Evidence for high activity of xylem parenchyma and ray cells in the interface of host stem and Agrobacterium tumefaciens-induced tumours of Ricinus communis.

Rapidly developing tumours at hypocotyls of Ricinus communis, induced by Agrobacterium tumefaciens strain C58, were characterized by strong differentiation of vascular bundles and their functional connection to the host bundles. The stem/tumour interface showed increased xylem, with numerous vessels accompanied by multiseriate unlignified rays. To know how nutrients efficiently accumulate in the tumour sink tissue, cell electropotentials (E(m)) in cross-sections were mapped.

Toxicity of Fusarium mycotoxins on maize plants.

Synergistic effects of Fusarium - toxins mixture (moniliformin, fumonisin B1, fusaproliferin, zearalenone, zearalenol and deoxynivalenol, each at concentration 3.5 μg mL-1) on maize plants of resistant and susceptible cultivars were studied. After 72-hour treatment the biomass production with both cultivars was approximately 6% lower than in the respective controls.

Mineral nutrition of plum trees as an important factor of protection against plum pox virus disease.

The experimental results obtained from a fruit garden at Krajné pointed out a different content of macrobiogenic elements in the leaves of plum trees infected with plum pox virus (PPV) as compared to healthy ones. Mineral nutrition of diseased trees was characteristic by lower relational values of topical levels of macrobiogenic elements especially those of N/P, N/K, (Ca + Mg)/K, and (N/P)/(N/K).

Relationship between concentration of plum pox virus and content of pigments in virus-infected symptomatic apricot leaves.

Besides other factors, occurrence of plum pox virus (PPV)-caused spots and mosaic symptoms on leaves of stone fruits are known to influence important physiological functions including production of assimilates. Apricot (Prunus armeniaca L.) seedlings were used as a test material for typical manifestation of symptoms of the disease on the foliage.

Phenomenon of Rickettsiella phytoseiuli in Phytoseiulus persimilis mite.

An unknown microorganism occurring in a predaceous mite Phytoseiulus persimilis was described by the author in 1977 as a new species Rickettsiella phytoseiuli. Some new results on the relation between this agent and its hosts are presented in this paper.

Toxic effect of endocytobionts from Dermacentor reticulatus ticks in three tick species after in vivo application.

The endocytobionts from ovaries of partially engorged female Dermacentor reticulatus ticks, inoculated introcoelomally into females of three tick species, D. reticulatus, Ixodes ricinus and Haemaphysalis inermis, caused considerable morphological alterations in the examined cells and tissues of the synganglion, fat body, tracheal complex and ovary of these recipients.

Endocytobionts in Dermacentor reticulatus ticks (Ixodidae): an electron microscope study.

Endocytobionts (ECBs) were detected in the ovaries of Dermacentor reticulatus. Their developmental cycle is directly related to the developmental stages of tick oocytes. Two basic forms of ECBs occur in tick cells, i.

Zearalenone production in wheat cultivars infected with the fungusFusarium graminearum Schwabe.

In wheat plants of the eultivars "Danubia", "Agra", "Selekta" and "Jubilejna" the fungusFusarium graminsarum Schwabe produced toxic metabolite zearalenone/F-2/ which simultaneously influenced the development of plants characterized by a lower germinating capacity, a reduced growth rate and a higher production of side branches. The presence ofFusarium graminearum was confirmed only in infected plants after plating of organs (root, stem base, stem) and soil on agar medium. The mycotoxin production is dependent on the pathogen development in host plants.

Mixed infection of Rickettsiella phytoseiuli and Coxiella burnetii in Dermacentor reticulatus female ticks: electron microscope study.

Mixed infection of Rickettsiella phytoseiuli and Coxiella burnetii was investigated in hemolymph and organs of experimentally infected females of Dermacentor reticulatus ticks. Following intracoelomic infection, both agents, with the exception of Gene's organ, multiplied well in the cells of the tick host's organs. Two out of six developmental stages of R.

Experimental infection with Rickettsiella phytoseiuli in adult female Dermacentor reticulatus (Ixodidae): an electron microscopy study.

Rickettsiella phytoseiuli naturally occurring in Phytoseiulus persimilis mites was cultivated in adult female Dermacentor reticulatus ticks. It demonstrates all six known developmental stages: dense, intermediate, bacterial, giant, crystal-forming and small dark particles. These stages of rickettsiae were found in salivary glands, Malpighian tubules, synganglion, ovaries, tracheal complex, haemolymph, fat body and alimentary tract.

Attempt to cultivate Rickettsiella phytoseiuli in Dermacentor reticulatus ticks: an electron microscopic study.

Rickettsiella phytoseiuli occurring in Phytoseiulus persimilis mites was cultivated in Dermacentor reticulatus ticks. Rickettsiella multiplied similarly as in mites exerting all six developmental stages: dense, intermediate, bacterial, giant, crystal-forming and small dark particles.

Fiji and pseudo-Fiji diseases of sugar-cane.

Fijivirus, one of the group of phytoreoviruses, causes leaf galls known as Fiji disease of sugar-cane. In contrast, the so-called pseudo-Fiji disease, considered by some to be a virus disease, has been shown to be of non-viral origin.