Changes in cytoplasmic carbohydrate content during Helleborus pollen - PDF document

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/248971509 Changes in cytoplasmic carbohydrate content during Helleborus pollen presentation Article in Grana · January 2002 DOI: 10.1080/00173130260045459 CITATIONS READS 34 80 5 authors , including: Massimo Nepi Massimo Guarnieri Università degli Studi di Siena Università degli Studi di Siena 110 PUBLICATIONS 3,438 CITATIONS 37 PUBLICATIONS 621 CITATIONS SEE PROFILE SEE PROFILE Ettore Pacini Università degli Studi di Siena 215 PUBLICATIONS 6,894 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Boraginaceae View project Ovular secretion composition in anemophilous and ambophilous gymnosperms View project All content following this page was uploaded by Massimo Nepi on 20 November 2014. The user has requested enhancement of the downloaded file.

This article was downloaded by: [ Ingenta Content Distribution (Publishing Technology)] On: 13 October 2014, At: 19: 04 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Grana Publication details, including instructions for authors and subscription information: http:/ / www.tandfonline.com/ loi/ sgra20 Changes in cytoplasmic carbohydrate content during Helleborus pollen presentation José L. Vesprini , Massimo Nepi , Laura Cresti , Massimo Guarnieri & Ettore Pacini Published online: 05 Nov 2010. To cite this article: José L. Vesprini , Massimo Nepi , Laura Cresti , Massimo Guarnieri & Ettore Pacini (2002) Changes in cytoplasmic carbohydrate content during Helleborus pollen presentation, Grana, 41:1, 16-20, DOI: 10.1080/ 00173130260045459 To link to this article: http:/ / dx.doi.org/ 10.1080/ 00173130260045459 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http: / / www.tandfonline.com/ page/ terms-and-conditions

Grana 41: 16±20, 2002 Changes in cytoplasmic carbohydrate content during Helleborus pollen presentation  L. VESPRINI, MASSIMO NEPI, LAURA CRESTI, MASSIMO GUARNIERI and ETTORE PACINI JOSE Vesprini, J. L., Nepi, M., Cresti, L., Guarnieri, M. & Pacini, E. 2002. Changes in cytoplasmic carbohydrate content during Helleborus pollen presentation. ± Grana 41: 16±20. Pollen grains of Helleborus foetidus and H. bocconei were exposed to low temperature treatments to Downloaded by [Ingenta Content Distribution (Publishing Technology)] at 19:04 13 October 2014 simulate the natural events in pollen presentation of these two winter � owering species and to analyze the pollen carbohydrate content (glucose, fructose, sucrose and starch). In both species, cytoplasmic polysaccharides, monosaccharides and sucrose were found, while only Helleborus foetidus contained starch. Polysaccharide, sucrose and monosaccharide content varied as low temperature exposure time varied, a decrease in temperature decreases polysaccharide content and increases sucrose and monosac- charides. The relative quantities of the various types of carbohydrates were not a V ected by variations in the naturally occurring thermal cycles. Treatments did not greatly a V ect pollen viability. Although the occurrence of carbohydrates in pollen is known since many years, their function is still unclear. The � ndings of this research suggest a role of cytoplasmic pollen carbohydrates in resistance to low temperature exposure. The inter-conversion of carbohydrate type may be an adaptation for sustaining viability during pollen presentation that is particularly important for a winter � owering species such as Helleborus foetidus and H. bocconei . JoseÂL. Vesprini, Facultad de Ciencias Agrarias UNR. cc14 S2125ZAA Zavalla Argentina. Ettore Pacini (Corresp.Author), Massimo Nepi & Laura Cresti, Sezione Botanica, Dipartimento di Scienze Ambientali, Universita Á degli Studi di Siena, Via Mattioli 4, 53 100 Siena; Massimo Guarneri, Laboratorio Didattico di Biologia Sperimentale, C. Serv. Fac. Sci.Matem.Fis.Nat.,Universita Á di Siena, Via Laterina 8, 53 100 Siena; Italy. E-mail: pacini@unisi.it ( Manuscript received 12 July 2001; accepted 12 February 2002 ) The various types of carbohydrates found in pollen di V er The average lifetime of a pollen grain can range from a according to the degree of polymerisation, function and few hours to a few months, and seems to be linked to localisation (Franchi et al. 1996; Pacini 1996, Speranza et al. physiological characteristics such as water content during 1997). Carbohydrates in pollen grains can be found as dispersion and the type of carbohydrate present (Hoekstra monosaccharides, disaccharides, oligosaccharides and poly- & van Roekel 1988, Nepi & Pacini 1993, Pacini 1996). Nepi saccharides and may function either as structural carbohyd- et al. (2001) recognized two di V erent type of pollen on the rates or as metabolic reserves. Structural carbohydrates are basis of water content: partially hydrated pollen (PHP, water content > 30 % ) and partially dehydrated pollen (PDP, water polysaccharides, while reserves usually include monomers, and polymers of di V erent molecular weight. Stored carbohyd- content < 30 % ). Generally pollen longevity is shorter in PHP rates are either dissolved in the cytoplasm or found in vesicles than in PDP because PHP tends to lose water causing a or plastids. The most common soluble carbohydrates are decrease of viability (Nepi et al. 2001). In some Poaceae glucose and fructose (monosaccharides) and sucrose (disacch- species, fructose and glucose content decreased in non-viable arides) (Speranza et al. 1997). Other soluble sugars found in pollen compared with viable pollen grains (Stanley & lesser amounts include ra Y nose, stachyose, ramnose and Linskens 1974). Speranza et al. (1997) showed that species arabinose (Stanley & Linskens 1974). with short-lived pollen have a low amount of soluble carbo- Starch is the most common polysaccharide reserve and is hydrates while, species with long-lived pollen have higher contained in amyloplasts. The presence of starch in mature amount of soluble carbohydrates and contain cytoplasmic pollen and its chemicophysical aspects have been investigated polysaccharides. The authors found a negative correlation from a taxonomic and ecological viewpoint by Baker & between starch content and sucrose in a number of species. Baker (1979) and by Franchi et al. (1996); these last authors Sucrose was shown to protect membranes in dehydrated pointed out the presence of polysaccharide reserves in the pollen (Hoekstra et al. 1989, 1991, 1992). cytoplasm. Carbohydrate content also varies in relation to the condi- Carbohydrates in pollen grains are not only structural or tions in which pollen is stored. Pine pollen maintained at reserves, but they seem to have a role in determining pollen 5 ß C and RH 25 % for 15 years has been shown to have longevity, although the biochemistry and physiology of such decreased glucose and oligosaccharide levels and less ger- process is not completely known (Hoekstra & van Roekel mination ability compared with that kept at the same temper- 1988, Hoekstra et al. 1989, 1992; Pacini 1996, Speranza ature and period but at RH 10 % (Stanley & Linskens 1974). et al. 1997). The aim of this study is to evaluate how carbohydrate Ñ 2002 Taylor & Francis. ISSN 0017-3134 Grana 41 (2002)