Effect of Crown Layers on Reproductive Effort and Success in Andromonoecious Aesculus indica (Wall. ex Camb.) Hook (Sapindaceae) in a Temperate Forest of Garhwal Himalaya.

The andromonoecy is an unusual sex expression in trees in which an individual plant bears both functionally staminate and hermaphrodite flowers on the inflorescences. This study aims to investigate the effect of crown layers on the floral biology and reproductive effort of Aesculus indica (Wall. ex Camb.) Hook. The results revealed that the peak period of anthesis was between 06:00 and 08:00 h of the day. Male flower production was predominantly higher as compared to the perfect flowers on the inflorescences. There was no significant variation between total pollen production in staminate and perfect flowers. Features like protogyny and inter-level asynchrony promote xenogamy; however, intra-level asynchrony results in geitonogamy. Controlled pollination treatments revealed the existence of self-incompatibility in flowers. Pollination syndromes in flowers support ambophily. A trend of consistent improvement in reproductive success from lower canopy layers to upper crown layers in the analyzed trees was recorded. The crown layers have a significant impact on flower production, fruit, and seed set. An increase in male flower production due to the increment in the crown is a mechanism of reproductive assurance as a pollen donor and pollinator recipient and also due to the differential cost of expenditure of reproduction in crown layers. Andromonoecy in A. indica promotes self-incompatibility, and there was a tapering trend of reproductive success in the crown layers.

Disruptive selection via pollinators and seed predators on the height of flowers on a wind-dispersed alpine herb.

PREMISE: Floral stalk height is known to affect seed dispersal of wind-dispersed grassland species, but it may also affect the attractiveness of flowers and fruits of animal-pollinated and animal-dispersed plants. Stalk height may thus be responsive to selection via interactions with both mutualist pollinators and seed dispersers, but also antagonist florivores and seed predators. In this study, we aimed to determine the effect of pollinators and seed predators on selection on floral stalk height in the insect-pollinated and wind-dispersed, alpine, andromonoecious herb Pulsatilla alpina, whose flowers also vary in their sex allocation and thus in the resources available to both mutualists and antagonists. METHODS: We measured the resource status of individuals in terms of their size and the height of the vegetation surrounding plants of P. alpina at 11 sites. In one population, we recorded floral stalk height over an entire growing season and investigated its association with floral morphology and floral sex allocation (pistil and stamen number) and used leaf-removal manipulations to assess the effect of herbivory on floral stalk height. Finally, in four populations, we quantified phenotypic selection on floral stalk height in four female components of reproductive success before seed dispersal. RESULTS: Stalk height was positively associated with female allocation of the respective flower, the resource status of the individual, and the height of the surrounding vegetation, and negatively affected by leaf removal. Our results point to disruptive selection on stalk height in terms of both selection differentials and selection gradients for fertilization, seed predation, and seed maturation rates and to positive selection on stalk height in terms of a selection differential for mature seed number. CONCLUSIONS: Stalk height of P. alpina is a costly trait that affects female reproductive success via interactions with both mutualists and antagonists. We discuss the interplay between the resource status and selection imposed on female reproductive success and its likely role in the evolution of sex-allocation strategies, especially andromonoecy.

Size-dependent sex allocation in Solanum lycocarpum St. Hil. (Solanaceae) / Alocação de sexo dependente de tamanho em Solanum lycocarpum St. Hil. (Solanaceae)

Resource allocation to reproduction can change depending on size, as predicted by the size-dependent sex allocation. This theory is based on the fact that small individuals will invest in the allocation of sex with lower cost of production, usually male gender. In plants, there are some andromonoecy species, presence of hermaphrodite and male flowers in the same individual. Andromonoecy provides a strategy to optimally allocate resources to male and female function, evolving a reproductive energy-saving strategy. Thus, our objective was to investigate the size-dependent sex allocation in Solanum lycocarpum St. Hil. We tested the hypothesis that plants with larger size will invest in the production of hermaphrodite flowers, because higher individuals have greater availability of resources to invest in more complex structures involving greater energy expenditure. The studied species was S. lycocarpum, an andromonoecious species. From June 2016 to March 2017 the data were collected in 38 individuals, divided in two groups: the larger plant group (n=18; height=3-5 m) and the smaller plant group (n=20; height=1-2 m).Our data show that there was effect of plant size on the flower production and the sexual gender allocation. The larger plants showed more flowers and higher production of hermaphrodite flowers. Furthermore, in the flower scale, we observed allometric relationship among the flower's traits with proportional investments in biomass, anther size and gynoecium size. Our results are in agreement with size-dependent sex allocation theory and andromonoecy hypothesis related to mechanisms for optimal resource allocation to male and female function.

