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Articles 61 - 90 of 125

Full-Text Articles in Life Sciences

Verbascum Hasbenlii (Scrophulariaceae), A New Species From Turkey, Zeki̇ Aytaç, Hayri̇ Duman Jan 2012

Verbascum Hasbenlii (Scrophulariaceae), A New Species From Turkey, Zeki̇ Aytaç, Hayri̇ Duman

Turkish Journal of Botany

Verbascum hasbenlii Aytaç & H.Duman sp. nov. (sect. Bothrosperma Murb.) is described and illustrated from Turkey. This new species was collected in B1 Çan (Çanakkale Province) area. V. hasbenlii appears to be closely allied to V. luciliae (Boiss.) O.Kuntze and V. haraldi-adnani Parolly & Eren. Its affinities with this and other related species are discussed. The characteristic features of pollen, seed, stomata structure, and hairs are studied using a scanning electron microscope and the distribution of the new species in Turkey is given.


Developing Biocontainment Strategies To Suppress Transgene Escape Via Pollen Dispersal From Transgenic Plants, Hong Seok Moon Aug 2011

Developing Biocontainment Strategies To Suppress Transgene Escape Via Pollen Dispersal From Transgenic Plants, Hong Seok Moon

Doctoral Dissertations

Genetic engineering is important to enhance crop characteristics and certain traits. Genetically engineered crop cultivation brings environmental and ecological concerns with the potential of unwanted transgene escape and introgression. Transgene escape has been considered as a major environmental and regulatory concern. This concern could be alleviated by appropriate biocontainment strategies. Therefore, it is important to develop efficient and reliable biocontainment strategies.

Removing transgenes from pollen has been known to be the most environmentally friendly biocontainment strategy. A transgene excision vector containing a codon optimized serine resolvase CinH recombinase (CinH) and its recognition sites RS2 were constructed and transformed into tobacco …


Developmental Evolution Of The Progamic Phase In Nymphaeales, Mackenzie Lorraine Taylor May 2011

Developmental Evolution Of The Progamic Phase In Nymphaeales, Mackenzie Lorraine Taylor

Doctoral Dissertations

The period between pollination and fertilization, or the progamic phase, is a critical life history stage in seed plants and innovations in this life history stage are hypothesized to have played an important role in the diversification of flowering plants. Over the course of this dissertation research, I investigated programic phase development in Nymphaeales (water lilies), an ancient angiosperm lineage that diverged from the basalmost or next most basal node of the angiosperm phylogenetic tree and that is represented in the oldest angiosperm fossil record. I used field experiments and microscopy to document pollination biology, breeding system, and reproductive developmental …


Pollen Morphology Of The Genus Seseli L. (Umbelliferae) In Turkey, Ebru Doğan Güner, Hayri̇ Duman, Nur Münevver Pinar Jan 2011

Pollen Morphology Of The Genus Seseli L. (Umbelliferae) In Turkey, Ebru Doğan Güner, Hayri̇ Duman, Nur Münevver Pinar

Turkish Journal of Botany

Morphological features of pollen of 11 Turkish taxa belonging to the complex genus Seseli L. were examined using light and scanning electron microscopy. On the basis of exine sculpturing, 3 main types were recognised in Seseli: Type 1, rugulate at equator, psilate-perforate at pole; Type 2, striate-reticulate at equator, rugulate at pole; and Type 3, rugulate at equator, striate at pole. The study revealed that palynological characters display taxonomic significance in the genus.


