Colpate Pollen Research Articles

Identification of Candidate Genes Involved in the Determinism of Pollen Grain Aperture Morphology by Comparative Transcriptome Analysis in Papaveraceae.

In the last decade, certain genes involved in pollen aperture formation have been discovered. However, those involved in pollen aperture shape remain largely unknown. In Arabidopsis, the interaction during the tetrad development stage of one member of the ELMOD protein family, ELMOD_E, with two others, MCR/ELMOD_B and ELMOD_A, can change the morphology of apertures from colpus (elongated) to pore (round). Here, comparative transcriptome analysis is used to identify candidate genes involved in the determination of pollen aperture morphology in Papaveraceae (order Ranunculales). Furthermore, the role of ELMOD genes in the genetic determinism of aperture shape was tested by comparative analysis of their expression levels using RNA-seq data and RT-qPCR. Two pairs of species belonging to two different subfamilies were used. Within each pair, one species has colpate pollen and the other porate (Fumarioideae-Dactylicapnos torulosa, 6-colpate, and Fumaria bracteosa, pantoporate; Papaveroideae-Eschsholzia californica, 5-7 colpate, and Roemeria refracta, 6-porate). The transcriptomes were obtained at the tetrad stage of pollen development. A total of 531 DEGs were found between the colpate and porate pollen species groups. The results from RNA-seq and RT-qPCR indicate that pollen aperture shape is not determined by the relative expression levels of ELMOD family genes in Papaveraceae. However, genes related to callose wall formation or cytoskeleton organisation were found, these processes being involved in pollen aperture formation. In addition, transcriptomes from anthers with pollen during the tetrad stage of three species (D. torulosa, R. refracta, and F. bracteosa) were obtained for the first time. These data will be available for further studies in the field of floral evolution and development.

High-precision U-Pb CA-ID-TIMS calibration of the Permian Lueckisporites-dominated assemblages in westernmost Gondwana: inferences for correlations

Palynology is one of the most useful tools for constructing biostratigraphic charts in the late Paleozoic basins of South America, but the lack of radiometric ages often makes it difficult to establish the precise age of the biozones. This paper focuses on two points: (i) the description of new Argentinian palynological assemblages referred to the Lueckisporites/Weylandites (LW) Biozone and (ii) the application of a new isotopic age that enables more confident large-scale correlations with the neighboring Paraná Basin of Brazil. The palynofloras were recovered from the upper part of the De La Cuesta Formation that crops out in the retroarc basin of the Paganzo Basin, more specifically obtained from mudstones intercalated with limestones, cherts, and tuffs interpreted as being deposited in a shallow water body. The assemblages are characterized by an abundance of bi-taeniate pollen grains of the Lueckisporites complex and multitaeniate pollen grains such as Lunatisporites, Protohaploxypinus, Striatopodocarpidites, Tornopollenites, and Vittatina. Colpate pollen grains are also represented by Marsupipollenites and Pakhapites. A U-Pb CA-ID-TIMS age of 278.84 ± 0.22 Ma, obtained from a tuff level interstratified with the fossiliferous strata, allows the age of the LW Biozone in the Paganzo Basin to be constrained for the first time and the adjustment of the record Lueckisporites virkkiae in Gondwana. Moreover, this date enables precise correlations with other basins, such as the San Rafael Basin (Yacimiento Los Reyunos Formation) in Argentina and the Brazilian Paraná Basin (Iratí Formation).

