Showing 5 results for Pathogenesis
Volume 2, Issue 1 (1-2016)
Abstract
The genus Pseudomonas consists of more than 120 species that are ubiquitous in moist environments such as water and soil ecosystems and are pathogenic to animals and humans. Within the genus of Pseudomonas, P. aeruginosa is most frequently associated with human infections. The bacterium is regarded as an opportunistic pathogen, primarily causing nosocomial infections in immunocompromised patients. The existing knowledge regarding the pathogenesis of P. aeruginosa has mainly been obtained through studying clinical isolates; particularly those involved in causing chronic lung infection in cystic fibrosis patients. Nosocomial infections commonly associated with P. aeruginosa include ventilator-associated pneumonia, catheter-associated urinary tract infections, wound infections in severe burn patients and septicaemia with their pathogenesis shown to be multifactorial. The bacterium is also capable of producing a number of toxins via the type III secretion system, as well as secreting enzymes and proteins including elastase, phospholipase C and siderophores. However, P. aeruginosa is also a waterborne pathogen, commonly found in environmental waters as well as in other sources such as sewage treatment plants. The public health implication of these bacteria whilst in the environment has not been fully investigated. Here we review our present knowledge about the pathogenesis of P. aeruginosa in clinical settings and the environment.
Volume 5, Issue 3 (9-2016)
Abstract
Blue mold disease caused by Penicillium expansum is a major post-harvest disease of apples. In this research, the biochemical basis of apple resistance to this pathogen was studied in two relatively resistant and susceptible cultivars, Granny smith and Mashhad, respectively. The activities of catalase (CAT), peroxidase (POX), superoxide dismutase (SOD) and polyphenol oxidase (PPO) enzymes and polyphenol content were compared at different time intervals of 0 to 7 days. Based on the results, fruit polyphenol content of Granny smith was higher than that of Mashhad PPO, SOD and CAT activity was higher in Granny smith than Mashhad but CAT activity decreased three days post-treatment. No detectable difference was found in POX activities in the two cultivars. It is concluded that polyphenols contribute in apple resistance to blue mold. Activation of PPO and SOD, lack of POX activity and decrease of CAT activity, all together, could lead to a toxic environment around the blue mold fungus.
Volume 7, Issue 3 (7-2005)
Abstract
Bioassay results confirmed the role of low molecular weight phytotoxin in the patho-genesis of Verticillium albo-atrum. The metabolites separated from 21-day-old culture fil-trate by adsorption on the resin Amberlite XAD-4, and further chromatographed on Bio-Gel P2 polyacrylamide gel, induced chlorosis and necrosis on the leaflets of tomato and potato cultivars, similar to those caused by the fungus on diseased plants. Leaflets from tolerant cultivars were much less sensitive to the toxin (s) than those from the susceptible ones. In the presence of toxin(s) plant tissues and individual cells showed ion-leakage and cell death to an extent relating to the plants reaction to the fungus. The relative specificity observed during pathogenicity tests between potato and tomato and their related isolates was shown to be related to the action of toxin (s).
Volume 12, Issue 3 (9-2021)
Abstract
Different defense pathways in plants evolved in reaction to pathogens. The main aim of this study was to investigate the mechanism of action of glyphosate in resistance induction to bacterial phytopathogens. To do so, glyphosate at an optimal concentration of 1.8 mg / l was used on transgenic potato, to induce resistance to two strains of pathogenic bacteria (21A of Pectobacterium atrosepticum and ENA49 of Dickeya dadantii). It was been shown that plant defense responses to pathogens can be stimulated by treatment plants at an optimal concentration of glyphosate. Transgenic potato leaves infected with potato pathogenic bacteria, and then treated with glyphosate showed a high level of expression of pathogenesis-related genes (PR-2, PR-3, PR-5), especially PR-2 gene and defense response genes (HSR-203j, HIN1), especially HSR-203j gene. The expression of PR-2 gene in leaves infected with these two bacteria were 1.5 and 2.9 times, for PR-3 gene 1.7 and 1.7 times, for PR-5 gene to 1.3 and 1.5 times and expression of HSR-203J gene to 2.5 and 2.4 times and - HIN1 gene to 1.7 and 1.7 times, with Dickeya dadantii and Pectobacterium atrosepticum infection, respectively. The expression of these genes in control samples didn’t significantly change. The results showed that there was a significant difference between the expression of genes in the experimental and control samples (plants treated by glyphosate compared to untreated plants). The results showed that the treatment of plants by glyphosate can induce a systemic acquired resistance to phytopathogens by inducing proteins and defense response genes.
B. Zahirnejad, B. Bahramnejad, J. Rostamzadeh,
Volume 20, Issue 6 (11-2018)
Abstract
Plant defensins are the
cysteine-rich peptides that are encoded by small multi-gene families in the plant kingdom. In this study, we designed primers based on conserved regions of defensin genes to clone and identify defensin genes in strawberry (Fragaria×ananassa cv. Paros) by reverse transcription PCR technique. Sequence analysis showed that the deduced amino
acid had significant similarity to other plant defensins from NCBI database and designated FaDef1. The predicted strawberry defensin protein encodes a 54 aa protein of 6.18 kDa, pI 9.22 and eight conserved cysteine residues with desired space conservation with other amino acids. Semi quantitative expressions of FaDef1 were analyzed in root, stem, leaf, flower, and fruit in three strawberry cultivars, namely, Queenelisa, Camarosa, and Paros. The results showed that the FaDef1 expression patterns were similar in different tissues of the three cultivars. The higher amount of relative expression of FaDef1 was in fruit and there was no observable expression in the root. The expression of FaDef1 increased after wounding and salicylic acid treatment. The expression level was higher in developed fruits compared to that of immature fruits. In fruits infected with the Gray mold agent (Botrytis cinerea), the expression of FaDef1 showed significant increase by development of disease symptom. Taken together, these results suggest that
FaDef1 is both responsive to biotic stress signal compounds and strawberry
B. cinerea and may be used as a candidate gene for engineering plants against gray mold.
