Genetic and environmental variation in anther,pollen and pistil dimensions in sesame

Measurements of anther (length, width, depth), pollen grain (percent fertility, polar diameter, equatorial diameter, polar diameter/equatorial diameter ratio, volume) and pistil (stigma length, style length, ovary length, total pistil length, stigma width, style width, ovary width) were taken on 12 diverse sesame (Sesamum indicum L.) genotypes on each of four collection dates in 1994. Highly significant differences among genotype means were obtained for all characters except polar diameter. Highly significant differences among environment (collection date) means were found for ten of the 15 characters measured. Highly significant genotype x environment interactions were obtained for all characters except anther length. For the anther characters measured, relatively high repeatability values were found, ranging from 99.8% for length to 87.6% for depth. For the pollen grain characters measured, the repeatability values ranged from 67.6% for percent fertility to 23.1% for polar diameter. For the pistil characters measured, the repeatability values ranged from 94.0% for style width to 49.6% for total pistil length. These results indicate that genotype and environment influence anther, pollen grain and pistil characters. Variation in some of these morphological aspects could influence the consistency and interpretation of male transmission studies on both the applied and evolutionary levels.     

孝顺竹(Bambusa multiplex)大孢子发生与雌配子体发育研究

为了解孝顺竹（Bambusa multiplex）的大孢子及雌配子体的发育过程,利用扫描电镜对孝顺竹的雌蕊形态以及大孢子和雌配子体的发育进行了观察。结果表明,孝顺竹雌蕊单子房,1室,双珠被,薄珠心;大孢子母细胞是由1个雌性孢原细胞直接发育而成,大孢子四分体为线性,位于珠孔端的1个大孢子分化成为功能大孢子,然后由功能大孢子依次经历二核、四核、最终形成1卵细胞2助细胞2极核3反足细胞的成熟胚囊。此外,孝顺竹为雌雄同熟类型,根据雌、雄蕊发育的对应关系,从雄蕊形态可估测雌配子体发育阶段。有少数雌蕊出现败育现象,可能是孝顺竹结实率低的原因之一。     

ECOLOGICAL CONSEQUENCES AND PHENOTYPIC CORRELATES OF PETAL SIZE VARIATION IN WILD RADISH,RAPHANUS SATIVUS (BRASSICACEAE)

In this paper we examine some ecological consequences and phenotypic correlates of flower size variation in wild radish, Raphanus sativus. Mean corolla diameter varied significantly among individuals within natural populations of R. sativus in California. On the average, almost 40% of flower biomass was allocated to corolla tissue. In field experiments, pollinator visitation increased significantly with corolla size. Large flowers also accumulated more nectar when pollinators were excluded from plants. In three populations, corolla size was positively correlated with allocation to pollen per flower (either anther weight or pollen grain number), but there was usually no phenotypic relationship between corolla size and several measures of female allocation (ovule number per flower, proportion fruit set, and total seed mass per fruit). Plants growing in the field produced fewer large flowers per unit of stem, and stem biomass was negatively related to corolla size for plants grown under controlled greenhouse conditions. Male and female fitness may covary differently with allocation to attractive floral features in species such as R. sativus, where seed production is often limited by resources rather than by pollen.     

Nectarless flowers with deep corolla tubes in Pedicularis: does long pistil length provide an arena for male competition?

Pollinator‐mediated selection does not seem to have a direct influence on the evolution of a long corolla tube in a nectarless flower. We hypothesized that the long pistil length of the nectarless flower with a deep corolla tube provided an opportunity for male competition. Pedicularis siphonantha, a nectarless and partially self‐incompatible lousewort with substantial variation in corolla tube length, was used to test the hypothesis. We tested whether and how corolla tube length affected seed production per capsule and seed germination rate with different pollination treatments. Flowers were hand‐pollinated with pollen from one self donor and one outcross donor and mixed pollen grains consisting of equal amounts from the two donor types, respectively. Additionally, seeds from open‐pollinated flowers with different corolla tube lengths were collected separately for measurement of germination rate. Pollination treatment and corolla tube length significantly affected number of seeds per capsule. Moreover, a significant positive relationship between seeds per capsule and corolla tube length was found when mixed hand pollination was conducted. Seeds of self hand‐pollinated flowers had a lower germination rate than those from outcross‐pollinated flowers. Under open pollination, seeds from flowers with longer corolla tubes tended to have higher germination rate. In P. siphonantha, outcross pollen may have a higher probability of contributing to the next generation when transferred to flowers with longer corolla tubes. The pistil length, therefore, should be seen as a female choice mechanism, which provides an arena for male‐to‐male competition. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 526–532.     

