Pollen Exine Sculpturing Research Articles

Pollen and Floral Organ Morphology of 18 Oil-Tea Genotypes and Its Systematic Significance

Oil-tea belongs to the Camellia genus, an important oil crop in China. However, oil-tea is taxonomically challenging due to its morphological variation, polyploidy, and interspecific hybridization. Therefore, the present study aimed to investigate the flower organs’ morphology and pollen micro-morphology of 18 oil-tea genotypes in detail and discussed their significance for oil-tea taxonomy. The quantitative parameters of flowers were measured using Vernier caliper measurements. Pollen morphology was observed and photographed using scanning electron microscopy (SEM). The results indicated that the flower size varied significantly among the tested oil-tea genotypes, with the corolla diameter ranging from 42.25 μm in C. meiocarpa ‘LP’ to 89.51 μm in C. oleifera ‘ASX09’. The pollen grains of oil-tea are monads and medium grade in pollen size. There were two types of polar views, including triangular or subcircular, with a polar axis length (P) ranging from 27.5 μm in C. oleifera ‘CY67’ to 59.04 μm in C. mairei (H. Lév.) Melch. var. lapidea (Y.C. Wu) Sealy. The equatorial views exhibited oblate, spherical, or oblong shapes, with an equatorial axis length (E) of 21.32 to 41.62 μm. The pollen exine sculpture was perforate, verrucate, and reticulate. The perforation lumina diameter (D) ranged from 0.29 μm in C. magniflora Chang to 1.22 μm in C. yuhsienensis Hu, and the perforation width (W) varied from 0.77 μm in C. osmantha to 1.40 μm in C. gauchowensis ‘HM349’, respectively. Qualitative clustering analysis (Q-type cluster) and principal component analysis (PCA) were conducted using eleven indexes of flower and pollen morphology, and the 18 oil-tea genotypes were classified into three categories. In addition, the correlation analysis showed that there was a significant correlation between pollen size and flower morphology or pollen exine sculpture. These results offer valuable information on the classification and identification of the 18 oil-tea germplasm resources.

Morpho-anatomical and palynological properties of endemic Astragalus tmoleus var. bounacanthus (Fabaceae)

Astragalus tmoleus Boiss. var. bounacanthus (Boiss.) Chamberlain is a member of the Pterophorus Bunge section of the Fabaceae family and consists of the spiny cushion-forming shrub. In this study, morphological, anatomical and pollen properties of the plant, an endemic species for Turkey, have been investigated in detail. Morphological characters such as the shape of paripinnate leaves, stipules and bracts, the flower number in the inflorescence, the stenonychioid type of standard and the reniform type of seed can be helpful to distinguish A. tmoleus var. bounacanthus. The stem, leaf and rachis characteristics of the plant were examined in anatomical studies. There is a secondary growth in stem anatomy. The number of vascular bundles is 15-18 in a circle. The shape of the transversal section of the rachis is polygonal or almost orbicular. The sclerenchyma tissue is located on the vascular bundles in the rachis. A. tmoleus var. bounacanthus has equifasial leaves. The stomata type is anomocytic and occurs on both leaflet epidermises. The pollen grains of A. tmoleus var. bounacanthus have tricolpate aperture and they are subprolate-shaped. While the pollen exine sculpturing is microreticulate, the seed surface sculpturing is a prominent undulate-ridged pattern formed by irregular cells. Scanning electron microscopy (SEM) is used to determine pollen and seed morphology.

Türkiye İçin Endemik Bir Bitki Olan Cousinia foliosa Boiss. & Bal. (Asteraceae) Üzerine Anatomik ve Palinolojik Bir Çalışma

Cousinia Cass. cinsi Asteraceae familyasının en büyük cinslerinden biri olup yaklaşık 700 türle temsil edilmektedir. Bu çalışma, Stenocephalae Bunge seksiyonu içerisinde yer alan Cousinia foliosa türünün anatomik ve palinolojik özelliklerinin belirlenerek cinsin sistematiğine katkı sağlamak amacıyla yapılmıştır. C. foliosa türünün polen mikromorfolojik özellikleri çalışılmış ve türe ait fotoğraflar verilmiştir. Bu türün anatomik çalışmasında gövde, yaprak ve orta damar özellikleri tespit edilerek fotoğrafları verilmiştir. Anatomik çalışmalar için bitki kısımları parafine gömülmüş ve dokuların boyanma işlemi için safranin fast green boyama metodu uygulanmıştır. Anatomik karakterlerden orta damar şeklinin dairemsi ve orta damardaki iletim demeti sayısının 8 olmasıyla bu karakterlerin türlerin ayrımında önemli olduğu belirlenmiştir. Palinolojik çalışmalar için ışık mikroskobu kullanılmış ve polen şekli subprolat olarak tespit edilmiştir. SEM mikroskobu kullanılarak polen ekzin yüzey süslerinin fotoğrafları çekilmiş ve polenlerin verrukoz olduğu belirlenmiştir.

