Juan Dong Assistant Professor Rutgers University Dept. of Plant Biology & Pathology Waksman Institute Piscataway. NJ 08854 (848) 445-7034 FAX - 5735 dong@waksman.rutgers.edu

Cell polarity, asymmetric cell division, stomatal development and patterning, plant cell and development, molecular genetics

Polarity is a fundamental feature of cells and can manifest itself both in overall morphology and in the unequal distribution of molecular components. Cell polarity, in both animals and plants, is of paramount importance for many developmental and physiological processes. Establishment and maintenance of cell polarity is required for asymmetric cell division (ACD), an indispensable mechanism for multi-cellular organisms to generate cellular diversity by producing daughter cells with distinctive identities from a single mother cell. Extensive studies in animal systems have revealed a set of conserved proteins that link cell polarization to asymmetric division control. Plant genomes do not seem to encode these “polarity” proteins and the molecular components and mechanical basis for plant asymmetric division has been an enigma for decades. Studies on the novel plant protein BASL (Breaking of Asymmetry in the Stomatal Lineage) provided the strong evidence that plant cells also have the capability to polarize non-transmembrane proteins and utilize polarized protein distribution to regulate asymmetric cell division (Dong, et al., 2009)(figure 1).

The formation and patterning of stomata (pores on the plant epidermis that regulate CO2 and H2O exchange with the atmosphere) proceeds via a series of asymmetric divisions. These divisions are required for cell fate specification, stem cell-like renewing divisions, and overall patterning. BASL was first demonstrated to regulate asymmetric cell divisions by its mutant phenotype; BASL’s striking sub-cellular polarization in the stomatal lineage cells (figure 1), however, was key data that suggested a molecular mechanism for the creation of plant cell polarity. By using BASL as an anchor for genetic and physical interactors screens, and by using features of the protein itself as a probe for cell’s ability to correctly establish polar cortical localization, my lab is interested in building a model for plant cell polarity and its regulation in ACD. This includes the identification of additional polarized proteins and of mutants that highlight specific subsets of polarity defects. In the future, my lab will continue to use Arabidopsis as a model system, by studying BASL and the other newly identified factors, to investigate how proteins become polarly localized, how polarity proteins are involved in establishment of cellular asymmetry, and how cell polarity is instructive of cell fate and differentiation in plants.

Selected Publications

Hachez C, Ohashi-Ito K, Dong J, Bergmann DC.(2011) Differentiation of Arabidopsis guard cells: analysis of the networks incorporating the basic helix-loop-helix transcription factor, FAMA. Plant Physiol. Mar;155(3):1458-72.

Dong J, Bergmann DC. (2010) Stomatal patterning and development. Curr Top Dev Biol. 91:267-97. Review.

Dong J, MacAlister CA, Bergmann DC. (2009) BASL controls asymmetric cell division in Arabidopsis. Cell. Jun 26;137(7):1320-30.

Kim ST, Zhang K, Dong J, Lord EM.(2006) Exogenous free ubiquitin enhances lily pollen tube adhesion to an in vitro stylar matrix and may facilitate endocytosis of SCA. Plant Physiol. Dec;142(4):1397-411.

Dong J, Kim ST, Lord EM. (2005) Plantacyanin plays a role in reproduction in Arabidopsis. Plant Physiol. Jun;138(2):778-89.

Kim S, Dong J, Lord EM. (2004) Pollen tube guidance: the role of adhesion and chemotropic molecules. Curr Top Dev Biol. 61:61-79. Review.

Kim S, Mollet JC, Dong J, Zhang K, Park SY, Lord EM. (2003) Chemocyanin, a small basic protein from the lily stigma, induces pollen tube chemotropism. Proc Natl Acad Sci U S A. Dec 23;100(26):16125-30.