Pollen Analysis Of Honeys From Varaždin County, Croatia, Mirjana Sabo, Mirjana Potocnjak, Ines Banjari, Danijela Petrovic Jan 2011

Pollen Analysis Of Honeys From Varaždin County, Croatia, Mirjana Sabo, Mirjana Potocnjak, Ines Banjari, Danijela Petrovic

Turkish Journal of Botany

The palynological properties of 8 honey samples commercially produced in 1 region in Croatia (Varazdin County) were determined. Each sample was examined to determine the pollen percentage and pollen spectrum. On the basis of honey pollen analysis, in these 8 samples different botanical origin was determined. In total, 20 different types of pollen grains were identified. The dominant group of pollen grains consisted of Castanea sativa Mill. in samples 2 and 8, Brassica napus L. in samples 4 and 5, and Trifolium pratense L. in samples 6 and 7. The pollen analysis revealed 6 unifloral and 2 multifloral honeys. Analysis …


What Brown Saw And You Can Too, Philip Pearle, Brian Collett, Kenneth Bart, David Bilderback, Dara Newman, D. Scott Samuels Dec 2010

What Brown Saw And You Can Too, Philip Pearle, Brian Collett, Kenneth Bart, David Bilderback, Dara Newman, D. Scott Samuels

Biological Sciences Faculty Publications

A discussion of Robert Brown’s original observations of particles ejected by pollen of the plant Clarkia pulchella undergoing what is now called Brownian motion is given. We consider the nature of those particles and how he misinterpreted the Airy disk of the smallest particles to be universal organic building blocks. Relevant qualitative and quantitative investigations with a modern microscope and with a “homemade” single lens microscope similar to Brown’s are presented.


Fire Regime Dynamics Following The Mid-Holocene Hemlock Decline In Eastern North America, Kennedy Helm Clark May 2010

Fire Regime Dynamics Following The Mid-Holocene Hemlock Decline In Eastern North America, Kennedy Helm Clark

Open Access Dissertations

Approximately 5,000 years ago, eastern hemlock (Tsuga canadensis) experienced a sudden, rapid, range-wide decline most probably due to pest, disease, or climate change. An aphid-like defoliating insect, the hemlock woolly adelgid (Adelges tsugae), recently (1950’s) introduced to eastern North America has been spreading across the eastern United States. The adelgid attacks all size and age classes of hemlocks causing up to 95% mortality in affected stands. The potential for another range-wide hemlock decline has raised a number of concerns including the increased threat of wildfire. Altered fuel loadings in modern adelgid-affected stands and the effects of presumably similar changes in …


A New Species Of Echinops (Asteraceae) From Turkey, Cem Vural, Mustafa Kemal Bi̇ter, Mehmet Yaşar Dadandi Jan 2010

A New Species Of Echinops (Asteraceae) From Turkey, Cem Vural, Mustafa Kemal Bi̇ter, Mehmet Yaşar Dadandi

Turkish Journal of Botany

Echinops dumanii C.Vural is described and illustrated from Adana province, South Anatolia, Turkey. It is considered to be endemic to Turkey. The morphological differences from the closely related species Echinops phaeocephalus Hand.-Mazz. are discussed. The International Union for Conservation of Nature (IUCN) threat category and observations on the ecology of the populations are noted. The geographical distribution of the new species is mapped.


Pollen Interception By Linyphiid Spiders In A Corn Agroecosystem: Implications For Dietary Diversification And Risk-Assessment, Julie A. Peterson, Susan Romero, James D. Harwood Jan 2010

Pollen Interception By Linyphiid Spiders In A Corn Agroecosystem: Implications For Dietary Diversification And Risk-Assessment, Julie A. Peterson, Susan Romero, James D. Harwood

West Central Research and Extension Center, North Platte

Dietary diversification, including consumption of plant tissues such as pollen, can enhance the fecundity of generalist predators, resulting in improved control of pest prey. Supplemental pollen feeding has been observed in many natural enemies, including sheet-web spiders (Araneae: Linyphiidae), which represent a major component of food webs in agroecosystems. Their horizontal, ground-based webs have the potential to intercept pollen grains during anthesis of crop plants, providing the opportunity for consumption of pollen to occur. In laboratory feeding trials, Frontinella communis and Tennesseellum formicum (Araneae: Linyphiidae) readily fed on pollen grains dusted on their webs, with 82 and 92% of spiders …


Pollen And Seed Morphology Of Velezia L. (Caryophyllaceae) Genus In Turkey, İlham Eröz Poyraz, Ebru Ataşlar Jan 2010

