Srchi24, A Chitinase Homolog Lacking an Essential Glutamic Acid Residue for Hydrolytic Activity, Is Induced during Nodule Development on Sesbania rostrata

• Published in: Plant physiology (Bethesda) Vol. 127; no. 1; pp. 78 - 89
• Main Authors: Goormachtig, Sofie, Van de Velde, Willem, Lievens, Sam, Verplancke, Christa, Sylvia Herman, Annick De Keyser, Holsters, Marcelle
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.09.2001; American Society of Plant Physiologists
• Subjects: Agronomy. Soil science and plant productions; Amino Acid Sequence; Azorhizobium caulinodans; Azorhizobium caulinodans - physiology; Biological and medical sciences; Chitinases - chemistry; Cytokinins - pharmacology; DNA, Bacterial; DNA, Complementary; Economic plant physiology; Fabaceae - microbiology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Glutamic Acid - metabolism; Hydrolysis; In Situ Hybridization; Infections; Inoculation; Legumes; Lipopolysaccharides - metabolism; maltose-binding protein; Membrane Proteins; Molecular Sequence Data; Nodulation; Nodules; Parasitism and symbiosis; Plant physiology and development; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plant roots; Plant Roots - metabolism; Plant Roots - microbiology; Plant Stems - metabolism; Plant Stems - microbiology; Plants; Plants Interacting with Other Organisms; RNA; Root primordia; Sequence Homology, Amino Acid; Sesbania rostrata; Srchi24 gene; Stem nodules; Symbiosis; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Symbiosis - genetics; Chitinase; Green manure; Plant nodule; Structure function relationship; Characterization; Azorhizobium caulinodans; Gene; Dicotyledones; Angiospermae; Leghemoglobin; Development; Bacteria; Localization; Aminoacid sequence; Symbiosis; Symbionte; Symbiotic relation; Enzyme; Biochemical marker; Tissue specificity; Cytokinin; Leguminosae; Glycosidases; Hydrolases; Isolation; Spermatophyta; Sesbania rostrata; O-Glycosidases; Catalyst activity
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.127.1.78

The interaction between the tropical legume Sesbania rostrata and the bacterium Azorhizobium caulinodans results in the formation of nodules on both stem and roots. Stem nodulation was used as a model system to isolate early markers by differential display. One of them, Srchi24 is a novel early nodulin whose transcript level increased already 4 h after inoculation. This enhancement depended on Nod factor-producing bacteria. Srchi24 transcript levels were induced also by exogenous cytokinins. In situ hybridization and immunolocalization experiments showed that Srchi24 transcripts and proteins were present in the outermost cortical cell layers of the developing nodules. Sequence analyses revealed that Srchi24 is similar to class III chitinases, but lacks an important catalytic glutamate residue. A fusion between a maltose-binding protein and Srchi24 had no detectable hydrolytic activity. A function in nodulation is proposed for the Srchi24 protein.