ASK1, a SKP1 homolog, is required for nuclear reorganization, presynaptic homolog juxtaposition and the proper distribution of cohesin during meiosis in Arabidopsis
- 288 Downloads
Nuclear reorganization and juxtaposition of homologous chromosomes at late leptotene/early zygotene are essential steps before chromosome synapsis at pachytene. We report the results of detailed studies, which demonstrate that nuclear reorganization and homolog juxtapositioning processes are defective in a null mutant, ask1-1. Our results from 4, 6-diamino-2-phenylindole (DAPI)-stained spreads showed that the “synizetic knot”, which is typically found in wild type (WT) meiosis during late leptotene and zygotene, was missing in the ask1-1 mutant. Furthermore, ask1-1 meiocytes exhibited only limited homolog juxtaposition at centromere regions at early zygotene. Immunodetection of the cohesin protein SYN1 identified ask1 defects in cohesin distribution from zygotene to anaphase I. Analysis of meiotic chromosomes in ask1-1 and syn1 single mutants, as well as an ask1-1 syn1 double mutant indicate that ASK1 is required for normal SYN1 distribution during meiotic prophase I and suggest that ask1 associated defects may be primarily related to SYN1 mislocalization.
KeywordsArabidopsis thaliana ASK1 Homolog juxtaposition Meiosis SYN1 synizetic knot Cohesin Synapsis
transmission electron microscopy
Unable to display preview. Download preview PDF.
We thank A. Omeis and J. Wang for plant care. We also thank E. Harris and M. Henry for their help with the identification of the ask1-1 syn1 double mutant plants. We are grateful for comments on this manuscript from C. Chen, W. Li, L. Harper, W. Ni, G. Wang, L.M. Zahn, W. Zhang, and M. Zolan. This work was supported by grants from the National Science Foundation [MCB-0092075 (HM); MCB-0322171 (CAM)], the National Institutes of Health [RO1 GM63871 (HM)], and the Department of Energy [DE-FG02-02ER15332 (HM and DZ)] and by funds from the Department of Biology and the Huck Institutes of the Life Sciences at the Pennsylvania State University. H.M. gratefully acknowledges the support of the John Simon Guggenheim Memorial Foundation.
- de la Espina SMD (1995) Nuclear matrix isolated from plant cells. Int Rev Cytol 162:75–139Google Scholar
- Trelles-Sticken E, Scherthan H (1999) Bouquet formation in budding yeast does not require homologous chromosomes. Cytogen Cell Genet 85:181–181Google Scholar
- Wang Y, Yang M (2006) The Arabidopsis Skp1-like1 (ASK1) protein acts predominately from leptotene to pachytene and represses homologous recombination in male meiosis. Planta 223:613–617Google Scholar
- Yang W.-C, Ye D, Xu J, Sundaresan V (1999b) The SPOROCYTELESS gene of Arabidopsis is required for the initiation of sporogenesis and encodes a novel nuclear protein. Genes Dev 13:2108–2117Google Scholar
- Zhao D, Yu Q, Chen M, Ma H (2001) The ASK1 gene regulates b function gene expression in cooperation with UFO and Leafy in Arabidopsis. Dev 128:2735–2746Google Scholar