RT Journal Article
T1 Allelic variation in the indoleacetic acid-lysine synthase gene of the bacterial pathogen Pseudomonas savastanoi and its role in auxin production
A1 Pintado Calvillo, Adrián
A1 Domínguez Cerván, Hilario
A1 Pastor, Victoria
A1 Vincent, Marissa
A1 Goo Lee, Soon
A1 Flors, Víctor
A1 Ramos-Rodríguez, Cayo Juan
K1 Pseudomonas syringae - Genética
AB Indole-3-acetic acid (IAA) production is a pathogenicity/virulence factor in the Pseudomonas syringae complex, including Pseudomonas savastanoi. P. savastanoi pathovars (pvs.) genomes contain the iaaL gene, encoding an enzyme that catalyzes the biosynthesis of the less biologically active compound 3-indole-acetyl-ϵ-L–lysine (IAA–Lys). Previous studies have reported the identification of IAA–Lys in culture filtrates of P. savastanoi strains isolated from oleander (pv. nerii), but the conversion of IAA into a conjugate was not detectable in olive strains (pv. savastanoi). In this paper, we show the distribution of iaaL alleles in all available P. savastanoi genomes of strains isolated from woody hosts. Most strains encode two different paralogs, except for those isolated from broom (pv. retacarpa), which contain a single allele. In addition to the three previously reported iaaL alleles (iaaLPsv, iaaLPsn and iaaLPto), we identified iaaLPsf, an exclusive allele of strains isolated from ash (pv. fraxini). We also found that the production of IAA–Lys in P. savastanoi pv. savastanoi and pv. nerii depends on a functional iaaLPsn allele, whereas in pv. fraxini depends on iaaLPsf. The production of IAA–Lys was detected in cultures of an olive strain heterologously expressing IaaLPsn-1, IaaLPsf-1 and IaaLPsf-3, but not when expressing IaaLPsv-1. In addition, Arabidopsis seedlings treated with the strains overproducing the conjugate, and thus reducing the free IAA content, alleviated the root elongation inhibitory effect of IAA. IAA–Lys synthase activity assays with purified allozymes confirmed the functionality and specificity of lysine as a substrate of IaaLPsn-1 and IaaLPsf-3, with IaaLPsf-3 showing the highest catalytic efficiency for both substrates. The IAA–Lys synthase activity of IaaLPsn-1 was abolished by the insertion of two additional tyrosine residues encoded in the inactive allozyme IaaLPsv-1.
AB These results highlight the relevance of allelic variation in a phytohormone-related gene for the modulation of auxin production in a bacterial phytopathogen.
PB Frontiers Media
YR 2023
FD 2023-06-06
LK https://hdl.handle.net/10630/39004
UL https://hdl.handle.net/10630/39004
LA eng
NO Pintado et al. (2023) Front. Plant Sci. 14:1176705
NO AP and HD-C were supported by the FPU14/05551 andPRE2021-099113 predoctoral grants, respectively. CR wassupported by the AGL2017-82492-C2-1-R and PID2020-115177RB-C21 project grants from the Spanish Ministry ofScience, Innovation and Universities (Spain), co-financed by theEuropean Regional Development Fund (ERDF). VP and VF weresupported by the GV/2018/115 and CIACO/2021/092 grantprojects from Generalitat Valenciana and the RTI2018-094350-BC33 grant from the Spanish Ministry of Science, Innovation andUniversities. MV and SL were supported by project grant A20-0079from The North Carolina Biotechnology Center (NCBC).
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 20 ene 2026