Fecha de publicación: -- Fuente: PubMed "Tomato process" Planta. 2026 Sep 1;264(4):112. doi: 10.1007/s00425-026-05137-1.ABSTRACTPAE8 and PAE9 double mutants reduce auxin concentration and enhance Arabidopsis thaliana resistance in a pathogen-dependent manner. Pectin O-acetylation is a key plant cell wall modification that influences developmental processes and stress responses. pectin acetylesterases (PAEs) are cell wall-modifying enzymes that are responsible for removing the acetyl group from pectin. In this study, we investigated the roles of PAE8 and PAE9 in regulating pectin O-acetylation, auxin concentration, and plant defense in Arabidopsis thaliana rosette leaves. Quantitative real-time PCR (qPCR) was conducted to evaluate the transcriptional profiles of PAE8 and PAE9 in 3- to 8-week-old rosette leaves that represent successive vegetative developmental stages, showing maximum expression at week 8 for both genes. The double mutant plants (pae8/pae9) showed significantly higher cell wall acetylation levels compared to the wild-type plants (Col-0) across all examined developmental stages. Indole-3-acetic acid (IAA) concentration was reduced in pae8/pae9 compared to Col-0 at week 8. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed a significant difference in cell wall acetylation between Col-0 and pae8/pae9. Detached leaf assay for 8-week-old rosette leaves demonstrated that pae8/pae9 plants exhibit enhanced resistance to Fusarium oxysporum, Macrophomina phaseolina, Aspergillus flavus, Pseudomonas viridiflava, and Pectobacterium carotovorum, whereas the bacterial growth of Pseudomonas syringae pv. tomato and Pectobacterium atrosepticum was not significantly different from Col-0 under the tested conditions. Together, altered pectin structure and reduced auxin concentration in pae8/pae9 may contribute to pathogen-dependent resistance although auxin's direct role remains to be determined. These findings highlight PAE8 and PAE9 as key regulators of pectin O-acetylation and suggest a potential link between cell wall acetylation, reduced IAA concentration, and pathogen-dependent defense responses.PMID:42680867 | DOI:10.1007/s00425-026-05137-1