Phrynops geoffroanus, Prochilodus argenteus, Pyura sp., Sylvia atricapilla, Teratosphaeria suttonii, Trialeurodes vaporariorum and Trypanosoma brucei. These loci were cross-tested on the following species: Dimorphandra coccicinea, Dimorphandra cuprea, Dimorphandra gardneriana, Dimorphandra jorgei, Dimorphandra macrostachya, Dimorphandra mollis, Dimorphandra parviflora and Dimorphandra pennigera., (© 2013 Blackwell Publishing Ltd.)

Floral nectar of some animal-pollinated plants usually harbours highly adapted yeast communities which can profoundly alter nectar characteristics and, therefore, potentially have significant impacts on plant reproduction through their effects on insect foraging behaviour. Bacteria have also been occasionally observed in floral nectar, but their prevalence, phylogenetic diversity and ecological role within plant-pollinator-yeast systems remains unclear. Here we present the first reported survey of bacteria in floral nectar from a natural plant community. Culturable bacteria occurring in a total of 71 nectar samples collected from 27 South African plant species were isolated and identified by 16S rRNA gene sequencing. Rarefaction-based analyses were used to assess operational taxonomic units (OTUs) richness at the plant community level using nectar drops as sampling units. Our results showed that bacteria are common inhabitants of floral nectar of South African plants (53.5% of samples yielded growth), and their communities are characterized by low species richness (18 OTUs at a 16S rRNA gene sequence dissimilarity cut-off of 3%) and moderate phylogenetic diversity, with most isolates belonging to the Gammaproteobacteria. Furthermore, isolates showed osmotolerance, catalase activity and the ability to grow under microaerobiosis, three traits that might help bacteria to overcome important factors limiting their survival and/or growth in nectar., (© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)