Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Genes Regulating Initiation Of Meiosis And Homologous Chromosome Pairing In Maize And Arabidopsis.

Wojtek, P. Pawlowski¹ , Inna N. Golubovskaya² , Jessica M. Szymaniak¹ , Arnaud Ronceret¹ , Rachel Wang² , W. Zacheus Cande² , Liang Shi³ , Tong Zhu³ , Marie-Pascal Doutriaux⁴

¹  Cornell University, Ithaca, NY 14853, USA.

²  University of California, Berkeley, CA 94720, USA.

³  Syngenta Biotechnology Inc., Research Triangle Park, NC 27709, USA.

⁴  Universite Paris XI, France.

We are combining cytological, genetic, and molecular approaches to identify and characterize genes involved in the initiation and progression of meiosis in maize and Arabidopsis. We are studying the initiation of meiosis, which in maize is controlled by the ameiotic1 (am1) gene. am1 is required for the establishment of meiotic chromosome structure and sister-chromatid cohesion, homologous chromosome pairing, and meiotic recombination. In most am1 mutants, male meiocytes, and often female meiocytes as well, undergo mitotic division. am1 encodes a protein of unknown biochemical function that localizes to maize chromosomes early during meiotic prophase. The protein sequence contains two predicted coiled-coil domains, frequently associated with protein-protein interactions. Based on results of expression profiling experiments, we propose that AM1 acts to regulate the entry into meiosis by directly or indirectly affecting expression of meiotic genes. We defined two conserved domains in the AM1 protein sequence, one required for initiation of meiosis, and the other one required for the progression through the leptotene – zygotene transition. We also are investigating the key meiotic protein in plants, encoded by the poor homologous synapsis1 (phs1) gene. phs1 plays a role in ensuring that pairing occurs exclusively between homologous chromosomes. The phs1 gene encodes a novel protein with several short conserved domains but with a low overall level of evolutionary conservation. However, in Arabidopsis, the phs1 homolog is also required for proper progression of meiosis. We are currently testing if it fulfills the same function as the phs1 gene in maize in regulating homologous chromosome pairing.