Pollen And Seed Morphology Of Velezia L. (Caryophyllaceae) Genus In Turkey, İlham Eröz Poyraz, Ebru Ataşlar

Turkish Journal of Botany

In this study, pollen and seed morphology of Velezia L. (Caryophyllaceae) species in Turkey were investigated by light and scanning electron microscopy. The genus is represented by 5 species in Turkey: V. tunicoides P.H.Davis, V. hispida Boiss., V. quadridentata Sibth. & Sm., V. pseudorigida Hub.-Mor. and V. rigida L. Endemism ratio of the genus is 60%, which shows that Turkey is the gene center for this genus. The pollen grains of Velezia species are radially symmetrical and isopolar, oblate-spheroidal, operculate, and polypantoporate, pores with conical spinules on operculum. Pollen ornamentation, pore numbers, exine thickness, pore diameter, operculum ornamentation, and spinule …


Comparative Rapd Analysis And Pollen Structure Studies Of Bellis Perennis L., Nesli̇han Kavalcioğlu, Leyla Açik, Nur Münevver Pinar Jan 2010

Comparative Rapd Analysis And Pollen Structure Studies Of Bellis Perennis L., Nesli̇han Kavalcioğlu, Leyla Açik, Nur Münevver Pinar

Turkish Journal of Botany

Random amplified polymorphic DNA (RAPD) is one of the easiest and most commonly used molecular techniques for genetic variability analysis. In the present study, the genetic diversity of analysis of Bellis perennis L. collected in 4 Turkish geographical locations was investigated by RAPD-PCR analysis. In addition to RAPD, pollen analysis of the 4 plant populations was also conducted. Out of 40 RAPD primers tested, 12 exhibited distinct banding patterns showing 45% to 79% polymorphism. Plants from these 4 localities were almost the same morphologically. Considerable differences were observed in the RAPD profile and pollen shape of plants from the Rize/Dereköy …


Functional Analysis Of Receptor-Like Kinases In Pollen-Pistil Interactions In Arabidopsis Thaliana, Mini Aggarwal Jan 2009

Functional Analysis Of Receptor-Like Kinases In Pollen-Pistil Interactions In Arabidopsis Thaliana, Mini Aggarwal

Masters Theses 1911 - February 2014

Rac/Rop GTPases are molecular switches in plants that control the growth of polarized cells such as pollen tubes and root hairs, differentiation, development, actin dynamics, production of reactive oxygen species (ROS) and disease resistance. These small GTPases are activated by guanine nucleotide exchange factors (GEFs) that replace GDP for GTP and are referred to as RopGEFs in plants. To identify upstream components of the RopGEF regulated signaling pathways, GEF1 from Arabidopsis thaliana was used as a bait to screen a seedling cDNA library in a yeast two-hybrid system. This yielded members of a small family of the Catharanthus roseus Receptor-like …


Lap3, A Novel Plant Protein Required For Pollen Development, Is Essential For Proper Exine Formation, Anna A. Dobritsa, Shuh-Ichi Nishikawa, Daphne Preuss, Ewa Urbanczyk-Wochniak, Lloyd W. Sumner, Adam Hammond, Ann L. Carlson, Rob Swanson Jan 2009

Lap3, A Novel Plant Protein Required For Pollen Development, Is Essential For Proper Exine Formation, Anna A. Dobritsa, Shuh-Ichi Nishikawa, Daphne Preuss, Ewa Urbanczyk-Wochniak, Lloyd W. Sumner, Adam Hammond, Ann L. Carlson, Rob Swanson

Biology Faculty Publications

We isolated lap3-1 and lap3-2 mutants in ascreen for pollen that displays abnormal stigma binding.Unlike wild-type pollen, lap3-1 and lap3-2 pollen exine isthinner, weaker, and is missing some connections betweentheir roof-like tectum structures. We describe the mappingand identification of LAP3 as a novel gene that contains arepetitive motif found in b-propeller enzymes. Insertionmutations in LAP3 lead to male sterility. To investigatepossible roles for LAP3 in pollen development, we assayedthe metabolite profile of anther tissues containing developingpollen grains and found that the lap3-2 defect leadsto a broad range of metabolic changes. The largest changeswere seen in levels of a straight-chain hydrocarbon …


