Cryptochrome 1 controls tomato development in response to blue light

Cryptochrome genes (CRY) are a novel class of plant genes encoding proteins that bear a strong resemblance to photolyases, a rare class of flavoproteins that absorb light in the blue (B) and UV-A regions of the spectrum and utilise it for photorepair of UV-damaged DNA. In Arabidopsis, both CRY1 and CRY2 are implicated in numerous blue light-dependent responses, including inhibition of hypocotyl elongation, leaf and cotyledon expansion, pigment biosynthesis, stem growth and internode elongation, control of flowering time and phototropism. No information about the in vivo function of CRY genes is available in other plant species. The tomato CRY1 gene (TCRY1) encodes a protein of 679 amino acids, which shows 78% identity and 88% similarity to Arabidopsis CRY1. In order to verify the in vivo function of TCRY1, we constructed antisense tomato plants using the C-terminal portion of the gene. Partial repression of both mRNA and protein levels was observed in one of the transformants. The progeny from this transformant showed an elongated hypocotyl under blue but not under red light. This character co-segregated with the transgene and was dependent on transgene dosage. An additional, partially elongated phenotype was observed in adult plants grown in the greenhouse under dim light and short days with no artificial illumination. This phenotype was suppressed by artificial illumination of both short and long photoperiods. The synthesis of anthocyanins under blue light was reduced in antisense seedlings. In contrast, carotenoid and chlorophyll levels and second positive phototropic curvature were essentially unaltered.