Effect of the pollen dispersal strategy on the reproductive chemotropism in Orchidaceae

• Grant number: 23/14421-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2024
• End date: December 31, 2024
• Field of knowledge: Biological Sciences - Botany
• Principal Investigator: Maria Teresa Portes
• Grantee: Luigi Pietrafesa dos Santos Eugenio
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/26129-6 - The pollen tube quest to find the ovule: spatio-temporal ion regulation as a mechanism for apical growth and guidance in single cells, AP.JP

Abstract

Orchidaceae presents diverse pollen dispersal strategies, ranging from monads, tetrads and pollinia, which are related to the phylogeny of the different subfamilies of the group, with the pollinia being characteristic of the two richest groups in species (Orchidoideae and Epidendroideae). After pollen germination, it is known that pollen tube growth is oscillatory, as are other cellular processes that oscillate synchronously with apical growth. However, the biological function of these oscillations is still under investigation. One hypothesis is that the oscillations observed in pollen tubes may be involved in signaling and intercellular communication processes. Thus, the present proposal aims to evaluate the involvement of oscillations in intercellular communication between male gametophytes in Orchidaceae, with the main objective of analyzing the behavior of male gametophytes when dispersed individually and collectively. In addition to pollen dispersal density, we intend to investigate possible interactions of cooperation and competition between male gametophytes under the context of kin selection. For that, experimental assays will be developed to quantify the coherence of individual and collective reproductive chemotropism in genetically related and unrelated male gametophytes. Species that have distinct dispersal units present in Orchidaceae subfamilies will be selected, aiming to analyze intercellular communication between pollen tubes in tetrads and pollinia, in relation to monads. This interdisciplinary approach can generate completely original results, which may contribute to a better understanding of the species richness in Orchidaceae, which is concentrated in groups that have pollinia as dispersal unit, which seems to have contributed to the group's high reproductive success. Thus, the unit and density in which pollen is dispersed can impact the interactions between pollen tubes and, consequently, the success of the reproductive process, revealing functional aspects of different dispersal strategies, focusing on interactions between male gametophytes and possible cooperation and competition relationships.