title: Salicylic acid differentially affects suspension cell cultures of Lotus japonicus and one of its non-symbiotic mutants.
abstract: Salicylic acid (SA) is known to play an important role in the interaction between plant and micro-organisms, both symbiotic and pathogen. In particular, high levels of SA block nodule formation and mycorrhizal colonization in plants. A mutant of Lotus japonicus, named Ljsym4-2, was characterized as unable to establish positive interactions with Rhizobium and fungi (NOD(-), MYC(-)); in particular, it does not recognize signal molecules released by symbiotic micro-organisms so that eventually, epidermal cells undergo PCD at the contact area. We performed a detailed characterization of wild-type and Ljsym4-2 cultured cells by taking into account several parameters characterizing cell responses to SA, a molecule strongly involved in defense signaling pathways. In the presence of 0.5 mM SA, Ljsym4-2 suspension-cultured cells reduce their growth and eventually die, whereas in order to induce the same effects in wt suspension cells, SA concentration must be raised to 1.5 mM. An early and short production of nitric oxide (NO) and reactive oxygen species (ROS) was detected in wt-treated cells. In contrast, a continuous production of NO and a double-peak ROS response, similar to that reported after a pathogenic attack, was observed in the mutant Ljsym4-2 cells. At the molecular level, a constitutive higher level of a SA-inducible pathogenesis related gene was observed. The analysis in planta revealed a strong induction of the LjPR1 gene in the Ljsym4-2 mutant inoculated with Mesorhizobium loti.
authors.affiliation: Department of Biology, Padova University, Via U. Bassi 58/B, 35131 Padua, Italy.
authors.forename: Fiorenza
authors.initials: F
authors.lastname: Bastianelli
authors.forename: Alex
authors.initials: A
authors.lastname: Costa
authors.forename: Marco
authors.initials: M
authors.lastname: Vescovi
authors.forename: Enrica
authors.initials: E
authors.lastname: D'Apuzzo
authors.forename: Michela
authors.initials: M
authors.lastname: Zottini
authors.forename: Maurizio
authors.initials: M
authors.lastname: Chiurazzi
authors.forename: Fiorella
authors.initials: F
authors.lastname: Lo Schiavo
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D000070116:Lotus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012231:Rhizobium / Q000502:physiology; D020156:Salicylic Acid / Q000378:metabolism / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013559:Symbiosis / Q000235:genetics / Q000502:physiology
chemical_list: D017931:DNA Primers; D018744:DNA, Plant; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D020156:Salicylic Acid