[Effect of the lipopolysaccharide-protein complex of Pseudomonas syringae PV. atrofaciens on the process of tumor formation caused by Agrobacterium tumefaciens]. / Vplyv lipopolisakharyd-bilkovoho kompleksu Pseudomonas syringae PV. atrofaciens na protses pukhlynoutvorennia, sprychynenyi Agrobacterium tumefaciens.

It has been found that the agent of bacterial spotting of rye P. syringae pv. atrofaciens 8281 has no antagonistic action on the strains 9052 and 9054 of Agrobacterium tumefaciens--the agent of crown gall tumor. Lipopolysaccharide-protein complex of P. syringae pv. atrofaciens 8281 when added to the culture medium does not affect the growth and development of A. tumefaciens bacteria. It has been experimentally established that the lipopolysaccharide-protein complex of P. syringae pv. atrofaciens 8281, when used to treat the potato explants before inoculation of A. tumefaciens, decreases induction and development of tumours on the explants. Tumour formation inhibition depends on concentration of lipopolysaccharide-protein complex solution.

Structure and characterization of the crown gall opines heliopine, vitopine and ridéopine.

The crown gall opines heliopine from tumors induced by octopine type Agrobacterium tumefaciens strains A6, A136(pTiB6-806), E9, A652 and 1590-1 and vitopine from tumor induced by grapevine strains S4 and T2 are identical to synthetic N2-(1'R-carboxyethyl)-L-glutamine. Tumors produced by strains S4 and T2 do not contain octopine or lysopine, but they do contain heliopine and the new opine ridéopine identified as N-(4'-aminobutyl)-D-glutamic acid. Grapevine strains S4 and T2 grow normally on tumor heliopine or synthetic heliopine and on tumor and synthetic ridéopine as well as on ridéopine lactam as sole carbon source. While octopine strains A6 and A136(pTiB6-806) do not grow on heliopine, mutant colonies do appear after a few weeks. Heliopine catabolism by octopine strains is not induced by octopine.

Bruchins: insect-derived plant regulators that stimulate neoplasm formation.

Pea weevil (Bruchus pisorum L.) oviposition on pods of specific genetic lines of pea (Pisum sativum L.) stimulates cell division at the sites of egg attachment. As a result, tumor-like growths of undifferentiated cells (neoplasms) develop beneath the egg. These neoplasms impede larval entry into the pod. This unique form of induced resistance is conditioned by the Np allele and mediated by a recently discovered class of natural products that we have identified from both cowpea weevil (Callosobruchus maculatus F.) and pea weevil. These compounds, which we refer to as "bruchins," are long-chain alpha,omega-diols, esterified at one or both oxygens with 3-hydroxypropanoic acid. Bruchins are potent plant regulators, with application of as little as 1 fmol (0.5 pg) causing neoplastic growth on pods of all of the pea lines tested. The bruchins are, to our knowledge, the first natural products discovered with the ability to induce neoplasm formation when applied to intact plants.

5-azacytidine-induced tumorous transformation and DNA hypomethylation in Nicotiana tissue cultures.

The phenomenon of habituation is considered in plant tissue cultures to be a real process of chemical tumorogenesis; the cultures acquire the capacity of autonomous growth in a hormone-free medium under the influence of a variety of chemical and physical agents. Treatments with 5-azacytidine (AzaC) of in vitro cultured cells of the Nicotiana glauca x N. langsdorffii nontumorous hybrid (NNT) during the culture cycle led to the induction of a habituated phenotype. The repetitive DNA sequences showed a significant lower level of endogenous methylation in the treated cells in comparison with the normal ones. It is worth noting that it was impossible until now to habituate this strain by conventional methods and that the treatments were effective only in the first 5 days of subculturing; various evidence (cytological and biochemical) pointed out a phenomenon of DNA amplification, occurring in the same period. Moreover, analysis of DNA from control and treated cells shows the induction of variations in the endogenous methylation pattern by AzaC in a critical period of cell culture. These results suggest that demethylation can act as a switch from hormone-dependent to autonomous proliferation by activation of genes coding for or regulating the synthesis of growth factors.

The in vitro effects of opines and other compounds on DNAs originating from bacteria, and from healthy and tumorous plant tissues.