Mechanical design of apertures and the infolding of pollen grain

When pollen grains become exposed to the environment, they rapidly desiccate. To protect themselves until rehydration, the grains undergo characteristic infolding with the help of special structures in the grain wall-apertures-where the otherwise thick exine shell is absent or reduced in thickness. Recent theoretical studies have highlighted the importance of apertures for the elastic response and the folding of the grain. Experimental observations show that different pollen grains sharing the same number and type of apertures can nonetheless fold in quite diverse fashions. Using the thin-shell theory of elasticity, we show how both the absolute elastic properties of the pollen wall and the relative elastic differences between the exine wall and the apertures play an important role in determining pollen folding upon desiccation. Focusing primarily on colpate pollen, we delineate the regions of pollen elastic parameters where desiccation leads to a regular, complete closing of all apertures and thus to an infolding which protects the grain against water loss. Phase diagrams of pollen folding pathways indicate that an increase in the number of apertures leads to a reduction of the region of elastic parameters where the apertures close in a regular fashion. The infolding also depends on the details of the aperture shape and size, and our study explains how the features of the mechanical design of apertures influence the pollen folding patterns. Understanding the mechanical principles behind pollen folding pathways should also prove useful for the design of the elastic response of artificial inhomogeneous shells.

Pollen morphology of Passiflora section Granadillastrum (Passifloraceae) with a detailed description of the aperture

Passiflora subgenus Passiflora possesses about 236 species divided into six supersections, among which Stipulata with Granadillastrum is one of its sections. The objective of the present study was to analyse the pollen morphology of 19 species subordinate to the section Granadillastrum and to identify attributes important for the taxonomy of the group. Pollen grains were acetolysed, measured, described and illustrated under light and scanning electron microscopy. Two pollen types differing in polarity were found in the section: Pollen Type I with apolar pollen grains and Pollen Type II with isopolar pollen grains. Type I included large, colpate pollen grains (varying from six to nine colpi), while Type II included large, 6-syncolpate or 3-colpate pollens. All of the studied species had a reticulate exine, sinuous muri, continuous with or without perforations, and ornamented lumina. Hierarchical cluster analysis and principal component analysis (PCA) were used to interpret the formation of the principal pollen groups based on morphology. Two of the analysed species of section (Passiflora imbeana and P. setulosa) are at risk of extinction. The present study is extremely important for characterising pollen morphology such that taxa can be delimited and knowledge acquired for conservation purposes. Five of the studied species had their pollen characterised for the first time, which will be useful to future taxonomic and phylogenetic analyses. This species have pollen characters, such as the number and type of apertures that are important for delimiting some species, while ornamentation in general is similar among taxa and characterises the section.

RESULTS OF SSR ANALYSIS, PROPERTIES OF PLANT MORPHOLOGY AND BIOCHEMICAL COMPOSITION OF CHINESE BROCCOLI – A NEW VEGETABLE CROP FOR RUSSIA

The results of estimation of growth and development parameters, SSR analysis, electron microscopic examination of the surface of pollen and seeds, biochemical composition (ascorbic acid, carotenoids, carotenes, macro- and microelements content in the stem part of plant) of 8 Chinese broccoli, Brassica oleracea var. alboglabra samples grown in the unheated greenhouse of the Central Siberian Botanical Garden SB RAS, Novosibirsk (54°49′33″ N, 83°06′34″ E) and phy- totron of N. I. Vavilov Institute of Plant Genetic Resources (VIR) have been presented. Through the study, the large surface cellularity of B.oleracea var. alboglabra (cv. “Siji Xianggu jie lan” [“SX”]) seeds was similar with seed coat surface of B.oleraceae var. capitata f. alba cv. "Slava". A scanning electron microscopic study of Chinese broccoli pollen (cv. “SX”) revealed the formation of colpate pollen with ellipsoidal shape with a size of 32.9 ± 0.76 x 17.8 ± 0.42 μm, characterized by foveolate ornamentation with a length-to-diameter ratio – 1.85.The duration of the period from emergence stage to thickening of a stalk and flower-bud formation of cv. “SX” continued for 49-54 days. Сlose correlation was established between the largest diameter of the stem and the length of the leaf petiole (r=0,87, p < 0,001) and between the length of the leaf petiole and the weight of the stem (r=0,77, p < 0,001). As a result of molecular screening of Chinese broccoli using 5 SSR markers (Na10D09, Ol12F02, Ra2E12, BC 7 и BC 65) the greatest polymorphism was in the test with the BC 7 marker - five alleles from 160 to 295 bp in size. In the “SX” variety single flowering (10%) occurred on 59 ... 63 day and mass flowering (75%) – on 65 ... 68 day. The stem part of B. oleracea var. alboglabra is a fairly good source of vitamin C, accumulating as much as 32-46 mg/100 g, and also increased concentration of K, Ca, Mg and Cu. At the end of the season the fruits, together with the phytomass of stems are well-seasoned for 3-4 weeks forming viable seeds with germination above 85% corresponding to the Russian state standard (GOST 32592-2013) for white cabbage seeds.

