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The NAC24 transcription factor in maize : from aquaporin regulation to plant development by Estelle TEIRLINCKX -
Mercredi 25/06/2025 à 17h30 - Salle Jean-Baptiste Carnoy (B.059) - Bâtiment Carnoy - Croix du Sud - 1348 Louvain-la-Neuve
The regulation of gene expression is fundamental to plant development and adaptation to environmental challenges. Transcription factors (TFs) play a key role in transcriptional regulation by integrating developmental, tissue-specific and environmental signals, enabling complex and context-specific gene activity.
Aquaporins belonging to the plasma membrane intrinsic proteins (PIPs) subfamily are channels that facilitate water movement across the plasma membrane. They are involved in many physiological processes, such as the hydraulic regulation of roots and leaves, cell expansion, organ development and stress responses. Despite extensive research on their functional roles, the molecular mechanisms underlying the transcriptional regulation of PIP genes remain poorly understood.
An expression quantitative trait loci (eQTL) analysis performed in maize identified NAC24 as a potential regulator of PIP2;5 expression. NACs constitute one of the largest plant-specific TF families and are involved in many developmental processes as well as stress responses.
Here, we demonstrated that NAC24 localized in the nucleus and activated the PIP2;5 promoter in transactivation assays. Overexpression of NAC24 in maize suspension cells increased PIP2;5 expression, while maize nac24 knockdown plants showed reduced PIP2;5 expression accompanied by stunted growth, abnormal leaf morphology, and reduced pollen fertility. These pleiotropic defects are probably due to a broader disruption of gene regulation rather than a reduction of PIP2;5 expression alone. DNA affinity purification sequencing (DAP-seq) identified NAC24-bound genomic regions, including promoters of genes involved in auxin and ethylene signaling, such as Aux/IAA14, PILS6, and ARGOS1. NAC24 bound directly to a palindromic consensus sequence in the promoters of ARGOS1 and LDSH5, activating them, while repressing Aux/IAA14. Our study revealed that NAC24 as a key regulator of PIP2;5 expression and maize growth, potentially influencing organ size through the regulation of ARGOS1 and LDSH5 expression.
Jury members :
Prof. François Chaumont (UCLouvain) (Promoteur)
Prof. Michel Ghislain (UCLouvain) (Président)
Prof. Charles Hachez (UCLouvain) (Secrétaire)
Prof. René Rezsohazy (UCLouvain)
Prof. Lieven De Veyler (VIB – UGent)
Prof. Micaela Carvajal (CEBAS-CSIC, University of Murcia)
Pay attention : the public defense of Estelle Teirlinckx will also take place in the form of a videoconference