Trends in evolution of floral ontogeny in Cassia sensu stricto,Senna, and Chamaecrista (Leguminosae: Caesalpinioideae: Cassieae: Cassiinae); a study in convergence

Distinctions in floral ontogeny among three segregate genera (Cassia sensu stricto, Chamaecrista, and Senna) of Cassia L. support their separation. In all species studied, the order of floral organ initiation is: sepals, petals, antesepalous stamens plus carpel, and lastly antepetalous stamens. Sepal initiation is helical in all three genera, which however differ in whether the first sepal is initiated in median abaxial position (Senna), or abaxial and off-median (Cassia javanica), a rare character state among legumes. Order of petal initiation varies: helical in Senna vs. unidirectional in Cassia and Chamaecrista. Both stamen whorls are uniformly unidirectional. Intergeneric ontogenetic differences occur in phyllotaxy, inflorescence architecture, bracteole formation, overlap of initiation among organ whorls (calyx/corolla in Cassia; two stamen whorls in Chamaecrista), eccentric initiation on one side of a flower, anther attachment, anther pore structure, and precocious carpel initiation in Senna. The asymmetric corolla and androecium in Chamaecrista arise by precocious organ initiation on one side (left or right). The poricidal anther character can result from differing developmental pathways: lateral slits vs. sealing of lateral sutures; clasping hairs vs. sutural ridges; terminal pores (one or two) vs. none; and clamp layer formation internally that prevents lateral dehiscence. Genera differ in corolla aestivation patterns and in stigma type. Convergence is shown among the three genera, based on intergeneric dissimilarities in early floral ontogeny (floral position in the inflorescence, bracteole presence, position of the first sepal initiated, order of petal initiation, asymmetric initiation, overlap between whorls, anther morphology, and time of carpel initiation) resulting in similarities at anthesis (showy, mostly yellow salverform flowers, heteromorphic stamens, poricidal anther dehiscence, bee pollination, and chambered stigma).     

Floral traits and mating systems in sister species of <Emphasis Type="Italic">Nicotiana</Emphasis>: interpopulational variability and sympatry effects

Mating systems of Angiosperms are important determinants of population genetic structure and evolutionary potential. Nicotiana longiflora and N. plumbaginifolia are self-compatible, sister species, with contrasting floral morphology and can be found in allopatry and sympatry in North Argentina. In two sympatric and 10 nearby allopatric populations we studied their natural interpopulational variability and sympatry effects on corolla length and anther–stigma distance. We also estimated seed set by selfing and via pollinators using pollination treatments. Both corolla length and anther–stigma distance varied significantly among N. longiflora, but not among N. plumbaginifolia populations. We did not detect an effect of sympatry in either species for any of the floral traits studied. Pollination treatments suggest that N. longiflora is mainly an outcrosser, although selfing occurs at some extent. Seed set attributed to pollinators was significantly higher in N. longiflora whereas most seeds in N. plumbaginifolia were sired through self-pollination. In N. plumbaginifolia, selfing seems to assure reproduction in sympatric populations, where floral visitors have a strong preference for N. longiflora. Corolla length was significantly negatively correlated with an increase in the percentage of self-seeds estimated by pollination treatments. Within N. longiflora, anther–stigma distance showed a positive correlation with selfing.     

