Convergence between shade and submergence responses

ROCÍO FERNÁNDEZ; ROMINA SELLARO

Congreso; RAFV Conference 2023 XXXIV Argentinian Meeting of Plant Physiology; 2023

In the coming years, an increase in flooding is expected in our country due to the impact of climate change, which could produce water stress in the affected vegetation. Some plants have growth responses to escape from these unfavorable conditions either through the active promotion of organ development, such as stems, petioles and leaves that elongate or changes in angle in response to submergence. These morphological changes resemble those experienced by plants in response to the presence of neighboring plants. Given that some species show this convergence in phenotype in the face of different environmental stresses, it is plausible to hypothesize that they share signaling pathways and that if they occur simultaneously, they could have a synergistic effect. Preliminary data from our working group have shown that the transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4), which plays a central role in regulating shade avoidance responses, is also involved in responses to submergence. Many of the PIF4 targets that cause hypocotyl elongation are involved in auxin synthesis and signaling, among them is AUXIN/INDOLE-3-ACETIC ACID 19 (IAA19). The aim of this work was to evaluate the role of IAA19 in the responses of Arabidopsis thaliana to shade and submergence conditions. Hypocotyl length responses of wild-type and iaa19 mutant plants and IAA19 expression were analyzed using two transgenic lines with the IAA19 promoter fused to reporter genes (Gus and Luciferase) under shade and submergence conditions. We found a synergistic response in IAA19 expression when plants were exposed with both stresses together. These results suggest that auxins participate in the convergence between the signaling pathway triggered by flooding and shade.