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Functional diversification in the Nudix hydrolase gene family drives sesquiterpene biosynthesis in Rosa × wichurana.
Plant J, 104(1):185-199.
Roses use a non-canonical pathway involving a Nudix hydrolase, RhNUDX1, tosynthesize their monoterpenes, especially geraniol. Here we report thecharacterization of another expressed NUDX1 gene from the rose cultivar Rosa xwichurana, RwNUDX1-2. In order to study the function of the RwNUDX1-2 protein, weanalyzed the volatile profiles of an F(1) progeny generated by crossingR. chinensis cv. 'Old Blush' with R. x wichurana. A correlation test of thevolatilomes with gene expression data revealed that RwNUDX1-2 is involved in thebiosynthesis of a group of sesquiterpenoids, especially E,E-farnesol, in additionto other sesquiterpenes. In vitro enzyme assays and heterologous in plantafunctional characterization of the RwNUDX1-2 gene corroborated this result. Aquantitative trait locus (QTL) analysis was performed using the data ofE,E-farnesol contents in the progeny and a genetic map was constructed based ongene markers. The RwNUDX1-2 gene co-localized with the QTL for E,E-farnesolcontent, thereby confirming its function in sesquiterpenoid biosynthesis in R. xwichurana. Finally, in order to understand the structural bases for the substratespecificity of rose NUDX proteins, the RhNUDX1 protein was crystallized, and itsstructure was refined to 1.7 Å. By molecular modeling of different rose NUDX1protein complexes with their respective substrates, a structural basis forsubstrate discrimination by rose NUDX1 proteins is proposed.
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