Diversity of the genus Hypnea (Gigartinales, Rhodophyta) from São Paulo State, based on molecular markers and morphology

Author(s)

Natália Rodrigues Guimarães

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2011-09-13

Examining board members

Mariana Cabral de Oliveira; Valéria Cassano

• Advisor: Mariana Cabral de Oliveira

Abstract

The genus J.V. Lamouroux (1813) (Cystocloniaceae, Gigartinales), comprises 67 described species, has a wide geographical distribution on the tropical shores around the world. Some species of Hypnea are used for the production of carrageenan, hydrocolloids of great importance in today´s industry. The taxonomy of the genus is very problematic and Hypnea species identification is complicated by a relatively simple morphology that is often influenced by the conditions of the habitat. Although some regional reviews have been carried out, the right number of species and the status of some species remain in doubt. Molecular studies have been carried out mainly dealing with species from Asia. The technique of \"DNA barcoding\" has been successfully tested in Rhodophyta for rapid identification of species using the 5 \'region of the mitochondrial gene cytochrome c oxidase subunit I, the marker cox1. Recently, another marker tested as \"DNA barcode\" is the domain V of the plastidial 23S gene, the marker UPA. In addition, the plastidial marker rbcL has been used as a tool for phylogenetic studies of the genus Hypnea. In this study, were sequenced for the marker cox1, 49 samples from the coast of São Paulo State, a sample from the State of Rio de Janeiro and five samples maintained in culture from the coastal states from the States of São Paulo and Espirito Santo. We identified six different taxonomic groups according to the marker cox1. Representatives of each of these groups were sequenced for the UPA and rbcL markers. The divergence found among the cox1 sequences in this study was from 62 to 100 bp (10.1 - 16.3%), for the UPA marker was from 9 to 16 bp (2.5 to 4.4%), and for the rbcL marker was 42 to 88 bp (3.2 - 6.7%). The intraspecific divergences for the samples sequenced in this study were 0-5 bp (0 -0.9%) for the cox1, 0-1 bp (0 - 0.3%) for the UPA and 0-6 bp (0 - 0.5%) for the rbcL. The observed divergences for the three molecular markers confirm the existence of six different taxonomic entities. After analysis of the morphology and comparison with sequences available in GenBank for the genus Hypnea these taxonomic entities were named as: H. cervicornis, H. flexicaulis, H. musciformis, H. spinella, Hypnea sp. 1 and sp2. As the species Hypnea flexicaulis this is the first citation to the Atlantic Ocean. Based on morphological and molecular studies, we conclude that the species H.nigrescens, quoted earlier for the State of São Paulo, is actually a morphological variation of H. musciformis. Still, we conclude that the species H. cervicornis and H.spinella should not be placed in synonymy since its morphological characteristics and differences in the sequences obtained from the three molecular markers show that they are two distinct species (AU)

• FAPESP's process: 09/01077-1 - Diversity of Hypnea genus(Gigartinales, Rhodophyta) from São Paulo State based on molecular markers and morphology.
• Grantee: Natália Rodrigues Guimarães
• Support Opportunities: Scholarships in Brazil - Master