Pollen And Seed Morphology Of The Genus Hesperis L. (Brassicaceae) In Turkey, Münevver Pinar, Ahmet Duran, Tali̇p Çeter, G. Ni̇lhan Tuğ Jan 2009

Pollen And Seed Morphology Of The Genus Hesperis L. (Brassicaceae) In Turkey, Münevver Pinar, Ahmet Duran, Tali̇p Çeter, G. Ni̇lhan Tuğ

Turkish Journal of Botany

Pollen and seed morphology were examined in 35 specimens representing 25 Turkish species of the taxonomically complex genus Hesperis L. by light and scanning electron microscopes. Three main types and 2 subtypes were recognized based on the seed coat surface, pollen shape, and exine sculpturing. The seed coat ornamentation of Type I was ocellate, and pollen shape was oblate-spheroidal. While Type II was represented by reticulate seed coat and prolate-spheroidal pollen shape, Type III had tuberculate seed coat. This study revealed that both palynological and seed morphological characters are of significant importance in the taxonomy of the genus.


Investigations On The Pollen Morphology Of Some Fruit Species, Yasemi̇n Evrenosoğlu, Adalet Misirli Jan 2009

Investigations On The Pollen Morphology Of Some Fruit Species, Yasemi̇n Evrenosoğlu, Adalet Misirli

Turkish Journal of Agriculture and Forestry

Morphological characters are used to identify plant material. Pollen morphology is an important parameter. This is of great importance in detailed investigations by scanning electron microscope (SEM). In order to develop a plant material identification tool, this research was carried out to determine the pollen morphology of some fruit species using SEM on apple, pear, quince, apricot, plum, peach, almond, chestnut, walnut, pomegranate, and persimmon cultivars. The surface features, as well as length, width, and P/E ratio of pollen were observed. Pollen length and width changed with investigated species and cultivars; the longest and widest pollen grains were detected in …


Pollen Morphology Of Some Gypsophila L. (Caryophyllaceae) Species And Its Taxonomic Value, Ebru Ataşlar, İsmühan Potoğlu Erkara, Süleyman Tokur Jan 2009

Pollen Morphology Of Some Gypsophila L. (Caryophyllaceae) Species And Its Taxonomic Value, Ebru Ataşlar, İsmühan Potoğlu Erkara, Süleyman Tokur

Turkish Journal of Botany

Pollen morphology of 12 taxa (6 of them endemic) that belong to the genus Gypsophila L. were investigated using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Differences in pollen morphology between these taxa were determined based on palynological studies. Pollen grains are spheroidal and polyporate. The exine structure is tectate, but that of G. sphaerocephala var. sphaerocephala is intectate. The exine sculpture is granulate-microechinate-microperforate, but that of G. sphaerocephala var. sphaerocephala displays clavate-microechinate ornamentation. The operculum exists in the form of scattered pieces in G. curvifolia, while it exists as a whole in the other …


Pollen From Western Australia At A Glance, Rob Manning Sep 2008

Pollen From Western Australia At A Glance, Rob Manning

Bulletins 4000 -

Western Australian pollen proteins are high compared to many other plant species. Banksia pollens are highest at greater than 30% followed by eucalypt and acacia, which range from 20-28%.