Pollen micromorphological analysis of tribe Acacieae (Mimosaceae) with LM and SEM techniques.

The morphology of pollen grains of the 06 species of tribe Acacieae (Mimosaceae) belonging to one genus were investigated using scanning electron microscopic (SEM) and light microscopic (LM) approach. Lactic acid acetolysis method was used for (LM) while non-acetolysis for (SEM). The species were examined for the both qualitative and quantitative palynological features. Qualitatively the pollen was studied for the shape, exine sculpturing, pollen shape, and pollen type. Oblate spheroidal shape of pollen was observed in Accacia modesta. Subprolate shape in Accaca nilotica. In Accacia farnesiana, prolate pollen was examined while prolate spheroidal in Acacia tortilis and spheroidal pollen grains were studied in Acacia catechu, respectively. Pollen exine sculpturing of the studied tribe possesses novel variation. Foveolate, reticulate, foveolate-psilate, faint reticulate, fossulate, perforate, and scrabate exine sculpturing were noticed. Colpi were absent in all species. Excessive variation was observed in both qualitative and quantitative character of pollen. SPSS software was use for the quantitative measurement of the pollen grains. The current study will be helpful for the identification of the problematic species and phylogenetic studies of family Mimosaceae.

Pollen morphology in selected Cupressaceae Gray. and Sciadopityaceae Luerss. species in an experimental culture

Pollen grains of Cunninghamia lanceolata, Cryptomeria japonica and Sciadopitys verticillata were exam- ined by light and scanning electron microscopy. The pollen grains were non-saccate, generally oblate-sphe- roidal, spheroidal, prolate-spheroidal or subprolate. The pollen grains had papillae of different sizes and shapes on the distal face. The papillae were more conspicuous in C. japonica than in C. lanceolata. The pollen exine sculpture in the proximal view was verrucate-granulate and verrcucate with microechinate supras- culpture in SEM. The surface of the exine was covered with echinate orbicules in Cupressaceae species. There were some differences in the size of the verrucae, perforation on the proximal surface and distal face between S. verticillata pollen grains and other species. This study of the pollen grain morphology provided some important new data which have not been reported in literature so far.

Classification of Chinese Wintersweet ( Chimonanthus praecox) Cultivars Supported by Pollen Morphology

To classify the Chinese wintersweet ( Chimonanthus praecox) cultivars and to study their evolution based on pollen morphology. Pollens of 12 representative wintersweet cultivars were examined by scanning electron microscopy (SEM). Q-cluster analysis was carried out based on the observation results. Results are as follows: (1) The pollen grains were 2- lobed circular in polar view, elliptic in equatorial view. The pollen shapes were spheroidal or super-spheroidal by P/E (polar axis length/equatorial axis length) criteria. (2) According to pollen exine ornamentation, it was indicated that white wintersweet is most original. Yellow floral group could be classified into three subgroups: purple-hearted, halo-hearted and yellow-hearted type. Their evolutionary relationship was purple-hearted→halo-hearted→yellow-hearted. (3) Different wintersweet cultivars showed a different exine sculpture. Palynological analysis could be used in the classification of wintersweet cultivars. The result of cluster analysis indicated that the cultivars could be classified into three groups with a similarity coefficient of 0.41. Each group had similar pollen exine sculpture. It was found that the palynological classification coincided well with morphological classification. Our results support the suggestion that purple streaks or patches of inner-petals should be served as the first-order criteria in wintersweet classification.

