Pseudomonas savastanoi pv. savastanoi Contains Two iaaL Paralogs, One of Which Exhibits a Variable Number of a Trinucleotide (TAC) Tandem Repeat

Abstract

In this study, Pseudomonas savastanoi pv. savastanoi isolates were demonstrated to contain two iaaL paralogs, which are both chromosomally located in most strains. Comparative analysis of iaaL nucleotide sequences amplified from these two paralogs revealed that one paralog, iaaL Psn , is 100% identical to iaaL from P. savastanoi pv. nerii, while the other paralog, iaaL Psv , exhibited 93% identity to iaaL from Pseudomonas syringae pv. tomato (iaaL Pto ). A 3-nucleotide motif (TAC) comprised of 3 to 15 repeats, which remained stable after propagation of the strains in olive plants, was found in iaaL Psv . Based on the observed nucleotide sequence variations, a restriction fragment length polymorphism assay was developed that allowed differentiation among iaaL Psn , iaaL Psv , and iaaL Pto. In addition, reverse transcriptase PCR on total RNA from P. savastanoi pv. savastanoi strains demonstrated that both iaaL Psv and iaaL Psn containing 14 or fewer TAC repeats are transcribed. Capillary electrophoresis analysis of PCR-amplified DNA fragments containing the TAC repeats from iaaL Psv allowed the differentiation of P. savastanoi pv. savastanoi isolates.Infections with Pseudomonas savastanoi pv. savastanoi (46), pv. fraxini, and pv. nerii (13) result in knots and galls on members of the Oleaceae family, and P. savastanoi pv. nerii also causes galls on oleander. Symptoms of infected trees include hypertrophy formation on the stems and branches and occasionally on the leaves and fruits. In the olive, the disease is considered to reduce both olive yield and productivity (41, 42); however, quantitative data on the impact of the disease on crop yield or crop quality are not available (19). Nevertheless, losses can be caused directly by localized infections that inhibit flowering and affect fruit development, as well as taste, and can be caused indirectly by weakening immature main leader branches that result in later damage to the tree frame (48).Currently, the only molecular P. savastanoi determinants known to be involved in knot development are the phytohormones indoleacetic acid (IAA) and cytokinins (1,15,33,38,45), as well as biosynthesis of a functional type III secretion system, encoded by the hrp-hrc gene clusters (43,44). Recently, a global genomic analysis of P. savastanoi pv. savastanoi plasmids allowed the identification of several putative virulence factors in the olive pathogen, including several type III secretion system protein effectors and a variety of genes encoding known Pseudomonas syringae virulence factors (32).The genetic determinants of P. savastanoi that are involved in the conversion of tryptophan (Trp) to IAA are Trp monooxygenase (encoded by the iaaM gene), which converts Trp to indoleacetamide (IAM), and IAM hydrolase (encoded by the iaaH gene), which catalyzes transformation of IAM to IAA (28). IAA can be further metabolized in P. savastanoi to an amino acid conjugate, 3-indole-acetyl-ε-L-lysine (IAA-lysine), through the action of the iaaL gene (14). In P. savastanoi pv. savastanoi and pv. ne...

Pseudomonas savastanoi pv. savastanoi: some like it knot

“…) provides evidence of horizontal transfer. This is not surprising because iaaL is often found in several copies and located in plasmids (Glickmann et al ., ; Matas et al ., ), although the transfer appears to preferentially occur within the P. syringae complex (not shown). Conversely, highly conserved iaaMH alleles are present in only a handful of P. syringae complex strains (Table S2, see Supporting Information) (Glickmann et al ., ); nevertheless, diverse pathovars contain CDSs (Baltrus et al ., ) whose deduced products show very low identity to those of iaaMH (e.g.…”

“…Although P. savastanoi pv. savastanoi strains contain two iaaL alleles (Matas et al ., ), IAA‐lysine has not been detected in culture filtrates of P. savastanoi strains isolated from olive (Evidente et al ., ; Glass and Kosuge, ). Two chromosomally encoded iaaM , iaaH and iaaL alleles were also found in the genome of P. savastanoi pv.…”

A New Bacterial Disease on Mandevilla sanderi, Caused by Pseudomonas savastanoi: Lessons Learned for Bacterial Diversity Studies

“…nerii PLVM2 and with one of the alleles (iaaL-1) of pv. savastanoi NCPPB 3335 (15,20), suggesting that they share a recent common origin. Phylogenetic analyses were also performed for hopAF1 and iaaM sequences (see Fig.…”

Bacterial multispecies studies and microbiome analysis of a plant disease

“…savastanoi (Marchi et al, 2009;Matas et al, 2009;Pérez-Martínez et al, 2008Ramos et al, 2012;Rodríguez-Moreno et al, 2009;Scortichini et al, 2004;Surico et al, 1985). The description of several virulence factors Iacobellis et al, 1994;Matas et al, 2009;Matas et al, 2012;Pérez-Martínez et al, 2010;Ramos et al, 2012;Rodríguez-Moreno et al, 2008Rodríguez-Palenzuela et al, 2010;Rojas et al, 2004;Surico et al, 1985) and the normal localization on the intercellular space of the parenchymal tissue as a biofilm structure are, to our knowledge, the main recent discoveries (Rodríguez-Moreno et al, 2009).…”