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Background and Aims: Sexual polymorphisms of flowers have traditionally been interpreted as devices that promote cross-pollination, but they may also represent adaptations for exploiting particular pollination niches in local environments. The cross-pollination function of enantiostyly, characterized by flowers having either left- or right-deflected styles, has been uncertain in some lineages, such as the Haemodoraceae, because the positioning of stamens and styles is not always completely reciprocal among morphs., Methods: We examined the floral biology of populations of the poorly known species Barberetta aurea (Haemodoraceae) across its native range in South Africa to establish the general features of its enanatiostylous reproductive system and the agents and mechanism of pollen transfer., Results: We confirmed that B. aurea has a system of dimorphic enantiostyly. Style morph ratios varied among populations sampled, but with an overall tendency to being equal. Crossing experiments demonstrated that B. aurea is fully self-compatible, that intra- and inter-morph crosses are equally fertile and that it is wholly dependent on pollinator visits for seed production. Pollination is mainly by syrphid flies that transfer the sticky pollen via their wings, which contact the anthers and stigma precisely as they hover during approach and feeding. The majority of syrphid fly visitors feed on a film of highly concentrated nectar situated at the base of ultraviolet-absorbent 'nectar guides'. Because one of the three stamens is deflected in the same direction as the style, we predicted a high likelihood of intra-morph pollination, and this was corroborated by patterns of transfer of coloured dye particles in cage experiments involving syrphid flies., Conclusions: Barbaretta aurea exhibits dimorphic enantiostyly and, in contrast to most enantiostylous species, which are pollinated by bees, its flowers are specialized for pollination by syrphid flies. The lack of complete reciprocity of the enantiostylous arrangement of sexual organs facilitates both inter- and intra-morph pollen transfer on the wings of these flies., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Annals of Botany Company.)

One of the most fundamental, although controversial, questions related to the evolution of plant mating systems is the distribution of outcrossing rates. Self-compatibility, and especially autonomous self-pollination, can become particularly beneficial in anthropogenically degraded habitats with impoverished pollinator assemblages and increased pollen limitation. In a hand-pollination experiment with 46 meadow plants from the Železné hory Mts., Czech Republic, we evaluated the species' ability to adopt different mating systems. For a subset of the species, we also tested seed germination for inbreeding depression. Subsequently, we analysed relationships between the species' mating systems and 12 floral and life-history traits. We found a relatively discrete distribution of the studied species into four groups. Fully and partially self-incompatible species formed the largest group, followed by self-compatible non-selfers and mixed mating species. The germination experiment showed an absence of inbreeding depression in 19 out of 22 examined species. Nectar sugar per flower, nectar sugar per shoot and dichogamy were significant associated with the mating system. Spontaneous selfing ability and self-incompatibility in species of the meadow communities had a discrete distribution, conforming to the general distribution of mating and breeding systems in angiosperms. The low frequency of spontaneous selfers and the lack of inbreeding depression at germination suggest the existence of a selection against selfing at the later ontogenetic stages. Some floral traits, such as the level of dichogamy and amount of nectar reward, may strongly impact the balance between selfing and outcrossing rates in the self-compatible species and thus shape the evolution of mating systems., (© 2019 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Self-incompatibility (SI) is a sophisticated system for pollen selectivity to prevent pollination by genetically identical pollen. In Brassica, it is genetically controlled by a single, highly polymorphic S-locus, and the male and female S-determinant factors have been identified as S-locus protein 11 (SP11)/S-locus cysteine-rich protein (SCR) and S-locus receptor kinase (SRK), respectively. However, the overall molecular system and identity of factors in the downstream cascade of the SI reaction remain unclear. Previously, we identified a self-compatible B. rapa mutant line, TSC28, which has a disruption in an unidentified novel factor of the SI signaling cascade. Here, in a genetic analysis of TSC28, using an F 2 population from a cross with the reference B. rapa SI line Chiifu-401, the causal gene was mapped to a genetic region of DNA containing markers BrSA64 and ACMP297 in B. rapa chromosome A1. By fine mapping using an F 2 population of 1,034 plants, it was narrowed down to a genetic region between DNA markers ACMP297 and BrgMS4028, with physical length approximately 1.01 Mbp. In this genomic region, 113 genes are known to be located and, among these, we identified 55 genes that were expressed in the papilla cells. These are candidates for the gene responsible for the disruption of SI in TSC28. This list of candidate genes will contribute to the discovery of a novel downstream factor in the SP11-SRK signaling cascade in the Brassica SI system.

Plant species that are effective colonisers of transient habitats are expected to have a capacity for uniparental reproduction and show flexibility in pollination systems. Such traits may enable populations to be established from a small number of founding individuals without these populations succumbing to reductions in fecundity arising from pollinator limitation. We tested these predictions for Aloe thraskii (Xanthorrhoeaceae), a succulent treelet that colonises shifting coastal dunes and has both bird and bee pollinators. We performed hand-pollination experiments, and selectively excluded bird visitors to determine differences in pollinator effectiveness. We measured pollinator visitation rates and fecundity in populations varying in their size, density and isolation distance. Controlled hand-pollinations revealed that unlike most other Aloe species, A. thraskii is self-compatible and thus capable of uniparental reproduction. The species does however depend on pollinators and is visited by various bird species as well as by bees. Fruit and seed set are not affected by selective exclusion of birds, thus indicating that bees are effective pollinators. Bird visitation rates increased with increasing plant height and population size, while bee visitation rates increased with increasing population size and density. We found that seed set per flower was lower in large populations than in small populations. These results suggest that establishment of populations of A. thraskii from a small number of individuals is unlikely to be limited by the fecundity of individual plants., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Self-incompatibility (SI), a phenomenon that is widespread among flowering plants (angiosperms), promotes outbreeding, resulting in increased genetic diversity and species survival. SI is also important in establishing intra- or interspecies reproductive barriers, such as those that are evident in the tomato clade, Solanum section Lycopersicon, where they limit the use of wild species inbreeding programs to improve cultivated tomato. However, the molecular mechanisms underlying SI are poorly understood in the tomato clade. In this study, an SI (Solanum chilense, LA0130) and a self-compatible (SC, Solanum pimpinellifolium, LA1585) tomato species were chosen to dissect the mechanism of SI formation using a comparative proteomics approach. A total of 635 and 627 protein spots were detected in two-dimensional electrophoresis (2-DE) maps of proteins from the SI and SC species, respectively. In the SC species, 22 differently expressed proteins (DEPs) were detected in SCP versus SCUP (self-pollination versus non-pollination in SC species). Of these, 3 and 18 showed an up-or down-regulated expression in the SCP protein sample, respectively, while only one DEP (MSRA, Solyc03g111720) was exclusively expressed in the SCP sample. In the SI species, 14 DEPs were found between SIP/SIUP, and 5 of these showed higher expression in SIP, whereas two DEPs (MLP-like protein 423-like, gene ID, 460386008 and (ATP synthase subunit alpha, gene ID, Solyc00g042130) were exclusively expressed in SIP or SIUP, respectively. Finally, two S-RNases (gene IDs, 313247946 and 157377662) were exclusively expressed in the SI species. Sequence homology analysis and a gene ontology tool were used to assign the DEPs to the 'metabolism', 'energy', 'cytoskeleton dynamics', 'protein degradation', 'signal transduction', 'defence/stress responses', 'self-incompatibility' and 'unknown' protein categories. We discuss the putative functions of the DEPs in different biological processes and how these might be associated with the regulation of SI formation in the tomato clade., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

The evolution of self-compatibility (SC) is the first step in the evolutionary transition in plants from outcrossing enforced by self-incompatibility (SI) to self-fertilization. In the Brassicaceae, SI is controlled by alleles of two tightly linked genes at the S-locus. Despite permitting inbreeding, mutations at the S-locus leading to SC may be selected if they provide reproductive assurance and/or gain a transmission advantage in a population when SC plants self- and outcross. Positive selection can leave a genomic signature in the regions physically linked to the focus of selection when selection has occurred recently. From an SC population of Leavenworthia alabamica with a known nonfunctional mutation at the S-locus, we collected sequence data from a ∼690 Kb region surrounding the S-locus, as well as from regions not linked to the S-locus. To test for recent positive selection acting at the S-locus, we examined polymorphism and the site-frequency spectra. Using forward simulations, we demonstrate that recent selection of the strength expected for SC at a locus formerly under balancing selection can generate patterns similar to those seen in our empirical data., (© 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.)