Estudio Palinológico de la Formación la Veteada en su Localidad Tipo (Pérmico Superior), Sierra de Famatina, la Rioja, Argentina. Granos de Polen Estriados, Plicados y Colpados

PALYNOLOGICAL STUDY OF LA VETEADA FORMATION AT ITS TYPE LOCALITY (UPPER PERMIAN), FAMATINA RANGE, LA RIOJA PROVINCE, ARGENTINA. STRIATE, PLICATE AND COLPATE POLLEN GRAINS. This is a systematic study of the palynological assemblages recorded in the upper part of the La Veteada Formation (upper La Veteada Association), which constitutes the section of the type locality, La Rioja Province, Argentina. In this contribution, 72 species of striate (monosaccate and bisaccate), plicates and colpate pollen grains are presented. Four new species are described: Meristocorpus veteadensis sp. nov., Lueckisporites biformis sp. nov., Lunatisporites lenticularis sp. nov., and Marsupipollenites costatus sp. nov. and, a new combination, i.e., Striatopodocarpites gopadensis (Bharadwaj and Srivastava) comb. nov is proposed. This palynoflora has a marked dominance of striate pollen grains which have great species diversity of Striatopodocarpites (with 11 species)-Protohaploxypinus (9 species)-Lueckisporites (9 specics)-Lunatisporites (8 species) complex, showing scarse participation of the genera Vittatina, Weylandites, Marsupipollenites, Corisaccites, Staurosaccites and Pakhapites, as well as pollen grains referred to Cordaitales (Potonieisporites, Cannanorop ollis, Caheniasaccites, Plicatipollenites, Barakarites). It shares taxa recorded in the LW (Argentina), Vc-Lv (Brazil) and IS-AC (Uruguay) biozones. Tables include full taxonomic composition of the microflora of the La Veteada Formation at its type locality, the palynostratigraphic correlation of the Neopaleozoic strata of central Argentina, southern Brazil and Uruguay, and the global previous stratigraphic records of the species recorded and discussed herein. The palynoflora of the upper La Veteada Formation is referred to the Late Permian (Lopingian) based on the stratigraphic range of all the recognized species. Consequently, it is considered the youngest Permian palynoflora recorded hitherto in Argentina and South America.

Molecular phylogeny of the platycodonoid group (Campanulaceae s.str.) with special reference to the circumscription of Codonopsis

AbstractPhylogenetic analyses of 41 taxa representing all genera except Ostrowskia of the platycodonoid group were done using sequences of five DNA fragments from the chloroplast and nuclear genomes. The results show that the platycodonoid group is a monophyletic group, and that four major clades can be recognized: (1) the Platycodon clade with colporate pollen, including Platycodon, Canarina, Cyclocodon, and Echinocodon; (2) the Cyananthus clade with colpate pollen and a superior ovary, including only Cyananthus; (3) the long‐colpus clade with long‐colpus pollen, an inferior ovary, and a disc or glands, including Codonopsis subg. Codonopsis, Campanumoea, and Leptocodon; and (4) the short‐colpus clade with short‐colpus pollen, an inferior ovary, and without a disc or glands, including Codonopsis subg. Pseudocodonopsis, subg. Obconicicapsula, and C. purpurea of Codonopsis subg. Codonopsis. These four major clades are strongly supported and well correlated with pollen type and morphology. The results support the separation of Cyclocodon from Codonopsis as a genus. The results also indicate that Campanumoea and Leptocodon should be merged with Codonopsis, whereas all taxa of the short‐colpus clade should be separated from Codonopsis.