Purified total DNAs were isolated from oncogenic or nononcogenic Agrobacterium tumefaciens cells as well as from normal and crown gall tissues. Opines (octopine, nopaline, lysopine), plant hormone (auxin IAA) and some carcinogenic compounds were used in order to correlate their effects on in vitro strand separation and synthesis of DNAs with in vivo tumorous cell multiplication. Octopine (or nopaline) induced chain opening of DNAs originating from octopine (or nopaline)-metabolizing bacteria and from same bacteria strain-induced tumorous cells. This phenomenon was measured by the increase in DNA hyperchromicity which is concentration dependent. The tested compounds stimulated the in vitro synthesis of the same DNAs. Under the same conditions, in vitro strand separation and synthesis of healthy plant DNA was not (or only slightly) enhanced, except in the case of particular hormone-connected healthy cell DNA. IAA and carcinogens stimulated in vitro synthesis and induced in vitro strand separation (dose-dependent effect) of DNAs isolated from crown gall cells and inducing bacteria. Compared to healthy cell DNAs, these DNAs were thus susceptible to structurally very diversified molecules and in this way behave as do mammalian tissue DNAs. The opine and IAA actions observed here were specific for plant tissue DNA; cancerous human or animal tissue DNAs were insensitive. By their presence in the crown gall cells, opines possibly maintain destabilized areas (required for rapid growth and division) on tumor cell DNA. The cooperative actions of IAA and opines as well as small RNA and RNA fragments on gene activation, might explain the autonomy of plant tumor cells.

[Stimulation of induction or inhibition of crown-gall tumor development by RNA-fragments U2. Interference by auxin]. / Stimulation de l'induction--ou inhibition du d'eveloppement--des tumeurs de Crown-gall par des ARN-fragments U2. Interférence de l'auxine.

RNA-fragments U2 obtained by mild degradation with RNase U2 of ribosomal RNA containing A and G nucleotides in excess are capable of exhibiting either a stimulatory effect on the induction of Crown-gall tumors or an inhibitory action on their subsequent development. These different effects are dependent on the moment at which RNA-fragments were introduced into wounded Pea seedlings infected by Agrobacterium tumefaciens B6. The results obtained in vitro and in vivo suggest that an interaction between auxin and RNA-fragments U2 may take place, either increasing the tumor induction or inhibiting the proliferation of tumourous cells.

Adenosine 3',5'-cyclic monophosphate levels in normal and IAA-induced tumours in bean (Phaseolus vulgaris L.) embryos.

Endogenous levels of adenosine 3',5'-cyclic monophosphate in indole-3-acetic acid induced tumours, and control bean embryos were measured with Gilman protein binding assay. No significant differences in cAMP concentrations were found in IAA-induced tumours, which suggests that IAA does not mediate cAMP synthesis in bean embryos.

Oxygen-dependent chemical tumorigenesis in a Nicotiana hybrid: inhibition by ascorbic acid and dinitrophenol.

Aqueous solutions of molecular oxygen, per se, or in combination with either pyrogallol or 6-azauracil increased tumorigenesis in Nicotiana suaveolens X Nicotiana langsdorffii seedlings relative to control seedlings. The biological activities of the organic chemicals were O2-dependent, because the substitution of N2 or O2 or the degassing of 0.1-1 mM solutions of the compounds eliminated or greatly reduced their tumorigenic effects. Rates of tumorigenesis exceeded 95% for 0.5 mM solutions of either pyrogallol or 6-azauracil solutions in the presence of l mM O2. Although tumors developed in 20% of seedlings in the presence of 1 mM O2, alone, 4-5 times more tumors were induced by the organic chemical--O2-H2O systems. Dinitrophenol and ascorbic acid, compounds which affect cellular respiration or redox systems, strongly inhibited the chemically-mediated tumorigenesis. Dinitrophenol was equally effective at one-tenth of the molar concentrations of ascorbic acid that were required for the suppressions of oncogenesis. Dehydroascorbic acid was much less inhibitory than ascorbic acid.

A scanning electron microscopic study of trichomes of IAA-induced tumours in bean embryos (Phaseolus vulgaris L.).

A scanning electron microscopic study of trichome morphology of bean embryo, growing in semi-solid synthetic medium, has been undertaken. The work shows some distinct differences in trichome morphology as well as variation in their development, due to the effect of indole-3-acetic acid (IAA).

[Reaction of the seedlings of flowering plants to the effects of imino-di-(paradimethylaminophenyl)-methane-aurine-00]. / Reaktsiia propostkov tsvetkovykh rastenii na vozdeistvie imino-di-(paradimetilaminofenil)-metana-auramina-00

The influence of auramine-00 on seedlings of three species of plants - Cucurbita pepo L., Helianthus annuus L., Zea mays L.-was investigated. Auramine was added in agar-agar, on which the seedlings were growing. Two concentrations of auramine were used--0.001%. Besides the delay in growth, also the formation of local overgrowth of cotyledons and hypocotyl of C. pepo, the base of cotyledons of H. annuus and mezocotyl of Z. mays were observed. The histological analysis has shown these swellings to arise on the grounds of two processes: pathological proliferation and hypertrophy.