pectins and oryzalin

Pectins are abundant in the cell walls of dicotyledonous plants, but how they interact with other wall polymers and influence wall integrity and cell growth has remained mysterious. Here, we verified that QUASIMODO2 (QUA2) is a pectin methyltransferase and determined that QUA2 is required for normal pectin biosynthesis. To gain further insight into how pectin affects wall assembly and integrity maintenance, we investigated cellulose biosynthesis, cellulose organization, cortical microtubules, and wall integrity signaling in two mutant alleles of Arabidopsis (

Topics: Arabidopsis; Arabidopsis Proteins; Cell Adhesion; Cell Wall; Cellulose; Dinitrobenzenes; Gene Expression Regulation, Plant; Hypocotyl; Methyltransferases; Microtubules; Mutation; Pectins; Plant Cells; Plants, Genetically Modified; Sulfanilamides; Uronic Acids

Application of the dintroaniline compound, oryzalin, which inhibits microtubule formation, to the unicellular green alga Penium margaritaceum caused major perturbations to its cell morphology, such as swelling at the wall expansion zone in the central isthmus region. Cell wall structure was also notably altered, including a thinning of the inner cellulosic wall layer and a major disruption of the homogalacturonan (HG)-rich outer wall layer lattice. Polysaccharide microarray analysis indicated that the oryzalin treatment resulted in an increase in HG abundance in treated cells but a decrease in other cell wall components, specifically the pectin rhamnogalacturonan I (RG-I) and arabinogalactan proteins (AGPs). The ring of microtubules that characterizes the cortical area of the cell isthmus zone was significantly disrupted by oryzalin, as was the extensive peripheral network of actin microfilaments. It is proposed that the disruption of the microtubule network altered cellulose production, the main load-bearing component of the cell wall, which in turn affected the incorporation of HG in the two outer wall layers, suggesting coordinated mechanisms of wall polymer deposition.

Topics: Antibodies, Monoclonal; Cell Shape; Cell Wall; Cellulose; Chlorophyta; Dinitrobenzenes; Glycoside Hydrolases; Immunohistochemistry; Microarray Analysis; Microtubules; Models, Biological; Pectins; Polysaccharides; Sulfanilamides