Genetic diversity among Fusarium oxysporum f.sp. vasinfectum isolates revealed by UP-PCR and AFLP markers

Fusarium wilt of cotton is responsible for significant yield losses worldwide. In this study we used UPPCR and AFLP molecular marker techniques to evaluate and study the genetic similarity and phylogeny of 20 Fusarium oxysporum f. sp. vasinfectum isolates. On the basis of comparisons of genetic similarity matrices, AFLP markers were very similar to UP-PCR markers for estimating intra-specific genetic relationships. Dendrograms constructed with both AFLP and UP-PCR revealed that all accessions of F. oxysporum f. sp. vasinfectum isolates were grouped into the same cluster, in good agreement with the pathogenicity tests. The principal difference between the two techniques was that AFLP markers gave better resolution than UP-PCR for discriminating closely related Fusaria

Bacterial quality control of domestic and imported brands of bottled water in Saudi Arabia

Water is one of the most abundant and essential commodities of man occupying about 70% of the earth's surface and 60% of the human body therefore it should be continuously protected against microbial infections. Also, the mineral content in drinking water should be maintained within the acceptable range. Quality control of drinking water emerged with the invention of bottled drinking water. In this study, samples of bottled drinking water from Saudi markets were compared with tap water samples collected from different areas in Riyadh; both samples were tested for the presence of pathogenic bacteria. The bacterial isolates identified by the Biolog system (Hayward, CA, USA) include Bacillus cereus, Staphylococcus sp. and Pseudomonas aeruginosa in bottled drinking water, whereas tap water was mainly contaminated by P. aeruginosa. Bacterial contamination was highly observed in tap water samples and higher mineral content, determined by inductively coupled plasma-mass spectrometry (ICP-MS) was also observed in tap water. Bacterial cell count determined as CFU/ml was observed in bottled drinking water. Decreased water bacterial number was achieved with the solar disinfection system (SODIS) for one day with direct exposure to sunlight in polyethylene terephthalate (PET) plastic bottles. Thus water considered to be consumed by humans must maintain good microbial and mineral qualities within the acceptable ranges and must undergo effective treatment in order to reduce bacterial count and infection

Trichogenic Silver-Based Nanoparticles for Suppression of Fungi Involved in Damping-Off of Cotton Seedlings

Mycogenic silver nanoparticles (AgNPs) produced by some biocontrol agents have shown the ability to inhibit the growth of numerous plant pathogenic fungi, which may be a unique method of disease management. This study describes the extracellular production of AgNPs by Trichoderma harzianum. The size, shape, charge, and composition of the AgNPs were subsequently studied by UV-visible spectroscopy, DLS, zeta potential, TEM, SEM, and EDX, among other methods. The AgNPs had sizes ranging from 6 to 15 nm. The antifungal activities of bio-synthesized AgNPs and two commercial fungicides (Moncut and Maxim XL) were tested against three soil-borne diseases (Fusarium fujikuroi, Rhizoctonia solani, and Macrophomina phaseolina). Cotton seedling illnesses were significantly reduced under greenhouse settings after significant in vitro antifungal activity was documented for the control of plant pathogenic fungi. The use of biocontrol agents such as T. harzianum, for example, may be a safe strategy for synthesizing AgNPs and using them to combat fungus in Egyptian cotton

Non-differential interaction between isolates of Rhizoctonia solani and flax cultivars

The pathogenicity of 24 isolates of Rhizoctonia solani (7 isolates from anastomosis group AG-2 and 17 from AG-4) was evaluated on 10 flax cultivars under greenhouse conditions. Survival, plant height, and dry weight were used as criteria to evaluate pathogenicity. Analysis of variance (ANOVA) showed that the cultivar was a highly significant source of variation in all the tested parameters (P < 0.0002). Isolate was always a highly significant source of variation in all the tested parameters (P = 0.0000). Cultivar x isolate interaction was always a nonsignificant source of variation. The results of the ANOVA in the present study suggest that physiologic specialization did not occur within R. solani isolates pathogenic on flax. They also imply that resistance of the tested cultivars was only horizontal, and there were significant differences among cultivars in this type of resistance. Similarly, pathogenicity of the tested isolates was only aggressiveness, and the isolates significantly differed in this type of pathogenicity. A hierarchical cluster analysis was conducted in order to group the isolates according to disease variables measured on the tested cultivars. Cluster analysis divided the isolates into groups; however, grouping the isolates was not related to their geographic origin nor the AG.Sýkingareiginleikar 24 stofna af Rhizoctonia solani (7 stofnar af netjuðum sveppum AG-2 og 17 af AG-4) voru metnir á 10 kvæmum af hör í gróðurhúsi. Lifun, hæð plöntu og þurrefni voru notuð til að meta sýkingareiginleika. Fervikagreining (ANOVA) sýndi að kvæmi var mjög marktæk uppspretta breytileika í öllum þáttum sem skoðaðar voru (P < 0.0002). Stofn var alltaf mjög marktæk uppspretta breytileika í öllum þáttum sem skoðaðir voru (P = 0.0000). Víxlverkun á milli stofns og kvæmis var aldrei marktæk ástæða breytileika. Niðurstöður fervikagreiningarinnar benda til þess að engin lífeðlisfræðileg sérhæfing hafi átt sér stað í R. solani stofnun sem sýkja lín. Jafnframt benda niðurstöðurnar til þess að varnir kvæmanna sem prófaðir voru séu einungis byggðar á almennri mótstöðu og að það væri marktækur munur milli kvæma í þeirri gerð mótstöðu.. Jafnframt að sýkingareiginleikar stofnanna sem prófaðir voru séu eingöngu háðir sýkingarhæfni og að munur hafi verið á stofnunum hvað þetta varðar. Klasagreining skipti sveppastofnunum í hópa en þeir voru hvorki tengdir landfræðilegum uppruna né AG