scholarly journals Pollen dimorphism and androgenesis in Hordeum vulgare

2014 ◽  
Vol 51 (2) ◽  
pp. 153-156 ◽  
Author(s):  
Krystyna Idzikowska ◽  
Aleksandra Ponitka ◽  
Fortnat Młodzianowski
Keyword(s):  
Hordeum Vulgare ◽  
Pollen Grains ◽  
Pollen Dimorphism ◽  
Dense Cytoplasm ◽  
Small Pollen

Dimorphism of binucleate pollen grains of <em>Hordeum vulgare</em> has been confirmed. It is considered, however, in contrast to the accepted opinions, that some of the large pollen grains with dense cytoplasm lying close to the tapetum are the outset forms for embryoids, and not the small pollen grains with scarce cytoplasm lying in the pollen sac centre.

Incompatibility, stamen movement and pollen economy in a heterostyled tropical forest tree, Cratoxylum formosum (Guttiferae)

1982 ◽  
Vol 214 (1195) ◽  
pp. 273-283 ◽  
Keyword(s):  
Critical Level ◽  
Pollen Grains ◽  
Forest Tree ◽  
Incompatible Pollen ◽  
Insect Visitation ◽  
Small Pollen ◽  
Evolutionary Step ◽  
Novel Method ◽  
Compatible Pollinations ◽  
Compatible Pollen

Cratoxylum formosum shows all the classical features of a distylic species. The two types are: long-styled plants with short stamens and small pollen grains and short-styled plants with long stamens and large pollen grains. Compatible pollinations are only between the two types; incompatible pollen tubes are inhibited in the style. A significant morphological feature distinguishes Cratoxylum from distylic plants in other families. Instead of having a small number of anthers making well separated narrow discs in the two types, Cratoxylum has many anthers (144) and they are arranged on staminal bundles that produce long cylinders of anthers that partially occupy similar height zones in the two types of flower. A novel method of separation of the two height zones is achieved by the bending of the stamens of the long-styled type when the flower opens, which converts the cylinder to a narrow disc of anthers at the same height as the ‘short’ stigma. The bending coincides with anther dehiscence and is slightly later than the first daily insect visitation. The anthers return to the upright position later in the day, when the pollination is complete. There was a 20-fold difference between the amounts of pollen deposited on the two types of stigmas. The ‘long’ stigmas received 1200 pollen grains per flower, in the ratio of 46 ‘long’ to 54 ‘short’, which is close to the ratio of two types of pollen produced in the population. This random deposition of pollen on ‘long’ stigmas is, however, more than adequate for the 36 seeds produced per flower. ‘Short’ stigmas received only 64 pollen grains per flower, in the ratio of 90 ‘long’ to 10 ‘short’, and several flowers had below the critical level of 36 compatible pollen grains for full seed production. Pollen loads of the pollinating bee, Apis javana , consisted of ‘long’ and ‘short’ pollen on the thorax in the ratio found on the ‘long’ stigma, and on the head of the bee in a ratio close to the 9:1 found on the ‘short ’ stigma. The corbicular loads reflected accurately the pollen of the tree in which the bee was caught. For Cratoxylum the accurate positioning of the anthers of the long-styled plant in relation to the visiting bees head was an important evolutionary step in the effective pollination of the short-styled form, which, at least in this species, is one critical and highly selected feature of the system.

Virola dominicana sp. nov. (Myristicaceae) from Dominican amber

Botany ◽  
2013 ◽  
Vol 91 (8) ◽  
pp. 530-534 ◽  
Author(s):  
George Poinar ◽  
Royce Steeves
Keyword(s):  
New Species ◽  
Intraspecific Variation ◽  
Pollen Grains ◽  
First Record ◽  
Western Hemisphere ◽  
Dominican Amber ◽  
The Family ◽  
Small Pollen ◽  
Male Flowers ◽  
Staminal Column

The Myristicaceae is a member of the early diverging angiosperm order Magnoliales; however, the family is poorly represented by fossil collections. We describe Virola dominicana sp. nov. (Myristicaceae), the first record of fossilized Myristicaceae flowers, from mid-Tertiary (45–15 million years ago) Dominican amber. The description is based on 24 male flowers in 17 pieces of amber, thus providing some indication of intraspecific variation, including a two-tepaled flower. Diagnostic characters of the new species are the long-simple or few-branched trichomes on the perianth margins, the small pollen grains, and a short staminal column. These fossils also show co-occurring insects, some of which could be Virola pollinators. It is speculated that V. dominicana disappeared from Hispaniola during the Pliocene–Pleistocene cooling events leaving no native members of the Myristicaceae in this region today. Additionally, these fossils demonstrate that Myristicaceae was present in the Western Hemisphere during the mid-Tertiary.

