Hermaphrodite Flowers Research Articles

Differences in sex expression and mating systems in three pollination morphs of Cimicifuga simplex

AbstractCimicifuga simplex (Ranunculaceae) has three genetically distinct pollination morphs. Here, we report that each of the three pollination morphs of C. simplex differs from the others with regard to sex expression and mating system: morph I consists mostly of ramets with hermaphroditic flowers and ramets with only female flowers, morph II consists of ramets with hermaphroditic flowers and ramets with hermaphroditic and male flowers, and morph III consists mostly of ramets with hermaphroditic flowers. A microsatellite analysis of seed DNA showed that morph III has a high self‐fertilization rate. Flowering season and flower visitor assemblages, which also differ among the three morphs, may influence the evolution and maintenance of the differences in sex expression and mating systems in the morphs.

Breakdown of gametophytic self-incompatibility in subdivided populations.

In many hermaphroditic flowering plants, self-fertilization is prevented by self-incompatibility (SI), often controlled by a single locus, the S-locus. In single isolated populations, the maintenance of SI depends chiefly on inbreeding depression and the number of SI alleles at the S-locus. In subdivided populations, however, population subdivision has complicated effects on both the number of SI alleles and the level of inbreeding depression, rendering the maintenance of SI difficult to predict. Here, we explore the conditions for the invasion of a self-compatible mutant in a structured population. We find that the maintenance of SI is strongly compromised when a population becomes subdivided. We show that this effect is mainly caused by the decrease in the local diversity of SI alleles rather than by a change in the dynamics of inbreeding depression. Strikingly, we also find that the diversity of SI alleles at the whole population level is a poor predictor of the maintenance of SI. We discuss the implications of our results for the interpretation of empirical data on the loss of SI in natural populations.

A Toolkit for Teasing Apart the Early Stages of Pollen-Stigma Interactions in Arabidopsis thaliana.

In hermaphroditic flowering plants, the female pistil serves as the main gatekeeper of mate acceptance as several mechanisms are present to prevent fertilization by unsuitable pollen. The characteristic Brassicaceae dry stigma at the top of pistil represents the first layer that requires pollen recognition to elicit appropriate physiological responses from the pistil. Successful pollen-stigma interactions then lead to pollen hydration, pollen germination, and pollen tube entry into the stigmatic surface. To assess these early stages in detail, our lab has used three experimental procedures to quantitatively and qualitatively characterize the outcome of compatible pollen-stigma interactions that would ultimately lead to the successful fertilization. These assays are also useful for assessing self-incompatible pollinations and mutations that affect these pathways. The model organism, Arabidopsis thaliana, offers an excellent platform for these investigations as loss-of-function or gain-of-function mutants can be easily generated using CRISPR/Cas9 technology, existing T-DNA insertion mutant collections, and heterologous expression constructs, respectively. Here, we provide a detailed description of the methods for these inexpensive assays that can be reliably used to assess pollen-stigma interactions and used to identify new players regulating these processes.

Anatomy and development of gynoecium in Tapiscia sinensis Oliv. and its implications for the origin of carpels

Tapiscia sinensis Oliv. (Tapisciaceae) is a rare tree endemic in China. Characteristic of its androdioecy is the coexistence of male and hermaphroditic flowers. Its bisexual flower bears five stamens surrounding the gynoecium, which is composed of a terminal style and an ovary at the base. The style has a bifid stigmata, which is hollow and longer than stamens. The ovary is syncarpous, unilocular, formed by two fused carpels, with a basal or subbasal placenta. Ovule is bitegmic, anatropous, borne on the placenta and supplied by an amphicribral vascular bundle arising directly from receptacle. The carpel wall is supplied by a collateral vascular bundle. The ovule’s position changes from initially inserted on the ovary base to later attached to the middle of the ovary wall due to unequal growth of the embryo sac. Based on the present observation and others, the implications of vascular system in Tapiscia for the evolution of carpel are discussed.

