A mechanistic exploration of signaling crosstalk regulating light responses, growth and immunity in Arabidopsis

Abstract

Using the model plant Arabidopsis thaliana, our research focuses on the intersection between pathogen defense and photobiology. PIXL is a putative resistance protein found to be an interactor of phototropin1. Mutants lacking PIXL have altered light responsiveness, suggesting the wild-type protein could act as an intermediary between light and defense signaling. Additionally, phototropin double mutants exhibited less accumulation of pathogenesis-related protein 2, suggesting a role in induction or stability of the protein. We also provide further characterization of immune regulatory protein SRFR1. Cross kingdom homology is seen across the length of SRFR1. In certain genetic backgrounds, srfr1 mutants have markedly different morphology, reduced viability, appear stunted and constitutively express several defense related genes. When a srfr1 mutant plant is transformed with orthologous MmSRFR1 from Mus musculus, the drastic srfr1 phenotype is reduced. This observation suggests a level of conserved function for MmSRFR1 in Arabidopsis. Further study of immune regulation, light responsiveness and convergence of these two systems provides a model for the interface between biotic and abiotic stress.