This fungus can survive for many years in soil as mycelium, and also by producing sclerotia, which makes the management of the disease using conventional means very difficult. Integrated pest management has been most successful; it includes timely fungicide applications, crop rotation and attention to soil moisture levels. Recent developments in biocontrol may provide other tools to control R. solani in tobacco.
To identify Nicotiana tabacum genes involved in resistance and susceptibility to Rhizoctonia solani, suppression subtractive hybridization was used to generate a cDNA library from transcripts that are differentially expressed during a compatible and incompatible interaction. This allowed the isolation of a protein kinase cDNA that was down-regulated during a compatible and up-regulated during an incompatible interaction. Quantitative RT-PCR analysis of this gene confirmed the differential expression patterns between the compatible and incompatible interactions. Over-expression of this gene in tobacco enhanced the resistance to damping-off produced by an aggressive R. solani strain. Furthermore, silencing of this protein kinase gene reduced the resistance to a non-aggressive R. solani strain. A set of reported tobaccoresistant genes were also evaluated in tobacco plants over-expressing and silencing the protein kinase cDNA. Several genes previously associated with resistance in tobacco, like manganese superoxide dismutase, Hsr203J, chitinases and phenylalanine ammonia-lyase, were up-regulated in tobacco plants over-expressing the protein kinase cDNA. Potentially, the protein kinase gene could be used to engineer resistance to R. solani in tobacco cultivars susceptible to this important pathogen.
Bayoud caused by Fusarium oxysporum f.sp. albedinis (Foa), is the most destructive disease of the date palm (Phoenix dactylifera L.) in Morocco and Algeria and there is no effective control strategy. We found that although Foa isolates vary morphologically, Foa strains can be identified by species-specific primers. PCR analysis revealed that the strains that we isolated from infected date palm rachis were the Bayoud pathogen Foa. We used these strains to evaluate the antifungal activity of tar extracted from Acacia tortilis subsp. raddiana. The A. raddiana tar had a density of 1.15, a refraction index of 1.3850, a pH of 5.2 and a dried matter ratio of 48.75%. The A. raddiana tar effectively inhibited the growth of Foa in vitro with a minimum inhibitory concentration of 3 µg/ml.
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