Male Sterility and its Commercial Exploitation in Hybrid Seed Production of Vegetable Crops: A Review

Male sterility is described as absence of functional pollen grains in hermaphrodite flowers facilitating large scale production of hybrid seeds in vegetable crops. It eases hybrid seed production at commercial level in crops like tomato, chilli, capsicum, carrot, onion, cabbage, cauliflower and cucurbits. Male sterility would reduce the cost of hybrid seed production by limiting the labour making it efficient and economical. Incorporation of biotechnological tools in conventional plant breeding techniques would aid the breeders in limiting the drawbacks surrounding exploitation of male sterility for development of new hybrids. The present review is an attempt to summarize and to know the commercial utilization of male sterile line in hybrid seed production of vegetables.

Doña Aurelia: nuevo cultivar de piñón para el trópico de México

Durante más de ocho años, el INIFAP ha realizado trabajos de investigación enfocados a los insumos para la producción de biocombustibles entre ellos el piñón mexicano (Jatropha curcas L.). A lo largo de este tiempo, se establecieron ensayos genéticos en cuatro ambientes tropicales de México basados en genotipos seleccionados de acuerdo con sus atributos agronómicos e industriales. Los principales criterios de selección abordados fueron: rendimiento de grano, contenido de aceite, hábito de crecimiento y presencia de flores femeninas. Los mejores genotipos de los ensayos fueron dos variedades con presencia de 100% de flores femeninas y una variedad con predominio de flores masculinas, pero también con la presencia de flores femeninas y hermafroditas. Una de estas variedades con flores 100% femeninas se registró con la denominación ‘Doña Aurelia’ con título de obtentor número 1541. Esta variedad ha demostrado ser estable en cuanto a sus características morfológicas y de producción en los años de evaluación. Esta variedad tiene un rendimiento promedio en ambientes del trópico húmedo de 0.49 t ha-1 en el primer año del cultivo, con un rendimiento potencial al primer año de 0.98 t ha-1, bajo condiciones de trópico seco. Alcanza rendimientos de 3 t de grano seco por hectárea al cuarto año de producción. El contenido promedio de aceite en las semillas de la variedad es de 53.4%. Las características fisicoquímicas del aceite son: 98.57 gI2/100 de índice de yodo, 0.921 g cm-3 de densidad, 34.894 mm2 s-1 de viscosidad y 2.974 mg KOH g-1 de índice de acidez y composición de ácidos grasos de 35.36% de ácidos grasos saturados y 64.64% de ácidos grasos insaturados, de acuerdo con la norma americana ASTM ‘Doña Aurelia’ se considera de buena calidad como materia prima para obtener biodiesel.

Androgynomonoecious Jatropha curcas: Chromosomes, Isozymes, and Flowers Gender

Jatropha curcas (J. curcas) is usually monoecious plants, which have male and female flowers on the same inflorescence. However, J. curcas can be found as an androgynomonoecious plant (have male, female, and hermaphrodite flowers), even though very rare. Androgynomonoecious J. curcas can be identified after six months of planting when it had started flowering. Therefore, it is important to identify the characteristics of androgynomonoecious J. curcas that can differentiate between androgynomonoecious and monoecious plants in earlier stages of growth. The objectives of the research were to observe isozymes, chromosome and flowers gender of androgynomonoecious and monoecious J. curcas Banten and Lampung accessions. Seeds from five genotypes of J. curcas were used in the research. The observation was carried out on the chromosome and isozymes (Peroxidase and Esterase isozymes) could be used as markers to differentiate androgynomonoecious and monoecious plants. Observations about the flower gender from offsprings derived from different seeds were important to know the inheritance of flower gender. The androgynomonoecious and monoecious J. curcas were diploid with number of chromosomes 2n=2x=22. The chromosomes of androgynomonoecious have longer than that of monoecious J. curcas. The isozymes of androgynomonoecious J. curcas had four alleles and monoecious J. curcas (Banten female monoecious) had three alleles. The flower inflorescence and gender derived from androgynomonoecious plants were unstable, due to androgynomonoecious is intermediate state.

