Number Of Stamens Research Articles

Sexually-trimorphic interactions with colour polymorphism determine nectar quality in a herbaceous perennial

Amongst gynodioecious plant breeding systems, there can exist intermediate morphs with a reduction in their male function (i.e. reduced number of functional anthers). Along with this sexual trimorphism, plants can also show floral colour polymorphism. Such intricate mixtures of phenotypes within a species may have complex effects on floral rewards. Floral rewards are known to vary between sexually dimorphic species and to a lesser extent between colour morphs. However, the interactive effect of sexual trimorphism and colour polymorphism is unexplored. We measured nectar’s sugar content in the sexually trimorphic Geranium sylvaticum, a gynodioecious plant with a light/dark floral polymorphism. We found that nectar reward differed across genders and colour morphs. Results were not however consistent within the three genders; dark female and hermaphrodite flowers had higher sugar content than light morphs, whereas intermediate flowers did not. As expected, females and hermaphrodites had different nectar reward, with intermediate morphs being midway between the other genders. In intermediates, the sugar content was not related to the number of functional stamens. We show for the first time the existence of sex-specific differences between flower gender and colour morphs in nectar rewards. Our results demonstrate the importance of considering multiple and conflicting selection pressures to explain rewards.

Phylogenetic study of the tribe Potentilleae (Rosaceae), with further insight into the disintegration of Sibbaldia

AbstractPotentilleae, one of 10 tribes of the Rosaceae, are mainly distributed in alpine regions of the Northern Hemisphere. The taxonomy of Potentilleae has been challenging due to extensive hybridization, polyploidization, and/or apomixis characterizing several genera of Potentilleae, such as Alchemilla, Argentina, and Potentilla. To help clarify relationships within Potentilleae, a phylogenetic analysis of the tribe with an emphasis on the polyphyletic genus Sibbaldia was carried out using nuclear ribosomal internal and external transcribed spacer regions and the plastid trnL‐F and trnS‐G spacer regions. In agreement with previous phylogenetic analyses, three major clades were identified in the present study: the subtribe Fragariinae, the genera Argentina, and Potentilla. The 15 species of Sibbaldia were recovered in five distinct clades: three in subtribe Fragariinae, one in Argentina, and the last in Potentilla. The recently established genus Chamaecallis, comprising a single species formerly treated in Sibbaldia that has intermediate floral character states with respect to Fragariinae and Potentilla, was recovered as sister to Drymocallis. Morphological character state reconstruction indicated that a reduction in the number of stamens (≤10) is a derived character state that has arisen multiple times in Potentilleae. Molecular dating analyses agreed with previously published estimates and suggested that crown group Potentilleae arose in the Middle to Late Eocene, with most generic‐level divergences occurring in the Oligocene and Miocene.

Floral development of Berberidopsis beckleri - can an additional species of the Berberidopsidaceae add evidence to floral evolution in the core eudicots?

Berberidopsis beckleri is one of three species of the family Berberidopsidaceae. The flower of Berberidopsis is unusual for core eudicots in being spiral with an undifferentiated perianth. In a previous study of the sister species B. corallina , it was suggested that Berberidopsidaceae represent a prototype for the origin of the bipartite perianth and pentamery in core eudicots. The floral development of B. beckleri was investigated with a scanning electron microscope and compared with previous studies on B. corallina and Aextoxicon punctatum of Berberidopsidales. Flowers are inserted at the end of short shoots, which are not distinguishable from a pedicel. The initiation of perianth parts is highly predictable and spiral with a divergence angle of 137·5°, in a progression of a variable number of bracts to weakly differentiated sepaloid and petaloid tepals. The androecium most often consists 11 stamens arising in a rapid sequence. Compared with B. corallina , the number of perianth parts and stamens is more variable and there is no evidence of an alternation of shorter and longer plastochrons leading to a whorled arrangement. However, the gynoecium is generally pentamerous and arises from five primordia. The carpels are laterally connected into massive intercarpellary ridges on which ovules are initiated. The position of Streptothamnus within Berberidopsidaceae is questioned. It is demonstrated that the floral development of Berberidopsis beckleri lies within a gradient from spiral flowers without perianth differentiation leading to flowers with differentiated sepals and petals. The arrangement of flowers in compact inflorescences in B. corallina and Aextoxicon leads to a more stabilized arrangement of organs in whorls. The inherent variability of the flower of Berberidopsis is well correlated with the limited canalization of flowers in taxa at the base of the core eudicots and could act as a prototype for the current eudicot floral Bauplan.

