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1.
J Vis Exp ; (167)2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33554968

RESUMO

Researchers often collect and analyze corbicular pollen from honey bees to identify the plant sources on which they forage for pollen or to estimate pesticide exposure of bees via pollen. Described herein is an effective pollen-trapping method for collecting corbicular pollen from honey bees returning to their hives. This collection method results in large quantities of corbicular pollen that can be used for research purposes. Honey bees collect pollen from many plant species, but typically visit one species during each collection trip. Therefore, each corbicular pollen pellet predominantly represents one plant species, and each pollen pellet can be described by color. This allows the sorting of samples of corbicular pollen by color to segregate plant sources. Researchers can further classify corbicular pollen by analyzing the morphology of acetolyzed pollen grains for taxonomic identification. These methods are commonly used in studies related to pollinators such as pollination efficiency, pollinator foraging dynamics, diet quality, and diversity. Detailed methodologies are presented for collecting corbicular pollen using pollen traps, sorting pollen by color, and acetolyzing pollen grains. Also presented are results pertaining to the frequency of pellet colors and taxa of corbicular pollen collected from honey bees in five different cropping systems.


Assuntos
Abelhas/fisiologia , Pólen/fisiologia , Manejo de Espécimes/métodos , Ácido Acético/química , Animais , Polinização , Coloração e Rotulagem
2.
PLoS One ; 15(12): e0235028, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33362256

RESUMO

Cyclocephalini beetles of the genus Cyclocephala (Coleoptera: Melolonthidae: Dynastinae) use flowers of some plants as food, shelter, and mating sites. However, little is known about floral scent chemistry involved in this interaction. Here we show that a sesquiterpene alcohol mediates attraction of Cyclocephala paraguayensis Arrow, on bottle gourd flowers, Lagenaria siceraria (Cucurbitaceae). Both males and females started to aggregate on the flowers at twilight; after that, mating began and remained for the entire night. GC-FID/EAD analysis of the L. siceraria floral scent collected in the field revealed that only the major constituent of the airborne volatiles elicited electroantennographic responses on male and female antennae of C. paraguayensis. This compound was identified as (3S,6E)-nerolidol, which was tested in two field trapping trials in Brazil. In the first bioassay, traps baited with nerolidol (mix of isomers) captured significantly more adult C. paraguayensis than control traps. In the second field trial, catches in traps baited with a mixture of isomers or enantiopure nerolidol were significantly higher than captures in control traps, but the treatments did not differ significantly. Analysis from the gut content of adult C. paraguayensis showed the presence of pollen, suggesting that they also use bottle gourd flowers for their nourishment. Taken together, these results suggest that (3S,6E)-nerolidol plays an essential role in the reproductive behavior of C. paraguayensis by eliciting aggregation, mating, and feeding.


Assuntos
Besouros/fisiologia , Cucurbita/metabolismo , Sesquiterpenos/metabolismo , Animais , Brasil , Besouros/metabolismo , Cucurbita/fisiologia , Cucurbitaceae/metabolismo , Cucurbitaceae/fisiologia , Feminino , Flores/fisiologia , Masculino , Odorantes/análise , Feromônios/análise , Pólen/fisiologia , Polinização , Sesquiterpenos/análise
3.
PLoS One ; 15(12): e0243856, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33326483

RESUMO

Pollen viability is crucial for wheat breeding programs. The unique potential of the protoplasm of live cells to turn brown due to the synthesis of silver nanoparticles (AgNPs) through rapid photoreduction of Ag+, was exploited for testing wheat pollen viability. Ag+-viability test medium (consisting of 0.5 mM AgNO3 and 300 mM KNO3) incubated with wheat pollen turned brown within 2 min under intense light (~600 µmol photon flux density m-2s-1), but not in dark. The brown medium displayed AgNPs-specific surface plasmon resonance band in its absorption spectrum. Light microscopic studies showed the presence of uniformly stained brown protoplasm in viable pollen incubated with Ag+-viability medium in the presence of light. Investigations with transmission electron microscope coupled with energy dispersive X-ray established the presence of distinct 5-35 nm NPs composed of Ag. Powder X-ray diffraction analysis revealed that AgNPs were crystalline and biphasic composed of Ag0 and Ag2O. Conversely, non-viable pollen and heat-killed pollen did not turn brown on incubation with Ag+-medium in light. We believe that the viable wheat pollen turn brown rapidly by bio-transforming Ag+ to AgNPs through photoreduction. Our findings furnish a novel simplest and rapid method for testing wheat pollen viability.