Anatomy and RNA-Seq reveal important gene pathways regulating sex differentiation in a functionally Androdioecious tree, Tapiscia sinensis

BackgroundGametogenesis is a key step in the production of ovules or pollen in higher plants. The sex-determination aspects of gametogenesis have been well characterized in the model plant Arabidopsis. However, little is known about this process in androdioecious plants. Tapiscia sinensis Oliv. is a functionally androdioecious tree, with both male and hermaphroditic individuals. Hermaphroditic flowers (HFs) are female-fertile flowers that can produce functional pollen and set fruits. However, compared with male flowers (MFs), the pollen viability and number of pollen grains per flower are markedly reduced in HFs. MFs are female-sterile flowers that fail to set fruit and that eventually drop.ResultsCompared with HF, a notable cause of MF female sterility in T. sinensis is when the early gynoecium meristem is disrupted. During the early stage of HF development (stage 6), the ring meristem begins to form as a ridge around the center of the flower. At this stage, the internal fourth-whorl organ is stem-like rather than carpelloid in MF.A total of 52,945 unigenes were identified as transcribed in MF and HF. A number of differentially expressed genes (DEGs) and metabolic pathways were detected as involved in the development of the gynoecium, especially the ovule, carpel and style. At the early gynoecium development stage, DEGs were shown to function in the metabolic pathways regulating ethylene biosynthesis and signal transduction (upstream regulator), auxin, cytokinin transport and signalling, and sex determination (or flower meristem identity).ConclusionsPathways for the female sterility model were initially proposed to shed light on the molecular mechanisms of gynoecium development at early stages in T. sinensis.

Differential gene expression among three sex types reveals a MALE STERILITY 1 (CpMS1) for sex differentiation in papaya

BackgroundCarica papaya is a trioecious plant species with a genetic sex-determination system defined by sex chromosomes. Under unfavorable environmental conditions male and hermaphrodite exhibit sex-reversal. Previous genomic research revealed few candidate genes for sex differentiation in this species. Nevertheless, more analysis is still needed to identify the mechanism responsible for sex flower organ development in papaya.ResultsThe aim of this study was to identify differentially expressed genes among male, female and hermaphrodite flowers in papaya during early (pre-meiosis) and later (post-meiosis) stages of flower development. RNA-seq was used to evaluate the expression of differentially expressed genes and RT-qPCR was used to verify the results. Putative functions of these genes were analyzed based on their homology with orthologs in other plant species and their expression patterns. We identified a Male Sterility 1 gene (CpMS1) highly up-regulated in male and hermaphrodite flower buds compared to female flower buds, which expresses in small male flower buds (3–8 mm), and that might be playing an important role in male flower organ development due to its homology to MS1 genes previously identified in other plants. This is the first study in which the sex-biased expression of genes related to tapetum development in the anther developmental pathway is being reported in papaya. Besides important transcription factors related to flower organ development and flowering time regulation, we identified differential expression of genes that are known to participate in ABA, ROS and auxin signaling pathways (ABA-8-hydroxylases, AIL5, UPBEAT 1, VAN3-binding protein).ConclusionsCpMS1 was expressed in papaya male and hermaphrodite flowers at early stages, suggesting that this gene might participate in male flower organ development processes, nevertheless, this gene cannot be considered a sex-determination gene. Due to its homology with other plant MS1 proteins and its expression pattern, we hypothesize that this gene participates in anther development processes, like tapetum and pollen development, downstream gender specification. Further gene functional characterization studies in papaya are required to confirm this hypothesis. The role of ABA and ROS signaling pathways in papaya flower development needs to be further explored as well.