Nectar Secondary Compounds Affect Self-Pollen Transfer: Implications For Female And Male Reproduction, Rebecca E. Irwin, Lynn S. Adler Aug 2008

Nectar Secondary Compounds Affect Self-Pollen Transfer: Implications For Female And Male Reproduction, Rebecca E. Irwin, Lynn S. Adler

Dartmouth Scholarship

Pollen movement within and among plants affects inbreeding, plant fitness, and the spatial scale of genetic differentiation. Although a number of studies have assessed how plant and floral traits influence pollen movement via changes in pollinator behavior, few have explored how nectar chemical composition affects pollen transfer. As many as 55% of plants produce secondary compounds in their nectar, which is surprising given that nectar is typically thought to attract pollinators. We tested the hypothesis that nectar with secondary compounds may benefit plants by encouraging pollinators to leave plants after visiting only a few flowers, thus reducing self-pollen transfer. We …


The Effects Of Feeding Pollen Cake Containing Royal Jelly On Bombus Terrestris L. (Hymenoptera: Apidae) Colony Development, Fehmi̇ Gürel, Ayhan Gösteri̇t Jan 2008

The Effects Of Feeding Pollen Cake Containing Royal Jelly On Bombus Terrestris L. (Hymenoptera: Apidae) Colony Development, Fehmi̇ Gürel, Ayhan Gösteri̇t

Turkish Journal of Veterinary & Animal Sciences

This study was performed to determine the effects of feeding pollen cake containing honeybee royal jelly on Bombus terrestris colony development. In total, 125 bumblebee queens, 68 of which were fed pollen cake containing 10% royal jelly and 57 of which were fed normal pollen cake, were used. We found that 84% of the queens fed pollen cake containing royal jelly and 82% of those fed normal pollen cake laid eggs; 56% of the queens fed normal pollen cake established colonies, whereas queens fed pollen cake containing royal jelly did not establish any colonies and their larvae died. The results …


The Structure And Ultra Structure Of Anther Epidermis And Pollen In Lagerstroemia Indica L. (Lythraceae) In Response To Air Pollution, Farkhondeh Rezanejad Jan 2008

The Structure And Ultra Structure Of Anther Epidermis And Pollen In Lagerstroemia Indica L. (Lythraceae) In Response To Air Pollution, Farkhondeh Rezanejad

Turkish Journal of Botany

The structure of the anthers and pollen of Lagerstroemia indica L. (crepe myrtles) (Lythraceae) in samples collected from clean and polluted areas was studied by OM, SEM, and TEM. The epidermal cells of the anthers enlarged during anther development. Their cuticle content increased and became thick and folded. The cytoplasm of epidermal cells was peripheral and degenerated in mature anthers. At this time, their major content was phenolic compounds. The epidermal cells in the anthers collected from polluted areas were shrunken, fragile, and burned at the tip, compared to those collected from non-polluted areas. Flavonoid stainability was greater in the …


Inflorescence Architecture And Floral Morphology Of Aratitiyopea Lopezii (Xyridaceae), Lisa M. Campbell, Dennis Wm. Stevenson Dec 2007

Inflorescence Architecture And Floral Morphology Of Aratitiyopea Lopezii (Xyridaceae), Lisa M. Campbell, Dennis Wm. Stevenson

Aliso: A Journal of Systematic and Floristic Botany

Aratitiyopea lopezii is a robust perennial species of Xyridaceae from seasonally saturated, mid- to high-elevation, sandstone and granite sites in northern South America. The species lacks the scapose inflorescence characteristic of Xyridaceae and, having the gestalt of a rhizomatous bromeliad, it is seemingly aberrant in the family. However, closer examination confirms features consistent with the family and the previously noted morphological similarities to Orectanthe. Details of inflorescence structure and floral morphology are presented and compared to other genera of Xyridaceae.


Determination Of Pollen Production And Quality Of Some Local And Foreign Walnut Genotypes In Turkey, Mehmet Sütyemez Jan 2007

Determination Of Pollen Production And Quality Of Some Local And Foreign Walnut Genotypes In Turkey, Mehmet Sütyemez

Turkish Journal of Agriculture and Forestry

The pollen grains of 32 different walnut cultivars and types were tested in vitro to determine their viability, germination ability, and pollen production level. Viability of pollens was determined by TTC and FDA tests. The hanging drop method and agar in petri method were used for pollen germination. Pollen production of the cultigens was determined with the hemacytometric method. The rate of pollen viability of all the investigated cultigens was high (> 80%). The germination rate of the pollens ranged from 33.28% to 50.19% and the Van 4 cultivar had the highest pollen germination rate. Although similar results were obtained …