Pollen viability and germination in some neotropical aroids

Botany ◽  
2008 ◽  
Vol 86 (1) ◽  
pp. 98-102 ◽  
Author(s):  
Denis Barabé ◽  
Karine Lavallée ◽  
Marc Gibernau
Keyword(s):  
Pollen Viability ◽  
Pollen Grains ◽  
Total Loss ◽  
Small Pollen

Pollen viability and germination were observed in six species of neotropical Araceae. In Anaphyllopsis americana (Engl.) A. Hay, 50% of pollen grains remain viable after 70 h following dehiscence, and it takes over 210 h for total loss of viability to occur. In Montrichardia arborescens (L.) Schott, approximately 50% of pollen grains are not viable after 24 h, and no germination occurs after 36 h. Monstera adansonii Schott and Philodendron pedatum (Hook.) Kunth have the lowest initial pollen viability (40%–55%) and lose half of this viability after approximately 30 h. Pollen grains of Monstera adansonii remain viable for at least 60 h and that of P. pedatum for approximately 40 h, and constitute another group with a similar viability pattern. In Philodendron melinonii Brongn. ex Regel and Philodendron solimoesense A.C. Sm., pollen loses 50% of its viability after 24 h, but remains viable for at least 48 h. The percentage of viability decreases in a pattern from species having a long flowering cycle and small pollen grains (A. americana) to species with a short flowering cycle and large pollen grains (M. arborescens).

Influence of Fe concentration in the medium on multicellular pollen grains and haploid plants induced by mannitol pretreatment in barley (Hordeum vulgare L.)

PROTOPLASMA ◽  
2006 ◽  
Vol 228 (1-3) ◽  
pp. 101-106 ◽  
Author(s):  
A. Pulido ◽  
F. Bakos ◽  
A. Castillo ◽  
M. P. Vallés ◽  
B. Barnabás ◽  
...  
Keyword(s):  
Hordeum Vulgare ◽  
Pollen Grains ◽  
Hordeum Vulgare L ◽  
Haploid Plants

scholarly journals Pollen Dimorphism of Several Members of Nymphaeaceae and Nelumbonaceae: An Index of Geographical and Ecological Variation

2012 ◽  
Vol 4 (3) ◽  
pp. 38-44 ◽  
Author(s):  
Somnath BHOWMIK ◽  
Badal Kumar DATTA
Keyword(s):  
Electron Microscopy ◽  
Pollen Morphology ◽  
Size Variation ◽  
Pollen Grains ◽  
Pollen Dimorphism ◽  
Geographical Variations ◽  
Genetic Impact ◽  
The Difference ◽  
Morphological Differences ◽  
Scanning Electron

Pollen morphology of five Nymphaea (Nymphaeaceae) species, growing in Tripura, India were analysed using Scanning Electron Microscopy. Pollen grains of Nymphaea are dimorphic (ellipsoidal and spheroidal). The exine pattern also varies among the species. The variation as reported in the present study in terms of exine pattern of the studied species suggests the feasibility of applying the data in the identification of the genus of Nymphaea. The difference in exine patterns with the earlier reports may be interpreted as reflections of genetic variations possibly due to mutational changes effected by ecological conditions. The present pollen dimorphism may be attributed by introgression of populations. The variability in pollen morphology, including size variation and morphological differences, is often associated with hybrids among angiosperm groups. The examinations of percentages of aborted grains, generally considered a good indicator of hybridity. The occurrence of monosulcate pollens in Nelumbo nucifera along with dominant tricolpate pollens may be considered as aberrant pollens because of very low percentage of occurrence of monosulcate pollens. The ecological and geographical variations in pollen morphology could be an index of the genetic impact of the environment on the plant. Thus the present difference in terms of exine pattern could be useful to separate them at varietal level.

scholarly journals Morphological analysis of pollen grains from heterodynamous stamens of some Aeschynomene L. (Le guminosae - Papilionoideae - Dalbergieae)