Assuntos
Citoplasma/metabolismo , Citoplasma/efeitos da radiação , Luz , Pólen/fisiologia , Prata/metabolismo , Coloração e Rotulagem , Sobrevivência de Tecidos/fisiologia , Triticum/fisiologia , Pólen/ultraestrutura
4.
PLoS One ; 15(9): e0239377, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32986735

RESUMO

Double pollen fertility neutral genes, San and Sbn, can control pollen sterility in intersubspecific (indica × japonica) rice hybrids, which has excellent potential to increase rice yield. Previous studies showed that polyploidy could increase the interaction of three pollen sterility loci, i.e. Sa, Sb and Sc, which cause pollen sterility in autotetraploid rice hybrids, and hybrid fertility could be improved by double neutral genes, San and Sbn, in autotetraploid rice hybrids. We compared cytological and transcriptome data between autotetraploid and diploid rice hybrid during meiosis and single microspore stages to understand the molecular mechanism of neutral genes for overcoming pollen sterility in autotetraploid rice hybrids, which harbored double neutral genes. Cytological results revealed that the double neutral genes resulted in higher pollen fertility (76.74%) and lower chromosomal abnormalities in autotetraploid hybrid than in parents during metaphase I, metaphase II, anaphase I and anaphase II. Moreover, autotetraploid rice hybrid displayed stronger heterosis than a diploid hybrid. Compared with diploid rice hybrid, a total of 904 and 68 differently expressed genes (DEGs) were identified explicitly in autotetraploid hybrid at meiosis and single microspore stages, respectively. Of these, 133 and 41 genes were detected in higher-parent dominance and transgressive up-regulation dominance, respectively, which were considered autotetraploid potential heterosis genes, including a meiosis-related gene (Os01g0917500, MSP1) and two meiosis specific-genes (Os07g0624900 and Os04g0208600). Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genomes pathway (KEGG) analysis revealed that DEGs significantly enriched in amino acid metabolism and photosynthesis metabolism. These results indicated that meiosis-specific and meiosis-related genes, and amino acids and photosynthesis metabolism-related genes contribute to higher yield and pollen fertility in autotetraploid rice hybrid. This study provides a theoretical basis for molecular mechanisms of heterosis in autotetraploid rice harboring double neutral genes for pollen fertility.


Assuntos
Análise Citogenética , Diploide , Perfilação da Expressão Gênica , Genes de Plantas/genética , Oryza/genética , Tetraploidia , Cromossomos de Plantas/genética , Fenótipo , Infertilidade das Plantas/genética , Pólen/genética , Pólen/fisiologia
5.
J Plant Res ; 133(6): 883-895, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32929552

RESUMO

The tapetum plays important roles in anther development by providing materials for pollen-wall formation and nutrients for pollen development. Here, we report the characterization of a male-sterile mutant of glycine-rich protein 2 (OsGRP2), which exhibits irregular cell division and dysfunction of the tapetum. GRP is a cellwall structural protein present in the cell walls of diverse plant species, but its function is unclear in pollen development. We found that few GRP genes are expressed in rice and thus focused on one highly expressed gene, OsGRP2. The tapetal cell walls of an OsGRP2 mutant did not thicken at the pollen mothercell stage, as a result, pollen maturation and fertility rate decreased. High OsGRP2 expression was detected in male-floral organs, and OsGRP2 was distributed in the tapetum. OsGRP2 participated in establishment of the cellwall network during early tapetum development. In conclusion, our results indicate that OsGRP2 plays important roles in the differentiation and function of the tapetum.


