The cryptochrome family of blue-light photoreceptors is involved in the control of plant photomorphogenesis and photoperiodic responses. Two cryptochromes have been described in Arabidopsis and tomato. To investigate the composition of the cryptochrome gene family in angiosperms, we used a 'garden PCR' approach, amplifying DNA from different plant species with the same pair of degenerated oligonucleotides representing conserved sequences from the flavin-binding domain. Different numbers of Cry-homologous sequences were found in different species: two each in Arabidopsis (Dicots, Brassicaceae), melon (Dicots, Cucurbitaceae) and banana tree (Monocots, Musaceae); three each in tomato (Dicots, Solanaceae) and barley (Monocots, Graminaceae). These sequences contain open reading frames (OFRs) with high homology to cryptochromes, but not photolyases, and are transcribed into RNA. In each case, a Cry1- and a Cry2-like sequence was recognizable. The third gene of tomato and barley seems to have arisen from recent, independent duplications of Cry1, and was thus named Cry1b. The tomato Cry1b gene encodes a protein of 583 amino acids (the shortest of the three tomato cryptochromes), with a high similarity to Cry1. The C-terminus of Cry1b is truncated before the conserved Ser-Thr-Ala-Glu-Ser-Ser-Ser (STAESSS) motif found in both Cry1a and Cry2. The Cry1b mRNA is expressed throughout the tomato plant, reaching maximal levels of expression in the flower (like Cry1a and Cry2). We conclude that tomato and barley contain at least one additional expressed member of the Cry1 gene family.

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