Abstract
Recent studies have established that boron in plant cells occurs as the borate-rhamnogalacturonan II (RG-II) complex, but the physiological function of the complex has yet to be investigated. 3-Deoxy-D-manno-oct-2-ulosonic acid (KDO) is a specific component monosaccharide of RG-II. Mutant plants defective of KDO biosynthesis would have altered RG-II structure and should be useful to study the function of B-RG-II complex. To obtain such a mutant we have been characterizing the KDO biosynthesis in Arabidopsis.
KDO cytidylyltransferase (CMP-KDO synthetase; CKS, EC 2.7.7.38) activates KDO prior to its incorporation into RG-II. Arabidopsis has one CKS gene (At1g53000). In T-DNA insertion lines of this gene, no homozygous mutants were obtained. Crossing experiment revealed that cks mutation was not transmitted through male, suggesting that normal B-RG-II complex is essential for pollen function. Effects of cks mutation on pollen tube growth is now under investigation.