Assuntos
Regulação da Expressão Gênica de Plantas , Oryza/fisiologia , Proteínas de Plantas/fisiologia , Pólen/fisiologia , Diferenciação Celular , Parede Celular , Flores/fisiologia , Glicina , Proteínas de Plantas/genética
6.
J Vis Exp ; (160)2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32628154

RESUMO

Self-incompatibility in Rosaceae is determined by a Gametophytic Self-Incompatibility System (GSI) that is mainly controlled by the multiallelic locus S. In apricot, the determination of self- and inter-(in)compatibility relationships is increasingly important, since the release of an important number of new cultivars has resulted in the increase of cultivars with unknown pollination requirements. Here, we describe a methodology that combines the determination of self-(in)compatibility by hand-pollinations and microscopy with the identification of the S-genotype by PCR analysis. For self-(in)compatibility determination, flowers at balloon stage from each cultivar were collected in the field, hand-pollinated in the laboratory, fixed, and stained with aniline blue for the observation of pollen tube behavior under the fluorescence microscopy. For the establishment of incompatibility relationships between cultivars, DNA from each cultivar was extracted from young leaves and S-alleles were identified by PCR. This approach allows establishing incompatibility groups and elucidate incompatibility relationships between cultivars, which provides a valuable information to choose suitable pollinizers in the design of new orchards and to select appropriate parents in breeding programs.


Assuntos
Polinização , Prunus armeniaca/fisiologia , DNA de Plantas/análise , Flores/fisiologia , Genótipo , Microscopia de Fluorescência , Folhas de Planta/genética , Pólen/fisiologia , Reação em Cadeia da Polimerase , Prunus armeniaca/genética
7.
Sci Rep ; 10(1): 9476, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32528048

RESUMO

Intraspecific floral colour polymorphism is a common trait of food deceptive orchids, which lure pollinators with variable, attractive signals, without providing food resources. The variable signals are thought to hinder avoidance learning of deceptive flowers by pollinators. Here, we analysed the cognitive mechanisms underlying the choice of free-flying stingless bees Scaptotrigona aff. depilis trained to visit a patch of artificial flowers that displayed the colours of Ionopsis utricularioides, a food deceptive orchid. Bees were trained in the presence of a non-rewarding colour and later tested with that colour vs. alternative colours. We simulated a discrete-polymorphism scenario with two distinct non-rewarding test colours, and a continuous-polymorphism scenario with three non-rewarding test colours aligned along a chromatic continuum. Bees learned to avoid the non-rewarding colour experienced during training. They thus preferred the novel non-rewarding colour in the discrete-polymorphic situation, and generalized their avoidance to the adjacent colour of the continuum in the continuous-polymorphism situation, favouring thereby the most distant colour. Bees also visited less flowers and abandoned faster a non-rewarding monomorphic patch than a non-rewarding polymorphic patch. Our cognitive analyses thus reveal that variable deceptive orchids disrupt avoidance learning by pollinators and exploit their generalization abilities, which make them favour distinct morphs.


Assuntos
Abelhas/fisiologia , Cognição/fisiologia , Comportamento Alimentar/fisiologia , Polinização/fisiologia , Animais , Aprendizagem da Esquiva/fisiologia , Cor , Flores/fisiologia , Orchidaceae/fisiologia , Pólen/fisiologia
8.
PLoS One ; 15(6): e0234498, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32584843

RESUMO

Bumble bee communities are strongly disrupted worldwide through the population decline of many species; a phenomenon that has been generally attributed to landscape modification, pesticide use, pathogens, and climate change. The mechanisms by which these causes act on bumble bee colonies are, however, likely to be complex and to involve many levels of organization spanning from the community down to the least understood individual level. Here, we assessed how the morphology, weight and foraging behavior of individual workers are affected by their surrounding landscape. We hypothesized that colonies established in landscapes showing high cover of intensive crops and low cover of flowering crops, as well as low amounts of local floral resources, would produce smaller workers, which would perform fewer foraging trips and collect pollen loads less constant in species composition. We tested these predictions with 80 colonies of commercially reared Bombus impatiens Cresson placed in 20 landscapes spanning a gradient of agricultural intensification in southern Québec, Canada. We estimated weekly rate at which workers entered and exited colonies and captured eight workers per colony over a period of 14 weeks during the spring and summer of 2016. Captured workers had their wing, thorax, head, tibia, and dry weight measured, as well as their pollen load extracted and identified to the lowest possible taxonomic level. We did not detect any effect of landscape habitat composition on worker morphology or body weight, but found that foraging activity decreased with intensive crops. Moreover, higher diversity of local floral resources led to lower pollen constancy in intensively cultivated landscapes. Finally, we found a negative correlation between the size of workers and the diversity of their pollen load. Our results provide additional evidence that conservation actions regarding pollinators in arable landscapes should be made at the landscape rather than at the farm level.


