Pectin secretion and distribution in the anther during pollen development in Lilium |
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Authors: | Aouali N Laporte P Clément C |
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Institution: | (1) Université de Reims Champagne Ardenne, UFR Sciences, Biologie et Physiologie Végétales, BP 1039, 51687 Reims Cédex 2, France, FR |
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Abstract: | Using the monoclonal antibodies JIM 5 and 7, pectin was immunolocalized and quantitatively assayed in three anther compartments
of Lilium hybrida during pollen development. Pectin levels in both the anther wall and the loculus increased following meiosis, were maximal
during the early microspore stages and declined during the remainder of pollen ontogenesis. In the microspores/pollen grains,
pectin was detectable at low levels during the microspore stages but accumulated significantly during pollen maturation. During
early microspore vacuolation, esterified pectin epitopes were detected both in the tapetum cytoplasm and vacuoles. In the
anther loculus, the same epitopes were located simultaneously in undulations of the plasma membrane and in the locular fluid.
At the end of microspore vacuolation, esterified pectin epitopes were present within the lipids of the pollenkitt, and released
in the loculus at pollen mitosis. Unesterified pectin epitopes were hardly detectable in the cytoplasm of the young microspore
but were as abundant in the primexine matrix as in the loculus. During pollen maturation, both unesterified and esterified
pectin labelling accumulated in the cytoplasm of the vegetative cell, concurrently with starch degradation. In the mature
pollen grain, unesterified pectin epitopes were located in the proximal intine whereas esterified pectin epitopes were deposited
in the distal intine. These data suggest that during early microspore development, the tapetum secretes pectin, which is transferred
to the primexine matrix via the locular fluid. Further, pectin is demonstrated to constitute a significant component of the
pollen carbohydrate reserves in the mature grain of Lilium.
Received: 3 July 2000 / Accepted: 19 October 2000 |
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Keywords: | :Lilium (pollen) Locular fluid Monoclonal antibody (JIM 5 and 7) Pectin (pollen reserves/pollen wall) Tapetum (secretion) |
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