Phylogeny of Pyroleae (Ericaceae): implications for character evolution

Pyroleae (Ericaceae) consist of four genera, all of which are distributed widely in temperate coniferous or sometimes deciduous forests of the Northern Hemisphere. To investigate the phylogenetic relationships among these genera and to explore the evolution of the characteristics of the subfamily, we conducted maximum parsimony and Bayesian analyses with nrDNA ITS and three cpDNA intergenic spacers (atpB-rbcL, trnS-trnG and trnL-trnF). The results from cpDNA and combined cpDNA+ITS data sets strongly support the monophyly of Pyroleae as well as a sister relationship between Pyrola and Moneses-Chimaphila, with Orthilia as the basal lineage. The sister-group relationship between Moneses and Chimaphila is supported by a set of synapomorphies, e.g., single flower, colpate pollen, five bundles in the style, straight fruiting pedicel orientation, complete capsule dehiscence, and the basic chromosome number, x=13. The Moneses-Chimaphila-Pyrola clade is supported by at least one homologous character of pollen in tetrads. Conflicts associated with the phylogenetic position of Orthilia may imply a hybrid origin for it, and therefore further study is needed.

A Review of the Genera Roentgenia and Potamoganos (Bignoniaceae)

Roentgenia and Potamoganos (Bignoniaceae) are small genera of lianas with corollas that are closely related to larger and more well known genera such as Cydista, Clytostoma, and perhaps Phryganocydia. Roentgenia is ditypic, containing R. bracteomana and R. sordida, whereas Potamoganos is monotypic, containing only P. microcalyx. The two species of Roentgenia have white to lavender, campanulate-funnelform, Cydista-type corollas, stems with eight phloem arms, bi-trifid tendrils, 3(-4)-colpate pollen with reticulate exine, 2-seriate ovule organization, nectariferous disk lacking, linear-oblong fruit, and winged seeds. Roentgenia bracteomana is distributed from southern Colombia to northern Bolivia and north-central Brazil, whereas R. sordida is restricted to eastern Venezuela, Guyana, Suriname, French Guyana, and portions of northern Brazil. Potamoganos microcalyx has lavender to magenta, campanulate-funnelform, Cydista-type corollas, with four phloem arms, trifid tendrils, 3-colpate pollen with reticulate exine, 4-seriate ovule organization, and a nectariferous disk. Potamoganos microcalyx is known from southern Venezuela, Guyana, Suriname, and northernmost Brazil. A key to species, maps of species distributions, reproductive phenology, and illustrations of R. bracteomana and P. microcalyx are provided.

A Palynological Study of Crotonoideae (Euphorbiaceae)

Pollen of 69 species representing 34 genera from 12 of the 13 tribes of Crotonoideae sensu Webster was examined in light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The pollen of the vast majority of the subfamily is inaperturate, and all Crotonoideae exines have a similar architecture: triangular supratectal elements attached to a network of muri having short or irregular columellae. These three components, triangular supratectal elements, muri, and modified columellae constitute the Croton structure. The triangular elements, designated subunits, can be psilate, striate, furrowed and ridged, or pitted, and with echinate, rounded, or long-attenuate apices; the subunits can be closely spaced or arrayed in more open configurations. A Croton sculpture refers to the presence of triangular sculpture elements, which may or may not have muri and modified columellae. Inaperturate grains have thin footlayers and thin endexines, whereas colpate pollen bas both footlayer and endexine well developed; in porate grains, the footlayer and endexine appear intermediate between inaperturate and colpate. Tribes Micrandreae (Hevea, Micrandra, Micrandropsis examined) and Adenoclineae (Adenocline, Ditta, Glycydendron, Endospermum, Klaineanthus, Tetrorchidium) are 3-colpate and probably primitive, having retained not only apertures but (prominent) footlayers and endexines as well; Manihoteae (Manihot, Cnidoscolus examined) and Gelonieae (Suregada) are porate. The thicker aperturate exines, especially in the colpate grains, may be linked with retention of apertures. The remaining 22 genera examined, including the two largest, Croton and Jatropha, have inaperturate pollen. A thin footlayer/endexine also occurs in Oldfieldioideae, and a tectum with triangular elements is found in some Acalyphoideae. In both morphology and exine structure, the pollen of Crotonoideae closely resembles the (porate) pollen of Thymelaeaceae.