Assuntos
Abelhas/fisiologia , Ecossistema , Pólen/fisiologia , Polinização/fisiologia , Animais , Canadá , Produtos Agrícolas , Humanos , Quebeque , Estações do Ano
9.
PLoS Genet ; 16(5): e1008807, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32407354

RESUMO

Pollen wall consists of several complex layers which form elaborate species-specific patterns. In Arabidopsis, the transcription factor ABORTED MICROSPORE (AMS) is a master regulator of exine formation, and another transcription factor, TRANSPOSABLE ELEMENT SILENCING VIA AT-HOOK (TEK), specifies formation of the nexine layer. However, knowledge regarding the temporal regulatory roles of TEK in pollen wall development is limited. Here, TEK-GFP driven by the AMS promoter was prematurely expressed in the tapetal nuclei, leading to complete male sterility in the pAMS:TEK-GFP (pat) transgenic lines with the wild-type background. Cytological observations in the pat anthers showed impaired callose synthesis and aberrant exine patterning. CALLOSE SYNTHASE5 (CalS5) is required for callose synthesis, and expression of CalS5 in pat plants was significantly reduced. We demonstrated that TEK negatively regulates CalS5 expression after the tetrad stage in wild-type anthers and further discovered that premature TEK-GFP in pat directly represses CalS5 expression through histone modification. Our findings show that TEK flexibly mediates its different functions via different temporal regulation, revealing that the temporal regulation of TEK is essential for exine patterning. Moreover, the result that the repression of CalS5 by TEK after the tetrad stage coincides with the timing of callose wall dissolution suggests that tapetum utilizes temporal regulation of genes to stop callose wall synthesis, which, together with the activation of callase activity, achieves microspore release and pollen wall patterning.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Pólen/fisiologia , Fatores de Transcrição/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Epigênese Genética , Regulação da Expressão Gênica de Plantas , Glucosiltransferases/metabolismo , Histonas/metabolismo , Metilação , Plantas Geneticamente Modificadas/fisiologia , Pólen/genética , Regiões Promotoras Genéticas
10.
J Plant Physiol ; 248: 153156, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32244105

RESUMO

Next to global warming, excessive deposition of nitrogen has an alarming environmental impact on forest ecology, especially within dioecious species. Resource availability affects seed quality and can affect the distribution of plant species. Lower seed productivity can also be a result of limited pollen availability or lower pollen quality. A few studies have assessed the effect of nutrient availability on the quantity and quality of pollen grains produced. Therefore, rooted shoots of dioecious, male Juniperus communis L. grown in different nutritional conditions were used to assess the impact on productivity and quality attributes of produced pollen grains (pollen volume, morphology, germination, and chemical composition). The results indicated that nutrient availability impacts pollen grain development. Male plants growing in nutrient-rich environments appear to compensate for the lower quality of produced pollen grains by producing a higher number of male cones and thus a greater quantity of pollen. In contrast, the opposite was observed in plants growing in nutrient-poor environments. The availability of nitrogen and other nutrients will probably continue to impact soils in the foreseeable future due to anthropogenic activity and can be one of the drivers that can impact the reproduction and distribution of plants.


