[The participation of salicylic and jasmonic acids in genetic and induced resistance of tomato to Meloidogyne incognita (Kofoid and White, 1919)].

Salicylic (SA) and jasmonic (JA) acids are the best known mediators of signal systems in plants. In this investigation the participation and character of interactions between SA- and JA-signals under the induced and genetic resistance of plants to nematodes was investigated on the model system tomato (Lycopersicon esculentum) and the root-knot nematode Meloidogyne incognita. This study demonstrates that application of JA and SA to tomato foliage induces systemic effects that suppress root-knot nematode infestation, inhibition of nematode reproduction, and also increased activity of LOX and PAL, the enzymes of biosynthesis of JA and SA.

[Elicitor activity of chitosan and arachidonic acid: their similarity and distinction].

Two elicitors-chitosan and arachidonic acid-induced the same defense responses in potatoes, stimulating the processes of wound reparation and inducing the formation of phytoalexins, inhibitors of proteinase, and active forms of oxygen. However, chitosan induced the defense potential of plant tissues at concentrations higher than those of arachidonic acid. The protective action of chitosan was defined by two parameters, i.

[Involvement of salicylic acid in induction of nematode resistance in plants].

The role of salicylic acid (SA) as a possible signaling component in the case of the infection of plants with nematodes has been studied using a model system consisting of the tomato (Lycopersicon esculentum (Mill.) and race 1 of the gall eelworm Meloidogyne incognita (Kofoid and White, 1919; Chitwood, 1949). The pre-planting SA treatment of tomato seeds results in an increased nematode resistance of susceptible tomato cultivars; the protective effect is higher in the case of SA combined with chitosan, a biogenic elicitor of plant resistance.

[Wound repair in plant tissues (Review)].

Signaling systems responsible for repair processes in plants and manifestation of defensive effects in plant tissues were analyzed. Special attention was given to jasmonic acid, a mobile systemic repair signal, as well as to jasmonate biosynthesis and signal transport to the areas where protective responses of plants are induced. The main defense responses of potato tubers induced by wounding were considered.

[Immunomodulating activity of chitosan derivatives with salicylic acid and its fragments].

A study of biological activity of the derivatives of the chitin-chitosan oligomer with salicylic acid and its fragments showed that chitosan salicylate actively protected potato tubers against Phytophthora infestans but sharply inhibited reparation of potato tissues. N-(2-Hydroxybenzyl)chitosan exhibited good protective properties but did not influence wound reparation. N-(2-Hydroxy-3-methoxybenzyl)-N-pyridox-chitosan, which contained the pyridoxal and 2-hydroxy-3-methoxy fragments, was the most efficient, stimulating both defense against late blight and wound reparation in potato tissues.

[The inhibition of potato tubers wound reparation].

The multiple washing of the wound surface of potato tubers by water adversely affected the protective properties of wound periderm. Immune inhibitor beta-1,3-beta-1,6 glucan had a property of local effect and inhibited the process of wound healing. The pentasaccharide of xyloglucan caused necrosis of potato tuber tissue and prevented the wound reparation process.

[Wound healing and induced resistance in potato tubers].

It was demonstrated that biogenic elicitors, arachidonic acid and chitosan, locally and systemically stimulated wound healing in potato tuber tissues by increasing the number of wound periderm layers, accelerating the development of cork cambium (phellogen), and inducing proteinase inhibitors. The signal molecules, jasmonic and salicylic acids, had different effects on the development of wound periderm: jasmonic acid locally and systemically stimulated potato wound healing and elevated the level of proteinase inhibitors, whereas salicylic acid did not have any effect on wound healing and even blocked the formation of proteinase inhibitors.

[Activation of elicitor defensive properties by systemic signal molecules during the interaction between potato and Phytophthora].

The elicitor arachidonic acid in combination with jasmonic acid (JA) induced a higher level of defense against the late blight agent in potato (Solanum tuberosum L.) tissues than in combination with salicylic acid (SA). On the contrary, the elicitor chitosan displayed a higher inductive effect in combination with SA as compared with JA.

[Induced plant resistance and salicylic acid: a review].

Current understanding of the involvement of salicylic acid (SA) in the formation of plant resistance has been reviewed. SA acts as a signal molecule in the SA-dependent pathway. The so-called salicylate burst observed in tissues of plants after stress increases their resistance.

[Free and conjugated forms of salicylic acid: content and role in potato].

Hydrolysis of conjugated forms of salicylic acid and accumulation of its free form was observed after infection of potato tubers (Solanum tuberosum L.) with an incompatible race of phytophthora or treatment with an elicitor (chitosan). Infection of tubers with a compatible race of the pathogen or treatment with a suppressor (laminarin) decreased both the degree of hydrolysis of conjugated forms of salicylic acid and the accumulation of its free form.