A Method for Image Analysis of the Pollen Exine Sculpture

A Method for Image Analysis of the Pollen Exine Sculpture

Evaluation of pollen morphology as a taxonomic character for generic delimitation in Scilla s.l. (Hyacinthaceae)

Scilla L. s.l. (Hyacinthaceae) comprises about 100 species distributed in south Europe, the Mediterranean region, and central and western Asia with 10 species reported from Iran.However, according to recent studies based on molecular data Scilla s.l. is not monophyletic and should be divided into several smaller genera, i.e. Fessia Speta, Othocallis Salisb., Pfosseria Speta, Prospero Salisb., Scilla s.s. and Zagrosia Speta.In the present study the pollen grains of 13 species representing six segregate genera within Scilla s.l. were studied to evaluate the taxonomic value of pollen characters for generic delimitation. Pollen grains of all examined species were found to be monosulcate, prolate or sub‐prolate and heteropolar. Three different types of exine sculpturing were recognized: fossulate, perforate–reticulate and perforate.In Prospero autumnale (=Scilla autumnalis) pollen exine sculpturing is fossulate. In Othocallis armena, O. mischtschenkoana, O. rosenii and O. siberica (=Scilla armena, S. mischtschenkoana, S. rosenii and S. siberica) exine sculpturing is perforate–reticulate with mainly large perforations surrounded by smaller ones. In Fessia gorganica, F. greilhuberi, F. hohenakeri, F. khorassanica and F. raewskiana (=S. gorganica, S. greilhuberi, S. hohenakeri, S. khorassanica and S. raewskiana) the exine is perforate with rather uniform perforation. Zagrosia persica (=S. persica) has the same exine type as Fessia spp. In Pfosseria, the exine is perforate with linear and circular perforations. Scilla s.s. has a perforate exine, but the perforations are not uniform and their size and shape are variable.Our results are generally congruent with the circumscription of the new genera previously included in Scilla s.l. and show that pollen exine morphology is useful as an additional taxonomic character for the delimitation these segregate genera.

A quantitative evaluation of the distylous syndrome in Sebaea grandis (Gentianaceae)

Distyly is a rare polymorphism characterized by short-styled [S] and long-styled [L] floral morphs. It has been hypothesized to reduce the gender conflict inherent in hermaphrodite flowers. In particular, the reciprocal arrangement of male and female parts promotes precise pollen transfer between morphs, and the heteromorphic incompatibility system that is associated with distyly can eliminate uniparental inbreeding depression. We studied the syndrome of floral traits associated with distyly in Sebaea grandis, a perennial herb common in South African grasslands. Flowers have the reciprocal reproductive organ arrangement characteristic of the distylous syndrome, and L- and S-morphs occurred at equal frequencies in the two populations that were studied. S- and L-morph flowers did not differ significantly in size, although the S-morph produced larger pollen grains and pollen exine sculpturing differed between the two morphs. Approximately 80% of the pollen deposited on the stigmas of either morph was legitimate (intermorph), suggesting that distyly in this species promotes cross-pollination. A controlled pollination experiment suggests that S. grandis possesses a heteromophic incompatibility system: no fruits were produced following intramorph pollinations, whereas intermorph pollinations resulted in 70% of flowers setting fruit. Fluorescence microscopy revealed clear differences among morphs in the site of incompatibility. Intramorph pollen grains did not grow beyond the stigmatic surface of the L-morph, and growth was arrested in the stylar canal of the S-morph, while intermorph pollen grains germinated on the stigmatic surface, grew through the stylar canal and entered the ovary. This study demonstrates that S. grandis displays the morphological traits and genetically controlled incompatibility system associated with heterostylous plants.

Phylogenetic relationships of Loasaceae subfamily Gronovioideae inferred from matK and ITS sequence data

Members of subfamily Gronovioideae are distinctive among Loasaceae in their androecial and gynoecial simplicity. The four genera of the subfamily differ, however, in chromosome number, floral novelties, and pollen exine sculpturing, which led to suggestions that the Gronovioideae were polyphyletic. Phylogenetic analyses based on sequences of the chloroplast gene matK and the internal transcribed spacer region (ITS) of nuclear rDNA have been conducted using parsimony and maximum likelihood methods to assess the monophyly of Gronovioideae and to determine the sister group relationships of gronovioid genera. The results show Gronovioideae are monophyletic and placed as the sister to Mentzelia. Within Gronovioideae, Petalonyx is sister to a clade consisting of Cevallia, Gronovia, and Fuertesia. Among the remaining Loasaceae, subfamily Mentzelioideae, as originally circumscribed, is paraphyletic. Subfamily Loasoideae is placed as the sister to the Gronovioideae-Mentzelia clade.

THE EFFECTS OF GENOTYPE AND PLOIDY LEVEL ON POLLEN SURFACE SCULPTURING IN MAIZE (ZEA MAYS L.)