Assuntos
Juniperus/fisiologia , Pólen/fisiologia , Nutrientes , Pólen/química , Pólen/citologia , Reprodução
11.
Biochem Biophys Res Commun ; 526(4): 1036-1041, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32305137

RESUMO

Pollen wall characteristics are dramatically changed during pollen maturation. Many genes have been identified as regulators of such changes in pollen wall characteristics, but mechanisms of such changes have not been completely understood. Here, a GDSL-type esterase/lipase gene, GELP77, is shown to regulate such changes in Arabidopsis thaliana. GELP77-deficient (gelp77) plants exhibited male sterility, and this phenotype was suppressed by introduction of a GELP77 genomic fragment. Mature pollen grains of wild-type Arabidopsis plants have an organized reticulate surface structure and are dissociated from each other. In contrast, pollen grains of gelp77 lacked such a structure and were shrunken and stuck to each other. Nuclei were not detectable in gelp77 microspores at a putative uninucleate stage, suggesting that GELP77 is required as early as this stage. In plants that have the GELP77 promoter-GELP77-GFP transgene, the GELP77-GFP fusion protein was detected in microspores, tapetal cells and middle layer cells in anthers at post-meiotic stages, whereas not anthers at pre-meiotic stages. Analysis of amino acid sequences suggests that GELP77 is phylogenetically distant from the other 104 GDSL-type esterase/lipase genes in Arabidopsis and that GELP77 orthologs are present in various plant species. Together, these results indicate that GELP77 regulates pollen wall characteristics in Arabidopsis.


Assuntos
Arabidopsis/genética , Arabidopsis/fisiologia , Genes de Plantas , Lipase/genética , Pólen/fisiologia , Arabidopsis/enzimologia , Arabidopsis/ultraestrutura , Sequência Conservada/genética , Fertilidade/fisiologia , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Lipase/metabolismo , Filogenia , Infertilidade das Plantas/genética , Pólen/ultraestrutura , Via Secretória
12.
Plant Mol Biol ; 103(1-2): 9-32, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32124177

RESUMO

KEY MESSAGE: In light of the available discoveries in the field, this review manuscript discusses on plant reproduction mechanism and molecular players involved in the process. Sperm cells in angiosperms are immotile and are physically distant to the female gametophytes (FG). To secure the production of the next generation, plants have devised a clever approach by which the two sperm cells in each pollen are safely delivered to the female gametophyte where two fertilization events occur (by each sperm cell fertilizing an egg cell and central cell) to give rise to embryo and endosperm. Each of the successfully fertilized ovules later develops into a seed. Sets of macromolecules play roles in pollen tube (PT) guidance, from the stigma, through the transmitting tract and funiculus to the micropylar end of the ovule. Other sets of genetic players are involved in PT reception and in its rupture after it enters the ovule, and yet other sets of genes function in gametic fusion. Angiosperms have come long way from primitive reproductive structure development to today's sophisticated, diverse, and in most cases flamboyant organ. In this review, we will be discussing on the intricate yet complex molecular mechanism of double fertilization and how it might have been shaped by the evolutionary forces focusing particularly on the model plant Arabidopsis.


Assuntos
Flores/fisiologia , Magnoliopsida/fisiologia , Polinização/fisiologia , Evolução Biológica , Gametogênese Vegetal , Óvulo Vegetal/fisiologia , Pólen/fisiologia , Sementes
13.
Mol Ecol ; 29(1): 184-198, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31755136

RESUMO

Assortative mating is a deviation from random mating based on phenotypic similarity. As it is much better studied in animals than in plants, we investigate for trees whether kinship of realized mating pairs deviates from what is expected from the set of potential mates and use this information to infer mating biases that may result from kin recognition and/or assortative mating. Our analysis covers 20 species of trees for which microsatellite data is available for adult populations (potential mates) as well as seed arrays. We test whether mean relatedness of observed mating pairs deviates from null expectations that only take pollen dispersal distances into account (estimated from the same data set). This allows the identification of elevated as well as reduced kinship among realized mating pairs, indicative of positive and negative assortative mating, respectively. The test is also able to distinguish elevated biparental inbreeding that occurs solely as a result of related pairs growing closer to each other from further assortativeness. Assortative mating in trees appears potentially common but not ubiquitous: nine data sets show mating bias with elevated inbreeding, nine do not deviate significantly from the null expectation, and two show mating bias with reduced inbreeding. While our data sets lack direct information on phenology, our investigation of the phenological literature for each species identifies flowering phenology as a potential driver of positive assortative mating (leading to elevated inbreeding) in trees. Since active kin recognition provides an alternative hypothesis for these patterns, we encourage further investigations on the processes and traits that influence mating patterns in trees.


