Matallana 2015 (Conference Paper) Bromeliaceae

Pollen and pistil interactions and hybridization in sympatric Bromeliaceae species in southeastern Brazil

Author(s):—G. Matallana & T. Wendt in Benko-Iseppon, A.M.; Alves, M. & Louzada, R. (2015) An overview and abstracts of the First World Congress on Bromeliaceae Evolution. Rodriguésia 66(2): A1-A66.

Publication:— (2015).

Abstract:—Pollen flow between sympatric species may result in hetero-specific crosses allowing hybridization. In these cases reproductive pre- and post-zygotic isolation barriers could be selected for the maintenance of species as entities. This study evaluates the inhibition of pre-zygotic pollen tube growth in intra-specific, inter-specific and inter-generic crosses in sympatric species of Bromeliaceae using fluorescence microscopy techniques. The possibility of hybridization between target species was tested and pistil length and speed of pollen tube growth in hetero-specific crosses were measured. Patterns of pollen tube growth inhibition and incongruity involving reactions of unilateral incompatibility in inter-generic and inter-specific crosses were the most frequent. However, egg penetration occurred in 26% of the crosses, pointing to the possibility of hybridization. The high frequency of egg penetration in inter-specific and inter-generic crosses in species such as Quesneliaquesneliana and Aechmea araneosa suggest weak pre-zygotic barriers. Egg penetration, in hetero-specific crosses, was more frequent in crosses where both parents had short pistils (48%) and in crosses where the recipient had a short pistil and the pollen donor had long pistil (33%). Pistil length seems to be significant in pollen tube growth and egg penetration.

Keywords:—Pre-zygotic Isolation; Atlantic Forest; Pollen Tube Growth.