Molecular Cloning and Expression Analysis of Cryptochrome Gene Ps CRY2in Tree Peony

摘要

Cryptochromes are blue/ultraviolet-A(UV-A) light receptors involved in regulating various aspects of plant growth and development.Investigations of the structure and functions of cryptochromes in plants have largely focused on herbaceous plants. However, few data on the function of CRY2 are available in woody plants. In this study, a cryptochrome 2(CRY2) gene was isolated from Paeonia suffruticosa by Reverse Transcription Polymerase Chain Reaction(RT-PCR). Sequence alignment and motif analysis showed that the deduced amino acids contained a PHR domain near the amino terminus and a CCT domain near the carboxy terminus. Ps CRY2 showed high identity with At CRY2 of Arabidopsis.Phylogenetic analysis indicated that it was closely related to Citrus sinensis. Gene expression analysis revealed that the highest expression levels of Ps CRY2 occurred in the bud and seed embryo of P. suffruticosa, followed by the roots, stems, and leaves. Ps CRY2 was upregulated during the entire process of bud differentiation, whereas this was downregulated during the early stage of bud development and upregulated in the middle and late stages. The highest level of Ps CRY2 expression was observed in the big bell-like flower buds. These results suggested that Ps CRY2 plays an important role in both bud differentiation and bud development. The expression patterns of Ps CRY2 in the buds of ‘Luoyanghong’ and ‘Qiufa1’ were similar, whereas that in the buds of ‘Qiufa 1’ was significantly higher than in the buds of ‘Luoyanghong’. The buds of plants subjected to different photoperiod treatments exhibited variations in Ps CRY2 expression patterns. The expression of Ps CRY2 decreased during bud sprouting and in the small bell-like flower buds that were subjected to short-day photoperiod compared to that observed under long-day photoperiod.