Because the 54 promoter is associated with genes regulated by physiological changes in various bacteria, the flaC gene might be similarly regulated in response to A. tumefaciens responding to host plant stimuli. Virulence studies showed that the bald strain was consistently reduced in virulence below that of the parental wild-type strain by at least 38%. The difference is statistically significant and suggests that the flagella may play a role in facilitating virulence.

Background Several chemical bactericides were applied for controlling soft rot bacteria, Pectobacterium carotovorum subsp. carotovorum, which causes the destructive soft rot disease to many economically important vegetables, but because of their toxic hazards on human and environment became limit. The biocontrol was applied to control many plant pathogens. Therefore, this work is aimed to study the antagonistic activity of bacterial agents, i.e. Bacillus subtilis, Bacillus pumilus, Bacillus megaterium and Pseudomonas fluorescens, and fugal agents, i.e. Trichoderma harzianum, Trichoderma viride and Trichoderma virens, to control bacterial soft rot disease under in vitro and in vivo tests. Results The tested treatments could protect the potato tubers against the development of soft rot. T. viride and T. virens were highly effective in reducing soft rot symptoms on inoculated potato tuber slices, when applied at the same time or 2 h before pathogen inoculation, while B. megaterium and T. harzianum were highly effective when applied at the same time or 2 h after pathogen inoculation. In whole potato tubers technique, B.pumilus highly protected the stored potato tuber under artificially infection conditions, than P. fluorescens, T. harzianum, B. subtilis, T. viride, T. virens and B. megaterium, respectively. Conclusion Application of fungal agents or specify the bacterial species can play an important role in controlling bacterial soft rot disease in vegetables and increase the stored periods of potato tubers under storage conditions without any toxic effects.

No abstract

hytoplasmas causing phyllody symptoms on rose was detected from naturally infected plants. The detected phytoplasma was transmitted by; grafting and dodder into healthy rose and periwinkle plants. Phytoplasma units ranging in diameters from 0.4 to 0.8 µm were detected inside phloem tissues of infected plants. DNA extracted from symptomatic samples was used as template for amplification of products of 1.8 kb using primer pair P1/P7 and 1.2 kb using primer pairs R16F2/R2 by direct and nested-PCR, respectively. Three samples from protected rose fields yielded PCR, amplicons of expected size (1,200 bp) by nested PCR, while no PCR products were obtained for the symptomless plants. Two concentrations of tetracycline hydrochloride, i.e. 250 and 300 ppm were used to control the disease by two different treatments, immersing transplants and soil drench. Immersing transplants with tetracycline at 300 ppm for either 15 or 30min gave best result. Also the concentration at 300 ppm for soil drench had a higher recovery effect than at 250 ppm. This study of Rose phyllody disease caused by phytoplasmas is carried out for the first time in Egypt.

No abstract