A alocação de recursos para reprodução pode mudar dependendo do tamanho, conforme previsto pela alocação sexual dependente do tamanho. Essa teoria é baseada no fato de que indivíduos pequenos investirão na alocação sexual com menor custo de produção, geralmente do sexo masculino. Nas plantas, existem algumas espécies andromonoicas, presença de hermafrodita e flores masculinas no mesmo indivíduo. A andromonoicia fornece uma estratégia para alocar recursos de maneira ideal às funções masculina e feminina, desenvolvendo uma estratégia reprodutiva de economia de energia. Assim, nosso objetivo foi investigar a alocação sexual dependente do tamanho em Solanum lycocarpum St. Hil. Testamos a hipótese de que plantas de maior tamanho investirão na produção de flores hermafroditas, pois indivíduos mais altos economizam mais disponibilidade de recursos para investir em estruturas mais complexas que envolvem maior gasto de energia. A espécie estudada foi S. lycocarpum, uma espécie andromonoica. De junho de 2016 a março de 2017, os dados foram coletados em 38 indivíduos, divididos em dois grupos: o maior grupo de plantas (n = 18; altura = 3-5 m) e o menor grupo de plantas (n = 20; altura =1-2 m). Nossos dados mostram que houve efeito do tamanho da planta na produção de flores e na alocação sexual. As plantas maiores apresentaram mais flores e maior produção de flores hermafroditas. Além disso, observamos uma relação alométrica entre as características da flor, com investimentos proporcionais em biomassa, tamanho da antera e tamanho do gineceu. Nossos resultados estão de acordo com a teoria de alocação de sexo dependente de tamanho e a hipótese de andromonoicia relacionada a mecanismos para a alocação ótima de recursos para a função masculina e feminina.

Size-dependent sex allocation in Solanum lycocarpum St. Hil. (Solanaceae) / Alocação de sexo dependente de tamanho em Solanum lycocarpum St. Hil. (Solanaceae)

Resource allocation to reproduction can change depending on size, as predicted by the size-dependent sex allocation. This theory is based on the fact that small individuals will invest in the allocation of sex with lower cost of production, usually male gender. In plants, there are some andromonoecy species, presence of hermaphrodite and male flowers in the same individual. Andromonoecy provides a strategy to optimally allocate resources to male and female function, evolving a reproductive energy-saving strategy. Thus, our objective was to investigate the size-dependent sex allocation in Solanum lycocarpum St. Hil. We tested the hypothesis that plants with larger size will invest in the production of hermaphrodite flowers, because higher individuals have greater availability of resources to invest in more complex structures involving greater energy expenditure. The studied species was S. lycocarpum, an andromonoecious species. From June 2016 to March 2017 the data were collected in 38 individuals, divided in two groups: the larger plant group (n=18; height=3-5 m) and the smaller plant group (n=20; height=1-2 m).Our data show that there was effect of plant size on the flower production and the sexual gender allocation. The larger plants showed more flowers and higher production of hermaphrodite flowers. Furthermore, in the flower scale, we observed allometric relationship among the flower's traits with proportional investments in biomass, anther size and gynoecium size. Our results are in agreement with size-dependent sex allocation theory and andromonoecy hypothesis related to mechanisms for optimal resource allocation to male and female function.

A alocação de recursos para reprodução pode mudar dependendo do tamanho, conforme previsto pela alocação sexual dependente do tamanho. Essa teoria é baseada no fato de que indivíduos pequenos investirão na alocação sexual com menor custo de produção, geralmente do sexo masculino. Nas plantas, existem algumas espécies andromonoicas, presença de hermafrodita e flores masculinas no mesmo indivíduo. A andromonoicia fornece uma estratégia para alocar recursos de maneira ideal às funções masculina e feminina, desenvolvendo uma estratégia reprodutiva de economia de energia. Assim, nosso objetivo foi investigar a alocação sexual dependente do tamanho em Solanum lycocarpum St. Hil. Testamos a hipótese de que plantas de maior tamanho investirão na produção de flores hermafroditas, pois indivíduos mais altos economizam mais disponibilidade de recursos para investir em estruturas mais complexas que envolvem maior gasto de energia. A espécie estudada foi S. lycocarpum, uma espécie andromonoica. De junho de 2016 a março de 2017, os dados foram coletados em 38 indivíduos, divididos em dois grupos: o maior grupo de plantas (n = 18; altura = 3-5 m) e o menor grupo de plantas (n = 20; altura = 1-2 m). Nossos dados mostram que houve efeito do tamanho da planta na produção de flores e na alocação sexual. As plantas maiores apresentaram mais flores e maior produção de flores hermafroditas. Além disso, observamos uma relação alométrica entre as características da flor, com investimentos proporcionais em biomassa, tamanho da antera e tamanho do gineceu. Nossos resultados estão de acordo com a teoria de alocação de sexo dependente de tamanho e a hipótese de andromonoicia relacionada a mecanismos para a alocação ótima de recursos para a função masculina e feminina.

