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Abstract Detail


Pollination Biology

Bittencourt Jr, Nelson S. [1], Gandolphi, Gabriel [1].

Evidence of post-zygotic self-pollinated pistil rejection in Tabebuia impetiginosa (Bignoniaceae), a species with late-acting self-incompatibility.

Late-acting self-incompatibility (LSI) has been defined as a genetic system that prevent seed-set by self-pollination in fertile plants despite an apparently normal self pollen tube growth throughout the style and penetration of most ovules. In strong self-sterile species of Bignoniaceae (e.g., Tabebuia impetiginosa), a delay in the progress of ovule penetration, fertilization and endosperm initiation in selfed vs. crossed pistils, and the following uniform abortion of the formers indicated the occurrence of LSI with post-zygotic rejection. Despite the observation of a presumed resting zygote/initiating proembryonal tube in selfed ovules, fusion of sperm and egg cell nuclei could not be previously confirmed due to the absence of adequate cytological analysis. In addition to the analysis of pistil longevity, embryo sac nuclei were presently investigated using microspectrofluorometry of DAPI-stained sections in self- vs. unpollinated pistils. Differences in both pistil longevity (5-9 vs. 3-6 days, n=14), and ovary dimensions (mm) at the point of pistil abscission (9.08±0.80 long, 2.48±0.11 wide vs. 6.58±0.43 long, 1.86±0.08 wide, n=12) between self- and unpollinated flowers, respectively, were significant. Unpollinated pistils on the 5th day of anthesis showed twice as much DNA in the secondary nucleus as in any other embryo sac nucleus, as expected in a Polygonum type megagametophyte. The presence of a presumed zygote in selfed ovules was verified from the 3rd day on, and these cells showed double of the DNA content in their nuclei relative to unfertilized egg cells (14.27±1.70 vs. 7.02±1.14 relative fluorescence units, respectively, n=54). The extended longevity of selfed pistils seems to result from long distance signaling between pollen tubes growing in the transmitting track and the ovules in the ovary, which is congruent with a LSI model, and the present cytological analysis clearly indicates the post-zygotic rejection of selfed pistils.


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Related Links:
Plant Anatomy Lab
MORPH (Molecular and Organismic Research in Plant History)


1 - Universidade Estadual Paulista (UNESP), Departamento de Zoologia e Botnica - IBILCE, Rua Cristvo Colombo, 2265, Jardim Nazareth, So Jos do Rio Preto, So Paulo, 15054-000, Brazil

Keywords:
self-incompatibility
DAPI
fertilization
Tabebuia
Bignoniaceae
microspectrofluoromety.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PPL005
Abstract ID:13

Canceled

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