The Operculum In Pollen Of Monocotyledons, Carol A. Furness, Paula J. Rudall Jan 2006

The Operculum In Pollen Of Monocotyledons, Carol A. Furness, Paula J. Rudall

Aliso: A Journal of Systematic and Floristic Botany

Within monocotyledons, monosulcate pollen is the predominant type and probably represents the plesiomorphic condition, but considerable variation occurs in sulcus morphology. An operculum is an exine thickening that covers most of an aperture. Monocot opercula are usually associated with sulci, although they can occur in ulcerate apertures, as in Poaceae. There are several other aperture types closely related to the monosulcate-operculate type, and confusion occurs in the palynological literature between monosulcate-operculate, pontoperculate, disulculate, disulcate, and zona-aperturate (zonasulculate or zonasulcate) pollen. Transmission electron microscopy (TEM) was used to determine the distribution of the thick apertural intine and to accurately identify these …


Aperture Pattern And Microsporogenesis In Asparagales, Sophie Nadot, Laurent Penet, Leanne D. Dreyer, Arlette Forchioni, Adrienne Ressayre Jan 2006

Aperture Pattern And Microsporogenesis In Asparagales, Sophie Nadot, Laurent Penet, Leanne D. Dreyer, Arlette Forchioni, Adrienne Ressayre

Aliso: A Journal of Systematic and Floristic Botany

The aperture pattern of pollen grains is a character defined as the number, shape, and position of apertures. Although this character is highly variable in angiosperms, two states are particularly widespread. Pollen grains with one polar aperture occur frequently in basal angiosperms and monocots while tricolpate pollen is a synapomorphy of the eudicots. Many morphological characters are the result of a compromise between selective forces (acting on morphology) and developmental constraints (limiting the range of possible morphologies). To investigate what are the respective roles of development and selection in the determination of aperture pattern in angiosperms, we have chosen to …


Morphological And Palynological Investigation On Silene Gigantea L. Var. Gigantea And Silene Behen L. (Caryophyllaceae) Distributed In Western Anatolia And Northern Cyprus, Kemal Yildiz Jan 2006

Morphological And Palynological Investigation On Silene Gigantea L. Var. Gigantea And Silene Behen L. (Caryophyllaceae) Distributed In Western Anatolia And Northern Cyprus, Kemal Yildiz

Turkish Journal of Botany

A comparative investigation was carried out on the morphology and palynology of Silene gigantea L. var. gigantea and Silene behen L. species of the family Caryophyllaceae distributed in Western Anatolia and Northern Cyprus. An examination conducted on S. gigantea var. gigantea revealed that the calyx length in Western Anatolian specimens was shorter than that of those from Northern Cyprus, that the basal petal blades of the Western Anatolian specimens did not have any ligula while those from Northern Cyprus did, and that the petal blades belonging to the specimens from Northern Cyprus demonstrated less clefting as compared to those from …


Identification Of A Lactic Bacterium Strain Used For Obtaining A Pollen-Based Probiotic Product, Adrian Vamanu, Emanuel Vamanu, Manuel Drugulescu, Ovidiu Popa, Gheorghe Campeanu Jan 2006

Identification Of A Lactic Bacterium Strain Used For Obtaining A Pollen-Based Probiotic Product, Adrian Vamanu, Emanuel Vamanu, Manuel Drugulescu, Ovidiu Popa, Gheorghe Campeanu

Turkish Journal of Biology

This study concerns the identification of a Lactobacillus acidophilus strain by conventional taxonomic techniques (cultivation at different temperatures, different pH values, use of different carbon sources, development on different media and determination of antibioresistance) and by molecular genetic techniques (determination of G and C content). The strain is used for inoculation in media with ground or unground pollen and honey, in order to obtain a probiotic product. Over 72 h the glucid consumption, cell viability and acid production is measured.


