[Show abstract][Hide abstract] ABSTRACT: For the first time, the phytopathogenicity of extracellular vesicles of Acholeplasma laidlawii PG8 (a ubiquitous mycoplasma that is one of the five common species of cell culture contaminants and is a causative agent for phytomycoplasmoses) in Oryza sativa L. plants was studied. Data on the ability of extracellular vesicles of Acholeplasma laidlawii PG8 to penetrate from the nutrient medium into overground parts of Oryza sativa L. through the root system and to cause alterations in ultrastructural organization of the plants were presented. As a result of the analysis of ultrathin leaf sections of plants grown in medium with A. laidlawii PG8 vesicles, we detected significant changes in tissue ultrastructure characteristic to oxidative stress in plants as well as their cultivation along with bacterial cells. The presence of nucleotide sequences of some mycoplasma genes within extracellular vesicles of Acholeplasma laidlawii PG8 allowed a possibility to use PCR (with the following sequencing) to perform differential detection of cells and bacterial vesicles in samples under study. The obtained data may suggest the ability of extracellular vesicles of the mycoplasma to display in plants the features of infection from the viewpoint of virulence criteria-invasivity, infectivity-and toxigenicity-and to favor to bacterial phytopathogenicity.
Full-text · Article · Nov 2012 · The Scientific World Journal
[Show abstract][Hide abstract] ABSTRACT: Mycoplasmas are the smallest, self-replicating, prokaryotic organisms with avid biochemical potential and spreading in higher eukaryotes in nature. In this study, Acholeplasma laidlawii PG8 cells were cultivated on a deficient medium for 480 days resulting in a mycoplasma culture that was adapted in vitro to unfavorable growth conditions. Cells that survive this condition had decreased sizes (about 0.2 microm) and increased phytopathogenicity. This resulted in more frequent appearance of various morphological alterations when plants of vinca (Vinca minor L.) were infected by adapted mycoplasma cells. The increasing pathogenicity was accompanied by changes in genome expression in these adapted cells. Further studies are needed to explore the exact mechanisms that permit adaptation to unfavorable growth conditions and changes in phytopathogenic potential.
Full-text · Article · Feb 2007 · The Scientific World Journal
[Show abstract][Hide abstract] ABSTRACT: The amplification of the 16S–23S spacer areas of the Acholeplasma laidlawii PG8 rRNA rrnA and rrnB operons has its own features. The attenuation of the polymerase chain reaction (PCR) signal of the nucleotide sequences of rrnA containing tRNA genes might be observed if DNA without enzyme deproteinization is used as a matrix. The phenomenon takes place due to dissociation of cell population caused by the active entering of the vegetative cell forms into ultramicroforms in the mycoplasma culture at unfavorable growth conditions. The DNA of A. laidlawii PG8 ultramicroforms showed selective amplification of the rrnB nucleotide sequences – tRNA-free rRNA operon. As to vegetative cells, the “equal” PCR signals for the nucleotide of rrnA and rrnB sequences were registered. In this connection, the use of specific nucleotide sequences of the rrnA spacer area as primers for PCR, as well as the mycoplasma cell DNA without special enzyme deproteinization as a matrix, may lead to wrong conclusions about the presence of A. laidlawii in the tested samples. The ability of A. laidlawii PG8 vegetative cell forms of actively entering into ultramicroforms at unfavorable growth conditions seems to demand a new approach to control mycoplasma infections, providing an efficient diagnosis to detect the vegetative cell forms and ultramicroforms of the mycoplasma in the tested samples.
No preview · Article · Jan 2007 · Journal of Rapid Methods & Automation in Microbiology
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT:As a result of cultivation of A. laidlawii PG8 cells on the deficient medium during 480 days, the mycoplasma culture adapted in vitro to unfavorable growth conditions was obtained. The culture consisted of cells with sizes less than 0.2 µm and features of A. laidlawii PG8 ultramicroforms, nanocells. A. laidlawii PG8 culture adapted in vitro to unfavorable growth conditions shows more evident phytopathogenicity than the unadapted one. Infecting plants V. minor L. by A. laidlawii PG8 culture adapted in vitro to UGC resulted in the appearance of chloroses in 75%, necrosis – 50%, leaves marcescence – 50% and abnormalities of bine development in 30% of plants through 12 days, while infecting plants by A. laidlawii PG8 culture unadapted to UGC led to respective signs in 40%, 25%, 25% and 0% of samples, respectively, through 30 days. The ability of A. laidlawii PG8 to form UMF resistant to stress factors in UGC with high phytopathogenic potential seems to demand a new approach to investigate the precise mechanisms of interacting the mycoplasma with host organisms.RESUMENComo resultado del cultivo de células de A. laidlawii PG8 en medio deficiente durante 480 días, fue obtenido un cultivo de mycoplasma adaptado in vitro a las condiciones desfavorables del crecimiento. El cultivo consistió en células con tamaño menor de 0.2 µm y características PG8 ultramicroformas de A. laidlawii nanocélulas. El cultivo de A. laidlawii PG8 adaptado in vitro a condiciones desfavorables del crecimiento muestra más evidente fitopatogenicidad que el inadaptado. Plantas infectadas V. minor L. por el cultivo del A. laidlawii PG8 adaptado in vitro a UGC dio como resultado la aparición de clorosis en el 75%, necrosis en el 50%, marcescencia de las hojas en el 50% y anormalidades del desarrollo del bine en el 30% de plantas a los 12 días, mientras que las plantas infectadas por el cultivo del A. laidlawii PG8 inadaptado a UGC, condujo a dichos signos en el 40%, 25%, 25% y 0% de las muestras, respectivamente en 30 días. La capacidad del A. laidlawii PG8 a formar UMF resistente a los factores de estres en UGC con alto potencial fitopatogénico, parece exigir un nuevo planteamiento para investigar los mecanismos precisos de interacción entre el mycoplasma y el huesped.