Radial flow in stems of Acer species: implications for ion-mediated changes in xylem hydraulic conductance

• Grant number: 19/08596-6
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: September 16, 2019
• End date: December 15, 2019
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Rafael Vasconcelos Ribeiro
• Grantee: Luciano Pereira
• Supervisor: Steven Jansen
• Host Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil
• Institution abroad: Ulm University, Germany
• Associated to the scholarship: 17/14075-3 - New methods to study xylem hydraulic properties and embolism in vivo in plants, BP.PD

Abstract

The water transport in plants is not a completely passive process and the presence of ions in the sap can increase the xylem conductance. Hypothetically, hydrogels (pectins) on intervessel pit membrane may shrink if ions are present in the sap, which results in reduced resistance to water flow. However, this explanation is challenged by the lack of pectins in mature intervessel pit membranes. Alternatively, we hypothesize that the ionic effect is related to radial flow, i.e., water transport from dead xylem conduits to surrounding living cells that are able to store water. Along this pathway, pectins occur in vessel-parenchyma pit membranes, which may explain the increment of hydraulic conductance in the presence of ions. In our main FAPESP post-doctoral project, we develop a method to study radial flow that can be validated and improved using pre-characterized species in relation to the ionic effect, as those ones studied by Dr. Steven Jansen's group. Thus, our goal is to test if the ionic concentration of the xylem liquid determines radial flow in various Acer species, and whether this may explain the ion-mediated effect. Radial flow in plant stems is fundamental for the understanding of plant water transport by the functional link between xylem and phloem and drought resistance mechanisms, which also determines the plant productivity under varying water conditions. (AU)