Tomato style is the pathway for pollen germination and pollen tubes growth from the stigma to the ovules where fertilization occurs. It is essential to supplying the nutrients for pollen tube growth and guidance for the pollen tubes. To our knowledge, style also regulates gametophytic self-incompatibility (SI) in tomato species. This study identified the metabolites and monitored the metabolic changes of self-incompatible and self-compatible tomato with self-pollinated or unpollinated styles by gas chromatography-mass spectrometry (GC-MS). A total of 9 classes of compounds were identified in SI and self-compatibility (SC) self-pollinated and unpollinated styles which included amino acids, sugars, fatty acids/lipids, amines, organic acids, alcohols, nitriles, inorganic acids and other compounds. The contents of d-Mannose-6-phosphate, Cellobiose, Myristic acid, 2,4-Diaminobutyric acid, Inositol and Urea were significantly decreased and the rest did not significantly change in SI styles. But change of metabolites content significantly happened in SC styles. In addition, among the total 9 classes of compounds, the different metabolites accounted for a different proportion in amino acids, sugars, amines, organic acids and alcohols compared SC and SI. The result indicated that the physiological changes of styles existed differences in SC and SI after self pollination., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Premise of the Study: Dichogamy is a common characteristic among angiosperms, including Piper species. In this genus, the tiny flowers are morphologically similar and have an asynchronous stamen development. However, there is no information on the duration of stigma receptivity and whether it overlaps with pollen release. To better understand mechanisms of floral function in Piper vicosanum, we provide a detailed characterization of the timing of pollen release from the four stamens and the period of stigma receptivity and exposure mode of the receptive areas., Methods: We investigated plants of a natural population in a semideciduous seasonal forest (Viçosa, Minas Gerais State, southeastern Brazil), based on chemical tests, light microscopy, and scanning electron microscopy analyses., Key Results: Incomplete protogyny-a mechanism that favors outcrossing-was recorded. The period of stigma receptivity was long (14 d), and the sequential exposure and senescence of stigmatic papillae occurred gradually and in a basipetal direction. Pollen release began 2-6 d after the beginning of the pistillate phase, with an average pollen viability of 87.7%, during the bisexual flower phase. Pollen was released for up to 6 d and occurred in one stamen at a time. The fruit set observed in tests of self-pollination indicated self-compatibility., Conclusions: The gradual and sequential exposure of stigmatic papillae in P. vicosanum flowers is described here as the mechanism for the long duration of receptivity. Anther development and pollen release were also sequential. These findings are yet unreported reproductive characteristics of the genus and offer new perspectives for future studies on the floral biology of other Piper species., (© 2015 Botanical Society of America, Inc.)

Lycoris aurea is a perennial herbaceous plant with important medicinal and ornamental values in the genus Lycoris Herb, the family Amaryllidaceae. The flower has a spider shape with highly exserted stigmas and anthers, which may represent a unique pollination type. In order to explore this type of pollination, we studied its floral characteristics, breeding system, and floral visitors and their behaviors. The results were as follows: (1) The single flower lasted (5.9±0.1) d and the pollen-ovule ratio (P/O) reached about 23 000. The flowers showed reverse herkogamy. On the beginning of flowering, the style and filaments were separated and the angle between them was about 30°. The style gradually moved towards the filaments in the middle and later stages and were finally on the same line with the stigma 2-3 cm higher than the anthers. The stigmas were receptive throughout the flowering period. (2) The breeding system test was self-compatible and bagged flowers cannot set fruit, indicating that pollinators were necessary for pollen transfer. Supplemental hand pollination significantly increased fruit production, indicating the existence of pollen limitation. (3) Four species of swallowtail butterfly were the effective pollinators. Due to the existence of herkogamy in L. aurea, on the beginning of flowering, their hindwings were likely to come into contact with the flattened anthers. Their hindwings might touch the stigma in the middle and later stages and thus the process of pollen transfer was accomplished. In conclusion, this study shows that the uqique floral characteristics of L. aurea are adapted for butterfly wing pollination and also will lay the foundation for its conservation and sustainable utilization. [ABSTRACT FROM AUTHOR]

Context: Knowledge of the reproductive biology of plants is fundamental for conservation, especially of the ones with a limited distribution. Aims: The sexual reproduction of the small-ranged Passiflora chrysophylla Chod. was studied. Methods: Controlled pollinations were performed to assess the breeding system, whereas floral traits and visitors (identity, frequency, activity on the flowers, dimensions and pollen load) were analysed to assess the pollination mechanism. Key results: Self-compatibility was partial. Anthesis was matinal. The odour emitted by the corona was sweet, whereas the odour emitted by the persistent sepals and bracts was similar to that of the leaves. Contrasting concentric circular reward guides were present in the visible and UV spectra. Nectar concentration was high, the volume increased throughout anthesis and, if removed, nectar was replenished only once during the flower lifespan. Style movements towards the anthers determined male and hermaphroditic phases in most of the flowers; in a few flowers (smaller, scented and nectarless), styles remained apart from the anthers, thus constituting a functionally andromonecious and deceptive automimicry system. The bees Ptiloglossa sp., Thygater analis and Xylocopa augusti acted as pollinators, whereas ants, butterflies and beetles were nectar or pollen thieves and florivores. Conclusions: P. chrysophylla is melittophilous and pollinators increase reproductive success. Implications: Pollination biology of P. chrysophylla , reported for the first time, would contribute to conservation management of this species with restricted distribution. The pollination of the tiny passion vine Passiflora chrysophylla , a small-ranged species from the southern hemisphere, has been studied for the first time. Its sexual reproduction and, consequently, its genetic variability, is partially dependant on native bees, mainly crepuscular ones, to which it offers highly concentrated nectar during the morning. Its floral biology is similar to that of its close relative P. foetida , which is widespread, even invasive, and provides useful information in case of conservation needs. Photograph by P. I. Picca. [ABSTRACT FROM AUTHOR]

SUMMARY: The successful interaction between pollen and stigma is a critical process for plant sexual reproduction, involving a series of intricate molecular and physiological events. After self‐compatible pollination, a significant reduction in reactive oxygen species (ROS) production has been observed in stigmas, which is essential for pollen grain rehydration and subsequent pollen tube growth. Several scavenging enzymes tightly regulate ROS homeostasis. However, the potential role of these ROS‐scavenging enzymes in the pollen‐stigma interaction in Brassica napus remains unclear. Here, we showed that the activity of ascorbate peroxidase (APX), an enzyme that plays a crucial role in the detoxification of hydrogen peroxide (H2O2), was modulated depending on the compatibility of pollination in B. napus. We then identified stigma‐expressed APX1s and generated pentuple mutants of APX1s using CRISPR/Cas9 technology. After compatible pollination, the BnaAPX1 pentuple mutants accumulated higher levels of H2O2 in the stigma, while the overexpression of BnaA09.APX1 resulted in lower levels of H2O2. Furthermore, the knockout of BnaAPX1 delayed the compatible response‐mediated pollen rehydration and germination, which was consistent with the effects of a specific APX inhibitor, ρ‐Aminophenol, on compatible pollination. In contrast, the overexpression of BnaA09.APX1 accelerated pollen rehydration and germination after both compatible and incompatible pollinations. However, delaying and promoting pollen rehydration and germination did not affect the seed set after compatible and incompatible pollination in APX1 pentuple mutants and overexpression lines, respectively. Our results demonstrate the fundamental role of BnaAPX1 in pollen rehydration and germination by regulating ROS homeostasis during the pollen‐stigma interaction in B. napus. Significance Statement: Our research found that self‐incompatibility in Brassica napus requires the accumulation of reactive oxygen species (ROS) levels in the stigma. We identified the importance of BnaAPX1 in regulating ROS homeostasis, which is critical for pollen rehydration and germination in B. napus. [ABSTRACT FROM AUTHOR]

Abstract: Letícia AF is a mutation of the plum cultivar Laetitia that confers self-compatibility. This work compared the Letícia AF mutant cultivar with the standard Laetitia regarding fruit set, self-compatibility, yield, and fruit quality traits during four growing seasons. The study was carried out in two plum orchards with the cultivar Letícia AF (orchard 1) and Laetitia plus pollinizers trees (orchard 2) and in an experimental unit with Letícia AF and Laetitia planted side by side. A self-compatibility test was performed on covered branches to prevent pollinating insects from reaching the flowers. Fruit set occurs in covered branches of Letícia AF, whereas it was rare in Laetitia. In commercial orchards, Leticia AF plums yield was higher than that of Laetitia over the years. The results suggest that the oscillation in productivity across the years, mainly due to unfavorable conditions for insect pollination, may be lower in the plum Leticia AF orchard. On the other hand, the requirement for fruit thinning may be greater in Leticia AF. No significant differences were found between the mutant and the standard cultivar regarding fruit quality at harvest and after 30 days of cold storage, indicating the mutation did not alter the fruit characteristics.

