期刊
PLANT JOURNAL
卷 76, 期 5, 页码 754-765出版社
WILEY
DOI: 10.1111/tpj.12330
关键词
bioinformatics-guided candidate gene identification; virus-induced gene silencing in Catharanthus roseus; 7-deoxyloganic acid hydroxylase; cytochrome P450; internal phloem parenchyma cells; spatial separation of secologanin biosynthesis
资金
- National Sciences and Engineering Research Council of Canada
- Canada Research Chair in Plant Biotechnology
- Centro de Instrumentacion Cientifico-Tecnica of the University of Jaen
- Genome Canada
- Genome Alberta
- Genome Prairie
- Genome Quebec
- Genome British Columbia
- Canada Foundation for Innovation
- Ontario Ministry of Research and Innovation
- National Research Council of Canada
Iridoids are a major group of biologically active molecules that are present in thousands of plant species, and one versatile iridoid, secologanin, is a precursor for the assembly of thousands of monoterpenoid indole alkaloids (MIAs) as well as a number of quinoline alkaloids. This study uses bioinformatics to screen large databases of annotated transcripts from various MIA-producing plant species to select candidate genes that may be involved in iridoid biosynthesis. Virus-induced gene silencing of the selected genes combined with metabolite analyses of silenced plants was then used to identify the 7-deoxyloganic acid 7-hydroxylase (CrDL7H) that is involved in the 3rd to last step in secologanin biosynthesis. Silencing of CrDL7H reduced secologanin levels by at least 70%, and increased the levels of 7-deoxyloganic acid to over 4mgg(-1) fresh leaf weight compared to control plants in which this iridoid is not detected. Functional expression of this CrDL7H in yeast confirmed its biochemical activity, and substrate specificity studies showed its preference for 7-deoxyloganic acid over other closely related substrates. Together, these results suggest that hydroxylation precedes carboxy-O-methylation in the secologanin pathway in Catharanthus roseus.
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