Specific amplification of iron receptor genes in Xylella fastidiosa strains from different hosts

Abstract

Bacterial production of siderophores may involve specific genes related to nonribosomal peptide and polyketide biosynthesis, which have not been fully identified in the genome of Xylella fastidiosa strain 9a5c. However, a search for siderophore-related genes in strain 9a5c indicated five membrane receptors, including siderophore, ferrichrome-iron and hemin receptors. All these biomolecules are thought to be associated with iron transport and utilization. Eighty isolates obtained from citrus orchards containing trees that developed citrus variegated chlorosis (CVC) were screened for siderophore production. The results demonstrated that only 10 of the isolates did not produce siderophores. Additional strains obtained from coffee, almond, mulberry, elm, ragweed, periwinkle and grape also infected by X. fastidiosa were also shown by the chromeazurol bioassay to produce siderophores. In order to correlate siderophore production with the presence of siderophore-related genes, a polymerase chain reaction (PCR) was developed using specific primers for the catechol-type ferric enterobactin receptor (pfeA) and the hydroxamate-type ferrisiderophore receptor (fiuA) genes of strain 9a5c. The PCR results confirmed our hypothesis by demonstrating that amplification products were detected in all strains except for those isolates that did not produce siderophores.

Biochemical and molecular characterization of DAPG-producing plant growth-promoting rhizobacteria (PGPR) of groundnut (Arachis hypogaea L.)

“…PCR amplification of the targeted genes using specific primers confirmed the presence of these genes in these plant growth promoting isolates. The observation was consistent with the earlier observations made with other pseudomonad strains (Sarvanankumar and Samiyappan, 2007;Ahmadzadeh et al 2006;Pacheco et al 2006). Ahmadzadeh et al (2006) used PCR analysis to detect 2,4-DAPG-producing Pseudomonas populations based on the amplification of phlD and phlA genes sequences.…”

Detection of siderophores in endophytic bacteria Methylobacterium spp. associated with Xylella fastidiosa subsp. pauca

“…The present study suggested, as preliminary results, that Xfp can use molecules produced by endophytic bacteria as siderophores. In this context, as a factor influencing the symptom of CVC (Silva-Stenico et al, 2005;Pacheco et al, 2006), the genus Methylobacterium could help Xfp to survive inside the xylem vessels. However, additional studies are needed to provide a better understanding on the effect of iron availability in the production of siderophores by Methylobacterium spp., which could be involved in the iron-related virulence of the phytopathogen Xfp.…”

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease

“…In a previous work, we demonstrated that X. fastidiosa 31b9a5c from citrus is able to produce iron-chelators (Silva-Stenico et al, 2005;Pacheco et al, 2006). In the xylem, there is a strong correlation between Fe and citric acid in exudate from numerous plants (Tiffin, 1970).…”