Assuntos
Repetições de Microssatélites/genética , Árvores/genética , Ecologia , Genótipo , Endogamia , Fenótipo , Pólen/genética , Pólen/fisiologia , Reprodução/genética , Árvores/fisiologia
14.
Plant Biol (Stuttg) ; 22(3): 480-486, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31860937

RESUMO

In explosive pollination, many structures and mechanisms have evolved to achieve high-speed stamen movement. The male flower of the submerged plant Hydrilla verticillata is reported to be able to release pollen explosively some time after leaving the mother plant time, but the mechanism of stamen movement and the related functional structure in this species are unclear. In this study, we observed the male flower structure and pollen dispersal process of H. verticillata. We analysed the stamen movements during the pollen dispersal process and conducted several controlled experiments to study the process of storage and release of elastic potential energy in explosive pollination. When the male flower of H. verticillata is bound to the united bracts, the sepals accumulate elastic potential energy through the expansion of basal extensor cells. After the male flower is liberated from the mother plant, the stamens unfold rapidly with the sepals under adhesion and transfer the elastic potential energy to the filament in seconds. Once stamens unfold to a critical angle, at which the elasticity of the filament just exceeds the adhesion between sepals and anthers, the stamens automatically rebound and release pollen in milliseconds. These results reveal that Catapult-like stamens, spoon-shaped sepals and enclosed united bracts in the spathe together constitute the functional structure in rapid stamen movement of H. verticillata. They ensure that the pollen can be released on the water surface, and thus adapt successfully to the pollen-epihydrophilous pollination.


Assuntos
Flores , Hydrocharitaceae , Polinização , Flores/anatomia & histologia , Hydrocharitaceae/anatomia & histologia , Hydrocharitaceae/fisiologia , Pólen/fisiologia , Polinização/fisiologia
15.
Plant Mol Biol ; 102(4-5): 359-372, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31848919

RESUMO

KEY MESSAGE: Protein degradation is essential in plant growth and development. The stability of Cullin3 substrate adaptor protein BPM1 is regulated by multiple environmental cues pointing on manifold control of targeted protein degradation. A small family of six MATH-BTB genes (BPM1-6) is described in Arabidopsis thaliana. BPM proteins are part of the Cullin E3 ubiquitin ligase complexes and are known to bind at least three families of transcription factors: ERF/AP2 class I, homeobox-leucine zipper and R2R3 MYB. By targeting these transcription factors for ubiquitination and subsequent proteasomal degradation, BPMs play an important role in plant flowering, seed development and abiotic stress response. In this study, we generated BPM1-overexpressing plants that showed an early flowering phenotype, resistance to abscisic acid and tolerance to osmotic stress. We analyzed BPM1-GFP protein stability and found that the protein has a high turnover rate and is degraded by the proteasome 26S in a Cullin-dependent manner. Finally, we found that BPM1 protein stability is environmentally conditioned. Darkness and salt stress triggered BPM1 degradation, whereas elevated temperature enhanced BPM1 stability and accumulation in planta.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Flores/fisiologia , Estresse Fisiológico , Fatores de Transcrição/fisiologia , Ácido Abscísico , Arabidopsis/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Proteínas de Fluorescência Verde , Raízes de Plantas/fisiologia , Plantas Geneticamente Modificadas , Plasmídeos/genética , Pólen/fisiologia , Complexo de Endopeptidases do Proteassoma/fisiologia , Proteólise , Sementes/fisiologia , Ubiquitina-Proteína Ligases/fisiologia
16.
Evolution ; 74(2): 283-296, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31883274

RESUMO

Interactions between plant community members are an underexplored driver of angiosperm floral variation. We investigate character displacement as a potential contributor to floral variation in Pelargonium communities. Pelargoniums all place pollen on the ventral sides of their pollinators, potentially leading to interspecific pollen transfer (IPT) in sympatry. We show that the positions of pollen placement and receipt are determined by anther and style exsertion lengths. Using field experiments, we demonstrate that heterospecific species experience higher IPT if they have similar style lengths than when they have greater style length differences. Using crosses, we show that IPT has negative consequences on seed set. In combination, these results suggest that character displacement in style length is likely to reduce IPT and increase female fitness in sympatry. Patterns of style length variation across 29 different Pelargonium communities suggest that character displacement has occurred in multiple communities. Furthermore, analyses using a wide-ranging species pair show that style lengths are more different between sympatric populations than they are between allopatric populations. In addition to pollinators as agents of floral divergence, this study suggests that variation in Pelargonium community structure has driven style length variation through character displacement.


