Genetic dissection of blue-light sensing in tomato using mutants deficient in cryptochrome 1 and phytochromes A, B1 and B2.
Several novel allelic groups of tomato (Solanum lycopersicum L.) mutants with impaired photomorphogenesis have been identified after gamma-ray mutagenesis of phyA phyB1 double-mutant seed. Recessive mutants in one allelic group are characterized by retarded hook opening, increased hypocotyl elongation and reduced hypocotyl chlorophyll content under white light (WL). These mutants showed a specific impairment in response to blue light (BL) resulting from lesions in the gene encoding the BL receptor cryptochrome 1 (cry1). Phytochrome A and cry1 are identified as the major photoreceptors mediating BL-induced de-etiolation in tomato, and act under low and high irradiances, respectively. Phytochromes B1 and B2 also contribute to BL sensing, and the relative contribution of each of these four photoreceptors differs according to the light conditions and the specific process examined. Development of the phyA phyB1 phyB2 cry1 quadruple mutant under WL is severely impaired, and seedlings die before flowering. The quadruple mutant is essentially blind to BL, but experiments employing simultaneous irradiation with BL and red light suggest that an additional non-phytochrome photoreceptor may be active under short daily BL exposures. In addition to effects on de-etiolation, cry1 is active in older, WL-grown plants, and influences stem elongation, apical dominance, and the chlorophyll content of leaves and fruit. These results provide the first mutant-based characterization of cry1 in a plant species other than Arabidopsis.
Laboratory of Plant Physiology, Graduate School for Experimental Plant Sciences, Wageningen University, Arboretumlaan 4, NL-6703 BD Wageningen, Netherlands.
J L
JL
Weller
G
G
Perrotta
M E
ME
Schreuder
A
A
van Tuinen
M
M
Koornneef
G
G
Giuliano
R E
RE
Kendrick
D000483:Alleles; D001483:Base Sequence; D056931:Cryptochromes; D017931:DNA Primers; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000235:genetics / Q000502:physiology*; D008027:Light; D045342:Light-Harvesting Protein Complexes; D018551:Solanum lycopersicum / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D010834:Phytochrome / Q000235:genetics / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled
D056931:Cryptochromes; D017931:DNA Primers; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila; D010834:Phytochrome