[Effect of systemic signaling molecules on the rate of spread of the immunizing effect of elicitors over potato tissues].

Mobile systemic signaling molecules (salicylic and jasmonic acids) enhance and accelerate the spread of systemic immunizing effect of elicitors (arachidonic acid and chitosan) over potato tuber tissues (Solanum tuberosum L.).

[Biochemical aspects of plant interactions with parasite nematodes. (A review)].

The review summarizes reports on molecular aspects of interactions of phytoparasitic nematodes with plant hosts. Data on the secrets of nematodes affecting plants (elicitors, toxins, products of parasitism genes, etc.) are analyzed and information flow pathways comprising all elements of the plant-parasite interaction (from elicitors to defense responses of plant cells), described.

[Regulation of potato immune responses by laminarin].

Laminarin blocks potato immune responses by inhibiting the reaction of oversensitivity, formation of phytoalexins, wound repair, and the activity of proteinase inhibitors. It was found that laminarin exhibits antielicitor activity. Addition of salicylic acid to laminarin enhances its immunosuppressing effect, which becomes systemic.

[Induced phytophthora resistance in transgenic potato tubers].

Resistance of transgenic cultivars based on the expression of one or more resistance genes is sooner or later broken by pathogens whose race-producing rates are high. Thus, combining transgenesis with elicitor-induced resistance is a promising approach. The elicitor-induced resistance is based on the expression of multiple resistance genes, which can prevent the adaptation of pathogens to transgenic races, maintain the stability of cultivars, and increase their lifespan.

[The use of elicitors for defense of agricultural plants demands caution].

Hazards of the use of biogenic elicitors for inducing protective mechanisms in plants without considering the possible negative effects of the elicitors are considered.

[Immunosuppressors in pathogenesis of potato-pathogen blight].

The properties and effects of two plant resistance suppressors (1,3-beta-1,6-beta-glucan and a pentasaccharide of xyloglucan origin) involved in the pathosystem of potato (Solanum tuberosum) and the causal agent of blight (Phytophthora infestans (Mont) de Bary) were compared. The microbial 1,3-beta-1,6-beta-glucan suppressed the defense response over a narrow concentration range (10(-2) M), whereas the plant pentasaccharide had a broad range of effective concentrations (10(-12) to 10(-6) M). In the pathosystem of potato-causal agent of late blight, the beta-glucan caused a local and race-specific suppressor effect on the plant host defense response.

[Modulation of plant resistance to diseases by water-soluble chitosan].

Low-molecular-weight water-soluble chitosan with a molecular weight of 5 kDa obtained after enzymatic hydrolysis of native crab chitosan was shown to display an elicitor activity by inducing the local and systemic resistance of Solanumi tuberosum potato and Lycopesicon esculentum tomato to Phytophthora infestans and nematodes, respectively. Chitosan induced the accumulation of phytoalexins in tissues of host plants, decreased the total content and changed the composition of free sterols producing adverse effects on infesters, activated chitinases, beta-glucanases, and lipoxygenases, and stimulated the generation of reactive oxygen species. The activation of protective mechanisms in plant tissues inhibited the growth of taxonomically different pathogens (parasitic fungus Phytophthora infestans and root knot nematode Meloidogyne incognita).

[Derivatives of chitin and chitosan as elicitors of potato resistance to late blight].

Water-soluble low-molecular-weight (3-10 kDa) chitosan obtained by enzymatic degradation of high-molecular-weight chitosan, as well as its deaminated derivatives, can be used as elicitors of late blight resistance in potato.

[Study of the amino acid residue topography of the adenosine triphosphatase center of (Ca--Mg)-dependent sarcoplasmic reticulum adenosine triphosphatase by kinetic and spectral methods].

The topography of HS- and NH2-groups and tryptophane residues in ATPase centre of (Ca--Mg)-ATPase on sarcoplasmic reticulum (SR) was investigated by kinetics, electron spectroscopy and spectrofluorimetry method. Both o-phthalaldehyde interacting with lysine or arginine residue or with end amino acid and fluorescein dimercuric acetate interaction with cysteine residue of HS-groups make (Ca--Mg)-ATPase both in SR and the pure enzyme completely inactive at molar ratio enzyme: inhibitor equal to 1 : 1. A 500 molar ATP surplus reduces drastically the enzyme inactivation rate by both inhibitors.

[Fungiotoxic properties of steroid saponins from the rhizomes of deltoid dioscorea].

Experiments were carried to test the fungitoxic effect of steroid glycosides--deltoside and deltonine--(representatives of spiro and furostanol saponins) on the growth of conidia F. solani and zoospores Ph. infestans.