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Distinct response of Medicago suspension cultures and roots to Nod factors and chitin oligomers in the elicitation of defense‐related responses
Author(s) -
Savouré Arnould,
Sallaud Christophe,
ElTurk Joumana,
Zuanazzi José,
Ratet Pascal,
Schultze Michael,
Kondorosi Adam,
Esnault Robert,
Kondorosi Eva
Publication year - 1997
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1997.11020277.x
Subject(s) - nod factor , nod , chalcone synthase , isoflavonoid , medicago , biochemistry , biology , chitin , phytoalexin , gene expression , gene , rhizobia , flavonoid , symbiosis , genetics , chitosan , bacteria , antioxidant , resveratrol
The induction of plant defense‐related responses by chitin oligomers and the Rhizobium meliloti lipo‐chito‐oligosaccharide nodulation signals (Nod factors) in Medicago cell cultures and roots was investigated by following the expression of genes encoding enzymes of the isoflavonoid biosynthetic pathway, such as chalcone synthase, chalcone reductase, isoflavone reductase, as well as genes encoding a pathogenesis‐related protein and a peroxidase. In suspension‐cultured cells, all genes except the peroxidase gene were induced by both the R. meliloti Nod factor NodRm‐IV(C16:2,S) and chitin oligomers with a minimum of three sugar residues. However, activation of these genes was not elicited by the symbiotically inactive, desulfated NodRm‐IV(C16:2). Moreover, the cells were more sensitive to the chitin oligosaccharides than to the Nod factor. Analysis of flavonoids in Medicago microcallus cultures revealed differences between cells treated with N ‐acetyl‐chitotetraose and those treated with Nod factor and demonstrated increased production of the phytoalexin medicarpin in the presence of Nod factor. In Medicago roots, none of the tested genes was activated by the N ‐acetylchitotetraose, whereas the Nod factor at micro‐molar concentration enhanced transient expression of the isoflavonoid biosynthetic genes. The differential responses to Nod factors and chitin oligomers suggest that Medicago cells possess distinct perception systems for these related molecules.