Hoehnea ◽  
2018 ◽  
Vol 45 (4) ◽  
pp. 669-676
Author(s):  
Higor Antonio-Domingues ◽  
Angela Maria da Silva Corrêa ◽  
Monica Lanzoni Rossi ◽  
Adriana Pinheiro Martinelli ◽  
Cynthia Fernandes Pinto da Luz
Keyword(s):  
Pollen Morphology ◽  
Morphological Analysis ◽  
Pollen Grains ◽  
Size Group ◽  
Morphological Data ◽  
Pollen Dimorphism ◽  
Standard Methodology ◽  
Morphological Differences ◽  
Taxonomic Studies ◽  
Group Species

ABSTRACT Flowers with heterodynamous stamens can present differences in the pollen grains of each stamen size group. Species of Aeschynomene L. present didynamous stamens (five long and five short) but little is known about their pollen dimorphism. The objective of this study was to increase the knowledge about the pollen characteristics in Aeschynomene and emphasize the possible morphological differences between the pollen grains of long and short stamens in order to contribute to ecological and taxonomic studies. Pollen grains from the two groups of stamens size of ten species were analyzed separately, according to the standard methodology for studies of pollen morphology. In addition, analyses of variance, comparison of means and base index were performed. The results showed that the amb, shape, endoaperture type and sexine ornamentation did not vary in the pollen grains of the long and short stamens in the same specimen, but they varied among the species. However, in relation to the size of the pollen grains of the two groups of stamens, four species presented significant differences regarding the size of the polar and equatorial axes. The pollen morphological data obtained considering the heteromorphism of the stamens can contribute to the knowledge of the repro ductive dynamics of the genus, and to the systematic studies.

scholarly journals Supergene evolution via stepwise duplications and neofunctionalization of a floral-organ identity gene

2020 ◽  
Vol 117 (37) ◽  
pp. 23148-23157 ◽  
Author(s):  
Cuong Nguyen Huu ◽  
Barbara Keller ◽  
Elena Conti ◽  
Christian Kappel ◽  
Michael Lenhard
Keyword(s):  
Pollen Grains ◽  
Floral Organ ◽  
Mads Box ◽  
Style Length ◽  
Insertion Point ◽  
Class Function ◽  
Organ Identity ◽  
Small Pollen ◽  
The Difference ◽  
Insight Into

Heterostyly represents a fascinating adaptation to promote outbreeding in plants that evolved multiple times independently. While l-morph individuals form flowers with long styles, short anthers, and small pollen grains, S-morph individuals have flowers with short styles, long anthers, and large pollen grains. The difference between the morphs is controlled by an S-locus “supergene” consisting of several distinct genes that determine different traits of the syndrome and are held together, because recombination between them is suppressed. In Primula, the S locus is a roughly 300-kb hemizygous region containing five predicted genes. However, with one exception, their roles remain unclear, as does the evolutionary buildup of the S locus. Here we demonstrate that the MADS-box GLOBOSA2 (GLO2) gene at the S locus determines anther position. In Primula forbesii S-morph plants, GLO2 promotes growth by cell expansion in the fused tube of petals and stamen filaments beneath the anther insertion point; by contrast, neither pollen size nor male incompatibility is affected by GLO2 activity. The paralogue GLO1, from which GLO2 arose by duplication, has maintained the ancestral B-class function in specifying petal and stamen identity, indicating that GLO2 underwent neofunctionalization, likely at the level of the encoded protein. Genetic mapping and phylogenetic analysis indicate that the duplications giving rise to the style-length-determining gene CYP734A50 and to GLO2 occurred sequentially, with the CYP734A50 duplication likely the first. Together these results provide the most detailed insight into the assembly of a plant supergene yet and have important implications for the evolution of heterostyly.