The productivity of many tree crops is limited by low yield, partly due to high rates of fruitlet abscission during early fruit development. Early studies suggested that cross-pollinated fruitlets may be selectively retained during fruit development, although paternity testing of fruitlets to test this hypothesis was technically challenging. We used MassARRAY genotyping to determine the effects of pollen parentage on fruitlet retention and fruit quality of Hass avocado. We identified the paternity of abscised and retained fruitlets at 6 and 10 weeks, and mature fruit at 36 weeks, after peak anthesis. We measured the embryo mass, pericarp mass, total mass and nutrient concentrations of fruitlets, and the seed mass, flesh mass, total mass, diameter, length, nutrient concentrations and fatty-acid composition of mature fruit. The percentages of progeny on the tree that were cross-fertilised increased from 4.6% at 6 weeks after peak anthesis to 10.7% at fruit maturity. Only 1.0% of freshly abscised fruitlets on the ground at 10 weeks after peak anthesis were cross-pollinated even though 6.5% of retained fruitlets on the tree were cross-pollinated. At this stage, cross-pollinated fruitlets had similar nutrient concentrations to self-pollinated fruitlets, but they had higher total contents of P, K, Al, Ca, Fe, Mn and Zn due to having greater fruitlet mass. At maturity, cross-pollinated fruit were 6% heavier and had 2% greater diameter than self-pollinated fruit, without significant differences in flesh nutrient concentrations or fatty acid composition. The results demonstrate that Hass avocado trees selectively retain cross-pollinated fruitlets, which are larger than self-pollinated fruitlets and ultimately produce larger mature fruit. Avocado growers can increase fruit size and yield by improving the opportunities for cross-pollination, possibly by closely interplanting type A and type B cultivars and introducing more beehives into orchards. [ABSTRACT FROM AUTHOR]

The Dwarf Palm, Butia lallemantii Deble & Marchiori, is an endangered species endemic to the Pampa biome and typically grows in sandy and rocky soils. Given its economic, ecological, and cultural relevance, it is crucial to understand the ecology and biology of this species to encourage its preservation and highlight its significance for the Pampa. This study aims to investigate whether this palm relies on animal vectors for pollination, analyze its breeding system, and propose strategies for its conservation and sustainable use. We conducted field observations on pollination ecology, identified floral visitors, and designed six breeding system experiments to test cross-compatibility, self-compatibility, and apomixis. Additionally, we conducted a literature review to propose conservation strategies. Butia lallemantii is pollinator-dependent and self-compatible. The flowers are mostly melittophilous and offer pollen and nectar for floral visitors. The main pollinators are native Meliponinae and Halictinae bees and the introduced Apis mellifera. This study represents the first comprehensive and complete examination of the breeding system and pollination process on Butia palms. This palm can provide materials for industries, but urgent actions are needed to preserve the remaining populations through effective policies and strategies. Furthermore, this palm should be integrated into diversified agroecosystems to evaluate its adaptability to cultivation. [ABSTRACT FROM AUTHOR]

Walnut (Juglans regia L.) is a monoecious species and although it exhibits self-compatibility, it presents incomplete overlap of pollen shed and female receptivity. Thus, cross-pollination is prerequisite for optimal fruit production. Cross-pollination can occur naturally by wind, insects, artificially, or by hand. Pollen has been recognized as one possible pathway for Xanthomonas arboricola pv. juglandis infection, a pathogenic bacterium responsible for walnut blight disease. Other than the well-known cultural and chemical control practices, artificial pollination technologies with the use of drones could be a successful tool for walnut blight disease management in orchards. Drones may carry pollen and release it over crops or mimic the actions of bees and other pollinators. Although this new pollination technology could be regarded as a promising tool, pollen germination and knowledge of pollen as a potential pathway for the dissemination of bacterial diseases remain crucial information for the development and production of aerial pollinator robots for walnut trees. Thus, our purpose was to describe a pollination model with fundamental components, including the identification of the "core" pollen microbiota, the use of drones for artificial pollination as a successful tool for managing walnut blight disease, specifying an appropriate flower pollination algorithm, design of an autonomous precision pollination robot, and minimizing the average errors of flower pollination algorithm parameters through machine learning and meta-heuristic algorithms. [ABSTRACT FROM AUTHOR]

Pollination of Dipcadi saxorum Blatt. was studied in Thane and Mumbai suburban districts, Maharashtra, India, during the flowering season from June to August for a period of two years. The flowers are nocturnal, producing scent and nectar at nightfall, which extends up to morning hours, attracting many visitors. The study shows that the species is self-incompatible and that its foul-acrid odour is mainly because of aldehydes and esters. Settling moths, Heliothus peltigera and Chrysodexis acuta, as well as hovering moths, Macroglossum stellatarum and Cephanodes hylas, are pollinators of D. saxorum Blatt. [ABSTRACT FROM AUTHOR]

When reproductive success is determined by the relative availabilities of a series of essential, non‐substitutable resources, the theory of balanced fitness limitations predicts that the cost of harvesting a particular resource shapes the likelihood that a shortfall of that resource will constrain realized fitness. Plant reproduction through female function offers a special opportunity to test this theory; essential resources in this context include, first, the pollen received from pollinators or abiotic vectors that is used to fertilize ovules, and, second, the resources needed to provision the developing seeds and fruit. For many plants realized reproductive success through female function can be readily quantified in the field, and one key potential constraint on fitness, pollen limitation, can be assessed experimentally by manually supplementing pollen receipt. We assembled a comparative dataset of pollen limitation using only studies that supplement pollen to all flowers produced over the plant's reproductive lifespan. Pre‐ and post‐pollination costs were estimated using the weight of flowers and fruits and estimates of fruit set. Consistent with expectations, we find self‐incompatible plants make greater pre‐pollination investments and experience greater pollen limitation. However, contrary to theoretical expectations, when variation due to self‐compatibility is accounted for by including self‐compatibility in the statistical model as a covariate, we find no support for the prediction that plants that invest more heavily in pre‐pollination costs are subject to greater pollen limitation. Strong within‐species, between‐population variation in the expression of pollen limitation makes the quantification of mean pollen limitation difficult. We urge plant ecologists to conduct more studies of pollen limitation using whole‐plant pollen supplementation to produce a richer comparative dataset that would support a more robust test of the balanced limitations hypothesis. [ABSTRACT FROM AUTHOR]

