Reproductive biology of endemic Solanum melissarum Bohs (Solanaceae) and updating of its current geographic distribution as the basis for its conservation in the Brazilian Cerrado.

C P Coelho,L F Souza,F A G Guilherme,D C Gomes

doi:10.1590/1519-6984.01516

Abstract

The genus Solanum (family Solanaceae) includes more than 1400 species and has buzz-pollinated flowers with poricidal anthers. The present study aimed to describe the distribution, breeding system and pollination mechanism of Solanum melissarum, a species endemic to Brazil. The study of breeding system was conducted in an urban forest fragment in Jataí, GO. Distribution data were gathered from floristic surveys and digital plant databases. The floral morphology and the pollination mechanism were studied on through field observations and preserved flowers. The breeding system was determined through hand pollination treatments. The species has a distribution only in the Brazilian Atlantic forest coastal, and this study provides the first records of S. melissarum for the state of Goiás. The pendulous flowers have poricidal anthers close to the stigma, with membranous thecae joined by a connective bearing osmophores that attract males of Euglossa cordata bees. As they collect fragrances, the bees press the thecae and pollen is released through a bellows mechanism. Based on the hand-pollination treatments, this species is self-incompatible. Isolated forest fragments may not include enough pollinators to ensure the pollination of plants with specialized systems. However, they are essential for the conservation of species with interesting phytogeographic patterns, such as the vicariance observed in S. melissarum, and for the conservation of regional diversity.

Highlights

Solanum melissarum studied individuals were self‐incompatible, and natural pollinators were less effective than hand-pollination (Table 1), since there were significant differences in fruit set between cross‐pollination and pollination of open flowers by floral visitors
Pollen tube growth was not interrupted in the cross-pollination treatment, in contrast to self-pollinated flowers, where pollen tube growth stopped in the stigma or in the style, identifying possible sites of pre-zygotic self-incompatibility
The flowers of S. melissarum are pendulous and arranged into simple cyme inflorescences. This flower position facilitates pollen release through a bellows mechanism (Figure 2), which is aided by gravity

Summary

Introduction

L. Jussieu includes roughly 106 genera (Olmstead et al, 1999) and 2,300 species and has a cosmopolitan distribution, with its center of diversity and endemism in the New World (Hunziker, 2001). Jussieu includes roughly 106 genera (Olmstead et al, 1999) and 2,300 species and has a cosmopolitan distribution, with its center of diversity and endemism in the New World (Hunziker, 2001) In this family, the inflorescences are determinate and sometimes reduced to solitary terminal flowers. The flowers are bisexual and radial, normally with five connate persistent sepals that may expand during fruit development. The pentamerous petals form a disk-shaped, tubular, campanulate, or fusiform corolla. Capsules, or a schizocarp of nutlets (Souza and Lorenzi, 2005)

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Conclusion