Size-dependent sex allocation in Solanum lycocarpum St. Hil. (Solanaceae)

Abstract Resource allocation to reproduction can change depending on size, as predicted by the size-dependent sex allocation. This theory is based on the fact that small individuals will invest in the allocation of sex with lower cost of production, usually male gender. In plants, there are some andromonoecy species, presence of hermaphrodite and male flowers in the same individual. Andromonoecy provides a strategy to optimally allocate resources to male and female function, evolving a reproductive energy-saving strategy. Thus, our objective was to investigate the size-dependent sex allocation in Solanum lycocarpum St. Hil. We tested the hypothesis that plants with larger size will invest in the production of hermaphrodite flowers, because higher individuals have greater availability of resources to invest in more complex structures involving greater energy expenditure. The studied species was S. lycocarpum, an andromonoecious species. From June 2016 to March 2017 the data were collected in 38 individuals, divided in two groups: the larger plant group (n=18; height=3-5 m) and the smaller plant group (n=20; height=1-2 m).Our data show that there was effect of plant size on the flower production and the sexual gender allocation. The larger plants showed more flowers and higher production of hermaphrodite flowers. Furthermore, in the flower scale, we observed allometric relationship among the flowers traits with proportional investments in biomass, anther size and gynoecium size. Our results are in agreement with size-dependent sex allocation theory and andromonoecy hypothesis related to mechanisms for optimal resource allocation to male and female function.

Resumo A alocação de recursos para reprodução pode mudar dependendo do tamanho, conforme previsto pela alocação sexual dependente do tamanho. Essa teoria é baseada no fato de que indivíduos pequenos investirão na alocação sexual com menor custo de produção, geralmente do sexo masculino. Nas plantas, existem algumas espécies andromonoicas, presença de hermafrodita e flores masculinas no mesmo indivíduo. A andromonoicia fornece uma estratégia para alocar recursos de maneira ideal às funções masculina e feminina, desenvolvendo uma estratégia reprodutiva de economia de energia. Assim, nosso objetivo foi investigar a alocação sexual dependente do tamanho em Solanum lycocarpum St. Hil. Testamos a hipótese de que plantas de maior tamanho investirão na produção de flores hermafroditas, pois indivíduos mais altos economizam mais disponibilidade de recursos para investir em estruturas mais complexas que envolvem maior gasto de energia. A espécie estudada foi S. lycocarpum, uma espécie andromonoica. De junho de 2016 a março de 2017, os dados foram coletados em 38 indivíduos, divididos em dois grupos: o maior grupo de plantas (n = 18; altura = 3-5 m) e o menor grupo de plantas (n = 20; altura = 1-2 m). Nossos dados mostram que houve efeito do tamanho da planta na produção de flores e na alocação sexual. As plantas maiores apresentaram mais flores e maior produção de flores hermafroditas. Além disso, observamos uma relação alométrica entre as características da flor, com investimentos proporcionais em biomassa, tamanho da antera e tamanho do gineceu. Nossos resultados estão de acordo com a teoria de alocação de sexo dependente de tamanho e a hipótese de andromonoicia relacionada a mecanismos para a alocação ótima de recursos para a função masculina e feminina.

Differential reward in "male" versus "female" pollen of functionally dioecious Solanum.

PREMISE: Five to six percent of angiosperm species exhibit a dioecious sexual system, with unisexual "male" or "female" flowers borne on separate plants. The consequent need for inter-individual pollen exchange is a special challenge for taxa where pollen is the sole pollinator reward. Dioecious Australian Solanum assure visits from pollen-foraging bees via production of inaperturate pollen in functionally female (morphologically bisexual) flowers. Biochemical composition of pollen from Australian Solanum has not been assessed nor compared to porate pollen from staminate flowers to reveal whether these flowers differ in their pollinator reward potential. METHODS: Porate pollen from male flowers and inaperturate pollen from functionally female flowers of two functionally dioecious Australian species were compared for protein and amino acid content. We also assessed pollen from bisexual and staminate flowers of a closely related andromonoecious species, in which all pollen is porate, as a comparison across co-occurring sexual systems. RESULTS: In both functionally dioecious species, porate pollen grains from staminate flowers had significantly higher levels of proteins and amino acids than inaperturate pollen grains from functionally female flowers. Levels of proteins and amino acids were highest in bisexual and staminate flowers of the andromonoecious species. CONCLUSIONS: Higher levels of proteins and amino acids in porate pollen of "male" flowers in our functionally dioecious Solanum species suggests a greater nutritive reward for bees foraging on "male" plants than for those foraging on functionally "female" plants. Greater reward in porate pollen (including andromonoecious species) may be connected to the potential to generate a pollen tube.

