Poster: Signaling, cell-to-cell

Abs # 433: Control of Arabidopsis Anther Cell Fate Determination by EMS1, a Leucine-rich Repeat Receptor-like Protein Kinase

Presenter:	Zhao, Dazhong , dxz12@yahoo.com
Authors	Zhao, Dazhong  (A) (C)  Wang, Guanfang  (A) (B)  Hendrix, Carey  (A) (B)  Speal, Brooke  (A)   Ma, Hong  (A) (B)
Affiliations:	(A): Department of Biology, 312 Wartik Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802, USA (B): The Intercollege Graduate Program in Plant Physiology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA (C): Address after August: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA

In flowering plants, male gametophytes develop in the anther where cell differentiation and subsequent degeneration are essential for successful reproduction. The anther contains highly specialized cell types. The reproductive cells, microsporocytes (pollen mother cells), undergo meiosis and, in turn, develop into pollen. Non-reproductive cells or somatic cells, including epidermis, endothecium, middle layer, and tapetum, are required for the normal development and release of pollen. However, very little is known about the molecular mechanisms of cell fate determination in the anther development. One of the Arabidopsis mutants identified via the transposon mutagenesis is ems1 (excess microsporocytes1), which produces excess microsporocytes, lacks tapetal cells, and abnormally retains the middle layer (Zhao et al. Genes & Dev. 2002, 16: 2021). The number of excess microsporocytes in the mutant is close to the sum of wild-type microsporocytes and tapetal cells, indicating that the tapetum precursor cells differentiate into microsporocytes in the mutant. The male meiotic nuclear division seems normal in the mutant, but meiotic cytokinesis does not occur, resulting in the failure of microsporogenesis and male sterility. Therefore, the tapetum is required for meiotic cytokinesis and pollen development. The EMS1 gene encodes a leucine-rich repeat receptor-like protein kinase (LRR-RLK), and its expression is associated with the differentiation of the microsporocytes and tapetal cells, indicating that EMS1 signals fate determination of reproductive cells and their adjacent somatic cells, particularly the tapetal cells. Our future research will focus on defining the EMS1 gene function and elucidating the EMS1-dependent signal transduction pathway in anther cell differentiation.