Composition and phylogenetic analysis of wheat cryptochrome gene family

Cryptochrome (CRY) gene family encodes photoreceptors mediating developmental responses to blue light throughout the life of plants. We report here the characterization of CRY gene family in hexaploid wheat. Degenerate PCR amplification of the regions encoding the conserved flavin-binding domain of CRY proteins yielded seven bands, resulting from amplification of CRY1a, CRY1b and CRY2 homologous genes. Assignment of individual amplicons to subgenomes was accomplished by comparing their sequence compositions with those from the ancestor species of wheat. ESTs coding for CRY-DASH like proteins were identified in wheat EST database in GenBank. Southern blot showed that TaCRY1a, TaCRY1b and TaCRY2 are single copy genes. We mapped TaCRY1a and TaCRY2 to chromosomes of homoeologous group 6, TaCRY1b to group 2, and TaCRY-DASH to group 7. Phylogenetic analysis showed that CRY subfamily diversification occurred before the divergence of monocots and dicots. The regulatory and functional changes of CRY members within subfamily are discussed.