Is increased male flower production a strategy for avoidance of predispersal seed predation in andromonoecious plants?

Floral gender in angiosperms often varies within and among populations. We conducted a field survey to test how predispersal seed predation affects sex allocation in an andromonoecious alpine herb Peucedanum multivittatum. We compared plant size, male and perfect flower production, fruit set, and seed predation rate over three years among nine populations inhabiting diverse snowmelt conditions in alpine meadows. Flowering period of individual populations varied from mid-July to late August reflecting the snowmelt time. Although perfect flower and fruit productions increased with plant size, size dependency of male flower production was less clear. The number of male flowers was larger in the early-flowering populations, while the number of perfect flowers increased in the late-flowering populations. Thus, male-biased sex allocation was common in the early-flowering populations. Fruit-set rates varied among populations and between years, irrespective of flowering period. Fruit-set success of individual plants increased with perfect flower number, but independent of male flower number. Seed predation by lepidopteran larvae was intense in the early-flowering populations, whereas predation damage was absent in the late-flowering populations, reflecting the extent of phenological matching between flowering time of host plants and oviposition period of predator moths. Seed predation rate was independent of male and perfect flower numbers of individual plants. Thus, seed predation is a stochastic event in each population. There was a clear correlation between the proportion of male flowers and the intensity of seed predation among populations. These results suggest that male-biased sex allocation could be a strategy to reduce seed predation damage but maintain the effort as a pollen donor under intensive seed predation.

Phytohormone and integrated mRNA and miRNA transcriptome analyses and differentiation of male between hermaphroditic floral buds of andromonoecious Diospyros kaki Thunb.

BACKGROUND: Persimmon (Diospyros kaki Thunb.) has various labile sex types, and studying its sex differentiation can improve breeding efficiency. However, studies on sexual regulation patterns in persimmon have focused mainly on monoecy and dioecy, whereas little research has been published on andromonoecy. In order to reveal the sex differentiation regulation mechanism of andromonoecious persimmon, we performed histological and cytological observations, evaluated OGI and MeGI expression and conducted phytohormones assays and mRNA and small RNA transcriptome analyses of the male and hermaphroditic floral buds of the andromonoecious persimmon 'Longyanyeshi 1'. RESULTS: Stages 2 and 4 were identified as the critical morphological periods for sex differentiation of 'Longyanyeshi 1' by histological and cytological observation. At both stages, OGI was differentially expressed in male and hermaphroditic buds, but MeGI was not. This was different from their expressions in dioecious and monoecious persimmons. Meantime, the results of phytohormones assays showed that high IAA, ABA, GA3, and JA levels at stage 2 may have promoted male floral bud differentiation. However, high JA levels at stage 4 and high ZT levels at stages 2 and 4 may have promoted hermaphroditic floral bud differentiation. In these phytohormone biosynthesis and signaling pathways, 52 and 54 differential expression genes (including Aux/IAA, ARFs, DELLA, AHP, A-ARR, B-ARR, CYP735A, CRE1, PP2C, JAZ, MYC2, COI1, CTR1, SIMKK, ACO, and MPK6) were identified, respectively. During the development of male floral buds, five metacaspases genes may have been involved in pistil abortion. In addition, MYB, FAR1, bHLH, WRKY, and MADS transcription factors might play important roles in persimmon floral bud sex differentiation. Noteworthy, miR169v_1, miR169e_3, miR319_1, and miR319 were predicted to contribute to phytohormone biosynthesis and signaling pathways and floral organogenesis and may also regulate floral bud sex differentiation. CONCLUSION: The present study revealed the differences in morphology and phytohormones content between male and hermaphroditic floral buds of 'Longyanyeshi 1' during the process of sex differentiation, and identified a subset of candidate genes and miRNAs putatively associated with its sex differentiation. These findings can provide a foundation for molecular regulatory mechanism researching on andromonoecious persimmon.

The Ethylene Biosynthesis Gene CpACO1A: A New Player in the Regulation of Sex Determination and Female Flower Development in Cucurbita pepo.

