An EAR-dependent regulatory module promotes male germ cell division and sperm fertility in Arabidopsis.

Borg, M., Rutley, N., Kagale, S., Hamamura, Y., Gherghinoiu, M., Kumar, S., Sari, U., Esparza-Franco, M.A., Sakamoto, W., Rozwadowski, K., Higashiyama, T., and Twell, D. (2014). "An EAR-dependent regulatory module promotes male germ cell division and sperm fertility in Arabidopsis.", Plant Cell, 26(5), pp. 2098-2113. doi : 10.1105/tpc.114.124743  Access to full text

Abstract

The production of the sperm cells in angiosperms requires coordination of cell division and cell differentiation. In Arabidopsis thaliana, the germline-specific MYB protein DUO1 integrates these processes, but the regulatory hierarchy in which DUO1 functions is unknown. Here, we identify an essential role for two germline-specific DUO1 target genes, DAZ1 and DAZ2, which encode EAR motif–containing C2H2-type zinc finger proteins. We show that DAZ1/DAZ2 are required for germ cell division and for the proper accumulation of mitotic cyclins. Importantly, DAZ1/DAZ2 are sufficient to promote G2- to M-phase transition and germ cell division in the absence of DUO1. DAZ1/DAZ2 are also required for DUO1-dependent cell differentiation and are essential for gamete fusion at fertilization. We demonstrate that the two EAR motifs in DAZ1/DAZ2 mediate their function in the male germline and are required for transcriptional repression and for physical interaction with the corepressor TOPLESS. Our findings uncover an essential module in a regulatory hierarchy that drives mitotic transition in male germ cells and implicates gene repression pathways in sperm cell formation and fertility.

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