Aperture Evolution in the Pollen of Primitive Angiosperms

Diversity of pollen apertures in 35 families of the ranalean complex is compared through a series of representative scanning electronmicrographs, and the evolution of pollen aperture types in primitive angiosperms is outlined. A classification of pollen apertures found in the ranalean complex is presented, and ten basic aperture types are recognized: anasulcate, anatrichotomosulcate, zonasulculate, anaulcerate, catasulcate-cataulcerate, inaperturate, disulculate-diulculate, forate, colpate, and porate. Evidence is adduced for the primitive (ancestral) status of anasulcate pollen, and transitional stages in the evolution of other pollen aperture types in the ranalean complex are examined. From an early stock of ranalean angiosperms with anasulcate pollen, there appears to have been development of a number of interesting but evolutionally dead-end lines, represented among others by zonasulculate, anaulcerate, and catasulcate-cataulcerate pollen types. The most important evolutionary trend in early angiosperm pollen seems to have been the development of inaperturate pollen grains in many families of primitive angiosperms, from which there was a second major radiation of aperture types, including evolution of disulculate and forate pollen. Comparative study of pollen apertures observed in living primitive angiosperms suggests a de novo origin of the uniquely angiospermous (dicotyledonous) colpate pollen type from such inaperturate pollen.

APERTURE EVOLUTION IN THE POLLEN OF PRIMITIVE ANGIOSPERMS

Diversity of pollen apertures in 35 families of the ranalean complex is compared through a series of representative scanning electronmicrographs, and the evolution of pollen aperture types in primitive angiosperms is outlined. A classification of pollen apertures found in the ranalean complex is presented, and ten basic aperture types are recognized: anasulcate, anatrichotomosulcate, zonasulculate, anaulcerate, catasulcate‐cataulcerate, inaperturate, disulculate‐diulculate, forate, colpate, and porate. Evidence is adduced for the primitive (ancestral) status of anasulcate pollen, and transitional stages in the evolution of other pollen aperture types in the ranalean complex are examined. From an early stock of ranalean angiosperms with anasulcate pollen, there appears to have been development of a number of interesting but evolutionally dead‐end lines, represented among others by zonasulculate, anaulcerate, and catasulcate‐cataulcerate pollen types. The most important evolutionary trend in early angiosperm pollen seems to have been the development of inaperturate pollen grains in many families of primitive angiosperms, from which there was a second major radiation of aperture types, including evolution of disulculate and forate pollen. Comparative study of pollen apertures observed in living primitive angiosperms suggests a de novo origin of the uniquely angiospermous (dicotyledonous) colpate pollen type from such inaperturate pollen.

Supposedly Colpate Pollen Grains from the Jurassic

AbstractSome Mesozoic spores and pollen grains claimed in a recent publication to exhibit angiosperm-like features are discussed. It is suggested that Poroplanites Pflug, is actually a trilete fern spore. The “ germinal apparatus ” of the Poroplanites type is simply an optical section of the characteristic folding of a lobe of a trilete spore, flattened along the polar axis and seen in equatorial view. It is shown that Pflug's Poroplanites type can be reproduced almost exactly in the trilete spores of a living tree fern. Classopollis Pflug, Circumpollis Pflug, and Canalopollis Pflug are pollen grains with distinct annular thickening, similar to the pollen grains of the Jurassic araucarian, Pagiophyllum connivens Kendall.