Introduction: Monoecy is usually interpreted as an important evolutionary route of the plant sexual system from hermaphroditism to dioecy. This floral mechanism can effectively reduce self-interference during the reproductive process, and the services provided by pollinators may play an essential role in monoecious species; however, relevant research is still lacking. Thus, we aimed to determine whether monoecious plants could effectively avoid selfinterference and promote the evolution of monoecy under the service of pollinators. Methods: Here, we successfully performed manipulation experiments to test self-compatibility, pollinator behavior, and self-interference between male and female functions in Akebia trifoliata, a typical monoecious species. Results: We demonstrated that experimental self-pollination did not yield any fruit, and supplemental pollination significantly increased fruit set and fruit weight compared to natural pollination, suggesting that this species is completely selfincompatible and experiences strong pollen limitation. Simultaneous self- and cross-pollination and self-pollination prior to cross-pollination significantly reduced reproductive fitness, but self-pollination after cross-pollination did not, indicating self-interference in this plant. Moreover, both male flower probing preference and switching modes within inflorescences by pollinators successfully reinforced self-interference and were also responsible for decreasing reproductive fitness in A. trifoliata. Discussion: In summary, pollinator-mediated self-interference significantly reduced selfing, providing potential dynamics for the maintenance and evolution of monoecy. [ABSTRACT FROM AUTHOR]

Pollination is essential for the reproductive output of crops. Anthropogenic disturbance and global pollinator decline limit pollination success, reducing the quantity or quality of pollen. Relationships between the abundance of flower visitors and fruit production are often poorly understood. We aimed to (1) identify and quantify flower visitors in a mango orchard; (2) assess how much of the crop resulted from self- versus cross-pollination at increasing distances from a cross-pollen source in large, single-cultivar blocks of the cultivar Kensington Pride or the cultivar Calypso; and (3) determine how pollen parentage affected the size, colour, flavour attributes, and nutritional quality of fruit. Mango flowers were mostly visited by rhiniid flies and coccinellid beetles. Approximately 30% of the fruit were the result of cross-pollination, with the percentage significantly decreasing with an increasing distance from a cross-pollen source in the cultivar Calypso. Self-pollinated Calypso fruit were slightly larger and heavier, with higher acid and total polyphenol concentrations than cross-pollinated fruit. Our results showed higher-than-expected levels of cross-fertilisation among fruit, although self-pollen was likely more abundant than cross-pollen in the large orchard blocks. Our results suggest the preferential cross-fertilisation of flowers or the preferential retention of cross-fertilised fruitlets, both representing strategies for circumventing inbreeding depression. Growers should establish vegetated habitats to support pollinator populations and interplant cultivars more closely to maximise cross-pollen transfer. [ABSTRACT FROM AUTHOR]

Euonymus americanus is a common understory shrub in mesic deciduous forests of eastern North America. Its inconspicuous greenish-white flowers appear in late April and May and are regularly visited by several species of ants and, by night, a species of cockroach. Because the species is self-compatible, these pollinators need not move between plants to effect fertilization and fruit-set. Flowers last for three days and are strongly protandrous with little if any overlap of male and female function. Based on a survey of five years of reports on iNaturalist in Georgia, Prenolepis imparis is the most commonly observed ant, followed by Camponotus pennsylvanicus and Crematogaster lineolata, though Camponotus castaneus was more common than the latter two species at our study sites. Each of these species was found to carry many viable pollen grains, as was a species of cockroach (Cariblatta lutea). Exclusion of ants from flowers resulted in near-zero fruit-set. Nevertheless, addition of pollen increased fruit-set significantly over open-pollinated levels, indicating pollen limitation. The upper limit in terms of potential seeds per fruit is 30, representing six seeds in each of the five locules of a mature capsule, but the average number of seeds per capsule was only 12. Seed viability was high, exceeding 95%. [ABSTRACT FROM AUTHOR]

The evolution and expression of floral traits are responsive to selection pressure from biotic and abiotic factors. Although floral traits significantly vary among environments, the flower remains unchanged. We aimed to understand the adaptation of Epimedium chlorandrum of floral traits to a frequently nocturnally rainy and wet environments and the roles of floral traits in pollination and reproduction. We observed flowering phenology, measured floral characteristics including the number of pollen grains and ovules per flower, measured pollen viability and stigma receptivity, tested the volume and sugar concentration of nectar and conducted flower-visit observations in this species. Different pollination treatments were performed to characterize the breeding system. The inner sepals and highly curved longer spurs of E. chlorandrum jointly formed an umbrella that shielded the anthers and stigma from rain wash and prevented nectar dilution. Epimedium chlorandrum was visited by six species, while Bombus trifasciatus was the only effective pollinator and fed on the nectar. One flower secreted approximately 17.06 µL of nectar with a 29.19 g/100 mL sugar concentration, and the pollination efficiency of B. trifasciatus was positively associated with the nectar sugar concentration. The self- and open-pollination treatments resulted in fewer fertile seeds than the cross-pollination treatment. In contrast, the autonomous self-pollination treatment failed to yield fertile seeds. In summary, pollen limitation caused by harsh weather and pollinator shortage occurred during the pollination process of E. chlorandrum , which was partially alleviated by self-compatibility. [ABSTRACT FROM AUTHOR]

Reproductive systems and pollination modes (pollination by animals vs. wind) can switch within clades, and many species with an intermediate pollination mode (ambophily, pollination by animals and wind) exist. Here, we investigate the reproductive systems and pollination modes of two common Eurasian species from the Agrimonieae (Rosaceae) that occur in open habitats, Sanguisorba minor and Sanguisorba officinalis. Based on observations from literature, the flowers of both species are visited by insects, but due to flower morphology S. minor is commonly regarded as wind pollinated, while S. officinalis is classified as insect pollinated. By measuring floral traits, such as pollen grain and ovule number per flower, observing flower visitors in natural habitats as well as in the botanical gardens and conducting pollination experiments we found that the reproductive systems and pollination modes of the two species differ: Sanguisorba minor is commonly but infrequently visited by short‐tongued insects but is nevertheless exclusively wind pollinated. However, in contrast to most other wind‐pollinated species, S. minor is highly self‐compatible and even able to set seeds by autogamous selfing. Sanguisorba officinalis, on the other hand, is largely insect pollinated, but wind also contributes to seed set (⁓17% after insect exclusion). This species is able to set seeds by geitonogmous selfing but seed set is higher by outcrossing than by selfing. Thus, our study demonstrates another example of a plant species with small, open flowers arranged in large inflorescences that can be shown to be ambophilous. Further, the study will help to reconstruct the complex evolution of pollination modes in Agrimonieae (Rosaceae). [ABSTRACT FROM AUTHOR]

The relationships of interspecific compatibility and incompatibility in Solanum section Petota are complex. Inquiry into these relationships in tomato and its wild relatives has elucidated the pleiotropic and redundant function of S-RNase and HT which tandemly and independently mediate both interspecific and intraspecific pollen rejection. Our findings presented here are consistent with previous work conducted in Solanum section Lycopersicon showing that S-RNase plays a central role in interspecific pollen rejection. Statistical analyses also demonstrated that HT-B alone is not a significant factor in these pollinations; demonstrating the overlap in gene function between HT-A and HT-B, as HT-A, was present and functional in all genotypes used. We were not able to replicate the general absence of prezygotic stylar barriers observable in S. verrucosum, which has been attributed to the lack of S-RNase, indicating that other non-S-RNase factors play a significant role. We also demonstrated that Sli played no significant role in these interspecific pollinations, directly conflicting with previous research. It is possible that S. chacoense as a pollen donor is better able to bypass stylar barriers in 1EBN species such as S. pinnatisectum. Consequently, S. chacoense may be a valuable resource in accessing these 1EBN species regardless of Sli status. [ABSTRACT FROM AUTHOR]

Strawberry flowers are hermaphroditic and most cultivars are self-compatible, but strawberry plants can produce a mixture of fruit that have arisen from self-pollination and cross-pollination. We aimed to determine whether size, shape, color, taste attributes and shelf life differ between self-pollinated and cross-pollinated fruit competing on the same Redlands Joy strawberry plant. Experiments were repeated at three fertilizer levels to determine the consistency of responses across different levels of crop nutrition. Cross-pollinated fruits were 4.2%–7.5% heavier and 2.7%–5.0% longer than self-pollinated fruits, with the differences being greater at lower levels of nutrient supply. They were also darker or redder than self-pollinated fruits. Cross-pollinated fruits sometimes had lower °Brix (sugar) or lower acidity than self-pollinated fruits, with the effect on sugar:acid ratio depending on the nutrient level. The shelf life of cross-pollinated fruits was approximately 4 days longer than self-pollinated fruits on plants that received medium or high levels of fertilizer. The results suggest that pollen-parent effects on fruit size become evident when self- and cross-pollinated strawberry fruits compete for resources on the same plant, and that the expression of pollen-parent effects can be affected by the level of crop nutrition. [ABSTRACT FROM AUTHOR]

