Alfalfa and tobacco cells react differently to chitin oligosaccharides and Sinorhizobium meliloti nodulation factors

Abstract

Alfalfa (Medicago sativa L.) suspension cultures respond to yeast elicitors with a strong alkalinization of the culture medium, a transient synthesis of activated oxygen species, and typical late defence reactions such as phytoalexin accumulation and increased peroxidase activity. The alkalinization reaction as well as the oxidative burst were also observed when tobacco (Nicotiana tabacum L. ) cell-suspension cultures were treated with yeast elicitors. Depending on the degree of polymerization, N-acetyl chitin oligomers induced the alkalinization response in both plant cell-suspension cultures, while only tobacco cell cultures developed an oxidative burst. Suspension-cultured tobacco cells responded to Sinorhizobium meliloti nodulation factors with a maximal alkalinization of 0.25 pH units and a remarkable oxidative burst. In contrast, addition of Sinorhizobium meliloti nodulation factors to suspension-cultured alfalfa cells induced a slight acidification of the culture medium, instead of an alkalinization, but no oxidative burst.

Silencing of the Rac1 GTPaseMtROP9inMedicago truncatulaStimulates Early Mycorrhizal and Oomycete Root Colonizations But Negatively Affects Rhizobial Infection

“…Infection with Sinorhizobium meliloti wild-type strain Rm2011 was performed as described previously (Schenkluhn et al, 2010). S. meliloti NFs were isolated from a NF-overproducing strain of S. meliloti strain 1021 p(EK327) as described by Baier et al (1999). Purified NF (10 27 M) was prepared from a 10 23 M stock (diluted in CH 3 CN) in PS buffer (7 g of Na 2 PO 4 , 5 g of NaCl, and 3 g of KH 2 PO 4 per liter, pH 7) and applied to the entire roots without touching them.…”

A LysM Receptor-Like Kinase Plays a Critical Role in Chitin Signaling and Fungal Resistance inArabidopsis

“…Purified chitooligosaccharides were able to induce various defense responses in plants or cultured cells, such as induction of defense-related genes, synthesis of phytoalexin, production of reactive oxygen species, and protein phosphorylation (Felix et al, 1993;Baier et al, 1999;Peck et al, 2001;Shibuya and Minami, 2001;Ramonell et al, 2005). Gene expression profiling studies also demonstrated that chitooligosaccharides can induce a large number of genes (including many defense-related genes) in different plant species (Day et al, 2002;Ramonell et al, 2002Ramonell et al, , 2005.…”

Differential Activation of Four Specific MAPK Pathways by Distinct Elicitors

“…Preparation and Sources of the Elicitors-The YE was prepared essentially as described (20). Briefly, bakers' yeast (250 g) was dissolved in 500 ml of citrate buffer (20 mM citrate, pH 7.5) by stirring at room temperature for 30 min.…”

“…Cell Culture Handling and Treatment-Suspension cultures were prepared from callus derived from alfalfa roots (Medicago sativa L.) and maintained as described (20). Log phase cells were used 3-4 days after a weekly 1:3 dilution in fresh medium.…”

“…Treating suspension-cultured cells with yeast elicitor (YE) induces typical defense responses, such as the rapid alkalinization of the medium and the production of active oxygen species (20). In-gel kinase analysis of extracts from YE-treated cells indicated that protein kinases with relative molecular masses of 46 and 44 kDa are rapidly and transiently activated after elicitor treatment.…”