A methanesulfonate-generated mutant has been identified in Cucurbita pepo that alters sex determination. The mutation converts female into hermaphrodite flowers and disrupts the growth rate and maturation of petals and carpels, delaying female flower opening, and promoting the growth rate of ovaries and the parthenocarpic development of the fruit. Whole-genome resequencing allowed identification of the causal mutation of the phenotypes as a missense mutation in the coding region of CpACO1A, which encodes for a type I ACO enzyme that shares a high identity with Cucumis sativus CsACO3 and Cucumis melo CmACO1. The so-called aco1a reduced ACO1 activity and ethylene production in the different organs where the gene is expressed, and reduced ethylene sensitivity in flowers. Other sex-determining genes, such as CpACO2B, CpACS11A, and CpACS27A, were differentially expressed in the mutant, indicating that ethylene provided by CpACO1A but also the transcriptional regulation of CpACO1A, CpACO2B, CpACS11A, and CpACS27A are responsible for determining the fate of the floral meristem toward a female flower, promoting the development of carpels and arresting the development of stamens. The positive regulation of ethylene on petal maturation and flower opening can be mediated by inducing the biosynthesis of JA, while its negative control on ovary growth and fruit set could be mediated by its repressive effect on IAA biosynthesis.

Mapping a Partial Andromonoecy Locus in Citrullus lanatus Using BSA-Seq and GWAS Approaches.

The sexual expression of watermelon plants is the result of the distribution and occurrence of male, female, bisexual and hermaphrodite flowers on the main and secondary stems. Plants can be monoecious (producing male and female flowers), andromonoecious (producing male and hermaphrodite flowers), or partially andromonoecious (producing male, female, bisexual, and hermaphrodite flowers) within the same plant. Sex determination of individual floral buds and the distribution of the different flower types on the plant, are both controlled by ethylene. A single missense mutation in the ethylene biosynthesis gene CitACS4, is able to promote the conversion of female into hermaphrodite flowers, and therefore of monoecy (genotype MM) into partial andromonoecy (genotype Mm) or andromonoecy (genotype mm). We phenotyped and genotyped, for the M/m locus, a panel of 207 C. lanatus accessions, including five inbreds and hybrids, and found several accessions that were repeatedly phenotyped as PA (partially andromonoecious) in several locations and different years, despite being MM. A cosegregation analysis between a SNV in CitACS4 and the PA phenotype, demonstrated that the occurrence of bisexual and hermaphrodite flowers in a PA line is not dependent on CitACS4, but conferred by an unlinked recessive gene which we called pa. Two different approaches were performed to map the pa gene in the genome of C. lanatus: bulk segregant analysis sequencing (BSA-seq) and genome wide association analysis studies (GWAS). The BSA-seq study was performed using two contrasting bulks, the monoecious M-bulk and the partially andromonoecious PA-bulk, each one generated by pooling DNA from 20 F2 plants. For GWAS, 122 accessions from USDA gene bank, already re-sequenced by genotyping by sequencing (GBS), were used. The combination of the two approaches indicates that pa maps onto a genomic region expanding across 32.24-36.44 Mb in chromosome 1 of watermelon. Fine mapping narrowed down the pa locus to a 867 Kb genomic region containing 101 genes. A number of candidate genes were selected, not only for their function in ethylene biosynthesis and signalling as well as their role in flower development and sex determination, but also by the impact of the SNPs and indels differentially detected in the two sequenced bulks.

The Effect of Macronutrient Availability on Pomegranate Reproductive Development.

Pomegranate cultivation has expanded significantly in the last two decades. However, there is limited information on its fertilization requirements and the effect of macronutrient availability on its reproductive development. Two commercial pomegranate cultivars-"Wonderful" and "Emek"-were grown in 500-L containers for 3 years, using a fertigation system. Development and reproduction indices were measured to explore the trees' responses to elevated levels of nitrogen (N), phosphorus (P) and potassium (K) in the irrigation solution. Andromonoecy rate was affected by nutrient levels only in the first year of the experiment, with higher levels of N and P leading to a greater proportion of hermaphrodites out of total flowers. P level had a positive effect on the total number of hermaphrodites per tree in both varieties. Differences recorded between hermaphroditic and staminate flowers included nutrient concentrations and dry weight. Fruit set and aril number were positively affected by N concentration in the irrigation solution. We conclude that only a severe deficiency of N and P affects the andromonoecy trait, and that at the levels examined in this study, K hardly influences pomegranate reproduction.

Both small and large plants are likely to produce staminate (male) flowers in a hermaphrodite lily.

