Journal Article

Fructokinase and Hexokinase from Pollen Grains of Bell Pepper (<i>Capsicum annuum</i> L.): Possible Role in Pollen Germination under Conditions of High Temperature and CO<sub>2</sub> Enrichment

LEAH KARNI and BENY ALONI

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 90, issue 5, pages 607-612
Published in print November 2002 | ISSN: 0305-7364
Published online November 2002 | e-ISSN: 1095-8290 | DOI: https://dx.doi.org/10.1093/aob/mcf234
Fructokinase and Hexokinase from Pollen Grains of Bell Pepper (Capsicum annuum L.): Possible Role in Pollen Germination under Conditions of High Temperature and CO2 Enrichment

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  • Ecology and Conservation
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The processes of pollen grain development and germination depend on the uptake and metabolism of pollen sugars. In pepper (Capsicum annuum L.), initial sugar metabolism includes sucrose hydrolysis by invertase and subsequent phosphorylation of glucose and fructose by hexose kinases. The main objective of this study was to investigate changes in fructokinase (EC 2.7.1.4) and hexokinase (EC.2.7.1.1) activities in pepper flowers during their development, and to study the possible roles of these enzymes in determining pollen germination capacity under high temperature and under CO2 enrichment, previously shown to modify sugar concentrations in pepper pollen (Aloni et al., 2001 Physiologia Plantarum 112: 505–512). Fructokinase (FK) activity was predominant in pepper pollen, and increased during pollen maturation. Pollen hexokinase (HK) activity was low and did not change throughout pollen development. High‐temperature treatment (day/night, 32/26 °C) of pepper plants reduced the percentage of pollen that germinated compared with that under normal temperatures (26/22 °C), and concomitantly reduced the activity of FK in mature pollen. High temperature also reduced FK and HK activity in the anther. Under high ambient CO2 (800 µl l–1) pollen FK activity was enhanced. The results suggest that pollen and anther FK may play a role in the regulation of pollen germination, possibly by providing fructose‐6‐phosphate for glycolysis, or through conversion to UDP‐glucose (UDPG) to support the biosynthesis of cell wall material for pollen tube growth. High temperature stress and CO2 enrichment may influence pollen germination capacity by affecting these pathways.

Keywords: Key words: (Capsicum annuum L.), pollen, fructokinase, hexokinase, high temperature.

Journal Article.  3822 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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