Evolutionary correlation between floral monosymmetry and corolla pigmentation patterns in <Emphasis Type="Italic">Rhododendron</Emphasis>

Floral symmetry and pigmentation are features of flowers that are believed to be associated due to their shared influence on pollinator behaviour. However, the evolution of such associations has so far not been examined. We analysed variation in Rhododendron flowers, in a phylogenetic context, to test whether the evolution of floral symmetry types and pigment patterns are correlated. Variation in floral symmetry due to variation in corolla form, stamen flexion, stamen arrangement, pistil flexion, as well as corolla pigment patterns was documented in 98 species of Rhododendron. Phylogenetic relations among these species were estimated using maximum likelihood (ML) and Bayesian methods, building on a published molecular dataset of sequences of RNA Polymerase II subunit (RPB2-I). Evolution of the floral traits was studied using phylogenetic correlation tests and ancestral state reconstructions (maximum parsimony, MP and ML methods). Significant correlations were found between corolla pigment pattern and type of floral symmetry at the level of corolla form, stamen flexion or arrangement, and pistil flexion. As expected from their similar roles in enhancing attractability to pollinator, monosymmetric corollas and presence of pigment pattern are correlated; in addition, monosymmetry involving other whorls too shows such a relationship with pigment patterns, and with each other. Multiple evolutionary shifts were detected between monosymmetry and polysymmetry of floral traits in Rhododendron. The relationship between floral monosymmetry attributes and presence of corolla pigment patterns, and additionally, frequent evolutionary shifts in these traits suggest pollinator-mediated selective pressures in Rhododendron.     

茜草科二型花柱植物滇丁香传粉精确性研究

异型花柱是一种受遗传因素控制的花型多态性现象,其适应意义在于提高不同花型间传粉精确性,从而促进异交。为检验二型花柱植物滇丁香（Luculia pinceana）是如何促进异交并确定有效传粉者的类型,实验统计自然种群中长、短柱型的植株数量,测量花部特征,统计自然种群植株柱头上的型间花粉落置的数量和比例,比较型内、型间花粉的萌发率以及花粉管长度,比较不同人工授粉处理结实情况,观察传粉昆虫类型并测量虫体特征。结果表明（1）滇丁香自然居群中长、短柱型植株的数量没有显著性差异。长柱型的筒深、筒直径、开口直径、雄蕊长和柱头长均显著小于短柱型,而长柱型的叶片长和宽、雌蕊长、花药体积、花粉粒体积、柱头厚均显著大于短柱型。（2）自然种群植株柱头上型间花粉所占比例显著低于型内花粉的比例。（3）型间授粉的花粉萌发率以及花粉管长度均大于型内授粉和混合授粉。（4）型间授粉的结实率显著高于型内授粉的结实率,型内授粉具有一定的结实。（5）夜行性长喙条背天蛾（Cechenena lineosa）是滇丁香的有效传粉者,其吻长和滇丁香的花筒深相适应。本研究表明二型花柱植物滇丁香主要是通过与其花部特征相匹配的长喙天蛾实现有效的传粉,通过促进型间花粉的萌发和花粉管的伸长而有利于型间授粉结实,提高传粉精确性。     

土壤养分对蝴蝶花的花形态可塑性的影响

为了研究土壤养分对蝴蝶花的花形态可塑性的影响,在田间实验中对蝴蝶花进行了高、中、低养分（N、P、K）水平处理。实验表明,随着土壤养分水平的增加,外轮花瓣长和宽、内轮花瓣长和宽、雌蕊长、雄蕊长、花冠直径均逐渐增加。花各组成部分的形态大小间相关性显著（P=0．05）。结合花部形态特征对环境异质性的生态适应意义,对实验结果进行了讨论。     

Reproductive conflicts ofPalicourea padifolia (Rubiaceae) a distylous shrub of a tropical cloud forest in Mexico

We studied a population of the distylousPalicourea padifolia (Rubiaceae) in a cloud forest remnant near Xalapa City, Veracruz, México to explore possible asymmetries between floral morphs in the attractiveness to pollinators, seed dispersers, nectar robbers, floral parasites, and herbivores. We first assessed heterostyly and reciprocal herkogamy by measuring floral attributes such as corolla length (buds and open flowers), style and anther heights, stigma and stamen lengths and the distance between the anther tip to the stigma lobe. We then estimated floral and fruit attributes such as flower size, anther height, number and size of pollen grains, fruit size, seed size, nectar production, and flower and fruit standing crops to assess differences between floral morphs in attracting and effectively using mutualistic pollinators and seed dispersers. Also, floral parasitism and nectar robbing were assessed in this study as a measure of flower attractiveness to antagonists. The system seems to conform well to classical heterostyly (e.g. reciprocal stamen/style lengths, pollen and anther dimorphism, intramorph incompatibility) yet, there were several tantalizing differences observed between pin and thrum morphs. Thrum flowers have longer corollas and larger but fewer pollen grains than pin flowers. Both morphs produced the same total number of inflorescences, developed the same number of buds, and opened the same number of flowers per inflorescence during the flowering season. Nectar production and sugar concentration were similar between floral morphs but the reward was not offered symmetrically to floral visitors throughout the day. Nectar concentration was higher in pin flowers in the afternoon. The numbers of developing, fully developed, and ripe fruits were the same between floral morphs, however, fruits and seeds were larger than those of thrums. The incidence of fly larvae was higher among thrum flowers and damage by nectar robbing was the same between floral morphs. Fruit abortion patterns of flowers manually pollinated suggest intra-morph sterility (self and intramorph incompatibility). There were no differences between morphs in fruit and seed set per flower following legitimate pollination although thrums were more leaky than the pins (intramorph compatibility).     