Determination of Blooming, Pollen and Fruit Set Characteristics in Punica granatum

The objective of this study was to investigate flowering, pollen, and fruit set characteristics of locally registered pomegranate cultivars between two consecutive years. ‘Dr. Ercan 35’, ‘Efenar 35’, ‘Kamilbey 35’, and ‘Tezeren 35’ cultivars have been developed by cross-breeding programs. Open-, cross-, and self-pollination studies were performed with these cultivars using three trees in each replicate in the field. Number of anthers per flower, number of pollen grains per anther, viability, and germination tests were conducted in the laboratory. Fruit set ratio of self-pollinated combinations were lower than open-pollination. The fruit set ratio from self-pollination was obtained from ‘Dr. Ercan’ (60.3%), ‘Efenar 35’ (62.4%), ‘Kamilbey 35’ (50.5%), and ‘Tezeren 35’ (25.2%). The highest fruit set ratio (49.7%) was obtained from ‘Kamilbey 35’ × ‘Dr. Ercan 35’ combination. The highest number of characteristics was as follows: ‘Tezeren 35’ (402 anthers/hermaphrodite flowers), ‘Kamilbey 35’ (8550 pollen/anther, male flowers in the beginning of flowering), ‘Efenar 35’ (84.7% pollen viability, hermaphrodite flowers), ‘Kamilbey 35’ (71.2%, pollen germination, hermaphrodite flowers). In conclusion, at least one, two or more, pollinator cultivars are necessary for commercial plantations using with these recently released pomegranate cultivars.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Ternstroemia guineensis (Ternstroemiaceae), a new endangered cloudforest shrub with neotropical affinities from Kounounkan, Guinea, W Africa

Ternstroemia guineensis is described from a sandstone table mountain at Kounounkan, possibly the last in the Fouta Djallon (Guinea Highlands) to remain largely unimpacted by humans and to have mainly intact natural habitats. It occurs about 2400 km westward of the nearest existing record (Nigeria) of the genus in Africa. It is confined to cloud (submontane) forest in galleries along watercourses. Its conservation status is assessed as Endangered using the IUCN 2012 criteria. The species differs from the other two African highland species, T. cameroonensis and T. polypetala, in having hermaphrodite flowers with a long subcylindric style and punctiform stigmas, and petals connate at the base into a tube (not dioecious, with a short style and cone-like stigmas, and free petals) resembling in these features the neotropical Ternstroemia species, as does also the lowland wetland T. africana of Nigeria, Gabon and Angola. Citation: Cheek M., Haba P. M., Konomou G. & Burgt X. M. van der 2019: Ternstroemia guineensis (Ternstroemiaceae), a new endangered cloudforest shrub with neotropical affinities from Kounounkan, Guinea, W Africa. – Willdenowia 49: 351–360. doi: https://doi.org/10.3372/wi.49.49306 Version of record first published online on 26 November 2019 ahead of inclusion in December 2019 issue.

Aspectos fitotécnicos do cultivo da oliveira no Rio Grande do Sul I: biologia reprodutiva

A oliveira (Olea europaea L.), apesar de apresentar flores hermafroditas e estaminadas, possui mecanismos que favorecem a alogamia, sendo desaconselhável a formação de pomares monovarietais. A polinização da oliveira é anemófila, produzindo grande quantidade de grãos de pólen espalhados no ar durante a floração. A viabilidade econômica da produção de azeite de oliva depende da produção de frutos e vários fatores podem afetar a frutificação. Esse estudo teve como objetivo entender as relações da biologia reprodutiva com a produção de frutos em oliveira, nas condições do sul do Brazil. O estudo foi realizado em 2016 e 2017, em olival comercial localizado em Barra do Ribeiro/RS, em espaçamento de 5x7, com as cultivares Koroneiki, Arbequina e Arbosana. Analisou-se o número de inflorescências por ramo, o número de flores por inflorescência, o número de flores hermafroditas, a qualidade do pólen e o sistema de polinização. ‘Arbosana’ apresentou o maior número de flores/inflorescência. ‘Arbequina’ apresentou o maior percentual de flores hermafroditas que ‘Koroneiki’ nos dois anos avaliados, não diferindo de ‘Arbosana’ em 2017. Houve redução do percentual de flores hermafroditas para as cultivares Koroneiki e Arbequina, no segundo ano avaliado. Houve redução na viabilidade do pólen em 2017, mais expressivo em ‘Koroneiki’. Independente da cultivar, a polinização livre proporcionou maior frutificação. ‘Koroneiki’ fixou mais frutos que ‘Arbequina’; os parâmetros avaliados não foram determinantes para a frutificação das cultivares estudadas.

