Authors: Juliane Mittasch Sabine Mikolajewski Frank Breuer Dieter Strack Carsten Milkowski
Publish Date: 2010/01/20
Volume: 120, Issue: 8, Pages: 1485-1500
Abstract
In oilseed rape Brassica napus the glucosyltransferase UGT84A9 catalyzes the formation of 1Osinapoylβglucose which feeds as acyl donor into a broad range of accumulating sinapate esters including the major antinutritive seed component sinapoylcholine sinapine Since downregulation of UGT84A9 was highly efficient in decreasing the sinapate ester content the genes encoding this enzyme were considered as potential targets for molecular breeding of low sinapine oilseed rape B napus harbors two distinguishable sequence types of the UGT84A9 gene designated as UGT84A91 and UGT84A92 UGT84A91 is the predominantly expressed variant which is significantly upregulated during the seed filling phase when sinapate ester biosynthesis exhibits strongest activity In the allotetraploid genome of B napus UGT84A91 is represented by two loci one derived from the Brassica Cgenome UGT84A9a and one from the Brassica Agenome UGT84A9b Likewise for UGT84A92 two loci were identified in B napus originating from both diploid ancestor genomes UGT84A9c Brassica Cgenome UGT84A9d Brassica Agenome The distinct UGT84A9 loci were genetically mapped to linkage groups N15 UGT84A9a N05 UGT84A9b N11 UGT84A9c and N01 UGT84A9d All four UGT84A9 genomic loci from B napus display a remarkably low microcollinearity with the homologous genomic region of Arabidopsis thaliana chromosome III but exhibit a high density of transposonderived sequence elements Expression patterns indicate that the orthologous genes UGT84A9a and UGT84A9b should be considered for mutagenesis inactivation to introduce the low sinapine trait into oilseed rapeThe authors thank Rod Snowdon University of Giessen Germany for providing the genomic BAC library from B napus for help with the library screen and for supplying the identified positive clones BAC end sequencing by Prisca Viehöver and Bernd Weisshaar University of Bielefeld Germany is greatly acknowledged Seeds of B napus B oleracea and B rapa were kindly provided by Norddeutsche Pflanzenzucht Holtsee Germany Excellent technical assistance was given by Sylvia Vetter Claudia Horn Anja Henning and Alexandra Jestadt This work was part of the research project “YelLowSin Rapeseed Functional genomics approaches for the development of yellowseeded low sinapine “YelLowSin” oilseed rape/canola Brassica napus” financially supported by the Bundesministerium für Bildung und Forschung
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