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Reproductive biology and hybridization in Hohenbergia Schult. & Schult.f. (Bromeliaceae) in the Atlantic Forest in Brazil

Grant number: 18/08276-9
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): November 01, 2018
Effective date (End): February 28, 2021
Field of knowledge:Agronomical Sciences - Agronomy
Principal Investigator:Adriana Pinheiro Martinelli
Grantee:Brayan Paiva Cavalcante
Home Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Bromeliaceae is a family of neotropical monocotyledons with 3551 species, presenting a high degree of endemism for Brazil, especially in the Atlantic Forest. It is a group that is highly targeted for its ornamental potential, mainly due to the visible inflorescences and the resistance capacity in environments with low humidity, being the hybridization between species for the selection of ornamental species. Recognized as one of the most remarkable cases of adaptive irradiation, the bromeliads have a variety of reproductive strategies, however, there is a lack of data on the mechanisms that allow the reproduction isolation when they are sympatric and about the speciation processes. The lack of data related to reproductive isolation and speciation processes is further aggravated for subf. Bromelioideae, which presents most of the systematic and taxonomic problems in the family. Hohenbergia is a genus of subf. Bromelioideae and are endemic to Brazil, with more than 70% of its species occurring in sympatry in Bahia, and the constant extractivism and loss of habitats put in risk many populations. With a loss of habitats, it is believed that there is a decrease in the ecological interactions between these species, particularly the pollination, resulting in a direct competition for the pollinators. In this case, there are of strong reproductive barriers that allow the coesion of populations, even over reproductive stress. Thus, this project aims to identify the reproductive strategies of species of Hohenbergia, in order to understand how the reproductive barriers act in the isolation and the cohesion of the species, comparing the reproductive strategies of highly dominant (isolated) species with those occurring in sympatry. Fifteen species will be used for this project, which will be collected, kept in a greenhouse, and analyzed for floral morphology, reproductive systems, hybridization capacity and cytogenetic characteristics. For the definition of the reproductive systems crosses will be made using the treatments of self-pollination and cross-pollination. Concurrently with the crosses, hybridization tests will be done using all parents to test the congruence (hybridization) between species. The reproductive barrier studies will be aproached in four moments: pre-pollination (phenology), pollinator (rewards and pollinators), post-pollination (polen tube growth), and post-zygotic (cytogenetics and hybrid mortality). Thus, it is expected to identify the mechanisms that allow the maintenance of sympatric and/or dominant species, to raise and characterize reproductive data for the genus Hohenbergia, allowing a better delimitation of this taxon, since it belongs to the subfamily Bromelioideae, in which the generic constituencies are extremely problematic. In addition, the hybrids obtained in interspecific crosses can be evaluated in the future for their ornamental potential, valuing the native species for xeric gardens and pot plants. (AU)