Chromosomal characteristics in two different sexual phenotypes of Stichoneuron membranaceum

The present investigation has been focussed on mitotic and meiotic chromosome study of androdioecious Stichoneuron membranaceum from the state of Tripura. The somatic chromosome number in both the sexual phenotypes was found to be 2n = 18 having one pair of chromosomes bearing secondary constriction. Meiosis is regular and the presence of nine bivalents in pollen mother cells of male and hermaphrodite flowers suggest that the basic chromosome number is X = 9. The accentuated chromosome homology in androecious and hermaphrodite plants of S. membranaceum is the intrinsic character of their karyotypes.

Flowering induction and formation of salak (Salacca sumaterana Becc) fruit with potassium and boron fertilization

Salak Sidimpuan is one of the superior commodities of Padang Sidimpuan that taste sweet, sour and make it different from Pondoh and Bali. Physiological conditions will greatly affect the growth and development plant especially the phase of flowering and fruit formation. Other factors that affect the flowering phase and fruit formation are nutritional status and relative water content in the plant. The purposes of study to get the best concentration of Potassium and Boron on fruit formation and Sidimpuan zalacca production off season. This research was conducted at Palopat Maria village, Padang Sidimpuan City. This study was conducted from July 2017 to March 2018. The experiment was conducted Split Plot Design with three replications. The main factor is the potassium fertilizer i.e. without potassium, 20 g and 40 g / tree potassium. The subplot is the B fertilizer dosage i.e. without fertilizer B, 1000, 2000, 3000 and 4000 ppm/tree. The results showed that Sidimpuan Salak Plant was a hermaphrodite flowering plant, carried out its own pollination and the time it took from flower up fruit ready to harvest about 5.5 to 6 months. The highest number of fruit Bunches (8.74 bunches) was obtained at 20 g / plant while in B 3000 ppm / tree was 9:01 bunches.

Importance of intraspecific variation in the pollination and seed dispersal functions of a double mutualist animal species

Although most plants depend on different animals for pollination and seed dispersal, sometimes the same animal species provides both functions, being thus involved in what has been termed a ‘double mutualism’. Very little is known on the effectiveness of such species as both pollinators and seed dispersers, and even less on the intraspecific level differences at the contribution of an animal mutualist to plant fitness. In this study, we focused on the interaction between a Mediterranean shrub Cneorum tricoccon (Rutaceae) and the Balearic lizard Podarcis lilfordi (Lacertidae) in order to assess: 1) the role of this lizard as a legitimate pollinator of the plant (previously thought to be exclusively insect‐pollinated), and 2) the intraspecific variation in the use of flowers and fruits by lizard individuals, comparing males, females and juveniles. We further evaluated whether lizards show different fruit size selection depending on sex and age, with potential consequences for seed germination. Lizards visited more flowers and selected more hermaphrodite flowers than insects did, leading to relative increases in both fruit and seed set. Interestingly, female and juvenile lizards were the main flower visitors, whereas males were the main fruit consumers. Males selected the largest fruits (bearing the largest seeds) though this did not increase seed germination, which was only ca 15%. We concluded that P. lilfordi acts as a legitimate pollinator of C. tricoccon and, thus, confirm that this system constitutes a new case of double mutualism, especially common in island compared to mainland systems. Moreover, our findings show a large variation among conspecific individuals in their role as either pollinators or seed dispersers, with potential implications for plant reproductive success. Our study, therefore, highlights the importance of evaluating plant–animal interactions at the intraspecific level, and calls for more in‐depth studies on the consequences of such intraspecific variation.

