Programmed Cell Death in Plants: Protective Effect of Phenolic Compounds against Chitosan and H₂O₂

---

V. D. Samuilov^1,2*, L. A. Vasil’ev¹, E. V. Dzyubinskaya^1,2, D. B. Kiselevsky^1,2, and A. V. Nesov¹

¹Department of Physiology of Microorganisms, Faculty of Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; fax: (495) 939-3807; E-mail: vdsamuilov@mail.ru

²Center for Mitoengineering, Lomonosov Moscow State University, 119991 Moscow, Russia

^* To whom correspondence should be addressed.

Received April 20, 2009; Revision received June 8, 2009

---

Addition of chitosan or H₂O₂ caused destruction of nuclei of epidermal cells (EC) in the epidermis isolated from pea leaves. Phenol, a substrate of the apoplastic peroxidase-oxidase, in concentrations of 10^–10-10^–6 M prevented the destructive effect of chitosan. Phenolic compounds 2,4-dichlorophenol, catechol, and salicylic acid, phenolic uncouplers of oxidative phosphorylation pentachlorophenol and 2,4-dinitrophenol, and a non-phenolic uncoupler carbonyl cyanide m-chlorophenylhydrazone, but not tyrosine or guaiacol, displayed similar protective effects. A further increase in concentrations of the phenolic compounds abolished their protective effects against chitosan. Malate, a substrate of the apoplastic malate dehydrogenase, replenished the pool of apoplastic NADH that is a substrate of peroxidase-oxidase, prevented the chitosan-induced destruction of the EC nuclei, and removed the deleterious effect of the increased concentration of phenol (0.1 mM). Methylene Blue, benzoquinone, and N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) capable of supporting the optimal catalytic action of peroxidase-oxidase cancelled the destructive effect of chitosan on the EC nuclei. The NADH-oxidizing combination of TMPD with ferricyanide promoted the chitosan-induced destruction of the nuclei. The data suggest that the apoplastic peroxidase-oxidase is involved in the antioxidant protection of EC against chitosan and H₂O₂.

---

KEY WORDS: apoplastic peroxidase, programmed cell death, chitosan, hydrogen peroxide, phenolic compounds, protective action, plants, epidermal cells

DOI: 10.1134/S0006297910020173

---