Analysis of the PHYB Gene Sequence in Arabidopsis Lines Identified in a Red-Light Genetic Suppressor Screen

Abstract

The capability to detect the amount and quality of light is critical for plant growth and development. Red and far-red light are detected by the phytochrome (phy) photoreceptors which mediate plant behavior1. The flowering plant Arabidopsis thaliana contains the genes LRB1 and LRB2 (Light-Response BTB 1 and 2) which encode proteins functioning as target adaptors in BTB/Cullin 3 E3 ubiquitin-ligase complexes. These complexes target phytochromes for ubiquitylation and degradation2. The phytochromes are red/far-red light receptors and plants containing mutations of both LRB1 and 2 genes express hypersensitivity to red light due to increases levels of these photoreceptors. In an attempt to identify additional genes involved in red-light response, the Gingerich lab conducted a genetic screen to identify mutations which suppress the phenotype caused by the lrb1 lrb2 double mutations. All suppressor mutants thus far analyzed have had mutations in the PHYB gene, which encodes a phytochrome that functions as the major red-light receptor in Arabidopsis. Over the past year we have sequenced parts of the PHYB gene in 6 suppressor mutants that had not yet been analyzed. Mutations in PHYB are potentially interesting for researchers who study this important mediator of plant environmental responses. Alternatively, absence of a mutation within the PHYB gene in these lines could indicate a mutation in a separate gene involved in red light response, which could lead to the discovery of new genes involved in the response.