Resource allocation to female and male function may vary among individual plants in species with variable sex expression. Size-dependent sex allocation has been proposed in hermaphrodites, in which female-biased allocation may increase with plant size. In many hermaphrodites with large floral displays, however, later-produced flowers tend to be functionally male. This paradoxical relationship between female and male function and plant size remains poorly understood. The subalpine lily Lilium lankongense has individuals of three sexual types: males with only staminate flowers, hermaphrodites with only perfect flowers, and andromonoecious plants with both perfect and staminate flowers. Here we tested theoretical predictions of size-dependent sex allocation in L. lankongense by measuring plant height and flower number of individuals of each sex at five field sites in the mountainous region of Shangri-La, southwestern China. To investigate variation in phenotypic gender, we identified sex expression of 457 individuals one year later. Our investigation showed that male plants, which usually produced one flower, were significantly smaller than andromonoecious and hermaphrodite plants. In addition, the total flower numbers of andromonoecious and hermaphrodite plants increased significantly with plant size. Large individuals were more likely to produce terminal staminate flowers, as there were more flowers in andromonoecious than in hermaphrodite individuals. Non-flowered plants were significantly smaller than flowering ones. Perfect flowers had significantly larger petals and pistils than staminate flowers, but they did not differ in dry weight of stamens. Our findings indicate that when plants are small, the less costly sex is favored, consistent with the 'size-advantage hypothesis'. When plants are large, both female and male investments change isometrically, as later-produced flowers tend to be functionally male.

Two androecious mutations reveal the crucial role of ethylene receptors in the initiation of female flower development in Cucurbita pepo.

Ethylene is the key regulator of sex determination in monoecious species of the family Cucurbitaceae. This hormone determines which individual floral meristems develop as female or male flowers and the female flowering transition. The sex determination genes discovered so far code for ethylene biosynthesis enzymes, but little is known about the importance of ethylene signaling components. In this paper we characterize two novel ethylene-insensitive mutations (etr1a-1 and etr1b) which block the female flowering transition of Cucurbita pepo; this makes plants produce male flowers indefinitely (androecy). Two missense mutations in the ethylene-binding domain of the ethylene receptors CpETR1A or CpETR1B were identified as the causal mutations of these phenotypes by using whole-genome resequencing. The distinctive phenotypes of single and double mutants for four etr mutations have demonstrated that the final level of ethylene insensitivity depends upon the strength and dosage of mutant alleles for at least three cooperating ETR genes, and that the level of ethylene insensitivity determines the final sex phenotype of the plant. The sex phenotype ranges from monoecy in ethylene-sensitive wild-type plants to androecy in the strongest ethylene-insensitive ones, via andromonoecy in partially ethylene-insensitive plants. The induction of female flowering transition was found to be associated with upregulation of CpACS11, CpACO2 and CpACS27, three ethylene biosynthesis genes required for female flower development. A model is proposed herein, integrating both ethylene biosynthesis and receptor genes into the genetic network which regulates sex determination in C. pepo.

Small RNA and mRNA Sequencing Reveal the Roles of microRNAs Involved in Pomegranate Female Sterility.

Female sterility is a key factor restricting plant reproduction. Our previous studies have revealed that pomegranate female sterility mainly arose from the abnormality of ovule development. MicroRNAs (miRNAs) play important roles in ovule development. However, little is known about the roles of miRNAs in female sterility. In this study, a combined high-throughput sequencing approach was used to investigate the miRNAs and their targeted transcripts involved in female development. A total of 103 conserved and 58 novel miRNAs were identified. Comparative profiling indicated that the expression of 43 known miRNAs and 14 novel miRNAs were differentially expressed between functional male flowers (FMFs) and bisexual flowers (BFs), 30 known miRNAs and nine novel miRNAs showed significant differences among different stages of BFs, and 20 known miRNAs and 18 novel miRNAs exhibited remarkable expression differences among different stages of FMFs. Gene ontology (GO) analyses of 144 predicted targets of differentially expressed miRNAs indicated that the "reproduction process" and "floral whorl development" processes were significantly enriched. The miRNA-mRNA interaction analyses revealed six pairs of candidate miRNAs and their targets associated with female sterility. Interestingly, pg-miR166a-3p was accumulated, whereas its predicted targets (Gglean012177.1 and Gglean013966.1) were repressed in functional male flowers (FMFs), and the interaction between pg-miR166a-3p and its targets (Gglean012177.1 and Gglean013966.1) were confirmed by transient assay. A. thaliana transformed with 35S-pre-pg-miR166a-3p verified the role of pg-miR166a-3p in ovule development, which indicated pg-miR166a-3p's potential role in pomegranate female sterility. The results provide new insights into molecular mechanisms underlying the female sterility at the miRNA level.

Development of microsatellite markers for the annual andromonoecious herb Commelina communis f. ciliata (Commelinaceae).