Incomplete loss of a conserved trait: function, latitudinal cline, and genetic constraints

Retention of nonfunctional traits over evolutionary time is puzzling, because the cost of trait production should drive loss. Indeed, several studies have found nonfunctional traits are rapidly eliminated by selection. However, theory suggests that complex genetic interactions and a lack of genetic variance can constrain evolution, including trait loss. In the mustard family Brassicaceae the conserved floral condition includes four long and two short stamens, but we show that short stamens in the highly self-pollinating mustard Arabidopsis thaliana do not significantly increase selfed seed set, suggesting that the trait has lost most or all of its function after the transition to selfing. We find that short stamen loss is common in native populations. Loss is incomplete and decreases with increasing latitude, a cline unexplained by correlations with flowering time or ovule count (which also vary with latitude). Using recombinant inbred lines derived from a cross between plants at the latitudinal extremes of the native range, we found three QTLs affecting short stamen number, with epistasis among them constraining stamen loss. Constraints on stamen loss from both epistasis and low genetic variance may be augmented by high selfing rates, suggesting that these kinds of constraints may be common in inbred species.

Comparative Morphology of the Genus <i>Tamarix</i> (Tamaricaceae) in Iran

Tamarix L. with almost 54 species is the largest genus of the Tamaricaceae. This study was carried out on species of Tamarix that growing in Iran. Morphological characters were obtained for 23 species recognized by recent taxonomic treatments from Iran. In this study we use 10 characters to identify species of Tamarix that growing in Iran. For SEM studies, we used dry sampels of leaves and flowers. Some characters are useful for segregating certain species, such as gross leaf morphology (vaginate vs. sessile), number of floral parts, certain aspects of androecial disk morphology, petal shape, presence or absence of hairs on the raceme rachis, and whether the filament is inserted under or from the side of the androecial disk. In some species the number of sepals, petals and stamens are constant and reliable. One of the problems in Tamarix is that in many species the number of certain floral organs is inconstant thus the number of floral parts alone can not serve as a diagnostic marker without being correlated with the relative position of the organs and their range of numerical variability.

Comparative Morphology of the Genus <i>Tamarix</i> (Tamaricaceae) in Iran

TamarixL. with almost 54 species is the largest genus of the Tamaricaceae. This study was carried out on species ofTamarixthat growing in Iran. Morphological characters were obtained for 23 species recognized by recent taxonomic treatments from Iran. In this study we use 10 characters to identify species ofTamarixthat growing in Iran. For SEM studies, we used dry sampels of leaves and flowers. Some characters are useful for segregating certain species, such as gross leaf morphology (vaginate vs. sessile), number of floral parts, certain aspects of androecial disk morphology, petal shape, presence or absence of hairs on the raceme rachis, and whether the filament is inserted under or from the side of the androecial disk. In some species the number of sepals, petals and stamens are constant and reliable. One of the problems inTamarixis that in many species the number of certain floral organs is inconstant thus the number of floral parts alone can not serve as a diagnostic marker without being correlated with the relative position of the organs and their range of numerical variability.

