Identification and Expression Characteristics of the Cryptochrome Gene Family in Chimonobambusa sichuanensis

Cryptochrome is an important class of blue light receptors involved in various physiological activities such as photomorphogenesis and abiotic stress regulation in plants. In order to investigate the molecular mechanism of blue light-induced color change in Chimonobambusa sichuanensis, we screened and cloned the gene encoding the blue light receptor Cryptochrome in Chimonobambusa sichuanensis, and analyzed the expression characteristics of Cryptochrome gene in Chimonobambusa sichuanensis under different light intensities, photoplasmas, and temperatures by qRT-PCR. Through homologous cloning, a total of four CsCRY genes were obtained in the Chimonobambusa sichuanensis genome, namely, CsCRY1a, CsCRY1b, CsCRY2, and CsCRY3. Structural domain analyses of the encoded proteins of the four genes revealed that all CsCRYs proteins had the typical photoreceptor structural domain, PRK. Phylogenetic tree analyses revealed that the four genes CsCRY1a, CsCRY1b, CsCRY2, and CsCRY3 could be categorized into three subfamilies, with CsCRY1a and CsCRY1b clustered in subfamily I, CsCRY2 classified in subfamily II, and CsCRY3 belonging to subfamily III. All CsCRYs had no signal peptide and the instability index was higher than 40, among which the isoelectric points of CsCRY1a, CsCRY1b, and CsCRY2 were around 5. qRT-PCR analysis revealed that the expression of all four CsCRYs genes was up-regulated at 75 µmol·m-²·s-1 blue light illumination for 4 h. In addition, under different treatments of light quality, the expression of CsCRY2 genes was significantly higher under blue light than under red light and a mixture of red light and blue light with a light intensity of 1:1; while under different temperature gradients, CsCRY2 genes were highly expressed under low temperature stress at -5 ℃ and 0 ℃. This study provides a basis for further research on blue light-induced color change in Chimonobambusa sichuanensis and expands the scope of Cryptochrome gene research.