Natural variation in Arabidopsis seedling photomorphogenesis reveals a likely role for TED1 in phytochrome signalling

Natural genetic variation present among accessions of Arabidopsis thaliana (L.) Heynh. (commonly referred to as ‘ecotypes’) is a valuable, yet under‐exploited genetic resource for the study of plant developmental, physiological. and evolutionary responses to the environment. Seedling photomorphogenic responses were surveyed in a set of 11 Arabidopsis accessions collected from a variety of edaphic habitats and geographic locations. We observed substantial variation in light‐dependent hypocotyl growth responses in a variety of light conditions (white, red, blue, far‐red enriched light). The genetic basis for differences in hypocotyl growth responses to light between the Columbia (Col‐0) and Bensheim (Be‐0) accessions was examined in an F₂ population. Quantitative genetic and quantitative trait locus (QTL) analyses were consistent with a model in which differences in light responses were conditioned by a single major gene with semi‐dominant effect, located on chromosome 4. Further experiments suggested that the genetic difference governing hypocotyl variation in this cross may be allelic to ted1, an extragenic suppressor of the de‐etiolated mutant det1, that was identified as an ethylmethane sulphonate‐induced mutation. This finding supports a role for ted1 in photomorphogenic signalling.