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Cryptochromes, a class of blue light photoreceptors, play vital roles in regulating growth and development in higher plants. Despite their control over various important traits, there have been few studies focusing on cryptochromes in forest trees to date. In this study, the Euphrates poplar (Populus euphratica) gene PeCRY1 (cryptochrome 1 of Populus euphratica) was isolated and heterologously expressed in Populus tomentosa. Three biological replicates of each of the PeCRY1 transgenic P. tomentosa (CRY1) and wild-type (WT) plants were processed for transcriptome profiling. We found 34792 commonly expressed transcripts among the 93868 detected unigenes. Using R package DESeq, we identified 357 differentially expressed genes (DEGs), including 132 upregulated and 225 downregulated genes. Gene ontology (GO) enrichment and KEGG pathway enrichment were used to better understand the functions of detected DEGs. Biosynthetic processes, such as starch and sucrose metabolism, which are closely related to growth and development, were highly enriched. Organic cyclic compound biosynthesis was downregulated, whereas carbohydrate metabolism was upregulated. Through KEGG pathway enrichment, we observed that the pentose phosphate pathway, photosynthesis, and circadian rhythm were significantly enriched. Another method of expression analysis based on quantitative reverse transcription polymerase chain reaction (qRT-PCR) validated our RNA sequencing (RNA-seq) results. [ABSTRACT FROM AUTHOR]

The andromonoecious poplar is an exceptional model system for studying sex-specific flower development in dioecious plants. There is increasing evidence that epigenetic regulation, particularly DNA methylation, is an important regulatory factor during flower development. Here, methylation-sensitive amplified polymorphism (MSAP) was used to screen for sex-specific DNA methylation alterations in the andromonoecious poplar. The sequences of 27 sex-specific amplified fragments were obtained from DNA prepared from sex-specific flower tissues. PtGT2, PtPAL3, and PtCER4, which are homologous to MF26, MF29, and MF35, respectively, were cloned as candidate genes. Expression analysis and DNA methylation pattern profiling of the three candidate genes revealed that gene expression upregulation was always associated with gene body methylation. The results suggested that DNA methylation sites have the potential to regulate the genes' transcript levels. These three genes were shown to play important roles during different phases of flower development. This study will help to provide candidates for future experiments aimed at understanding the mechanism, whereby DNA methylation regulates gene expression in poplar. Key messages: We report the first screen for sex-specific DNA methylation alterations in the andromonoecious poplar. 27 sex-specific methylation sites were identified. The gene expression levels and DNA methylation patterns were detected for three candidate genes. [ABSTRACT FROM AUTHOR]