Pollinator Behavior Drives Sexual Specializations in the Hermaphrodite Flowers of a Heterodichogamous Tree.

Dioecy, the specialization of individuals into either male-only or female-only sexual function, has multiple evolutionary origins in plants. One proposed ancestral mating system is heterodichogamy, two morphs of cross-fertilizing hermaphrodite flowers that differ in their timing of flowering. Previous research suggested that small specializations in these morphs’ functional genders could facilitate their evolution into separate sexes. We tested the possible role of pollinators in driving such specializations. Ziziphus spina-christi is an insect-pollinated heterodichogamous tree with self-incompatible flowers and two sympatric flowering morphs. We compared the flower development patterns, floral food rewards, pollinator visits, and fruit production between the two morphs. Male-phase flowers of Z. spina-christi’s “Early” and “Late” morphs open before dawn and around noon, respectively, and transition into female-phase 7–8 h later. Flowers of both morphs contain similar nectar and pollen rewards, and receive visits by flies (their ancestral pollinators) at similar rates, mostly during the morning. Consequently, the Early morph functions largely as pollen donor. The Late morph, functioning as female in the morning, produces more fruit. We developed an evolutionary probabilistic model, inspired by Z. spina-christi’s reproductive system, to test whether pollinator visit patterns could potentially play a role in an evolutionary transition from heterodichogamy towards dioecy. The model predicts that reproductive incompatibility within flowering morphs promotes their evolution into different sexes. Furthermore, the pollinators’ morning activity drives the Early and Late morphs’ specialization into male and female functions, respectively. Thus, while not required for transitioning from heterodichogamy to dioecy, pollinator-mediated selection is expected to influence which sexual specialization evolves in each of the flowering morphs.

The ethylene receptors CpETR1A and CpETR2B cooperate in the control of sex determination in Cucurbita pepo

High-throughput screening of an ethyl methanesulfonate-generated mutant collection of Cucurbita pepo using the ethylene triple-response test resulted in the identification of two semi-dominant ethylene-insensitive mutants: etr1a and etr2b. Both mutations altered sex determination mechanisms, promoting conversion of female into bisexual or hermaphrodite flowers, and monoecy into andromonoecy, thereby delaying the transition to female flowering and reducing the number of pistillate flowers per plant. The mutations also altered the growth rate and maturity of petals and carpels in pistillate flowers, lengthening the time required for flowers to reach anthesis, as well as stimulating the growth rate of ovaries and the parthenocarpic development of fruits. Whole-genome sequencing allowed identification of the causal mutation of the phenotypes as two missense mutations in the coding region of CpETR1A and CpETR2B, each one corresponding to one of the duplicates of ethylene receptor genes highly homologous to Arabidopsis ETR1 and ETR2. The phenotypes of homozygous and heterozygous single- and double-mutant plants indicated that the two ethylene receptors cooperate in the control of the ethylene response. The level of ethylene insensitivity, which was determined by the strength of each mutant allele and the dose of wild-type and mutant etr1a and etr2b alleles, correlated with the degree of phenotypic changes in the mutants.