In the production of blueberries, pollination is a key factor determining high quality yield. Problems with the process of pollination in blueberries occurs frequently. Lack of the effective pollination results in a lower yield and production of small fruits with low commercial value. The experiment described in this paper was carried out to test the effect of titanium organic complex (TOC) on the pollination and fertilization processes, seed formation, fruit setting and fruit development of blueberry in two consecutive years. The experiment consisted of two experimental factors: pollination type (self or open pollination) and application of TOC or lack of it. The presented study proves that TOC stimulates pollen adhesion and germination on the stigma, fruit setting, seed setting and fruit development. In self-pollinated flowers, the use of TOC increased the mass of each berry by 28% (in the first year) and 26% (in the second year), compared to non-treated plants. In open pollinated flowers, the application of TOC increased fruit mass by 38% (in the first year) and 29% (in the second year), compared to non-treated plants. Therefore, TOC may be treated as a substance stimulating the total fruit yield and mass of individual fruit. [ABSTRACT FROM AUTHOR]

The study of interactions between plants and animals is important for detecting the degree of vulnerability of species under the current scenario of forest fragmentation. The genus Passiflora (Passifloraceae) is widely distributed in forest formations in Brazil with about 157 species. Here we studied the pollination biology of Passiflora morifolia, a native species of Brazil that is widely distributed in the American continent. Floral biology observations, controlled pollination tests and the recording of floral visitors were carried out in an area of natural occurrence, a fragment of Araucaria Moist Forest, located in the state of Paraná, Brazil. The results showed that the species is self-compatible, with flowers that open at night and remain open and receptive in the morning. The greatest volume of secreted nectar was observed at the beginning of anthesis, when the flower released an intense sweet odor and received visits from nocturnal and crepuscular bees. The bees Megommation insigne and Ptiloglossa willinki were the first visitors to the opened flowers and also the main pollinators. [ABSTRACT FROM AUTHOR]

Boron plays a critical role in pollination and fertilization and can affect fruit set and yield. We applied 0 g, 15 g (manufacturer recommendation) or 30 g boron pre-flowering to Hass avocado trees to determine the effects on fruit set, fruitlet paternity, yield, fruit size, mineral nutrient concentrations and fatty acid composition. The boron applications did not significantly affect the initial fruit set at 3 or 6 weeks after peak anthesis or the proportions of self-pollinated fruitlets or mature fruit. Approximately 88–92% of the mature fruit were self-pollinated. However, applying 30 g boron per tree reduced the fruit set at 10 weeks after peak anthesis by 56% and the final yield by 25%. Attaining > 90% of the maximum yield was associated with foliar boron concentrations being below 104 mg/kg at 6 weeks after peak anthesis and between 39 and 68 mg/kg at 28 weeks after peak anthesis. Applying 15 g boron per tree increased the fruit mass by 5%, fruit diameter by 2%, flesh mass by 9%, flesh boron concentration by 55%, and the relative abundance of unsaturated fatty acids by 1% compared with control trees. Applying the recommended amount of boron provided a good yield of high-quality avocado fruit but applying boron at double the recommended rate reduced the yield. [ABSTRACT FROM AUTHOR]

Pollinator shift and its influence on floral traits have been well documented to explain the diversity of angiosperms, but such effects are still less known at the intraspecific level, especially the responses of different morphs of distylous plants. We hypothesized that the pollen transfer efficiency would decrease if the pollinator shifted from a long‐tongued to short‐tongued insect across populations, and plants would evolve towards selfing in response to the stressed pollination environment. Given the gender specialization between flower morphs, the long styled (L‐morph) plants would increase female reproduction. Our study showed that the short‐tongued Bombus tianshanicus, the most‐visit pollinator in high elevation populations of distylous Primula nivalis, was less efficient in pollen transfer than long‐tongued Bombylius major. The plants evolved to promote selfing through reducing the anther–stigma separation and increasing intramorph self‐compatibility. The hand pollination experiment showed that after intramorph selfing, the fruit set and seed set increased with increasing elevation. Moreover, anther and stigma were closer in the L‐morph than in the short styled (S‐morph) plants, and the L‐morphs showed higher pollen transfer efficiency than the S‐morphs. Along with increased self‐compatibility, the fruit set and seed set of L‐morph plants were significantly higher than those of S‐morph plants. We described the pollinator shifts along an elevation gradient in a distylous plant and the response of plants by promoting selfing, which confirmed our hypothesis and supported the pollinator‐shift model. Our study also highlighted the different response in self‐compatibility between flower morphs. [ABSTRACT FROM AUTHOR]

Iris verna L. var. smalliana Fernald ex M.E. Edwards (Family Iridaceae, hereafter referred to as Iris verna) is currently listed as endangered in Pennsylvania. The six extant populations in Pennsylvania are all located in one state forest and represent the northern end of the range for the species. There is little known about the basic biology of I. verna throughout its range, making preservation of threatened populations difficult. Iris verna was tested for self-compatibility and the ability to autonomously self-pollinate in 2016. Pollinator limitation studies were conducted on three of the Pennsylvania populations in 2015 and 2016 by comparing hand-pollinated and naturally pollinated flowers. Potential animal pollinators or seed dispersers were identified through in-person observation and video camera use. Iris verna was found to be self-compatible, with no significant reduction in seed production in selfed flowers, but the species does require a pollinator for pollen transfer. Seed production in I. verna was limited by pollinators during both years of the study and seed production in both control and hand-pollinated flowers was variable across years, suggesting resource availability also limits sexual reproduction. Ants were the only observed animals potentially coming in contact with reproductive organs while visiting flowers, and were also identified as seed dispersers. Our findings suggest that pollinators can be an important limiting factor to sexual reproduction in these endangered populations of I. verna in Pennsylvania. [ABSTRACT FROM AUTHOR]

Invasive alien plants often influence pollinator visitation to native plants when sharing pollinator guilds. It is of conservation concern when the invasive alien plant is characterized by floral resources that attract pollinators, thereby reducing the reproductive success of native species. This is well studied for insects, but whether the same is true for bird pollinators is largely unknown. We address this by considering the impact of an invasive alien plant (Banksia speciosa) on visitation rates of nectar‐feeding bird pollinators to native Protea compacta in the Cape Floristic Region of South Africa.We determined bird pollinator visitation rate to B. speciosa and P. compacta over 21 h of observation at three sites. We also quantified how visitation rate influenced reproductive success of both study species through different breeding experiments.Sugarbird visitation to P. compacta was significantly lower in the presence of B. speciosa, while there was no effect for sunbirds as they mostly avoided B. speciosa. Protea compacta had higher nectar volumes and sucrose per flower than B. speciosa. Sucrose per hectare was higher in all P. compacta plots compared to B. speciosa. Neither study species is pollen limited and they are self‐compatible to some extent. But pollinator visitation enhanced seed production in both species.We show here that the invasive alien B. speciosa flowers attract sugarbirds – but not sunbirds – away from native P. compacta. The long‐term effect of reduced pollinator visitation may reduce the fitness of P. compacta, but the long‐term demographic impact is unknown and would require further study. [ABSTRACT FROM AUTHOR]

Having hundreds of big mountains, the Qinghai–Tibetan Plateau and its southern boundary, the Hengduan Mountains Region, represent one of the world's biodiversity hotspots. In the so‐called "Third Pole of the earth", diverse effects of climate change and habitat heterogeneity could have driven the evolution of plant adaptive strategies. In this review, we collected and compiled recent sources of reproductive biology in animal‐pollinated plants, stressing the questions that need further attention, including pollination system, pollen limitation, self‐compatibility, and sexual system. We constructed plant–pollinator interaction networks based on the case studies from this region, showing that the majority of pollinators were bees, moths, butterflies, and flies were also important, and bats and birds were rare. As the unpredictable (cold, rainy or windy) weather affects pollinator activities, sexual reproduction seemed to be pollen limited, but available studies show that the exact pattern of pollen limitation is still under debate. Self‐compatibility could be either a solution, or a result from pollen limitation. Moreover, plant sexual systems can be regarded as an integrated module that counters pollen limitation. As phylogenetic relationships were constructed, diverse genera experienced rapid radiation were revealed in these mountainous areas. Further studies of evolutionary transitions in reproductive systems of congeners will unveil potential factors shaping the general pattern of adaptive strategies in animal‐pollinated plants. Further studies will be beneficial in using advanced new techniques, examining phenotypic selection under common gardens, and considering chemical ecology in interactions between plants and florivores, particularly in pollen fate. [ABSTRACT FROM AUTHOR]