Assuntos
Flores/fisiologia , Pelargonium/fisiologia , Polinização , Flores/crescimento & desenvolvimento , Aptidão Genética , Pelargonium/crescimento & desenvolvimento , Pólen/fisiologia , Simpatria
17.
J Plant Physiol ; 244: 153085, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31812029

RESUMO

Several signaling pathways have been shown to be involved in the regulation of pollen germination and pollen tube elongation. Among others, exogenously applied polyamines were found to strongly affect pollen maturation, pollen tube emergence and elongation. In this study, our aim was to investigate the regulatory relation among exogenous polyamines, and endogenous reactive oxygen species and nitric oxide under pollen germination and the apical growth of pollen tube in tobacco plants. We have found that the various polyamines differentially affected the metabolism of nitric oxide and reactive oxygen species during the processes of pollen germination in the grain and the lengthening pollen tube. It is hypothesized that their differential effects might be related to their distinct influence on the endogenous nitric oxide and reactive oxygen species levels.


Assuntos
Óxido Nítrico/metabolismo , Tubo Polínico/citologia , Pólen/fisiologia , Poliaminas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tabaco/fisiologia , Germinação , Homeostase , Poliaminas/administração & dosagem
18.
BMC Plant Biol ; 19(1): 542, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31805858

RESUMO

BACKGROUND: In water lily (Nymphaea) hybrid breeding, breeders often encounter non-viable seeds, which make it difficult to transfer desired or targeted genes of different Nymphaea germplasm. We found that pre-fertilization barriers were the main factor in the failure of the hybridization of Nymphaea. The mechanism of low compatibility between the pollen and stigma remains unclear; therefore, we studied the differences of stigma transcripts and proteomes at 0, 2, and 6 h after pollination (HAP). Moreover, some regulatory genes and functional proteins that may cause low pollen-pistil compatibility in Nymphaea were identified. RESULTS: RNA-seq was performed for three comparisons (2 vs 0 HAP, 6 vs 2 HAP, 6 vs 0 HAP), and the number of differentially expressed genes (DEGs) was 8789 (4680 were up-regulated), 6401 (3020 were up-regulated), and 11,284 (6148 were up-regulated), respectively. Using label-free analysis, 75 (2 vs 0 HAP) proteins (43 increased and 32 decreased), nine (6 vs 2 HAP) proteins (three increased and six decreased), and 90 (6 vs 0 HAP) proteins (52 increased and 38 decreased) were defined as differentially expressed proteins (DEPs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that the DEGs and DEPs were mainly involved in cell wall organization or biogenesis, S-adenosylmethionine (SAM) metabolism, hydrogen peroxide decomposition and metabolism, reactive oxygen species (ROS) metabolism, secondary metabolism, secondary metabolite biosynthesis, and phenylpropanoid biosynthesis. CONCLUSIONS: Our transcriptomic and proteomic analysis highlighted specific genes, incuding those in ROS metabolism, biosynthesis of flavonoids, SAM metabolism, cell wall organization or biogenesis and phenylpropanoid biosynthesis that warrant further study in investigations of the pollen-stigma interaction of water lily. This study strengthens our understanding of the mechanism of low pollen-pistil compatibility in Nymphaea at the molecular level, and provides a theoretical basis for overcoming the pre-fertilization barriers in Nymphaea in the future.


