The pollen tube quest to find the ovule: spatio-temporal ion regulation as a mechanism for apical growth and guidance in single cells

• Grant number: 19/26129-6
• Support Opportunities: Research Grants - Young Investigators Grants
• Start date: May 01, 2021
• End date: April 30, 2026
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Maria Teresa Portes
• Grantee: Maria Teresa Portes
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant(s): 21/09025-2 - Multi-user equipment approved in grant 2019/26129-6: Vibrating Probe Setup, AP.EMU
• Associated scholarship(s): 25/01581-4 - Data analysis of spatio-temporal behavior in single cells: methods for pollen tubes, BP.IC; 25/03753-7 - The oscillatory dynamics as a mechanism for intercellular communication in plant fertilization, BP.DD; 24/14395-1 - Growth and maintenance of plant species and plant genetic transformation, BP.TT; 23/14421-0 - Effect of the pollen dispersal strategy on the reproductive chemotropism in Orchidaceae, BP.IC; 21/05363-0 - The pollen tube quest to find the ovule: spatio-temporal ion regulation as a mechanism for apical growth and guidance in single cells, BP.JP

Abstract

Ionic regulation is central for cell development in all biological systems, with pollen tubes being an outstanding model for cell polarity and directional growth. Sperm cell delivery to the ovule relies on their fast growth and sensitivity to external guidance cues, as to target the ovule. Pollen tubes grow exclusively at the apex, which is thought to be sustained by tip-focused ion gradients generated by the anisotropic spatial distribution of ion channels, transporters and pumps. Synchronized oscillations between diverse cellular processes are observed, including growth rate, flux and cytosolic concentrations of H+, Ca2+ and Cl-, although their roles in pollen tube guidance are still unknown. Curiously, the double mutant chx21 chx23 (Cation/H+ exchangers) has a dramatic fertilization defect due to loss of pollen tube guidance, leading to almost complete sterility. My preliminary results on chx21 chx23 show a significant reduction in H+ influx at the tip, with a slower and more regular oscillatory pattern compared to wild type. Mutant pollen tubes show no guidance response to the attractant LURE1, and a decreased response to the repellent hormone Nitric Oxide. Although wild-type pollen tubes show chemotropism, they fail to respond when showing a similar oscillatory signature to chx21 chx23. These striking results provide the first clue of a biological function of oscillations in pollen tubes, while favoring an ion-based mechanism responsible for attraction. The aim of this project is to perform experiments and modeling to establish a novel mechanism of apical growth and guidance regulated by H+ and membrane potential. This research will create an unique experimental unit in the country, capable of non-invasive quantitative spatio-temporal measurements of multiple ions in diverse biological systems, fostering interdisciplinary research in an international level. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

DAMINELI, DANIEL S. C.; PORTES, MARIA TERESA; FEIJO, JOSE A.. Electrifying rhythms in plant cells. CURRENT OPINION IN CELL BIOLOGY, v. 77, p. 11-pg., 2022-07-06. (19/23343-7, 21/05363-0, 19/26129-6, 15/22308-2)

BADAIN, RAFAEL; DAMINELI, DANIEL S. C.; PORTES, MARIA TERESA; FEIJO, JOSE; BURATTI, STEFANO; TORTORA, GIORGIA; DE OLIVEIRA, HUGO NEVES; CESAR, ROBERTO M., JR.. AMEBaS: Automatic Midline Extraction and Background Subtraction of Ratiometric Fluorescence Time-Lapses of Polarized Single Cells. JOVE-JOURNAL OF VISUALIZED EXPERIMENTS, v. N/A, n. 196, p. 15-pg., 2023-06-01. (21/05363-0, 20/06744-5, 19/23343-7, 19/26129-6, 15/22308-2)

PORTES, MARIA TERESA; DAMINELI, DANIEL S. C.; FEIJO, JOSE A.. Spatiotemporal Quantification of Cytosolic pH in Arabidopsis Pollen Tubes. BIO-PROTOCOL, v. 11, n. 14, JUL 20 2021. (19/26129-6, 19/23343-7, 15/22308-2, 21/05363-0)