Cloning of SoDXR and its role in monoterpenoids synthesis in Syringa oblata

Abstract

Abstract [Objective] The purpose of this study is to examine the role of the DXR gene, encoding 1-deoxy- D-xylulose-5-phosphate reductoisomerase, in monoterpenoids synthesis in lilac (Syringa oblata), and to provide genetic resources and theoretical basis for the molecular breeding of floral fragrance of lilac. [Methods] Firstly, the SoDXR gene was cloned. Then, bioinformatics and subcellular localization analysis were performed, and qRT-PCR was used to analyze the gene expression patterns in different floral development stages and tissues. Finally, transient overexpression of SoDXR in the petals of snapdragon (Antirrhinum majus) was detected. [Results] ORF of SoDXR was 1 425 bp, encoding 474 amino acids. SoDXR protein contained the conserved domain of DXP_reductoisom, which had a similarity of up to 95% with Osmanthus fragrans and Olea europaea. Subcellular localization analysis showed that the protein was mainly located in the plastids, consistent with the software prediction. With flowering, the expression level of SoDXR was increased and then decreased, with the highest expression in the initial opening stage. SoDXR was differentially expressed in various tissues with the highest in petals and the lowest in stems. Transient overexpression revealed that the expression of SoDXR was higher than the control. Moreover, the main floral volatile components in snapdragon petals, myrcene and ocimene, were increased by 15.03 and 4.83 times, respectively. [Conclusion] The SoDXR gene positively regulates monoterpenoids synthesis in lilac, and may play an important role in the synthesis of secondary metabolites of floral fragrance.

Keywords

• syringa oblata
• terpenoids
• 1-deoxy-d-xylulose-5-phosphate reductoisomerase
• transient overexpression