Photomorphogenic mutants of tomato

Photomorphogenesis of tomato (Lycopersicon esculentum Mill.) is being studied with the aid of mutants which are modified either in their photoreceptor composition or in their signal transduction chain(s). Phytochrome chromophore mutants, presumably deficient in all phytochromes, and mutants specifically deficient in phytochrome A (phyA) or B1 (phyB1) have been used to study the roles played by phytochromes in photomorphogenesis, In addition, other mutants, including transgenic lines overproducing phyA, exhibit exaggerated photomorphogenesis, Studies using these mutants are reviewed, with emphasis being placed on anthocyanin biosynthesis and plastid development as model systems for the dissection of the complex interactions between photoreceptors and to elucidate the nature of photoreceptor transduction chains, Recently, new mutants have been isolated by screening in a phgA, phyB1-deficient background. The novel phenotypes selected are candidates for mutants in additional photoreceptors or their transduction chains.