Miox-genes are transiently expressed during development. The four stages of a flower development show the changing expression pattern visualized with the GUS reporter gene.
The enzyme myo-inositol oxygenase (MIOX) represents a unique enzyme catalyzing the ring cleavage of myo-inositol into glucuronic acid. The enzyme serves at least two purposes:
1) conversion of inositol into glucuronic acid to synthesize UDP-glucuronic acid as cell wall precursor
2) degradation of inositol (mainly in animals). It is a precursor for vitamin C in animals and possibly in plants
Arabidopsis has 4 isoforms of MIOX. A quadruple knockout in all 4 genes, obtained by several rounds of crossing, is viable, indicating that plants do not need this pathway under standard growth conditions ( Endres, S. and Tenhaken, R. (2011).
It is very interesting to see that knockout mutants in at least two of the four MIOX genes leads to plants, which exhibit a high nematode tolerance. The plants are otherwise normal ( Siddique et al. (2009) New Phytol. 184: 457-72). This finding was recently patented by Holger Bohlmann (Boku University, Vienna) and our group. It may lead to the further discovery of a novel type of nematode resistance and broadens the spectrum of methods to fight this group of serious plant diseases.