Floral Development of MonoeciousPseuduvaria Trimera(Annonaceae) and Comparative Morphology and Structure of Its Stamens and Indehiscent Staminodes

Premise of research. The comparative development of staminate and pistillate flowers in Pseuduvaria trimera (Annonaceae) was investigated for the first time to understand its sexual differentiation and developmental processes. The morphological and anatomical features of mature stamens and staminodes were also compared to clarify anther dehiscence and to understand the mechanism underlying staminode sterility.Methodology. Flowers at different developmental stages as well as mature stamens and staminodes were examined using SEM and LM.Pivotal results. Similar to other Annonaceae, the flowers of Pseuduvaria trimera have a complex whorled phyllotaxis. They have double positions in the outermost whorl of reproductive organs and variable numbers of stamens and carpels per whorl. The stomium region of each theca is composed of the septum and the stomium. The septum and stomium cells of stamens degenerate and facilitate anther opening, whereas those of staminodes remain intact and form indehiscent anthers.Conclu...

Morphogenesis and Gene Mapping of deformed interior floral organ 1 (difo1), a Novel Mutant Associated with Floral Organ Development in Rice

Floral organ identity and specific number directly affect anthesis habits, fertilization and grain yield. Here, we identified a deformed interior floral organ 1 (difo1) mutant from selfing progenies of indica cv. Zhonghui8015 (Zh8015) after 60Co γ-ray treatment. Compared with the Zh8015 spikelet, the interior floral organs of the difo1 mutant present various numbers of stamens and stigmas, with no typical filament and no mature pollen grains. Most difo1 flowers exhibited an increased number of stigmas that were attached to the stamens and an intumescent ovule-like cell mass in addition to the ovary. Transverse sections of spikelets and scanning electron microscopy analysis revealed an indeterminate number of interior floral organs and abnormal early spikelet development for the difo1 mutant. Instead of the linear-shaped surface of wild-type stamens, difo1 displayed a glossy stamen surface resulting in immature stamens and complete sterility. In addition, the difo1 mutant exhibited delayed anthesis, rapid anthesis and non-extended stamens compared with wild type. Genetic analysis and gene mapping revealed that difo1 was controlled by a single recessive gene, which was fine-mapped to a 54-kb interval on the short arm of chromosome 4 between markers S22 and RM16439 harboring nine ORFs. Sequence analysis revealed that the mutant carried a single nucleotide deletion in its promoter region, which likely corresponded to the phenotype, in a C2H2-type zinc finger protein gene (LOC_Os04g08600). Moreover, qRT-PCR analysis showed a significantly down-regulated expression pattern for DIFO1 and many floral organ identity genes in the interior floral organs of difo1. DIFO1 is therefore an important floral organ development gene in rice, particularly with regard to interior organ meristem identity and floret primordium differentiation.

Eugenia veraguensis (Myrtaceae), a new species from Golfo de Chiriquí in Veraguas Province, Panama, with notes on Eugenia rhombea

Eugenia veraguensis is described as a new species of Myrtaceae from Panama. It differs from E. rhombea, the most similar taxon, by a combination of its shrubby habit, a distinctive dichotomous branching pattern with 4 to 6 leaved branchlets, chartaceous or subcoriaceous leaves and its small number of stamens. It occurs in coastal forest and scrub on islands off Pacific Western Panama. Following the inclusion of a specimen of E. veraguensis as E. rhombea in Flora Mesoamericana, we discuss the occurrence of this latter species in Panama.

A Reconsideration of the Infrageneric Classification of Homalium Jacq. (Salicaceae)

Abstract Applequist, W.L. (2016). A reconsideration of the infrageneric classification of Homalium Jacq. (Salicaceae). Candollea 71: 231–256. In English, English and French abstracts. Homalium Jacq. (Salicaceae) is widespread in tropical regions and includes considerable diversity in floral morphology. Its modern infrageneric classification is complex, including two subgenera and nine sections. Morphological variation within the genus is described, and an emended classification including ten sections is proposed. Subgenera have been defined by stamen number : subg. Homalium has stamens in fascicles of two to 12, while subg. Blackwellia (Benth.) Warb. has one stamen per petal. These subgenera are not natural groups; since the relationships of some sections are uncertain, recognition of subgenera may not be of value and is not upheld here. Sect. Eumyriantheia Warb. is polyphyletic; it is herein restricted to Malagasy species, while sect. Polyanthera Warb. is revived for fasciculate-stamened species from Asi...