Island plants provide special opportunities for the study of evolution and ecology. In field and greenhouse studies we characterized a model reproductive system for Plocama pendula , endemic to the Canary Islands. This species has a complicated and not immediately obvious reproductive system. Pollination is biotic, and all flowers are morphologically hermaphroditic, but half of the plants characteristically bear flowers with nectar, pistils with reflexed stigmatic lobes and pollen-less anthers (i.e. they are functionally female flowers). The other half bear nectar-less flowers with abundant pollen and full-sized pistils that mostly have un-reflexed stigmatic lobes (i.e. they are hermaphroditic flowers functioning mostly as males). However, experiments show these pollen-bearing flowers to be self-compatible. Thus, the functionally male flowers have a breeding system that allows selfing in limited circumstances, but the functionally male flowers produce far fewer fruits than do functionally female flowers. With morphologically gynodioecious, functionally largely dioecious flowers, sometimes capable of selfing, the reproductive system of this species could be labelled as 'leaky' in many respects. Thus, we propose that P. pendula has colonized new habitats and persists in substantial populations at least in part because it manifests a reproductive system that is a model for successfully balancing the often-conflicting evolutionary demands of colonization, establishment and persistence. [ABSTRACT FROM AUTHOR]

The factors that facilitate successful colonization of islands should be especially evident where the establishment filter is strongest. Colonizers of small, remote oceanic islands should be initially rare, extremely mate-limited and often without pollinators. Hence, plant communities on such islands should reflect an establishment history in which young 'naturalized' species are most likely to display self-compatibility and autonomous selfing, whereas 'indigenous' species may exhibit more diverse reproductive strategies. To test this prediction, we characterized breeding systems of 28 species on Pohnpei, in the Federated States of Micronesia, a group of remote Pacific islands that are considered a global biodiversity hotspot. Three families with both naturalized and indigenous species were selected—Fabaceae, Malvaceae and Melastomataceae. Measurements included field observations of dichogamy/herkogamy and floral attraction traits, pollen:ovule (P:O) ratios and experimental hand-pollinations for self-compatibility and pollen limitation. Phylogenetic generalized least squares analyses tested for trait correlations between naturalized and indigenous species. Flowers of all 28 species were bisexual, and pollinator attraction features were common. Pollen:ovule ratios ranged from 9 to 557 (median = 87), and all 11 hand-pollinated species were self-compatible. All species had >5 ovules and <3500 pollen grains per flower. Indigenous species did not differ significantly from naturalized species for any trait. There is a dearth of data from remote islands bearing on the question of establishment history. In this study, we inferred all species to have some degree of autogamy and indigenous species were no more likely than naturalized species to display outcrossing mechanisms. On Pohnpei, high ovule numbers, and the inaccessibility of wind pollination and obligate outcrossing strategies, reflect the importance of retaining reproductive assurance mechanisms in the face of pollinator uncertainty. [ABSTRACT FROM AUTHOR]

Although plant species originated from Arctic regions commonly grow in alpine habitats at mid-latitudes, some populations of these species exist also in some specific habitats below the treeline. Local populations at lower elevations may have different origins, ploidy levels, mating systems and/or morphological traits from alpine populations, but comparative studies between alpine and low-elevation populations are scarce. We aimed to reveal the ecological and genetic differentiations between higher and lower populations of Vaccinium vitis-idaea in Hokkaido, northern Japan by comparing 22 populations growing in diverse environments. We analysed the ploidy level of individual populations using flow cytometry. Genetic differentiation among populations, and genetic diversity within populations were calculated using microsatellite markers. Fruit and seed production were recorded under natural conditions, and a pollination experiment was conducted to reveal the variations in mating system across populations. Furthermore, we compared shoot growth and leaf characteristics among populations. Most of the low-elevation populations were tetraploid, whereas all but one of the alpine populations were diploid. Tetraploid populations were clearly differentiated from diploid populations. Some tetraploid populations formed huge clonal patches but genetic diversity was higher in tetraploids than in diploids. Alpine diploids were self-incompatible and produced more seeds per fruit than tetraploid populations. In contrast, tetraploids showed high self-compatibility. Leaf size and foliar production were greater in tetraploid populations. Our results indicate that the genetic compositions of low-elevation tetraploid populations are different from those of alpine diploid populations. Most populations at lower elevations contained unique ecotypes suited to persistence in isolated situations. Local, low-elevation populations of typical alpine species maintain ecologically and genetically specific characteristics and could be valuable in terms of evolutionary and conservation biology. The present study demonstrates the biological importance of small and isolated populations at the edges of species distribution. [ABSTRACT FROM AUTHOR]

Variation in plant breeding systems has implications for pollinator‐mediated selection on floral traits and the ecology of populations. Here we evaluate pollinator contribution to seed production, self‐compatibility and pollen limitation in different floral colour forms of Drosera cistiflora sensu lato (Droseraceae). These insectivorous perennial plants are endemic to fynbos and renosterveld vegetation in the Cape Floristic Region of South Africa, and the species complex includes five floral colour forms (pink, purple, red, white and yellow), some of which are known to be pollinated by beetles.Controlled hand‐pollination experiments were conducted in 15 populations of D. cistiflora s.l. (two to four populations per floral colour form) to test whether the colour forms vary in their degree of self‐compatibility and their ability to produce seeds through autonomous self‐fertilization.Yellow‐flowered forms were highly self‐incompatible, while other floral colour forms exhibited partial self‐compatibility. Seed set resulting from autonomous selfing was very low, and pollinator dependence indices were high in all populations. Since hand cross‐pollination resulted in greater seed set than open pollination in 13 of the 15 populations, we inferred that seed production is generally pollen‐limited.Drosera cistiflora s.l. typically exhibits high levels of pollinator dependence and pollen limitation. This is unusual among Drosera species worldwide and suggests that pollinators are likely to mediate strong selection on attractive traits such as floral colour and size in D. cistiflora s.l. These results also suggest that the floral colour forms of D. cistiflora s.l. which are rare and threatened are likely to be vulnerable to local extinction if mutualisms were to collapse indefinitely. [ABSTRACT FROM AUTHOR]

Thespesia populnea is a coastal evergreen tree species which flowers seasonally. The flowers are hermaphroditic, self-compatible, self-pollinating, and principally melittophilous. The fruits are indehiscent, turban-shaped, capsules, which release seeds in tidal water upon the decay of their pericarp. Both fruits and seeds are buoyant and typically hydrochorous. This species is a source of wood, dye, food, traditional medicine, being also used as an ornamental and avenue tree. Therefore, it is important in coastal eco-restoration and carbon sequestration. [ABSTRACT FROM AUTHOR]

Some epiphytes are adapted to extreme environments with the ability to survive drought as a result of their morphological (xeromorphism), anatomical (foliar trichomes or scales) and physiological features. In contrast to vegetative features, they may have diverse sexual reproductive strategies. Here we compared the flowering morphology, floral biology, breeding system and pollinators of Tillandsia duratii , T. loliacea and T. recurvifolia (Bromeliaceae) adapted to an extreme environment, the Brazilian Chaco. Tillandsia duratii and T. recurvifolia flower for 5–6 months, whereas T. loliaceae flowers for 11 months, mainly in the dry season, with low to high flowering overlap between them. Although these species generally show similar flowering morphology, they differ in size, colour, odour and/or floral functionality, suggesting non-sharing of pollinators among them. Bimodal pollination occurs in T. duratii (bees, moths other than hawkmoths) and T. recurvifolia (butterflies, hummingbirds); in T. loliacea , we recorded no floral visitors. Tillandsia recurvifolia is self-incompatible, has flowers which approach herkogamy and protandry, and depends on pollen vectors for fruit set. The other two species show reverse herkogamy, autonomous self-pollination and self-compatibility (mixed breeding system); therefore, pollinators are not required. The disparity in reproductive strategies among the three species suggests the possibility of selection for diverse modes of reproduction. [ABSTRACT FROM AUTHOR]