Pollen exine sculpturing is a consistent feature of seed plant taxa, yet no mechanism for control of sculpturing pattern has been found. On grass pollen, exine sculpturing takes the form of closely packed spinules. Exine spinules on pollen grains from six maize populations representing all combinations of three genetic backgrounds (single cross hybrids W22 W23, N6 W23, R75 W23) and two ploidy levels (2x, 4x) were examined by scanning electron microscopy. Doubling ploidy levels from 2x to 4x increased pollen diameter (minor axis) with the magnitude of increase related to genetic background. For spinule density, only the effect of genetic background was statistically significant. Spinule density was altered by the genotype of the plant on which the pollen was produced but not by the ploidy level, including genome number and difference in surface area and cytoplasmic volume resulting from chromosome doubling.

Morphological Variation in Hawaiian Wikstroemia (Thymelaeaceae)

An analysis was made of morphological variation in the taxonomically complex Ha- waiian genus Wikstroemia. Previous authors had recognized 12 or 26 species. Multivariate analyses indicate that variation is continuous and that natural groups are not distinguishable on the basis of macromorphology. Two micromorphological characters, pollen exine sculpturing and seed coat morphology, were examined for their potential taxonomic utility; however, neither of these char- acters contributed any useful taxonomic information at the species level. The polyforate, crotonoid pollen grains from populations on the six major islands of Hawaii and from five extra-Hawaiian species are morphologically uniform. In contrast, seed coats showed intra- and interpopulation variability, but the variation patterns are not consistent at the population level or above. The genus Wikstroemia Endl. consists of 55- 70 species of shrubs and small trees distributed throughout the Pacific Basin, southeast Asia, and Australia (Peterson 1990). The continuous na- ture of morphological variation in Hawaiian Wikstroemia has led to much taxonomic confu- sion in attempts to distinguish species using morphological criteria. Previous authors have recognized 12 (Peterson 1990) or 26 species (Skottsberg 1972), all endemic. However, nei- ther of these treatments utilized distinctive, non- overlapping suites of characters. The aim of this study was to test the morphological separate- ness of the species recognized by Peterson us- ing multivariate statistical techniques and phe- netic methods and, if those species lacked distinctness, to determine whether distinct morphological taxa could be recognized in Ha- waiian Wikstroemia. Two micromorphological characters, pollen exine sculpturing and seed coat morphology, were examined for their po- tential taxonomic usefulness. In Hawaii, Wikstroemia has a very broad eco- logical range, occurring on rocky seaside cliffs and in dry forest, rain forest, and alpine habitats (defined by Carlquist 1980, as above 2000 m). The plants range in habit from decumbent or erect shrubs to trees. Leaf shape varies from the

Pollen Surface Sculpture of Wheat, Rice, Maize and Five Sorghum Species.

Pollen surface sculpture provides very useful information about taxonomy and evolution of plants. Pollen exine sculpture of five Sorghum species and those of wheat (Triticum aestivum L.), rice (Oryza sativa L.), and maize (Zea mays L.) were compared using a scanning electron microscope (SEM). Differences in pollen surface structure occurred at the genus level and at the species level among Sorghum species at various ploidy levels. S. bicolor (2n=20), S. halepense (2n=40), and S. purpureo-sericeum (2n=10) had similar pollen exine sculptures, whereas S. versicolor (2n=10) and S. nitidum (2n=10) had distinctly different pollen surface sculptures from that of S. bicolor. Sizes of seeds and pollen grains were correlated to some extent. Maize had the largest seed and pollen, and S. nitidum had the smallest seed and pollen. For those species in which sizes did not differ greatly, variations of pollen sizes also were negligible. Ploidy level in Sorghum genus did not seem to have a great impact on pollen sizes.

Intraspecific polymorphism of pollen sculpture inParis tetraphylla A. Gray (Liliaceae)

Paris tetraphylla has a greater diversity of pollen exine sculpture than was previously thought. On the basis of 357 plants from 52 localities of Japan, we distinguished seven sculpture types that are tentatively referred to here as G1, G2, G3, R1, R2, R3 and S. G1, G2 and G3 have gemmate sculpture in which the gemmae are characteristically large, medium and small in size, respectively; likewise, R1, R2 and R3, have coarsely to finely ruglate sculpture; and S, scrobiculate sculpture. In general, any one of the seven types always or predominantly occurs in each plant, thus allowing us to make comparisons among plants and further among local populations. We thus found that G2 and G3, respectively, are the most and the second most widespread and occur in plants of 41 and 22 respectively, of the localities examined, although their frequencies differ with locality. Generally R3 occurs in plants distributed at higher latitudes, while R2 is rather widespread and common to plants growing on high mountains. G1 and R1 are restricted to plants occurring south of Ibaraki Pref. and north of Gunma Pref., respectively. Such localized distributional patterns of some types may reflect the reproductive nature and the history of geographical isolation inParis tetraphylla over the Japanese Islands.