浙江省野生蜡梅花部形态变异及其与环境因子的相关性

以浙江省蜡梅自然分布区的5个居群为研究对象,采用巢式方差分析、主成分分析、相关分析、聚类分析等多种分析方法,探究蜡梅花部的形态变异及其与环境因子相关性以及居群间和居群内的表型多样性。结果表明:蜡梅花部性状中除雄蕊长度、雌蕊数、雌蕊长度、内被片数以外,其他12个性状在居群间均有极显著差异。胚珠数的平均变异系数最大,花冠内径的平均变异系数最小,各性状的平均变异系数为15.03%(10.81%—23.38%)。五尖山的表型多样性最丰富,碧东山居群最小,种群间平均表型分化系数为44.38%(1.57%—89.62%),种群内变异大于种群间变异,种群内变异是花部变异的主要来源。主成分分析显示花冠直径、花冠内径、花筒深度和中被片长对种群变异起主要贡献作用。花部多数性状间存在显著或极显著的相关关系,生态因子中花部性状与土壤酸度相关性最大,土壤中花部性状与大量元素相关性最大,微量元素次之,中量元素最小。通过UPGMA聚类分析可以将5个种群分成两组。浙江省野生蜡梅花部形态存在丰富的变异和多样性,花部部分性状与土壤中钙、铁、铜含量和海拔有显著或极显著相关关系。     

<Emphasis Type="Italic">Chirita luochengensis</Emphasis> (Gesneriaceae), a new species from limestone areas in northern Guangxi,China

Chirita luochengensis, a new species of Gesneriaceae from Guangxi, China, is described and illustrated. The new species is similar to C. linearifolia in leaf shape, but can be distinguished by the apex of leaf blade obtuse to round, corolla purplish, 3–4.2 cm long, corolla tube 2–2.5 cm long, 10–15 mm diameter at the mouth, staminodes 3, disc ca. 2.5 mm in height, pistil 2.5–3 cm long, stigma obtrapeziform, 4 mm long, and apex shallowly 2-lobed.     

一个辣椒功能性雄性不育系的花器形态及遗传研究

本报道了一个新型辣椒功能性雄性不育系的花器形态和遗传规律。研究表明,新发现的辣椒雄性不育花冠退化,大部分雄蕊萎缩,没有花丝、具发育不完整的花药;虽然花内１～２枚发育正常的雄蕊有少量可育花粉,但由于花萼畸长紧闭,不能开花。雌蕊发育正常,人工辅助自花或异花杂交可正常结果并产生种子。遗传杂交分析表明,该功能性雄性不育遗传上受一对隐性核基因控制,用基因的符号ｆｍｓ表示。     

MEASURING POLLINATOR-MEDIATED SELECTION ON MORPHOMETRIC FLORAL TRAITS: BUMBLEBEES AND THE ALPINE SKY PILOT,POLEMONIUM VISCOSUM