The eu-bromelioid clade provides a classic example of an exceptionally rapid radiation, in which many closely related species are found in sympatry. In this respect, species cohesion may be due to the rapid evolution of strong reproductive barriers, although interspecific and intergeneric hybridization is observed in the family. The objective of this study was to characterize the breeding systems and post-pollination reproductive barriers in Wittmackia patentissima and Hohenbergia ridleyi. Previously included in Aechmea , they show an almost complete absence of pre-pollination barriers, although their recent divergence may not have allowed time for complete ecological/reproductive isolation to have evolved. In manual pollinations, both species had > 40% fruit set in self and outcross treatments, but seed set from manual self-pollinations was < 50% that of outcrosses, and spontaneous self-pollination produced fewer than three seeds per fruit. Self-pollen and pollen tubes showed no evidence of self-incompatibility, but heterospecific pollen tubes were arrested in the lower part of the style and heterospecific seed set was zero in both species. The combination of self-compatibility and strong post-pollination, pre-fertilization reproductive barriers is consistent with the involvement of breeding system reproductive barriers in allowing closely related bromeliad species to occur in sympatry. [ABSTRACT FROM AUTHOR]

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Premise: As Baker's law suggests, the successful colonization of oceanic islands is often associated with uniparental reproduction (self‐fertility), but the high incidence of dimorphism (dioecy, gynodioecy) on islands complicates this idea. Lycium carolinianum is widespread, occurring on the North American mainland and the Hawaiian Islands. We examined Baker's ideas for mainland and island populations of L. carolinianum and examined inbreeding depression as a possible contributor to the evolution of gynodioecy on Maui. Methods: Controlled crosses were conducted in two mainland populations and two populations in Hawaii. Treatments included self and cross pollination, unmanipulated controls, and autogamy/agamospermy. Alleles from the self‐incompatibility S‐RNase gene were isolated and compared between mainland and island populations. Given self‐compatibility in Hawaii, we germinated seeds from self‐ and cross‐ treatments and estimated inbreeding depression using seven traits and a measure of cumulative fitness. Results: Mainland populations of Lycium carolinianum are predominately self‐incompatible with some polymorphism for self‐fertility, whereas Hawaiian populations are self‐compatible. Concordantly, S‐RNase allelic diversity is reduced in Hawaii compared to the mainland. Hawaiian populations also exhibit significant inbreeding depression. Conclusions: Self‐compatibility in Hawaii and individual variation in self‐fertility in mainland populations suggests that a colonization filter promoting uniparental reproduction may be acting in this system. Comparison of S‐RNase variation suggests a collapse of allelic diversity and heterozygosity at the S‐RNase locus in Hawaii, which likely contributed to mate limitation upon arrival to the Pacific. Inbreeding depression coupled with autonomous self‐fertilization may have led to the evolution of gynodioecy on Maui. [ABSTRACT FROM AUTHOR]

Highlights • Discovery of a new pollination systems not described elsewhere in the genus Viola. • Temporal flower closure (nyctinasty) provides self- and cross-pollination realized by a single flower. • The timing of nyctinastic movements is correlated with stigma receptivity. • Floral characters indicate that V. banksii may have a pollination deceit strategy. • Temporal flower closure seems to be endogenous but affected by changes from light to darkness. Abstract Viola banksii of the eastern Australian and Tasmanian sect. Erpetion produces exclusively chasmogamous flowers, unlike most other temperate taxa of Viola which additionally produce obligatory self-pollinated cleistogamous flowers. This study explored flower structure and nyctinastic flower movements (temporal flower closure), the correlation of the timing of nyctinastic movements with stigma receptivity, and self-compatibility of flowers. Petal movement in day/night cycles was documented by two cameras. Floral morphology, anther protuberance anatomy, stigma receptivity, and pollen tube growth were examined using scanning electron microscopy, fluorescent microscopy, histochemical and sectioning techniques. Diurnal petal movements that cause flowers to be open during the day and closed during the night were documented in V. banksii. Chasmogamous flower colour, fragrance, anterior petal venation, and the indurated green area at the base of the anterior petal are all likely to play roles for pollinator attraction. Unlike most other Viola species, the anther protuberances do not function as nectaries. The flowers offer pollinators no nectar reward. The short time of stigma receptivity (2–3 days) of individual flowers limits opportunities for insect visitation and cross-pollination. Night-closed flowers of V. banksii appear to facilitate self-pollination. Self-compatibility was confirmed by tracking the pollen tube growth from the stigma to the ovule in spontaneous and hand self-pollinated flowers. Over the floral phenological cycle, nyctinasty coincides in time with stigma receptivity and, hence, the ability of self-pollination. We discovered that the same chasmogamous flower of V. banksii can cross-pollinate while open during the day, but self-pollinate while closed during the night (i.e. acting as a cleistogamous-like flower). Several floral characters indicate that V. banksii exhibits a pollination deceit strategy. Such a pollination system has not been described elsewhere in Viola. [ABSTRACT FROM AUTHOR]

Knowledge of plant breeding systems may be critical to facilitate recovery of species considered at risk. Gesneria pauciflora is a threatened, rupiculous, and riverine species with floral-traits that suggest a hummingbird-pollination system. Because these habitat-pollinator conditions have been linked to pollinator-independent reproductive systems, we expected a breeding system that provides reproductive assurance. We assessed the breeding system and potential vulnerabilities during pollination phase using field observations and pollination experiments, to determine pollinator dependency and the existence of strategies for reproductive assurance. Gesneria pauciflora was pollinated by two hummingbird species but visitation rates were low, probably due to low nectar rewards. Fruit set and seed production were significantly higher in flowers when pollen was artificially delivered (self- and cross-pollination) compared to when it was not (control and autogamy), suggesting that reproduction is pollen-limited. Gesneria pauciflora is self-compatible, with some seeds produced via autonomous selfing without any effects of pollination mechanism on seed germination rates. Florivory by the native plume-moth Postplatyptilia caribica was observed, but its incidence was low (12%). Our findings are consistent with theory on the evolution of plant breeding systems on islands, and contribute to the understanding of the evolution of breeding systems in Caribbean gesneriads. Overall, data do not show immediate vulnerabilities to this listed species at the pollination phase, and autogamy may represent reproductive assurance counteracting unpredictable environmental factors that influence its reproduction. However, its capacity for selfing is small relative to other tubular Puerto Rican Gesneria which may explain its rare status. [ABSTRACT FROM AUTHOR]

Legitimate flowers visitors pollinate the flower during the visit and thus influence the production of fruits and seeds. We tested whether the visitation rate of potential pollinators is associated with the amount of seeds per fruit produced by the self-compatible bromeliad Tillandsia stricta (Bromeliaceae). We determined whether hummingbirds are legitimate visitors by testing for a correlation between visits and pollination (seed production) at the Guapiaçú Ecological Reserve (Reserva Ecológica de Guapiaçú), state of Rio de Janeiro. We tested 30 flowers, five of which were also monitored to test the possibility of spontaneous self-pollination. The remaining 25 flowers were exposed to floral visitors. Twenty-two flowers formed fruits and seeds, from which three formed seeds without floral visits. The hummingbird Amazilia fimbriata (Gmelin, 1788) was the only legitimate visitor. The average number (± standard deviation) of seeds was 27 units (±15) per fruit. The floral visitation rate by A. fimbriata was 6.6 (±3.4) visits/per flower. The number of floral visits and the amount of seed produced were positively correlated (r² = 0.58, p < 0.01). Thus, A. fimbriata is a legitimate floral visitor of T. stricta, and influences seed production per fruit in this bromeliad.

