Cellulose Synthase-Like D1 Is Integral to Normal Cell Division, Expansion, and Leaf Development in Maize    

Abstract

The Cellulose Synthase-Like D (CslD) genes have important, although still poorly defined, roles in cell wall formation. Here, we show an unexpected involvement of CslD1 from maize (Zea mays) in cell division. Both division and expansion were altered in the narrow-organ and warty phenotypes of the csld1 mutants. Leaf width was reduced by 35%, due mainly to a 47% drop in the number of cell files across the blade. Width of other organs was also proportionally reduced. In leaf epidermis, the deficiency in lateral divisions was only partially compensated by a modest, uniform increase in cell width. Localized clusters of misdivided epidermal cells also led to the formation of warty lesions, with cell clusters bulging from the epidermal layer, and some cells expanding to volumes 75-fold greater than normal. The decreased cell divisions and localized epidermal expansions were not associated with detectable changes in the cell wall composition of csld1 leaf blades or epidermal peels, yet a greater abundance of thin, dense walls was indicated by high-resolution x-ray tomography of stems. Cell-level defects leading to wart formation were traced to sites of active cell division and expansion at the bases of leaf blades, where cytokinesis and cross-wall formation were disrupted. Flow cytometry confirmed a greater frequency of polyploid cells in basal zones of leaf blades, consistent with the disruption of cytokinesis and/or the cell cycle in csld1 mutants. Collectively, these data indicate a previously unrecognized role for CSLD activity in plant cell division, especially during early phases of cross-wall formation.

The Maize MID-COMPLEMENTING ACTIVITY Homolog CELL NUMBER REGULATOR13/NARROW ODD DWARF Coordinates Organ Growth and Tissue Patterning

“…Disturbance of the cell cycle is also known to trigger pathogen responses (Bao et al, 2013). Cell wall synthesis CSDL mutants, warty and slender leaf, have overlapping phenotypes with nod-1, including reduced organ size, defects in cell division, and abnormal stomata differentiation (Hunter et al, 2012;Yoshikawa et al, 2013). Given that the cell wall composition of mature nod-1 tissues was nearly unchanged, it is unlikely that NOD contributes to cell wall synthesis, while a role in cell wall signaling cannot be excluded.…”

Regulation of planar growth by the Arabidopsis AGC protein kinase UNICORN

“…The ucn outgrowths are distinct from the wart-like epidermal cell swellings caused by several mutations in Arabidopsis and maize (31)(32)(33) or the multiplication of epidermal cell layers caused by the maize Xcl1 mutation (34). Furthermore, UCN is likely to function in a different pathway than ACR4 and ALE2 (SI Appendix, Fig.…”

Identification of PAN2 by Quantitative Proteomics as a Leucine-Rich Repeat–Receptor-Like Kinase Acting Upstream of PAN1 to Polarize Cell Division in Maize

“…To visualize nuclei and cell walls ( Figure 1A), mature leaf 3 tissue was fixed and stained with 100 µg/mL propidium iodide as described previously (Hunter et al, 2012), mounted in water, and imaged via confocal microscopy. Actin and nuclei were visualized via confocal microscopy of fixed tissues excised from the basal 1 cm of unexpanded leaf 3 or 4 stained with Alexafluor 488-phalloidin (Molecular Probes/Invitrogen) and 10 µg/mL propidium iodide as previously described (Cartwright et al, 2009).…”