Commelina communis f. ciliata (Commelinaceae), a newly distinguished taxon, is an annual andromonoecious herb exhibiting a mixed mating system, the details of which remain unclear. We developed microsatellite markers for use in exploring the evolution of andromonoecy and mixed mating in the species. Fifteen microsatellite loci were developed using next-generation sequencing. The primer sets were used to evaluate 65 C. communis f. ciliata individuals from three populations in Japan; we found 1-13 alleles per locus and the expected heterozygosity ranged from 0.00 to 0.76. The markers are potentially useful to examine intra- and interspecies genetic structure and the mixed mating strategy of Commelina species via paternity analysis.

Solanumplastisexum, an enigmatic new bush tomato from the Australian Monsoon Tropics exhibiting breeding system fluidity.

A bush tomato that has evaded classification by solanologists for decades has been identified and is described as a new species belonging to the Australian "Solanumdioicum group" of the Ord Victoria Plain biogeographic region in the monsoon tropics of the Northern Territory. Although now recognised to be andromonoecious, S.plastisexum Martine & McDonnell, sp. nov. exhibits multiple reproductive phenotypes, with solitary perfect flowers, a few staminate flowers or with cymes composed of a basal hermaphrodite and an extended rachis of several to many staminate flowers. When in fruit, the distal rachis may abcise and drop. A member of SolanumsubgenusLeptostemonum, Solanumplastisexum is allied to the S.eburneum Symon species group. Morphometric analyses presented here reveal that S.plastisexum differs statistically from all of its closest relatives including S.eburneum, S.diversiflorum F. Meull., S.jobsonii Martine, J.Cantley & L.M.Lacey, S.succosum A.R.Bean & Albr. and S.watneyi Martine & Frawley in both reproductive and vegetative characters. We present evidence supporting the recognition of S.plastisexum as a distinctive entity, a description of the species, representative photographs, a map showing the distribution of members of the S.eburneum species group and a key to the andromonoecious Solanum species of the Northern Territory of Australia. This new species is apparently labile in its reproductive expression, lending to its epithet, and is a model for the sort of sexual fluidity that is present throughout the plant kingdom.

Mating consequences of contrasting hermaphroditic plant sexual systems.

For hermaphroditic angiosperms with multiple flowers, the sex roles can be exclusively combined in bisexual flowers (monocliny), strictly separated among different flowers (monoecy), or arrayed in mixtures of bisexual flowers with female flowers (gynomonoecy) or male flowers (andromonoecy). The hypothesized benefits favoring the evolution of these contrasting hermaphroditic sexual systems are typically examined individually, usually by assessing success through only one sex role. We tested predictions of most hypotheses experimentally with an andromonoecious species, Anticlea occidentalis (Melanthiaceae), based on the performance of intact plants (andromonoecy) and those with emasculated bisexual flowers (functionally monoecious) or emasculated male flowers (functionally monoclinous with sterile peripheral flowers). Andromonoecy in this species enables efficient, size-dependent resource allocation, emphasizing female function in large plants. Emasculation revealed that anthers in male flowers promote female mating quality (outcrossing rate and mate diversity), whereas anthers in bisexual flowers promote male mating quantity (pollen dispersal distance and probability of any siring success). Thus, different hermaphroditic sexual systems likely evolve to capitalize on suites of benefits, rather than just one, and provide compromises between quantitative and qualitative reproductive components. These compromises apparently maximize an individual's combined genetic contributions through female and male functions, rather than separate contributions through each sex role.

Sexual expression and reproductive output in the ephemeral Geranium transversale are correlated with environmental conditions.

PREMISE OF THE STUDY: Abiotic environmental factors are often considered to be important in the distribution and maintenance of variation in sexual systems in flowering plants. Associations between sexes and abiotic factors are well documented in dioecious systems, but much less is known about this relationship in other sexually polymorphic systems. Species that are highly variable in sexual expression and habitat distribution can provide insights into the role of abiotic factors in maintaining variation in sexual expression. METHODS: Focusing on a sexually polymorphic species, Geranium transversale, we measured sexual expression at both the flower and the plant level and examined vegetative and floral traits, pollen deposition, and reproductive success. We also tested for correlations between sexual expression and other traits and examined whether and how these traits covaried with abiotic environmental conditions. KEY RESULTS: We identified unique variation of sexual expression in G. transversale. There are four sexual morphs that display different combinations of the three flower types (pistillate, staminate, and perfect). Sexual morphs that are phenotypically more female (i.e., female and gynomonoecious morphs) are found in wetter and milder environments, and flower earlier than morphs that are more male (i.e., hermaphroditic and andromonoecious morphs). Additionally, floral organ size and reproductive success are influenced not only by the flower type but also by the sexual morph of the plant. CONCLUSIONS: Environmental conditions are likely to cause some of the variation in sexual expression found in G. transversale. Both genetic and ecological factors likely contribute to the maintenance of sexual variation in this species.