Assuntos
Flores/fisiologia , Nymphaea/fisiologia , Melhoramento Vegetal , Proteoma/fisiologia , Transcriptoma/fisiologia , Ontologia Genética , Hibridização Genética , Nymphaea/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pólen/fisiologia
19.
Proc Natl Acad Sci U S A ; 116(49): 24707-24711, 2019 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-31712419

RESUMO

Insect pollination of flowering plants (angiosperms) is responsible for the majority of the world's flowering plant diversity and is key to the Cretaceous radiation of angiosperms. Although both insects and angiosperms were common by the mid-Cretaceous, direct fossil evidence of insect pollination is lacking. Direct evidence of Cretaceous insect pollination is associated with insect-gymnosperm pollination. Here, we report a specialized beetle-angiosperm pollination mode from mid-Cretaceous Burmese amber (99 mega-annum [Ma]) in which a tumbling flower beetle (Mordellidae), Angimordella burmitina gen. et sp. nov., has many tricolpate pollen grains attached. A. burmitina exhibits several specialized body structures for flower-visiting behavior including its body shape and pollen-feeding mouthparts revealed by X-ray microcomputed tomography (micro-CT). The tricolpate pollen in the amber belongs to the eudicots that comprise the majority of extant angiosperm species. These pollen grains exhibit zoophilous pollination attributes including their ornamentation, size, and clumping characteristics. Tricolpate pollen grains attached to the beetle's hairs are revealed by confocal laser scanning microscopy, which is a powerful tool for investigating pollen in amber. Our findings provide direct evidence of insect pollination of Cretaceous angiosperms, extending the range insect-angiosperm pollination association by at least 50 million years. Our results support the hypothesis that specialized insect pollination modes were present in eudicots 99 million years ago.


Assuntos
Evolução Biológica , Besouros/fisiologia , Magnoliopsida/fisiologia , Polinização/fisiologia , Âmbar , Animais , Arqueologia , Besouros/anatomia & histologia , Comportamento Alimentar/fisiologia , Fósseis , Boca/anatomia & histologia , Boca/diagnóstico por imagem , Boca/fisiologia , Mianmar , Pólen/fisiologia , Microtomografia por Raio-X
20.
Plant Physiol ; 181(3): 1114-1126, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31530628

RESUMO

SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) complex formation is necessary for intracellular membrane fusion and thus has a key role in processes such as secretion. However, little is known about the regulatory factors that bind to Qa-SNAREs, which are also known as syntaxins (SYPs) in plants. Here, we characterized Arabidopsis (Arabidopsis thaliana) Tomosyn protein (AtTMS) and demonstrated that it is a conserved regulator of SYPs in plants. AtTMS binds strongly via its R-SNARE motif-containing C terminus to the Qa domain of PM-resident, pollen-expressed SYP1s (SYP111, SYP124, SYP125, SYP131, and SYP132), which were narrowed down from 12 SYPs. AtTMS is highly expressed in pollen from the bicellular stage onwards, and overexpression of AtTMS under the control of the UBIQUITIN10, MSP1, or LAT52 promoter all resulted in defective pollen after the microspore stage in which secretion was inhibited, leading to the failure of intine deposition and cell plate formation during pollen mitosis I. In tobacco (Nicotiana benthamiana) leaf epidermal cells, overexpression of AtTMS inhibited the secretion of secreted GFP. The defects were rescued by mCherry-tagged SYP124, SYP125, SYP131, or SYP132. In vivo, SYP132 partially rescued the pMSP1:AtTMS phenotype. In addition, AtTMS, lacking a transmembrane domain, was recruited to the plasma membrane by SYP124, SYP125, SYP131, and SYP132 and competed with Vesicle-Associated Membrane Protein721/722 for binding to, for example, SYP132. Together, our results demonstrated that AtTMS might serve as a negative regulator of secretion, whereby active secretion might be fine-tuned during pollen development.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Proteínas SNARE/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Transporte Biológico , Membrana Celular/metabolismo , Expressão Gênica , Fusão de Membrana , Pólen/genética , Pólen/crescimento & desenvolvimento , Pólen/fisiologia , Ligação Proteica , Proteínas Qa-SNARE/genética , Proteínas Qa-SNARE/metabolismo , Proteínas SNARE/genética , Vesículas Secretórias/metabolismo , Tabaco/genética , Tabaco/fisiologia
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