Expression of B-class MADS-box genes in response to variations in photoperiod is associated with chasmogamous and cleistogamous flower development in Viola philippica.

BackgroundSome plants develop a breeding system that produces both chasmogamous (CH) and cleistogamous (CL) flowers. However, the underlying molecular mechanism remains elusive.ResultsIn the present study, we observed that Viola philippica develops CH flowers with short daylight, whereas an extended photoperiod induces the formation of intermediate CL and CL flowers. In response to long daylight, the respective number and size of petals and stamens was lower and smaller than those of normally developed CH flowers, and a minimum of 14-h light induced complete CL flowers that had no petals but developed two stamens of reduced fertility. The floral ABC model indicates that B-class MADS-box genes largely influence the development of the affected two-whorl floral organs; therefore, we focused on characterizing these genes in V. philippica to understand this particular developmental transition. Three such genes were isolated and respectively designated as VpTM6-1, VpTM6-2, and VpPI. These were differentially expressed during floral development (particularly in petals and stamens) and the highest level of expression was observed in CH flowers; significantly low levels were detected in intermediate CL flowers, and the lowest level in CL flowers. The observed variations in the levels of expression after floral induction and organogenesis apparently occurred in response to variations in photoperiod.ConclusionsTherefore, inhibition of the development of petals and stamens might be due to the downregulation of B-class MADS-box gene expression by long daylight, thereby inducing the generation of CL flowers. Our work contributes to the understanding of the adaptive evolutionary formation of dimorphic flowers in plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0832-2) contains supplementary material, which is available to authorized users.

Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity.

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years.

Floral organogenesis in Dysosma versipellis (Berberidaceae) and its systematic implications

The Berberidaceae and the six other families of Ranunculales form a sister clade to all other eudicots, and are crucial to reconstructing the common ancestor of flowering plants. Previous studies have suggested that the petals of most Berberidaceae are derived from stamens, and some are thought to develop petals from common petal/stamen primordia. However, the flower ontogeny is still poorly known in the family and the presence of common primordia needs to be re-evaluated from a comparative developmental perspective. Here, we used scanning electron microscopy to study the floral development of the endemic Chinese species Dysosma versipellis (Hance) M. Cheng ex Ying, which was originally placed in Podophyllum. Our results show that the floral organs are all free and the sepals, petals, and stamens are initiated centripetally in successive and alternate trimerous pairs of whorls around a single carpel. The nectarless petals are initiated separately and do not develop from common primordia with the stamens. Floral and developmental features of D. versipellis are similar to those of most members of Berberidaceae. The regular development of multiple flowers and absence of a secondary increase in the number of stamens in Dysosma support its exclusion from Podophyllum, and this is also inferred by the DNA sequence data.

Invasion history of Cardamine hirsuta in Japan inferred from genetic analyses of herbarium specimens and current populations

Multiple introductions of a species are thought to enhance its invasion success by increasing genotypic diversity; this involves frequent crossing among different lineages. However, genetic diversity through crossing is less likely in autogamous species. To understand the impact of multiple introductions on the colonization success of autogamous species, we studied hairy bittercress, Cardamine hirsuta, which invaded Japan several decades ago. We detected temporal changes in its population structure using nine microsatellite markers amplified from leaf samples collected from 87 sites between 2009 and 2010, and herbarium specimens collected between 1988 and 2007. To examine whether the phenotypic variation corresponded with the genetic population structure, we also investigated the geographic variation in the lateral stamen number of this species across 49 sites. The present populations can be divided into three genetic groups, which are distributed in northern, eastern, and western Japan. This finding suggests that there are three invasive lineages (North, East, and West) in Japan. The geographic variation in lateral stamen number corresponded to the distributions of these lineages. The former distributions of the North and West lineages mostly corresponded to those found at present, but they were also historically found in eastern Japan. However, the East lineage has apparently expanded into eastern Japan, resulting in a change in dominant lineages over only a few decades. For the autogamous C. hirsuta, multiple introductions contributed toward colonization success over a wider range, which was associated with a local change in the dominant lineages.

