The formation of the stigmatic surface in Passiflora elegans (Passifloraceae)

Adriano Silvério,Jorge Ernesto De Araujo Mariath

doi:10.1590/2175-7860201061316

Adriano Silvério, Jorge Ernesto De Araujo Mariath

Open Access

https://doi.org/10.1590/2175-7860201061316

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Journal: Rodriguésia	Publication Date: Sep 1, 2010
Citations: 13	License type: cc-by

Affiliation: Universidade Federal do Rio Grande do Sul

Abstract

Abstract The stigma surface is a complex multicellular structure where the development of the pollen tube begins. This development is necessary for sucess in fertilization and depends on recognition processes that involve the anatomy of the stigma. Passiflora is an economically important genus because of its edible fruits. Many authors have described the stigma of Passiflora but nothing is known about the ontogenesis of this structure. This work aimed to describe the formation of the stigmatic surface of Passiflora elegans. Results showed that, in bud, the stigmatic surface of this species is flat with small cells. The cells in the subdermal layer have large vacuoles and the nucleus, near to the external periclinal walls. During its development the stigma surface becomes uneven due to the elongation of cells in the subdermal layer. Elongation results in an increase of external secretory surface area of the stigmas, and probably plays an important role in pollen recognition. The polysaccharide content found in the inner walls of these structures might be involved in the signal process for pollen tube growth during its early development. The morphological evidence presented here shows that, as the stigma of Passiflora is formed by dermal and subdermal cells, it should not be characterized as colleters or papillae and, therefore, it is defined here as stigma emergences.

Highlights

The stigma surface is a complex multicellular structure where the development of the pollen tube begins
The goal of this work is to analyze the ontogenetic process of these structures at the stigmatic surface of Passiflora elegans Mast., an endemic species of southern Brazil
1% OsO4, washed in 0.1 M sodium phosphate buffer at pH 7.2 (Weber 1992), dehydrated in acetone, critical point dried (Gersterberger & Leins 1978), sputter-coated with gold using a Balzers SCD 050, and examined using a Jeol 6060 SEM. It was found, during the initial stages of development, that the apical portion of the stigma has a slightly sinuous surface (Fig. 1a), the dermal layer has cells with an evident nucleus and portions of condensed chromatin (Fig. 1b), and the subdermal layer has cells with large vacuoles and respective nucleus displaced near the external periclinal walls (Fig. 1b)

Summary

Introduction

The stigma surface is a complex multicellular structure where the development of the pollen tube begins. These authors noted that the papillate structures had cells with large vacuoles and thin walls. It was found, during the initial stages of development, that the apical portion of the stigma has a slightly sinuous surface (Fig. 1a), the dermal layer has cells with an evident nucleus and portions of condensed chromatin (Fig. 1b), and the subdermal layer has cells with large vacuoles and respective nucleus displaced near the external periclinal walls (Fig. 1b).

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Results

Conclusion