title: Suppression of ASKβ (AtSK32), a Clade III Arabidopsis GSK3, Leads to the Pollen Defect during Late Pollen Development.
abstract: Arabidopsis Shaggy-like protein kinases (ASKs) are Arabidopsis thaliana homologs of glycogen synthase kinase 3/SHAGGY-like kinases (GSK3/SGG), which are comprised of 10 genes with diverse functions. To dissect the function of ASKβ (AtSK32), ASKβ antisense transgenic plants were generated, revealing the effects of ASKβ down-regulation in Arabidopsis. Suppression of ASKβ expression specifically interfered with pollen development and fertility without altering the plants' vegetative phenotypes, which differed from the phenotypes reported for Arabidopsis plants defective in other ASK members. The strength of these phenotypes showed an inverse correlation with the expression levels of ASKβ and its co-expressed genes. In the aborted pollen of ASKβ antisense plants, loss of nuclei and shrunken cytoplasm began to appear at the bicellular stage of microgametogenesis. The in silico analysis of promoter and the expression characteristics implicate ASKβ is associated with the expression of genes known to be involved in sperm cell differentiation. We speculate that ASKβ indirectly affects the transcription of its co-expressed genes through the phosphorylation of its target proteins during late pollen development.
authors.affiliation: Department of Biological Science, College of Bioscience and Biotechnology, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Xiangshu
authors.initials: X
authors.lastname: Dong
authors.affiliation: Department of Horticulture, Sunchon National University, Jeonnam 540-742, Korea.
authors.forename: Ill-Sup
authors.initials: IS
authors.lastname: Nou
authors.affiliation: Department of Biological Science, College of Bioscience and Biotechnology, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Hankuil
authors.initials: H
authors.lastname: Yi
authors.affiliation: Department of Biological Science, College of Bioscience and Biotechnology, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Yoonkang
authors.initials: Y
authors.lastname: Hur
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D053263:Gene Regulatory Networks; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011058:Pollen / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
chemical_list: D038362:Glycogen Synthase Kinase 3
keywords: ASKβ (AtSK32, At3g61160); aborted pollen; antisense suppression; co-expressed genes; serine/threonine kinase; sperm cell formation