AOBPreview originally published online on May 30, 2006
Annals of Botany 2006 98(1):107-115; doi:10.1093/aob/mcl115
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The Unique Pollen Morphology of Duparquetia (Leguminosae: Caesalpinioideae): Developmental Evidence of Aperture Orientation Using Confocal Microscopy
1 Micromorphology Group, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AE, UK and 2 Natural History Museum, Cromwell Road, London SW7 5BD, UK
* For correspondence. E-mail h.banks{at}rbgkew.org.uk
Received: 1 November 2005 Returned for revision: 14 February 2006 Accepted: 15 March 2006 Published electronically: 30 May 2006
• Background and Aims The phylogenetic affinities of the aberrant monotypic genus Duparquetia (subfamily Caesalpinioideae) are at present unresolved. Preliminary results from molecular analyses suggest a basal, isolated position among legumes. A study of Duparquetia pollen was carried out to provide further morphological characters to contribute to multi-data set analyses. Understanding the development of Duparquetia pollen was necessary to clarify the orientation of the apertures.
• Methods Pollen grains and developing microspores were examined using light microscopy, confocal microscopy and scanning electron microscopy. Evidence for the orientation of the apertures was provided by the examination of microspores within developing tetrads, using (a) confocal microscopy to locate the position of the ectoapertures, and (b) light microscopy and Alcian blue stain to locate the position of the endoapertures.
• Key Results Confocal microscopy has been used for the first time to examine developing microspores in order to obtain information on ectoapertures that was unavailable using other techniques. Pollen in Duparquetia develops in tetrahedral tetrads as in other eudicots, with the apertures arranged in a modified pattern following Fischer's rule. Pollen grains are asymmetrical and have one equatorial-encircling ectoaperture with two equatorial endoapertures, a unique feature in Leguminosae, and in eudicots.
• Conclusions The pollen morphology of Duparquetia is so unusual that it provides little information to help determine its closest relatives. However, it does fit with a pattern of greater pollen morphological diversity in the first-branching caesalpinioid legume groups than in the more derived clades. The latitudinal ectoaperture of Duparquetia is unique within the Fabales and eudicot clades, resembling more closely the monosulcate pollen found in monocots and basal angiosperms; however, developmental patterns are recognizably similar to those of all other legume pollen types.
Key words: Duparquetia orchidacea, Leguminosae, pollen apertures, pollen development, confocal microscopy, tetrads
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  G. Prenner and B. B. Klitgaard Towards unlocking the deep nodes of Leguminosae: Floral development and morphology of the enigmatic Duparquetia orchidacea (Leguminosae, Caesalpinioideae) Am. J. Botany, November 1, 2008; 95(11): 1349 - 1365. [Abstract] [Full Text] [PDF]
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