Molecular Cloning and Linkage Mapping of Cryptochrome Multigene Family in Soybean

Abstract

The cryptochromes are a family of blue light photoreceptors that play important roles in the controls of plant development. Seven full-length cryptochrome cDNAs (GmCRY1a, GmCRY1b, GmCRY1c, GmCRY1d, GmCRY2a, GmCRY2b, and GmCRY2c) were isolated by cDNA library screening and reverse transcriptase–polymerase chain reaction from ‘Williams’ soybean [ (L.) Merr.], indicating that soybean cryptochrome genes comprise a multigene family. They had homologies ranging from 60 to 89% with CRY1 and CRY2 genes of and pea ( L.). Two types of transcripts were isolated in GmCRY1b, GmCRY1c, GmCRY1d, and GmCRY2a. One type was derived from four exons, whereas the other type was derived from five exons. Occurrence of the former transcript could be explained by retention of the fourth intron, suggesting existence of alternative splicing. Gene sequences were compared between a soybean line, Tokei 780, and an accession of soybean wild relative, , Hidaka 4. Based on a 10-bp indel, an amplicon length polymorphism (ALP) marker was designed for mapping of GmCRY2b. For mapping of the other cryptochrome genes, derived cleaved amplified polymorphic sequence (dCAPS) markers were constructed. The cryptochrome genes were individually assigned to different molecular linkage groups (MLG) (GmCRY1a: MLG C1; GmCRY1b: C2; GmCRY1c: B2; GmCRY1d: F; GmCRT2a: O; GmCRY2b: D1b; GmCRY2c: I). The distribution of cryptochrome genes that was deduced from the soybean genome database was consistent with mapping results.