CORRELATIONS BETWEEN POLLEN EXINE SCULPTURING AND ANGIOSPERM SELF‐INCOMPATIBILITY SYSTEMS—A REBUTTAL

SummaryData recently presented suggest no correlation exists between pollen exine sculpturing and self‐incompatibility systems in angiosperms is re‐examined. All the variation that permits rejection of the correlation resides among 27 taxa designated as having gametophytic self‐incompatibility. However, no empirical data have been published which support this designation. When these taxa are deleted and all the data are pooled there is a significant difference between exine perforations in sporophytic and gametophytic self‐incompatible plants at the 0.95 confidence interval.

Pollen ultrastructure of the Pontederiaceae

Abstract Pollen of eight genera and species of the Pontedcriaceae was investigated using SEM and TEM in order to elucidate interrelationships to other monocot families. All examined Pontederiaceae are diaperturate with furrow-shaped apertures and have a distinctly verrucate non-apertural exine sculpturing (except Pontederia, which is psilate to scabrate in sculpturing). Among investigated taxa the exine wall architecture exhibits a gradation between: (1) a 1-layered exine composed of laterally appressed, basally fused baculate elements, (2) a 2-layered exine, the outer layer composed of laterally appressed baculate elements and the inner forming a thin layer or composed of discrete papillate elements, and (3) a tectate-columellate exine, differing, however, from a typical tectate-columellate architecture by having short, narrow columellae and generally baculate tectal elements. Of the palynologically investigated families presumed closely related to the Pontederiaceae, only members of the tribe Haemodoreae of the Haemodoraceae have a verrucate sculpturing similar to that of most Pontederiaceae. In addition, the exine architecture of the nontectate-columellate genera of the Pontederiaceae is strikingly similar (and presumably homologous) to members of the family Haemodoraceae. It is proposed that the similarities in pollen exine sculpturing and architecture between the Pontederiaceae and Haemodoraceae are so by homology (common evolutionary origin) and constitute evidence for the close relationship and possible sister-group status of these families.

Correlations between pollen exine sculpturing and angiosperm self-incompatibility systems ? a reply

The exine morphology and pore size of pollen from diverse angiosperm taxa with homomorphic gametophytic, homomorphic sporophytic, and heteromorphic self-incompatibility have been studied. The results indicate that correlations alleged to exist between the type of self-incompatibility system and the nature of the pollen wall morphology should be treated with considerable caution.

The relation between pollen exine sculpturing and self-incompatibility mechanisms

In angiosperm pollen the reticulate-perforate exine sculpturing is associated with sporophytic self-incompatibility (S.S.I.) and imperforate and microperforate exine sculpturing is associated with gametophytic self-incompatibility. The earliest unequivocal angiosperm pollen conforms to exine morphology of pollen from plants with S.S.I. The orgin of S.S.I. is hypothesized to have coincided with the appearance of what is now the earliest recognizable angiosperm pollen. Other angiosperm characteristics correlated with S.I., functional stigmatic areas, large showy flowers (or aggregated inflorescences), and passive seed dispersal, provide some insight into the biological aspects of the earliest angiosperms.

The biology of heterostyly

Abstract Heterostyly is a genetically controlled floral polymorphism that is known to occur in 24 families of flowering plants. The floral morphs differ reciprocally in stamen and style lengths. They often differ in pollen grain size and production, and may differ in pollen exine sculpturing, pollen colour, presence of starch in pollen, stigmatic papillae, or corolla size or morphology. There are two morphs in distylous plants and three morphs in tristylous plants. Distyly is much more common than tristyly. Tristyly is known to occur only in the Lythraceae, Oxalidaceae, and Pontederiaceae, although there are unconfirmed reports in the Connaraceae and in Hugonia of the Linaceae. In distylous plants the supergene determining floral morphology also controls a diallelic sporophytic self-incompatibility system, so that only pollinations between morphs are compatible. Tristylous plants usually possess a two-locus diallelic sporophytic self-incompati-bility system associated with the floral trimorphism, but whet...