Unraveling the role of the SAMBA gene in fruit growth in tomato cv. Micro-tom

• Grant number: 23/11838-7
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: October 31, 2023
• End date: March 30, 2024
• Field of knowledge: Agronomical Sciences - Agronomy
• Principal Investigator: Nubia Barbosa Eloy
• Grantee: Perla Novais de Oliveira
• Supervisor: Nathalie Gonzalez
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE Nouvelle-Aquitaine Bordeaux), France
• Associated to the scholarship: 21/06611-8 - APC as an entry point to study small molecule regulation of the cell cycle, BP.PD

Abstract

The Anaphase-Promoting Complex/Cyclosome (APC/C) is an E3 ubiquitin ligase involved in ubiquitin-dependent proteolysis of key cell cycle regulators by the 26S proteasome. The identification of genes encoding APC/C subunits in Arabidopsis thaliana suggests that the complex has other specific functions during plant development. One of these proteins, SAMBA, proved to be a highly promising candidate in Arabidopsis regarding to increase productivity, through production of larger leaves, roots and seeds. Furthermore, in Arabidopsis, SAMBA has been shown to control the endoreduplication, resulting from increased fractions of 8C, 16C, and 32C nuclei, suggesting that despite the increased cell number, cells exit the division cycle faster. Thus, to gain more insight into the role of SAMBA and if it's involved in the control of endo-reduplication during tomato fruit development, we used Clustered Regularly Interspaced Palindromic Repeats/CRISPR-associated protein 9 (CRISPR/Cas9) to characterize sequence-specific mutations at Solanum lycopersicum (tomato) cv. Micro-tom in the SAMBA gene. We generated CRISPR-Cas9 samba mutants, which was confirmed by PCR and sequencing analysis. Based on our results SAMBA seems to play an important role in tomato fruit development, because disruption of SAMBA function decreased pollen viability, reduced the average fruit sizes and weights, and showed severe defects in their shape, seed number and development. In this project we aim to carry out cytological, morphometric and flow cytometry analyzes to identify differences in pathway in the mutant plants compared to the wild type that can contribute for the phenotypic changes observed in the mutant. Moreover, we also intend to carry out morphometric analyses of cell size, measurements of the number of cell layers and ploidy profiles of isolated nuclei from mutant's tomato pericarp over the course of fruit development, providing functional important insights for further discoveries of fundamental biological processes that will improve the performance of this commercial crop. (AU)