Irrigation water saving during pomegranate flowering and fruit set period do not affect Wonderful and Mollar de Elche cultivars yield and fruit composition

Adult pomegranate trees [Punica granatum (L.) cultivars Wonderful and Mollar de Elche] were submitted to different irrigation treatments during the 2015 and 2016 seasons. Control (T0) plants were drip irrigated to guarantee non-limiting soil water conditions; T1 plants were subjected to water withholding during flowering-fruit set period for 64 (2015) and 53 (2016) days, resuming irrigation as in T0 plants subsequently. In both cultivars, the results demonstrated that during the flowering-fruit set period the sensitivity to water stress is very small, being possible to suppress or reduce irrigation (at least, while plant water status maintains similar levels to those reported in this study) without affecting marketable yield and fruit size and composition. Thus, this period can be considered as a clearly non-critical period. In this sense, water saving was around 19–30% and water productivity (WP) increased around 4–14% in Wonderful and 10–16% in Mollar de Elche. Water stress increased flowering, but not the number of viable hermaphrodite flowers, and decreased shoot growth (TSG), which could favour a compensatory young fruit growth when irrigation was resumed due to a shift in the carbon allocation pattern. This WP increase, the reduction in pruning cost (TSG decrease), and the redder arils in T1 plants were key aspects to increase consumers’ acceptance and farmers’ crop revenues.

Ultrastructural observations of anthers, staminodes, and pollen grains of mango (Mangifera indica L. var. Beneshan; Anacardiaceae)

The ultrastructure of anthers, staminodes, and pollen of Mangifera indica L. was studied using scanning electron microscopy (SEM), and pollen viability assessed using light (LM) and fluorescence microscopy (FM). Ultrastructural observation revealed anther surfaces with polygonal cells and hollow centres arranged in a reticulate manner, with swollen cells on the edges of the anther surfaces. Anther dehiscence is longitudinal, with pollen released through a long slit in both thecae. The average length and width of staminodes of male and hermaphroditic flowers measured 0.7 mm × 0.35 mm and 0.65 mm × 0.3 mm, respectively. Distinct ridge and hook-like outgrowths on the adaxial surface of staminodes are described, as are staminode surfaces comprised of long, irregular cells with stomata exuding nectar. Staminodes produced no pollen. Anthers of male flowers produced more pollen grains (536–537) than did anthers of hermaphrodite flowers (510–511). Pollen grains are tricolporate, have reticulate perforate exine ornamentation, and are bi-cellular at dispersal. Anther and staminode size and pollen production was greater but not significantly different in male versus hermaphrodite flowers. In contrast, the fluorochromatic reaction (FCR) test and FM observations found significantly higher pollen viabilities in hermaphroditic (50.1%) versus male (40.4%) flowers. This research provides new ultrastructural characters potentially useful in future taxonomic studies of mango and other Anacardiaceae. Results presented here may also be useful in pollination studies, and in the improvement of mango breeding programmes and commercial fruit production.

Functional androdioecy in the ornamental shrub Osmanthus delavayi (Oleaceae).

Androdioecy is one of the rarest sexual systems among plants, characterized by males co-occurring with hermaphrodites. Osmanthus delavayi (Oleaceae), an ornamental shrub from southern China, is known to have both male and hermaphrodite individuals, but little is known regarding the breeding system of this species and whether it is functionally androdioecious, and how this potentially evolved. In this study, we explore the characteristics of the breeding system of O. delavayi through the study of phenology, sex ratio, floral organ morphology, pollen number, stigma receptivity, artificial pollination, pollinators, and gene flow within and between populations, while also discussing the evolution and maintenance of androdioecy within the genus. The proportion of males was less than 0.5 and the out-crossing index (OCI) was 5. Morphological androdioecy was observed, with hermaphrodite flowers having fertile pistils, while male flowers had degenerated pistils. Males and hermaphrodites both had large amounts of small and fertile pollen grains, although the pollen number of males was ca. 1.21 × more than that of hermaphrodites, and pollen was generally smaller. Self-pollination was found to produce a much lower fruit set than outcrossing under natural conditions. Gene flow between males and hermaphrodites within a population was greater (1.007) than that between populations (0.753). All these results indicate that O. delavayi is functionally androdioecious, which may be an intermediate state in the evolutionary transition from hermaphroditism to dioecy.