Understanding the reproductive biology of red algae (Rhodophyta) using physiological and molecular tools

• Grant number: 23/01804-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Effective date (Start): June 01, 2023
• Effective date (End): May 31, 2025
• Field of knowledge: Biological Sciences - Botany - Applied Botany
• Principal Investigator: Mutue Toyota Fujii
• Grantee: Fabiana Marchi dos Santos
• Host Institution: Instituto de Pesquisas Ambientais (IPA). Secretaria de Meio Ambiente, Infraestrutura e Logística (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

Red algae (Rhodophyta) share a series of ultrastructural characteristics, among them the absence of flagella and florid starch as a reserve product stored in the cytoplasm. In addition, they have ecological importance due to the fact that they are primary producers and habitat structurers. Floridiophyceae is one of the two main classes of the phylum considering the number of species, in addition, they have a triphasic life history characterized by the alternation of haploid and diploid generations. The gametophytic phase (n) is dioecious, free-living and isomorphic to the tetrasporophytic phase (2n), while the carposporophytic phase (2n) is microscopic and dependent on the female gametophyte. Many species of Floridiophyceae are economically important because they have phycocolloids such as agar or carrageenan in the cell wall, which has led to the exploitation and depletion of several natural populations along the Brazilian coast. In order to preserve a certain group or species, as well as use it to satisfy commercial demands through sustainable exploitation or ex-situ cultivation, it is necessary to know its genetic and physiological diversity. However, despite the notable importance of the group, so far little is known about its sex determination mechanisms (genetic and environmental influence), which can have several implications considering the possibility of large-scale commercial production and changes in population dynamics, mainly if we consider the advent of global climate change and pollution of the coastal region. Given the above, this work aims to investigate the influence of abiotic (temperature and nutrient availability) and genetic factors on the sex determination of Rhodophyta, using Gracilaria caudata as a model organism, in order to test the hypothesis that sexuality in Floridiophyceae stems from the interaction between genes from different loci, positioned on sex and autosomal chromosomes; and that the increase in temperature and nutritional concentration positively influence the apomitic process. For this, the genotyping of the genealogy of the species will be carried out using SNPs molecular markers, and later, the mapping of loci responsible for sexual determination will be carried out, considering the occurrence of reproductive variants. In addition, we will carry out physiological assessments (growth rates, photosynthesis, fertility and pigment concentration) in the face of environmental factors directly related to climate change (temperature) and pollution of the coastal region (increase in nutrient availability). Thus, the research results will support the proposal/validation of predictive models of changes in biodiversity in the face of these environmental stressors, contributing not only to the management and conservation of natural populations, but also to large-scale ex-situ production.