Genome-wide investigation of WRKY transcription factors in sweet osmanthus and their potential regulation of aroma synthesis

Wenjie Ding; Qixia Ouyang; Yuli Li; Tingting Shi; Ling Li; Xiulian Yang; Kongshu Ji; Lianggui Wang; Yuanzheng Yue

doi:10.1093/treephys/tpz129

Genome-wide investigation of WRKY transcription factors in sweet osmanthus and their potential regulation of aroma synthesis

Tree Physiol. 2020 Apr 8;40(4):557-572. doi: 10.1093/treephys/tpz129.

Authors

Wenjie Ding^{1

2}, Qixia Ouyang^{1

2}, Yuli Li^{1

2}, Tingting Shi^{1

2}, Ling Li^{1

2}, Xiulian Yang^{1

2}, Kongshu Ji³, Lianggui Wang^{1

2}, Yuanzheng Yue¹

Affiliations

¹ Key Laboratory of Landscape Architecture, Jiangsu Province, College of Landscape Architecture, Nanjing Forestry University, Nanjing 210037, PR China.
² Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, PR China.
³ Key Laboratory of Forest Genetics & Biotechnology, Ministry of Education, 210037, PR China.

PMID: 31860707
DOI: 10.1093/treephys/tpz129

Abstract

WRKY transcription factors, one of the largest transcription factor families, play important roles in regulating the synthesis of secondary metabolites. In sweet osmanthus (Osmanthus fragrans), the monoterpenes have been demonstrated as the most important volatile compounds, and the W-box, which is the cognate binding site of WRKY transcription factors, could be identified in most of the terpene-synthesis-related genes' promoters. However, the role of the WRKY family in terpene synthesis in sweet osmanthus has rarely been examined. In this study, 154 WRKY genes with conserved WRKY domain were identified and classified into three groups. The group II was further divided into five subgroups, and almost all members of IId contained a plant zinc cluster domain. Eight OfWRKYs (OfWRKY7/19/36/38/42/84/95/139) were screened from 20 OfWRKYs for their flower-specific expression patterns in different tissues. Simultaneously, the expression patterns of OfWRKYs and emission patterns of volatile compounds during the flowering process were determined and gas chromatography-mass spectrometry results showed that monoterpenes, such as linalool and ocimene, accounted for the highest proportion, contributing to the floral scent of sweet osmanthus in two cultivars. In addition, correlation analysis revealed the expression patterns of OfWRKYs (OfWRKY7/19/36/139) were each correlated with distinct monoterpenes (linalool, linalool derivatives, ocimene and ocimene derivatives). Subcellular localization analysis showed that p35S::GFP-OfWRKY7/38/95/139 were localized in the nucleus and OfWRKY139 had very strong transactivation activity. Collectively, the results indicated potential roles of OfWRKY139 and OfWRKYs with plant zinc cluster domain in regulating synthesis of aromatic compounds in sweet osmanthus, laying the foundation for use of OfWRKYs to improve the aroma of ornamental plants.

Keywords: WRKY; aroma; monoterpenes; sweet osmanthus.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Flowers
Gene Expression Regulation, Plant
Odorants
Oleaceae / genetics*
Plant Proteins / genetics
Transcription Factors / genetics*

Substances

Plant Proteins
Transcription Factors