Tinkering with transcription factor networks for developmental robustness of Ranunculales flowers.

The flowers of core eudicots and monocots are generally determined by the number of floral organs they produce, and their developmental set-up tolerates little change from the bauplan once the floral primordium is initiated. Many species outside the core eudicots and monocots are more plastic in the number of floral organs they produce. For example, the Nymphaeales (water lilies), within the basal angiosperms, arrange their floral organs spirally and show smooth transitions between floral organs, and many Ranunculales (buttercups) produce variable numbers of stamens by adjusting the number of stamen whorls generated from a specialized ring meristem. However, the interactions of regulatory genes governing those processes are unknown. This review provides an overview of the functional analyses of floral homeotic genes carried out in Ranunculales, summarizing knockdown and mutant phenotypes, and protein interactions to identify similarities and differences within the Ranunculales and in comparison with core eudicots. Floral gene regulatory networks in Ranunculales are identified showing intensive re-wiring amongst the floral homeotic genes to allow some degree of plasticity. The 'fading-border' model of floral organ identity evolution is extended by a hypothesis on how developmental plasticity can be achieved by interdependent regulation of floral homeotic genes. One aspect of floral plasticity may be achieved by regulation of the activity of a stamen-generating ring meristem and first ideas on its control are presented. While the amazing conservation of the major floral organ identity programme is being unravelled by analysing floral homeotic gene function and expression, we are only just beginning to understand the evolution of the gene network governing the organ identity genes, e.g. how plasticity can be achieved, and which aspects foster the robustness of the core eudicot floral bauplan.

Analysis of the Arabidopsis superman allelic series and the interactions with other genes demonstrate developmental robustness and joint specification of male-female boundary, flower meristem termination and carpel compartmentalization.

SUPERMAN is a cadastral gene controlling the sexual boundary in the flower. The gene's functions and role in flower development and evolution have remained elusive. The analysis of a contrasting SUP allelic series (for which the names superman, superwoman and supersex have been coined) makes it possible to distinguish early vs. late regulatory processes at the flower meristem centre to which SUP is an important contributor. Their understanding is essential in further addressing evolutionary questions linking bisexuality and flower meristem homeostasis. Inter-allelic comparisons were carried out and SUP interactions with other boundary factors and flower meristem patterning and homeostasis regulators (such as CLV, WUS, PAN, CUC, KNU, AG, AP3/PI, CRC and SPT) have been evaluated at genetic, molecular, morphological and histological levels. Early SUP functions include mechanisms of male-female (sexual) boundary specification, flower mersitem termination and control of stamen number. A SUP-dependent flower meristem termination pathway is identified and analysed. Late SUP functions play a role in organ morphogenesis by controlling intra-whorl organ separation and carpel medial region formation. By integrating early and late SUP functions, and by analyzing in one single experiment a series of SUP genetic interactions, the concept of meristematic 'transference' (cascade) - a regulatory bridging process redundantly and sequentially co-ordinating the triggering and completion of flower meristem termination, and carpel margin meristem and placenta patterning - is proposed. Taken together, the results strongly support the view that SUP(-type) function(s) have been instrumental in resolving male/female gradients into sharp male and female identities (whorls, organs) and in enforcing flower homeostasis during evolution. This has probably been achieved by incorporating the meristem patterning system of the floral axis into the female/carpel programme.

