Aspects Of Pollination Biology Research Articles

Nocturnal and diurnal pollination in Copaifera coriacea, a dominant species in sand dunes of the Middle São Francisco River Basin, Northeastern Brazil

Background and aims – Copaifera coriacea, a species in the resin-producing clade Detarioideae (Leguminosae), is an endemic and abundant species found in sand dunes in Brazilian Caatinga domain vegetation – a Quaternary paleodesert. We investigated floral traits and aspects of pollination biology, focusing on the pollination system of C. coriacea. Material and methods – Anthesis duration, stigma receptivity, pollen viability, nectar concentration, and the presence of osmophores and pigments reflecting UV light were assessed. Floral visitors were classified as potential pollinators, occasional pollinators or thieves, based on the time and foraging behaviour and resource collected. Pollination effectiveness were assessed for potential pollinators by the detection of pollen tubes on the stigma or stylar canal by epifluorescence microscopy.Key results – The species has white and small flowers, with anthesis beginning in the dark (ca 00:30) and the flowers are completely opened approximately 3 h later, when a sweet odour is perceptible. The onset of stigma receptivity and pollen grain viability occurs only after the completion of flower opening, and a concentrated nectar is available during the day. The presence of pollen tubes confirmed the efficiency of the main insects in the transfer of pollen. Conclusion – Our result demonstrates that C. coriacea has a generalist pollination system mediated mainly by two distinct guilds of insect pollinators: moths (nocturnal, searching for nectar) and bees (diurnal, pollen collectors). This finding can provide more information about diversification in the genus Copaifera.

Viability and longevity of pollen from transgenic and nontransgenic tall fescue (Festuca arundinacea) (Poaceae) plants

Pollen is an important vector of gene flow in plants, particularly for outcrossing species like tall fescue. Several aspects of pollination biology were investigated using pollen from transgenic and nontransgenic plants of tall fescue (Festuca arundinacea Schreb.), the most important forage species worldwide of the Festuca genus. To effectively assess in vitro pollen viability in tall fescue, an optimized germination medium (0.8 mol/L sucrose, 1.28 mmol/L boric acid and 1.27 mmol/L calcium nitrate) was developed. Treatment with relatively high temperatures (36° and 40°C) and high doses of UV-B irradiation (900-1500 μW/cm(2)) reduced pollen viability, while relative humidity did not significantly influence pollen viability. Viability of pollen from transgenic progenies (T1 and T2) was similar to that from seed-derived control plants. Pollen from primary transgenics (T0) and primary regenerants (R0) had various levels of viability. Hand pollination using the primary regenerants and transgenics revealed that no seed set could be obtained when pollen viability was lower than 5%. Pollen from transgenic progenies and nontransgenic control plants could survive up to 22 h under controlled conditions in growth chamber. However, under sunny atmospheric conditions, viability of transgenic and nontransgenic pollen reduced to 5% in 30 min, with a complete loss of viability in 90 min. Under cloudy atmospheric conditions, pollen remained viable up to 240 min, with about 5% viability after 150 min. This report is the first on pollen viability and longevity in transgenic forage grasses and could be useful for risk assessment of transgenic plants.

Biologia floral e sistema de reprodução de Annona squamosa L. (Annonaceae) na região de Petrolina-PE

Aspectos da biologia da polinização e do sistema de reprodução de Annona squamosa L. foram estudados em Petrolina-PE, nordeste do Brasil, no período de junho de 1999 a fevereiro de 2000, entre 6:00 e 18:00h. As flores de A. squamosa são hermafroditas, axilares, com cálice e corola carnosos, formando uma câmara floral, que funciona como abrigo, fonte alimentar e/ou local de acasalamento para os visitantes florais. As flores apresentam características da síndrome de cantarofilia, tais como pétalas carnosas, de coloração clara e emissão de odores fortes e desagradáveis. A antese é crepuscular, iniciando por volta das 17 horas e a duração das flores é de aproximadamente dois dias. As flores se apresentam em fase feminina nas primeiras 20 horas e em fase masculina nas 20 horas seguintes, caracterizando a dicogamia. Carpophilus hemipterus, Carpophilus sp e Haptoncus ochraceus (Nitidulidae) são os principais visitantes, sendo considerados como polinizadores desta anonácea. A espécie é autocompatível, contudo, os testes de germinação indicam que as sementes obtidas por polinização cruzada apresentam maior viabilidade do que as resultantes de geitonogamia.

Biotic pollination mechanisms in the Australian flora — a review

Abstract Various aspects of pollination biology in Australia are examined and the relevant literature is reviewed in detail. The history of Australian pollination studies is briefly discussed and particular emphasis given to the contributions made by some of the more outstanding workers in this field. The enormous diversity of the pollen-vector fauna is documented and emphasis given to the adaptations of particular vector types and of the blossoms that they visit. The pollination role of the Australian invertebrate fauna is discussed and an assessment made of the proportion of anthophilous (i.e., flower-frequenting) taxa in various insect groups. Critical examination of recorded feeding habits of the Australian coleopteran and dipteran faunas reveals that at least 28 of the 121 coleopteran families (i.e., 23%) and 44 of the 87 dipteran families (i.e., 51%) contain anthophilous species. The Australian bee fauna, consisting of c. 3000 species, is exclusively anthophilous and constitutes the most important group of invertebrate pollinators; a comprehensive table listing those bee taxa that have been recorded visiting the blossoms of native plant genera, is provided. Two vertebrate pollination systems are important in the Australian context: ornithophily, involving flower-visiting birds as the pollen vectors, and therophily whereby flying or non-flying mammals act as the pollen transporters. Mammal pollination (therophily) is discussed at length, and several new terms introduced to describe the syndromes of marsupial (metatherophily), placental (eutherophily), and rodent (sminthophily) pollination respectively; comprehensive tables listing the anthophilous chiropteran and marsupial taxa of Australia are also provided. The role of various types of pollen vectors in promoting convergent and divergent floral evolution in the Australian flora is illustrated with examples from selected plant taxa. New information on the pollination biology of the tribe Boronieae (Rutaceae) is presented, and some of the more unusual floral adaptations noted. The review concludes by emphasising those areas where future research is needed and where broad co-operative studies would be most productive.