Reproductive Efficiency in Muscadine Grapes

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 483c-483
Author(s):  
C.L. Gupton
Keyword(s):  
Production Efficiency ◽  
Fruit Set ◽  
Pollen Grains ◽  
Pollen Size ◽  
Reproductive Efficiency ◽  
Pollen Transfer ◽  
Cluster Number ◽  
Primary Means ◽  
Small Pollen ◽  
Black Beauty

To determine the berry production efficiency of selected muscadine grape cultivars, pollen production, size, and viability; time of pistil receptivity; mode of pollination; number of flower per cluster; and percentage fruit set were studied. Each of 17 hermaphroditic cultivars except `Noble' produced a high percentage of viable pollen grains. Pollen size averaged 32 and 51 μm in 2 years. Even at this small pollen size, our observations suggest insects rather than wind as the primary means of pollen transfer to pistillate flowers. Pistils were not receptive until the calyptra dehisced, thereby ensuring that pollen can reach the pistil when it is receptive. `Carlos' produced 68.5 and `Black Beauty', `Doreen', `Fry', `Sweet Jenny', and `Supreme' produced from 38 to 46 flowers per cluster. Percentage fruit set ranged from a high of 22 to 34 for `Fry', `Sweet Jenny', `Doreen', and `Supreme', and a low of 12 to 14 for `Carlos' and `Black Beauty'. These results suggest that pollination may not be a problem in present muscadine cultivars. Variation in yield among cultivars apparently relates to genetic differences in cluster number and berry weight.

scholarly journals Morphological Variation and Palynomorphology of Rosa laxa in Xinjiang, China

2018 ◽  
Vol 143 (6) ◽  
pp. 409-417
Author(s):  
Le Luo ◽  
Chao Yu ◽  
Xuelian Guo ◽  
Huitang Pan ◽  
Qixiang Zhang
Keyword(s):  
Morphological Variation ◽  
Pollen Grains ◽  
Glandular Trichome ◽  
Flower Color ◽  
Botanical Variety ◽  
Autonomous Region ◽  
Xinjiang Uygur Autonomous Region ◽  
Pollen Dimorphism ◽  
Botanical Varieties ◽  
Southern Xinjiang

Rosa laxa is widely distributed in the Xinjiang Uygur Autonomous Region of China and is highly adaptable and rich in variation. In this study, we investigated the morphology, habitats, and palynomorphology of R. laxa botanical varieties from Xinjiang, China. In addition to R. laxa var. laxa, there were three other botanical varieties of R. laxa growing in southern Xinjiang, including var. mollis, var. kaschgarica, and var. tomurensis. Together, these four botanical varieties exhibited morphological variation, mainly in the morphology of prickles and the glandular trichome and in flower color. The pollen grains of the R. laxa botanical varieties, all medium in size (21.77–48.39 μm), came in three shapes: perprolate, prolate, and subspheroidal. Their pollen exine sculptures were characterized by either a striate-perforation pattern or striate pattern, but perforation varied in terms of diameter and density and striae varied in depth and density. Palynomorphological assessment showed that three types of evolution, i.e., primitive, transitive, and evolved, were present among R. laxa botanical varieties, and pollen dimorphism was observed in the same botanical variety. Perprolate pollen with a dense striate pattern was the most evolved type. Based on morphological and palynomorphological investigations, var. tomurensis was considered to be the most evolved one among the studied botanical varieties.

Pollen morphology of North American species of Antennaria (Asteraceae: Inuleae)

1990 ◽  
Vol 68 (6) ◽  
pp. 1233-1238 ◽  
Author(s):  
J. G. Chmielewski ◽  
C. C. Chinnappa ◽  
B. G. Warner
Keyword(s):  
Electron Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Population Level ◽  
The Other ◽  
Future Studies ◽  
Small Pollen ◽  
Preliminary Study ◽  
Exine Morphology ◽  
Scanning Electron

The pollen of 90 individuals representing 28 species and subspecies in the genus Antennaria is described through the use of light and scanning electron microscopy. Two morphological groupings separated on the basis of exine morphology are evident from cluster analysis. One group consists of those species and subspecies in which the exine is perforate and the other group consists of those individuals in which the exine is not perforate (perforate-reticulate or striate-perforate-reticulate). These two pollen morphological groups do not correspond with previously defined groupings based on morphology or cytogenetics. Both large (> 19 μm in diameter) and small pollen grains occur in each of the cluster groups. Similarly, both long- (> 2 μm) and short-spined individuals occur in each of the cluster groups. Used in combination, these characters do however exhibit some sectional affinities. Section Alpinae is characterized by pollen grains with long spines. Section Dioicae is characterized by small pollen grains. Section Plantaginifoliae is characterized by large pollen grains with long spines. Species included in sections other than these are not consistent in their pollen morphology. The pollen groups recognized in this preliminary study form a basis for future studies at the geographic or population level.

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