Blyxa kasaragodensis,a new species of Hydrocharitaceae from the ponds in the laterite plateau of Malabar coast, Kerala, India

A new aquatic species Blyxa kasaragodensis, collected from the ponds in the lateritc plateau of the Malabar coast, Kerala, India, is described and illustrated. This new species is similar to Blyxa octandra and Blyxa quadricostata in the dioecious nature, elongation of petals at the anthesis and in the number of stamens, but it shows many variations from the similar species such as purplish leaves, submerged male flowers, globular anther lobes, presence of compound pollen grain, large pollen grains, apetalous female flowers and long tail of the seeds. The pollination of Blyxa kasaragodensis takes place with the help of water and the mechanism is new to the genus Blyxa.

Establishment of growth medium and quantification of pollen grains and germination of pear tree cultivars

To support breeding programs of pear tree, on the selection of cultivars to subtropical area in Brazil, the objective of this research was to adjust the growth medium basic to pollen grain germination. The pollen grains of 'D'Agua' cultivar were spread on the surface of Petri dishes containing 20 ml of culture medium in accordance with the following sequential experiments: 1) agar (4; 6; 8 and 10 g L-1) and pH (3,5; 4,5; 5,5 and 6,5); 2) sucrose (0; 30; 60 and 90 g L-1); 3) calcium nitrate (0; 200; 400 and 800 mg L-1); 4) boric acid (0; 400; 800 and 1200 mg L-1); 5) temperature of incubation (15; 20; 25 e 30 oC) and 6) emission time of the pollen tube (0; 1; 2; 3; 4; 5 and 6 hours after inoculation). After incubation, the germination rate of pollen grains of nine pear cultivars ('Rocha', 'Abate Fetel', 'Packham's Triumph', 'Atago', 'Hosui', 'Primorosa', 'Triunfo', 'Seleta' and 'D'Agua') was evaluated, and number of stamens, the number of pollen grains per anther and per flower. The protocol for germination of pollen grains of pear tree consist in the culture medium have to be solidified with 10 g L-1 agar, being the pH measured to 5,2 , added with 90 g L-1 sucrose, 145 mg L-1 calcium nitrate and 700 mg L-1 boric acid, with incubation temperature of 23 oC. The readings germination percentage should be performed after five hours of incubation. The pollen grain 'Rocha' cultivar showed higher germination percentage.

The effect of methyl jasmonate on Zea mays tassel development

Methyl jasmonate (MeJA) is a lipid-derived plant hormone that mediates diverse biological phenomena. Application of MeJA onto rice spikelet could exhibit abnormal floral organ development. Although jasmonic acid (JA) has been proved to be involved in maize tassel sex determination process, the roles of JA and its precursor MeJA in maize tassel development still remain obscure. In this study, we found that tassel development was decelerated by application of2 mMMeJA. Exogenous MeJA also influenced the number of palea and stamens of tassel spikelets. Exogenous MeJA increased the expression level of some key regulator genes, which may responsible for the phenotypic change in MeJA-treated tassel, and may mediate the crosstalk between MeJA and other hormones.

Floral development of Lewisia (Montiaceae): Investigating patterns of perianth and stamen diversity

This study illustrates the intricate floral development of Lewisia (Montiaceae) in an evolutionary context. Flowers are enclosed by two median bracteoles (involucrum), as most Portulacinae. Unlike most taxa of the Montiaceae (Caryophyllales), the petaloid perianth in Lewisia develops in two clearly separate steps: two lateral petaloids arise immediately after bracteole initiation, while the median petaloids lag behind and develop only after the stamens. Stamen number fluctuates between five and more than fifty. In studied species, the number of median petaloids is generally increased from three up to 17 organs, in close connection with the androecium. The involucrum has a strong influence on the arrangement of organs in the flower, by: (1) causing a delay on the growth and development of the petaloids, and (2) by moulding the floral apex in an elliptical shape, allowing an increase of median petaloid and stamen numbers, independently of changes in carpel number. Carpel number influences the position and number of upper stamens. Mechanical pressure of the enclosing involucrum plays a crucial role in the evolution of species of Lewisia and those species with fewer petaloids and stamens correspond to the ancestral condition.