The myrosinase gene family in Arabidopsis thaliana: gene organization,expression and evolution |
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Authors: | Jiaping Xue Mette Jørgensen Ulla Pihlgren Lars Rask |
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Affiliation: | (1) Uppsala Genetic Center, Department of Cell Research, Swedish University of Agricultural Sciences, Box 7055, S-75007 Uppsala, Sweden;(2) Present address: Banting and Best Department of Medical Research, University of Toronto, 112 College Street, M5G 1L6 Toronto, Ontario, Canada |
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Abstract: | Myrosinase (thioglucoside glucohydrolase, EC 3.2.3.1.) is in Brassicaceae species such as Brassica napus and Sinapis alba encoded by two differentially expressed gene families, MA and MB, consisting of about 4 and 10 genes, respectively. Southern blot analysis showed that Arabidopsis thaliana contains three myrosinase genes. These genes were isolated from a genomic library and two of them, TGG1 and TGG2, were sequenced. They were found to be located in an inverted mode with their 3 ends 4.4 kb apart. Their organization was highly conserved with 12 exons and 11 short introns. Comparison of nucleotide sequences of TGG1 and TGG2 exons revealed an overall 75% similarity. In contrast, the overall nucleotide sequence similarity in introns was only 42%. In intron 1 the unusual 5 splice border GC was used. Phylogenetic analyses using both distance matrix and parsimony programs suggested that the Arabidopsis genes could not be grouped with either MA or MB genes. Consequently, these two gene families arose only after Arabidopsis had diverged from the other Brassicaceae species. In situ hybridization experiments showed that TGG1 and TGG2 expressing cells are present in leaf, sepal, petal, and gynoecium. In developing seeds, a few cells reacting with the TGG1 probe, but not with the TGG2 probe, were found indicating a partly different expression of these genes. |
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Keywords: | Arabidopsis evolution expression genomic clone in situ hybridization myrosinase |
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