KNS4/UPEX1: A Type II Arabinogalactan β-(1,3)-Galactosyltransferase Required for Pollen Exine Development

Pollen is an essential component in angiosperm reproduction. Pollen grains are surrounded by a highly resistant wall called exine which enables survival of the male gametes in adverse environmental conditions. Suzuki et al. examined the contribution of an Arabinogalactan β-(1,3)-Galactosyltransferase in proper exine development through characterization of the KNS4 gene. The kaonashi mutant (kns4) was initially characterized by abnormal primexine deposition and a lack of proper exine wall patterning, leading to gross morphological defects in the pollen and degradation. This was found to have an impact on fertility as mutant plants yielded shorter siliques and fewer seeds compared to WT. Signal from antibodies against the protein of interest were severely diminished and exhibited altered localization in the mutant. The authors concluded that KNS4 and other arabinogalactan proteins play an important role in angiosperm fertility by promoting pollen exine development (Summary by Andrew Kirkpatrick) Plant Phys. 10.1104/pp.16.01385.