Cloning of the cryptochrome-encoding PeCRY1 gene from Populus euphratica and functional analysis in Arabidopsis.

Ke Mao,Rongling Wu,Wenhao Bo,Fang Xu,Libo Jiang,Ines Teichert

doi:10.1371/journal.pone.0115201

Abstract

Cryptochromes are photolyase-like blue/UV-A light receptors that evolved from photolyases. In plants, cryptochromes regulate various aspects of plant growth and development. Despite of their involvement in the control of important plant traits, however, most studies on cryptochromes have focused on lower plants and herbaceous crops, and no data on cryptochrome function are available for forest trees. In this study, we isolated a cryptochrome gene, PeCRY1, from Euphrates poplar (Populus euphratica), and analyzed its structure and function in detail. The deduced PeCRY1 amino acid sequence contained a conserved N-terminal photolyase-homologous region (PHR) domain as well as a C-terminal DQXVP-acidic-STAES (DAS) domain. Secondary and tertiary structure analysis showed that PeCRY1 shares high similarity with AtCRY1 from Arabidopsis thaliana. PeCRY1 expression was upregulated at the mRNA level by light. Using heterologous expression in Arabidopsis, we showed that PeCRY1 overexpression rescued the cry1 mutant phenotype. In addition, PeCRY1 overexpression inhibited hypocotyl elongation, promoted root growth, and enhanced anthocyanin accumulation in wild-type background seedlings grown under blue light. Furthermore, we examined the interaction between PeCRY1 and AtCOP1 using a bimolecular fluorescence complementation (BiFc) assay. Our data provide evidence for the involvement of PeCRY1 in the control of photomorphogenesis in poplar.

Highlights

Light is one of the most important environmental factors for plants as it provides the source of energy to sustain plant life [1]
To isolate a full-length cDNA sequence of the Euphrates poplar cryptochrome gene PeCRY1, expressed sequence tag (EST) clones with similarity to Arabidopsis cryptochrome 1 were identified by analysis of Euphrates poplar dbEST sequences in the National Center for Biotechnology Information (NCBI) database
A 581-bp PeCRY1 fragment was isolated from Euphrates poplar leaves and 59/39-Rapid Amplification of cDNA Ends (RACE) extension methods were used to obtain the missing PeCRY1 sequences

Summary

Introduction

Light is one of the most important environmental factors for plants as it provides the source of energy to sustain plant life [1]. Light is a key signal controlling virtually every aspect of plant growth and development [2]. Light signals are perceived through at least four distinct families of photoreceptors including red/far-red (600–750 nm) light receptor phytochromes [4], blue/UV-A (320–500 nm) light receptor phototropins [5], cryptochromes [6, 7], ZEITLUPE (ZTL), FLAVIN BINDING, KELCH REPEAT, F-BOX1 (FKF1), and LOV KELCH PROTEIN2 (LKP2) and the UV-B (280–320 nm) light receptor UVR8 [8]. Cryptochromes mediate blue light-dependent inhibition of hypocotyl elongation, deetiolation responses, control of vegetative growth, flowering initiation, anthocyanin accumulation, regulation of gene expression, and the maintenance of plant endogenous rhythms [7]

Methods

Results

Conclusion