Sweet-flowered plants of Polemonium viscosum in Colorado are visited by a fly-dominated pollinator fauna at timberline (krummholz), but almost exclusively by bumblebees in higher-elevation tundra habitats. Significant increases in flower size and height are associated with increasing elevation along this habitat gradient. This paper presents the results of an experiment designed to test whether bumblebees exert sufficient selection on morphometric floral phenotypes to account for the clinal shifts seen in natural populations. Two populations of sweet-flowered plants of krummholz origin were established: one randomly pollinated, the other solely bumblebee-pollinated. I tested the effects of two independent axes of floral variation, obtained by principal-components analysis, on mean seed set per flower of plants in each population. PC1, with strong correlations to corolla diameter, corolla length, and stem height, explained a significant amount of variance in seed set for bumblebee-pollinated plants but had no bearing on that of randomly pollinated plants. PC2, with strong correlation to flower number, did not influence seed set in either population. Bumblebee behavior was correlated with variation in PC1 scores of the selected population, yielding positive directional selection on morphometric floral traits associated with PC1. Selection coefficients for PC1, corolla length, corolla diameter, and inflorescence height were estimated, respectively, as 0.11, 0.09, 0.07, and 0.06 (P < 0.025 in all cases). These results support the hypothesis that pollinator-mediated selection can bring about changes in floral form, and can explain shifts in floral morphology of P. viscosum along natural habitat gradients.     

Patterns of contemporary phenotypic selection and flower integration in the hummingbird‐pollinated Nicotiana glauca between populations with different flower–pollinator combinations

We studied six populations of the hummingbird‐pollinated Nicotiana glauca to determine if the marked differences in the degree of floral‐pollinator mismatch between populations promote divergences in the pattern of pollinator‐mediated phenotypic selection on single traits and on the evolution of complexes of many interacting floral traits. We found evidence that flower phenotype is being shaped by pollinator‐mediated phenotypic selection, since corolla length was consistently under contemporary directional or stabilizing selection. Weak directional selection for longer corollas was found in two populations with low flower–pollinator mismatch; much stronger directional selection was detected for shorter corollas in two populations with high flower–pollinator mismatch; finally, the remaining two populations with intermediate flower–pollinator mismatch showed stabilizing selection for corolla length. N. glauca populations differed in every flower character measured but variations in pollinator‐mediated selection among populations were only observed for corolla length. Multiple covariation among traits was favoured, as suggested by the predominately functional patterns of integration and selection of complexes of many interacting floral traits. This was consistent with the patterns of correlational selection exhibited by four of the six populations, where corolla length was under significant selection in combination with corolla width, style length or stamen length. Overall floral integration was relatively high in all populations but phenotypic integration patterns were not clearly accounted by the degree of flower–pollinator mismatch or type of phenotypic selection, suggesting that trait covariation at the entire flower level is not explained by the current scenario of pollinator‐mediated selection.     

Floral trait variation in fourCyclamen (Primulaceae) species

The purpose of this study is to examine floral trait variation between fourCyclamen species that show variation in their ability to reproduce in the absence of pollinators and in levels of inbreeding. Pollen and ovule production, pollen/ovule ratio, pollen volume, petal length and width, diameter of the corolla mouth, pistil and stamen length, and stigma-anther separation varied significantly between the four study species. Flower, pollen and ovule production, pollen volume and corolla size were generally highest inC. hederifolium, the species with the lowest level of inbreeding (mean F_is = 0.329), intermediate in both species with relatively high levels of pollinator-mediated inbreeding,C. repandum (mean F_is = 0.658) andC. creticum (mean F_is = 0.748), and lowest in the highly inbredC. balearicum (mean F_is = 0.930). The two species with the most different inbreeding coefficients,C. hederifolium andC. balearicum, had lower pollen-ovule ratios and shorter longevities of stigma receptivity and pollen viability thanC. creticum andC. repandum. These patterns of variation in floral traits are discussed in relation to the relatedness, pollination ecology and levels of inbreeding of the four species.     

Variation in style length and anther–stigma distance in Ixiolirion songaricum (Amaryllidaceae)

Variation in style length and anther–stigma distance (ASD) was investigated in 18 populations of Ixiolirion songaricum, an early-spring ephemeral perennial herb in northern Xinjiang. The effect of ASD on autonomous self-pollen deposition and seed set was assessed using bagging experiments. Seed production under autonomous self-pollination, cross-pollination and natural pollination was determined by manual pollination experiments. Stigmas of multiple flowers within an individual were sandwiched between two separate anther levels, and no individuals possessed approach or reverse herkogamy. Style length varied continuously among flowers, resulting in a wide range of variation in ASD. There were fewer flowers with a small ASD than with a large ASD in populations. ASD was negatively correlated with autonomous self-pollen deposition and seed set, but it was positively correlated with natural pollination seed set. Seed production under natural pollination was higher than that under autonomous self-pollination, but it was smaller than that under cross-pollination. Variation in style length and ASD among flowers was not caused by style or stamen elongation in I. songaricum, which differ from other species reported in literature that have continuous variation in style length and ASD.     

