Disruption of the microtubule network alters cellulose deposition and causes major changes in pectin distribution in the cell wall of the green alga,Penium margaritaceum

Abstract

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.

Tubulin perturbation leads to unexpected cell wall modifications and affects stomatal behaviour inPopulus

“…Pectin vesicles were observed in close association with cortical MTs near the mucilage secretion pockets during Arabidopsis seed coat development ( McFarlane et al , 2008 ). Oryzalin treatment was shown to affect not only cellulose but also pectin deposition in unicellular green alga ( Domozych et al , 2014 ). Two recent studies showed that Arabidopsis mutants defective in kinesin motor proteins exhibited abnormal Golgi morphology, with altered pectin secretions and accumulation of arabinose-containing carbohydrates in the cell wall ( Kong et al , 2015 ; Zhu et al , 2015 ).…”

“…Disruption of the MT–MF alignment by cobtorin in tobacco BY-2 cells altered pectin distribution, which implicated not only pectins in MT–MF alignment, but also MTs in pectin deposition ( Yoneda et al , 2010 ). Similarly, depolymerization of MTs by oryzalin affected not only cellulose but also pectin deposition in Penium margaritaceum ( Domozych et al , 2014 ).…”

Isolation and manipulation of protoplasts from the unicellular green alga Penium margaritaceum

“…After testing several enzymes, we determined that only a mixture of cellulase and PL yielded protoplasts. PL catalyzes HG by β-elimination of (1 → 4)-α-d-galacturonan [30], and it has been reported to remove the HG-rich OL that forms the outer lattice in Penium [15,18]. Our results show that only PL, acting at the OL level of the cell wall, combined with cellulase, acting at the IL level, were sufficient to compromised wall integrity at the isthmus in order to release the protoplast.…”

“…Finally, recent molecular investigations [16] are providing new insights and creating opportunities for studying Penium as a model for plant cell physiology, development and evolution. All of these features make Penium an outstanding experimental system in plant cell biology [17,18].…”

Cell Wall Evolution and Diversity

“…In the desmid, Penium margaritaceum, a band of cortical microtubules found in the central pre-division expansion zone is arranged in the same orientation as that of the innermost layer of cellulose microfibrils (Ochs et al 2014). If the microtubules are altered using pharmacological agents (e.g., oryzalin), cellulose microfibril production is altered and the localized swelling of the cell occurs (Domozych et al 2014b). This cortical microtubule band also serves a "marker" for expansion prior to cell division, i.e., similar to a pre-prophase band.…”