A polarized nuclear position specifies the correct division plane during maize stomatal development.

Asymmetric cell division generates different cell types and is a feature of development in multicellular organisms. Prior to asymmetric cell division, cell polarity is established. Maize (Zea mays) stomatal development serves as an excellent plant model system for asymmetric cell division, especially the asymmetric division of the subsidiary mother cell (SMC).

The OPAQUE1/DISCORDIA2 myosin XI is required for phragmoplast guidance during asymmetric cell division in maize.

Formative asymmetric divisions produce cells with different fates and are critical for development. We show the maize (Zea mays) myosin XI protein, OPAQUE1 (O1), is necessary for asymmetric divisions during maize stomatal development. We analyzed stomatal precursor cells before and during asymmetric division to determine why o1 mutants have abnormal division planes.

Polarly localized WPR proteins interact with PAN receptors and the actin cytoskeleton during maize stomatal development.

Polarization of cells prior to asymmetric cell division is crucial for correct cell divisions, cell fate, and tissue patterning. In maize (Zea mays) stomatal development, the polarization of subsidiary mother cells (SMCs) prior to asymmetric division is controlled by the BRICK (BRK)-PANGLOSS (PAN)-RHO FAMILY GTPASE (ROP) pathway. Two catalytically inactive receptor-like kinases, PAN2 and PAN1, are required for correct division plane positioning.

The SCAR/WAVE complex polarizes PAN receptors and promotes division asymmetry in maize.

Pre-mitotic establishment of polarity is a key event in the preparation of mother cells for asymmetric cell divisions that produce daughters of distinct fates, and ensures correct cellular patterning of tissues and eventual organ function. Previous work has shown that two receptor-like kinases, PANGLOSS2 (PAN2) and PAN1, and the small GTPase RHO GTPASE OF PLANTS (ROP) promote mother cell polarity and subsequent division asymmetry in developing maize stomata. PAN proteins become polarized prior to asymmetric cell division, however, the mechanism of this polarization is unknown.

Parallel proteomic and phosphoproteomic analyses of successive stages of maize leaf development.

We performed large-scale, quantitative analyses of the maize (Zea mays) leaf proteome and phosphoproteome at four developmental stages. Exploiting the developmental gradient of maize leaves, we analyzed protein and phosphoprotein abundance as maize leaves transition from proliferative cell division to differentiation to cell expansion and compared these developing zones to one another and the mature leaf blade. Comparison of the proteomes and phosphoproteomes suggests a key role for posttranslational regulation in developmental transitions.

Division polarity in developing stomata.

Stomata are generated via asymmetric cell division in both dicots and monocots. Intrinsic or extrinsic polarity cues are perceived and acted upon to generate mother cell polarity and determine asymmetric division planes. Arabidopsis employs both intrinsic and extrinsic cues to orient a variable series of asymmetric stomatal divisions, using novel proteins such as BASL and POLAR to generate polarity.