title: Isolation of a novel nodulin: a molecular marker of osmotic stress in Glycine max/Bradyrhizobium japonicum nodule.
abstract: Symbiotic N(2) fixation of legume crops is highly sensitive to drought, which results in a dramatic drop of N accumulation and yield. The symbiosis between soybean (Glycine max) and Bradyrhizobium japonicum, because of its extreme sensitivity to drought, was chosen as a model to analyse the response to drought stress at a molecular level. The mRNA differential display technique was performed to isolate cDNA markers differentially expressed in well-watered [100% of N(2) fixation capacity (NFC)] and drought-stressed nodules (40% NFC). One gene noted, G93, appeared strongly down-regulated by drought and fully recovered after rehydration. In situ hybridization showed that G93 transcripts were localized in N(2)-fixing cells of mature nodules, indicating that G93 could be considered as a late nodulin. However, G93 expression was not directly correlated to N(2) fixation but mainly responded to osmotic stress. Other stresses that lead to decrease of N(2) fixation did not affect G93 expression. Sequence analyses showed that G93 presented a strong homology with two soybean expressed sequence tags (ESTs) and with the ZR1 protein of Medicago sativa. Putative roles of this nodulin in adaptation of soybean nodule to osmotic stress are proposed.
authors.affiliation: Unité Mixte de Recherche (UMR) 'Interactions Plantes Microorganimes et Santé Végétale' INRA1064-CNRS 6192-Université de Nice-Sophia Antipolis, Institut Sophia Agrobiotech, 400 Routes des Chappes, 06903 Sophia-Antipolis Cedex, France.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Clement
authors.forename: Eric
authors.initials: E
authors.lastname: Boncompagni
authors.forename: Janice
authors.initials: J
authors.lastname: de Almeida-Engler
authors.forename: Didier
authors.initials: D
authors.lastname: Herouart
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015415:Biomarkers; D020369:Bradyrhizobium / Q000502:physiology*; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000502:physiology; D009997:Osmotic Pressure; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger; D013025:Glycine max / Q000166:cytology / Q000378:metabolism* / Q000382:microbiology*; D013559:Symbiosis; D014867:Water / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; C045625:nodulin; D014867:Water