<Emphasis Type="Italic">Multiple impairments in male reproduction 1 (mimr1)</Emphasis>, a novel male-sterile mutant of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>, shows several defects in male reproductive development

We have characterized a new male-sterile mutant in Arabidopsis that exhibits conditional sterility but has restored fertility when drought-stressed. This mutant, multiple impairments in male reproduction 1 (mimr1), shows pleiotropic defects in both vegetative and reproductive development. Examination with dissecting and scanning electron microscopes revealed that its pollen grains are not effectively released from the anther locule after dehiscence, and anther differentiation is defective. Growth of the style and stamen filaments are also abnormal. Histological analysis demonstrated that these phenomena are due not only to a noticeably reduced extension of the stamen but also greater elongation of the pistil. Genetic analysis indicated that mimr1 is a single locus recessive nuclear mutant. The mutation can be mapped to a locus strongly linked to a 1200-kb region on Chromosome 3. Meta-analysis of expression patterning presented several candidate genes in that region. No mutants with similar phenotypes have previously been reported, suggesting that mimr1 is a novel male-sterile locus. Characterization of MIMR1 will provide further insights into the molecular basis for the development of plant reproductive organs.     

Post-pollination hybridization barriers in <Emphasis Type="Italic">Nicotiana</Emphasis> section <Emphasis Type="Italic">Alatae</Emphasis>

Nicotiana section Alatae contains eight species with variable flower sizes and morphologies. Section members readily hybridize in the glasshouse, but no hybrids have been observed in natural sympatric and parapatric populations. To investigate interspecific crossing relationships with respect to mechanisms preventing hybridization, all members of section Alatae were intercrossed in a complete diallel. We found positive correlation between the pistil length of the pollen donor and interspecific seed set relative to the conspecific cross. Pollen tube growth rate and pollen donor pistil length were positively correlated as well. Furthermore, pollen from short-pistil members of section Alatae could only grow a maximum distance proportional to, but greater than, their own pistil lengths. Our results show that pollen tube growth capacity (i.e., rate and distance), provides a hybridization barrier in long-pistil species × short-pistil species crosses. We also found another hybridization barrier not specifically related to pollen tube growth capacity in short-pistil species × long-pistil species. Taken together, these barriers can generally be described by a ‘pistil-length mismatch’ rule; in section Alatae, pollen has the most success fertilizing ovules from species with pistil lengths similar to their own. This rule could contribute to hybridization barriers in Section Alatae because the species display dramatically different pistil lengths. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Pollination adaptations of group-by-group stamen movement in a meadow plant with temporal floral closure

Floral sexual organ (stamen and pistil) movements are selective adaptations that have different functions in male-female reproduction and the evolution of flowering plants. However, the significance of stamen movements in the spatial–temporal function and separation of male and female organs has not been experimentally determined in species exhibiting floral temporal closure. The current study investigated the role of slow stamen (group-by-group) movement in male-female sexual function, and the effect of stamen movement on pollen removal, male-male and male-female interference, and mating patterns of Geranium pratense, a plant with temporal floral closure. This species uses stamen group-by-group movement and therefore anther-stigma spatial–temporal separation. Spatial separation (two whorls of stamen and pistil length) was shown to be stronger than temporal separation. We found that stamen movements to the center of the flower increase pollen removal, and the most common pollinators visited more frequently and for longer durations during the male floral stage than during the female floral stage. Petal movements increased both self-pollen deposition rate and sexual interference in G. pratense. The fruit and seed set of naturally and outcrossed pollinated flowers were more prolific than those of self-pollinated flowers. Group-by-group stamen movement, dehiscence of stamens, pistil movement, and male-female spatial–temporal functional separation of G. pratense before floral temporal closure may prevent male-female and stamen-stamen interference and pollen discounting, and may increase pollen removal and cross-pollination.