Unraveling the role of SlBBX20 in drought stress response in tomato

• Grant number: 25/07929-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: May 31, 2026
• Field of knowledge: Biological Sciences - Botany
• Principal Investigator: Juliene dos Reis Moreira
• Grantee: Gabriel Ponciano Carvalho Souza
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

BBX proteins encompass a group of zinc-finger transcription factors that contain at least one conserved B-box domain in the N-terminal region. In Arabidopsis thaliana, 32 BBX protein-encoding loci have been identified, which play important roles as regulators of flowering, photo and skotomorphogenesis, and biotic/abiotic stress responses. Recently, our group functionally characterised SlBBX20 tomato gene. SlBBX20 showed to positively regulate photomorphogenesis by repressing SlPIF4 in a post-transcriptional manner; while, Slbbx20 mutant displayed a constitutive shade avoidance response. Moreover, SlBBX20 interacts with the light master transcription factor SlHY5 to promote the expression of flavonoid biosynthetic genes resulting in mutant fruits with reduced levels of flavonoids. Furthermore, Slbbx20 plants displayed higher susceptibility to the fungus Botrytis cinerea and the herbivore Spodoptera frugiperda. By applying highthroughput protein-protein interaction techniques, our group has identified SlBBX20 putative interactors, several of which are involved in pathogen and water stress responses. Interestingly, preliminary results indicate that Slbbx20 mutant plants have higher tolerance to water stress than the wild-type counterparts. Facing the challenges imposed by climate change that will require the development of highly resilient crops, all these findings offer an invaluable system to investigate the role of BBX proteins in multi-stress responses. In this context, the present project proposes to contribute with this effort performing a physiological characterization of Slbbx20 mutant under water stress conditions, validating SlBBX20 physical interaction with drought-associated proteins and profiling the expression of drought-associated genes.