Strong alkalinization of Chara cell surface in the area of cell wall incision as an early event in mechanoperception

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• 作者：Alex ; er A. Bulychev ; Anna V. Alova ; Tatiana N. Bibikova
• 关键词：APW ; artificial pond water ; CW ; cell wall ; PFD ; photon flux density ; pHo ; pH in the outer medium near the cell surface ; PM ; plasma membrane ; PSI and PSII ; photosystems I and II
• 刊名：Biochimica et Biophysica Acta (BBA)/Biomembranes
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：1828
• 期：11
• 页码：2359-2369
• 全文大小：1182 K

文摘

Mechanical wounding of cell walls occurring in plants under the impact of pathogens or herbivores can be mimicked by cell wall incision with a glass micropipette. Measurements of pH at the surface of Chara corallina internodes following microperforation of cell wall revealed a rapid (10-30 s) localized alkalinization of the apoplast after a lag period of 10-20 s. The pH increase induced by incision could be as large as 3 pH units and relaxed slowly, with a halftime up to 20 min. The axial pH profile around the incision zone was bell-shaped and localized to a small area, extending over a distance of about 100 ¦Ìm. The pH response was suppressed by lowering cell turgor upon the replacement of artificial pond water (APW) with APW containing 50 mM sorbitol. Stretching of the plasma membrane during its impression into the cell wall defect is likely to activate the Ca^2 + channels, as evidenced from sensitivity of the incision-induced alkalinization to the external calcium concentration and to the addition of Ca^2 +-channel blockers, such as La^3 +, Gd^3 +, and Zn^2 +. The maximal pH values attained at the incision site (~ 10.0) were close to pH in light-dependent alkaline zones of Chara cells. The involvement of cytoskeleton in the origin of alkaline patch was documented by observations that the incision-induced pH transients were suppressed by the inhibitors of microtubules (oryzalin and taxol) and, to a lesser extent, by the actin inhibitor (cytochalasin B). The results indicate that the localized increase in apoplastic pH is an early event in mechanoperception and depends on light, cytoskeleton, and intracellular calcium.