SEX EXPRESSION, BREEDING SYSTEM AND POLLINATORS OF Piper caldense (PIPERACEAE) IN THE BRAZILIAN ATLANTIC FOREST / Expresión sexual, sistema reproductivo y polinizadores de Piper caldense (Piperaceae) en un bosque Atlántico

ABSTRACT Neotropical Piper species have bisexual flowers. Such reproductive trait is considered basal in this pantropical genus. However, neotropical species having unisexual (staminate) flowers along with bisexual ones have also been reported. Dichogamy is common in the genus, associated with either self-compatibility or -incompatibility, as well as with entomophily. We analyzed a natural population of Piper caldense in a Atlantic Forest area (Viçosa municipality, Minas Gerais state, southeastern Brazil). Preliminary observations indicated that the species produces two flower types. We analyzed flower sex in spikes of 50 plants. We obtained additional information through morphological and anatomical studies and scanning electron microscopy analyses. The longevity and exposure dynamics of stigmatic papillae and the pollen release sequence of all four stamens were investigated to verify the degree of dichogamy. Pollination tests were performed, pollinators were identified and their visitation frequency was recorded. Piper caldense has both bisexual and staminate flowers, each flower type being located on separate spikes. These spikes occurred on the same plant, thus indicating andromonoecy; furthermore, plants having only spikes with staminate flowers were also observed. This gender had not yet been reported to the genus. Gradual and sequential exposure of stigmatic papillae associated with asynchronous pollen release (one stamen a day) resulted in incomplete protogyny. Hand pollination tests showed that the species is self-incompatible. Social bees, mainly Apis mellifera and Melipona spp., were the major pollinator group. Our study reinforces the need to associate morphological analysis with floral biology and indicates future changes in studies addressing reproductive traits associated with the phylogeny of the Piper genus.

RESUMEN Las especies neotropicales de Piper presentan flores bisexuales, condición considerada basal al interior de este género pantropical. Sin embargo, fueron observadas especies neotropicales con flores unisexuales (estaminadas), además de las bisexuales. La dicogamia es común en el género y se encuentra asociada a la autocompatibilidad o incompatibilidad, al igual que la entomofilia. Fue analizada una población natural de Piper caldense en un área de bosque Atlántico (municipio de Viçosa, Minas Gerais, sureste de Brasil). Las observaciones preliminares indicaron que esta especie produce dos tipos florales, para lo cual fue analizada la sexualidad de las flores en 50 espigas a través de estudios morfológicos, anatómicos y análisis con microscopia electrónica de barrido. La longevidad y dinámica de exposición de las papilas estigmáticas y la secuencia de liberación de los granos de polen en los cuatro estambres fueron observados para verificar el grado de dicogamia. El sistema reproductivo se evaluó mediante el test de autopolinización espontánea y polinización abierta. Los visitantes florales fueron identificados y se registró su frecuencia de visita. Piper caldense presenta flores bisexuales y estaminadas, cada tipo floral se encuentra en espigas separadas. Estas espigas se encuentran en la misma planta, lo que indica que es andromonoica; adicionalmente, fueron observadas plantas que solo presentaban espigas con flores estaminadas, lo que se constituye en una combinación sexual inédita para el género. La exposición gradual y secuencial de las papilas estigmáticas asociada con la liberación asincrónica de los granos de polen (un estambre por día) indica una protoginia incompleta. Los test de polinización mostraron que la especie es autoincompatible. Las abejas sociales, principalmente Apis mellifera y Melipona spp., fueron los polinizadores principales. Este estudio refuerza la necesidad de asociar los analisis morfológicos con la funcionalidad de las estructuras florales, además indica los cambios futuros en estudios que abordan características reproductivas asociadas a la filogenia de las especies de Piper.

Solanum jobsonii, a novel andromonoecious bush tomato species from a new Australian national park.

A new species of Solanum from the Australian "andromonoecious bush tomato clade" of Solanum subgenus Leptostemonum is described. Solanum jobsonii Martine, J.Cantley, & L.M.Lacey, sp. nov. is part of the S. eburneum Symon species group. It most closely resembles S. eburneum and S. watneyi Martine & Frawley of the northwestern part of the Northern Territory, but is separated geographically from them by the Sturt Plateau. Morphometric analyses show that S. jobsonii differs statistically from S. eburneum, S. watneyi, and S. diversiflorum F.Muell. - a similar species in habit and leaf characters - in several key reproductive and vegetative characters. We provide morphometric evidence for the recognition of S. jobsonii, a complete description, a table of comparisons within its species group, and a map showing species group distributions. One of the first new species to be described from Limmen National Park (established 2012), S. jobsonii is a testament to the value of designating and protecting public lands, as well as supporting science relating to them.