Registros De Sedimentos Lacustres De La Vegetación Del Holoceno Y Historia Del Fuego En El Páramo De Costa Rica. (Lake-Sediment Records Of Holocene Vegetation And Fire History In The Costa Rican Páramos), Sally P Horn, Brandon L. League Jan 2005

Registros De Sedimentos Lacustres De La Vegetación Del Holoceno Y Historia Del Fuego En El Páramo De Costa Rica. (Lake-Sediment Records Of Holocene Vegetation And Fire History In The Costa Rican Páramos), Sally P Horn, Brandon L. League

Geography Publications and Other Works

We examined pollen, pteridophyte (ferns and fern-allies) spores, and charcoal in a 5.6 m long sediment core from Lago de las Morrenas 1, and charcoal in a 1.1 m long sediment core from Lago Chirripó, to reconstruct postglacial vegetation and fire history in the Chirripó páramo. Lago de las Morrenas 1, the largest lake in the Valle de las Morrenas of Chirripó National Park, is presently surrounded by treeless páramo vegetation and has apparently been so since deglaciation approximately 10,000 radiocarbon years ago. Pollen spectra suggest no pronounced changes in vegetation since ice retreat. Pollen percentages for Gramineae and other …


Palynological Study On The Pollen Grains Of Selected Turkish Grape (Vitis Vinifera L.) Cultivars, Bi̇rhan Marasali, Münevver Pinar, H. Nurhan Büyükkartal Jan 2005

Palynological Study On The Pollen Grains Of Selected Turkish Grape (Vitis Vinifera L.) Cultivars, Bi̇rhan Marasali, Münevver Pinar, H. Nurhan Büyükkartal

Turkish Journal of Agriculture and Forestry

The pollen morphology and ultrastructure of selected Turkish indigenous grape cultivars and newly released hybrid varieties were examined by light microscopy and scanning electron microscopy. The pollen differed in some microstructural parameters. The size of the pollen grains ranged from 19.0 x 22.4 µm in Beyaz Çavuş to 24.3 x 21.0 µm in Siyah Gemre. Hönüsü cultivar showed significant variations in the sizes of the polar and equatorial axes. The greatest colpus size was measured in Siyah Gemre (18.4 µm) and the longest pore size was observed in Ata sarısı (28 µm). The exine thickness of the pollen grains ranged …


Alkaloids And Old Lace: Pollen Toxins Exclude Generalist Pollinators From Death Camas, Melissa Weber May 2004

Alkaloids And Old Lace: Pollen Toxins Exclude Generalist Pollinators From Death Camas, Melissa Weber

Undergraduate Honors Capstone Projects

Many plants produce toxins to which specialist herbivores - typically insects - have evolved counter-adaptations, sometimes resulting in a co-evolutionary arms race. Although many non-social bee species are likewise taxonomic host specialists, the pollination guilds at their floral hosts frequently include diverse floral generalists as well, even on plants that are otherwise chemically defended. In this study, we show that pollen and nectar of foothills death camas (Toxicoscordion [=Zigadenus] paniculatum) contains zygacine, the alkaloid responsible for this plant's notorious mammalian toxicity. Many adults and larvae of the generalist solitary bee, Osmia lignaria (Megachilidae), were paralyzed and …


Species Specificity In Pollen-Pistil Interactions, Rob Swanson Dec 2003

Species Specificity In Pollen-Pistil Interactions, Rob Swanson

Rob Swanson

For pollination to succeed, pollen must carry sperm through a variety of different floral tissues to access the ovules within the pistil. The pistil provides everything the pollen requires for success in this endeavor including distinct guidance cues and essential nutrients that allow the pollen tube to traverse enormous distances along a complex path to the unfertilized ovule. Although the pistil is a great facilitator of pollen function, it can also be viewed as an elaborate barrier that shields ovules from access from inappropriate pollen, such as pollen from other species. Each discrete step taken by pollen tubes en route …