Mechanisms of photoreceptor mediated responses in photomorphogenesis and phototropism

Abstract

Photoreceptor facilitated light perception provides plants with critical environmental information from which they can direct their growth. We investigated the early photomorphogenic responses in Glycine max and Glycine soja with the aim of elucidating the effect that domestication has had on early light responses. Our study indicates that G. max exhibits growth in darkness that is more characteristic of growth in light. This finding suggests that domestication has resulted in a crop species that is partially constitutively photomorphogenic. We additionally investigated the effects of blue light-induced ubiquitination sites that were ubiquitinated dependently by NON-PHOTOTROPIC HYPOCOTYL3 (NPH3) in the red light photoreceptor phytochrome A (phyA) in Arabidopsis thaliana. We discovered that transgenic lines expressing phyA with the ubiquitination sites K555 and K603 converted to non-ubiquitinatable arginine residues displayed reduced degradation in blue light and additionally reduced phototropic curvature in high intensity blue light, while functioning normally in other responses tested: very low and low intensity blue light phototropism, far-red light hypocotyl growth inhibition, and red light-induced phyA degradation. This finding suggests a mechanism for a more direct route of blue and red light-signaling crosstalk than has been previously shown.