The deficiency of pollinators is indicated as the main factor limiting fruit set in orchids. Nectariferous species are more successful in setting fruits than nectarless species. In the present study, we tested whether pollinator limitation lowers reproductive success in populations of Cypripedium calceolus on environmental islands in the Biebrza National Park, NE Poland. Moreover, we analyzed how population size and structure affect pollination success. Our observations and results of experiments document the low level of fruiting in populations of nectarless C. calceolus (9.2% on average) and strong pollen limitation. Generally, we noted a positive relationship between pollination success and all parameters of population size (measured by both occupied area and number of clumps or shoots) and parameters measuring floral display (number of flowers in population, number of flowers in clumps, spatial structure of flowering shoots). We suggest that information about factors influencing the reproductive success of this endangered species may be useful for planning appropriate conservation actions. [ABSTRACT FROM AUTHOR]

Cuphea melvilla é uma espécie peculiar dentro de um gênero majoritariamente melitófilo. Dois agrupamentos de indivíduos, em bordas das matas de galeria do Córrego do Panga, Uberlândia, MG, foram estudados com o objetivo de investigar o sistema de polinização e sistema de reprodução da espécie na região. O estudo foi realizado de janeiro a junho de 1999. Cuphea melvilla é uma espécie arbustiva com características morfológicas e eventos florais que confirmam sua adaptação à polinização por beija-flores. A floração foi longa, com início em Janeiro, em plena estação chuvosa, e término em Julho, no início da seca. O tubo floral formado pelo hipanto é calcarado na base, onde se acumula o néctar produzido por nectário localizado na base do ovário. As flores são marcadamente protândricas, mas flores em diferentes fases podem ser encontradas nos racemos. Os dados mostraram que a espécie é autocompatível e não apomítica, mas devido à dicogamia marcada, necessita polinização ativa para formar frutos. Phaethornis pretrei, Amazilia fimbriata, Thalurania furcata, Eupetomena macroura e Chlorostilbon lucidus (fêmea) foram as espécies de beija-flores observadas visitando e polinizando as flores de C. melvilla. Amazilia fimbriata e C. lucidus apresentaram ocasionalmente comportamento territorial, P. pretrei apresentou forrageamento em linhas de captura, e T. furcata e E. macroura apresentaram forrageamento do tipo oportunístico, visitando as populações estudadas esporadicamente. Amazilia fimbriata, C. lucidus e P. pretrei foram considerados os polinizadores mais importantes, dada a sua constância. As características morfológicas das flores de Cuphea melvilla relacionadas a adaptações aos beija-flores parecem ser derivadas no gênero, sendo que a polinização por beija-flores nas distintas seções indica adaptação convergente a este modo de polinização.Cuphea melvilla is a peculiar species of a mostly melittophilous genus. Various aspects of the floral and reproductive biology of two groups of individuals, which occur on the edge of gallery forests on the Panga stream (in Uberlândia, southeastern Brazil), were studied. Observations were carried out during the flowering season of 1999. Cuphea melvilla is a shrub with floral features adapted to hummingbird pollination. It has a long flowering period, from January to July, but flowers the most during the rainy season. The flower tube of this species is of hypanthial origin, has a spur at the base, and accumulates nectar, which is produced by a nectary at the base of the ovary. The flowers were protandrous but different floral phases were present from the top to the bottom of the simple racemes. The species appears to be self-compatible but non-apomictic and needs active pollination to form fruits. Pheathornis pretrei, Amazilia fimbriata, Thalurania furcata, Eupetomena macroura and Chlorostilbon lucidus (female) were the hummingbird species observed visiting and pollinating the C. melvilla flowers. Amazilia fimbriata and C. lucidus showed occasional territorial behaviour in relation to the C. melvilla populations, whereas P. pretrei seemed to be trapliner. Thalurania furcata and E. macroura visited the studied populations sporadically. Amazilia fimbriata, C. lucidus and P. pretrei were considered the main pollinators for the studied populations due to their frequency. The flower features of Cuphea melvilla that are related to hummingbird pollination appear to be derived within the genus, and bird pollination, within different sections of the genus, indicate a convergent adaptation.

This study tested the hypothesis that self-compatibility would be associated with floral traits that facilitate autonomous self-pollination to ensure reproduction under low pollinator visitation. In a comparison of two pairs of Ipomoea species with contrasting breeding systems, we predicted that self-compatible ( SC) species would have smaller, less variable flowers, reduced herkogamy, lower pollinator visitation and higher reproductive success than their self-incompatible ( SI) congeners., We studied sympatric species pairs, I. hederacea ( SC)- I. mitchellae ( SI) and I. purpurea ( SC)-I. indica ( SI), in Mexico, over two years. We quantified variation in floral traits and nectar production, documented pollinator visitation, and determined natural fruit and seed set. Hand-pollination and bagging experiments were conducted to determine potential for autonomous self-pollination and apomixis., Self-compatible Ipomoea species had smaller flowers and lower nectar production than SI species; however, floral variation and integration did not vary according to breeding system. Bees were primary pollinators of all species, but visitation rates were seven times lower in SC than SI species. SC species had a high capacity for autonomous self-pollination due to reduced herkogamy at the highest anther levels. Self-compatible species had two to six times higher fruit set than SI species., Results generally support the hypothesis that self-compatibility and autonomous self-pollination ensure reproduction under low pollinator visitation. However, high variation in morphological traits of SC Ipomoea species suggests they maintain variation through outcrossing. Furthermore, reduced herkogamy was associated with high potential for autonomous self-pollination, providing a reproductive advantage that possibly underlies transitions to self-compatibility in Ipomoea. [ABSTRACT FROM AUTHOR]

Knowledge about mixed mating systems can improve our understanding of the evolutionary dynamics of reproductive systems. Here we report a study of the floral and reproductive biology ofHypericum elodes, an Atlantic-European soft-water pools specialist which shows a floral architecture consistent with both self- and cross-pollination. Controlled pollination experiments were performed in a natural population during three consecutive years. Marked flowers were monitored until fruit production, and laboratory germination experiments were conducted with the seeds produced. Plants were self-compatible (SCI>0.75), however, compared with selfing, cross-pollination enhanced fruit-set, seed-set and seedling growth, but not seed germination. Inbreeding depression (δ) was mild in the pre-dispersal stages (δ = 0.22 for fruit set, 0.18 for seed set and 0.13 for seed mass), low for germination percentage (δ = 0.003) and mild for seedling growth (δ = 0.23). The breeding system ofH. elodespromotes outcrossing and assures reproductive success by means of competitive autogamy. Our results suggest a mixed mating strategy for the studied population, characterized by mild inbreeding depression (cumulative δ = 0.57), highlighting the benefit of this reproductive mode in unpredictable habitat, as the typical shallow-water meadows whereH. elodesgrows. [ABSTRACT FROM PUBLISHER]

Annual alien species are dependent on their sexual reproductive success to establish, maintain and spread their populations. As the annual exotic Impatiens balfourii (Balsaminaceae) is spreading in several temperate countries, we assessed its characteristics linked to sexual reproduction. The reproductive traits and the breeding system which could indicate some trends that might favour population spread and invasion were examined. Hand pollination treatments were performed under controlled conditions to evaluate (1) autonomous selfing ability, (2) self-compatibility and (3) inbreeding depression. Floral biology including morphology as well as nectar and pollen production was also assessed. Impatiens balfourii presented large quantities (6.7 μl/flower) of sucrose dominant nectar. Sucrose dominant nectars are known as highly attractive for bees, potential pollinators of I. balfourii . Total sugar concentration of the nectar (47%) was high and situated within the range of bee-pollinated plants. Following hand pollination treatments, fruit and seed sets were similar after cross- and self- pollination. The species was thus self-compatible and no inbreeding depression was detected. The flowers were not totally protandrous as the stigmas were already receptive at bud stage. Autonomous selfing ability was high at the seed but low at the fruit level. In conclusion, the species presents traits linked to a high attractiveness for pollinators and a high fecundity that might allow high reproductive output. The invasive potential still needs to be estimated. [ABSTRACT FROM AUTHOR]