title: Plasmid-associated genes in the model micro-symbiont Sinorhizobium meliloti 1021 affect the growth and development of young rice seedlings.
abstract: Sinorhizobium meliloti strain 1021 and its closely related strain Rm2011 inhibit rice seedling (Oryza sativa L. cv. Pelde) growth and development under certain rice-growing conditions. Experiments showed that inoculation of seedlings with approximately less than 10 cells of 1021 was sufficient to cause this inhibition. By using a series of plasmid-cured and plasmid-deleted derivatives of Rm2011, it was found that interactions between genes encoded on pSymA, and possibly pSymB, of Rm2011, affected rice growth and development by affecting both/either the plant and/or the bacteria. Further studies found that genes potentially related to indole-3-acetic acid (IAA) synthesis and nitrate metabolism, encoded on pSymA, were involved in rice growth inhibition in Sm1021- and Sm2011-treated rice seedlings. We conclude that the rice growth inhibition by S. meliloti Sm1021 is pSymA-associated and is induced by environmental nitrate.
authors.affiliation: Genomic Interactions Group, Research School of Biological Sciences, The Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.
authors.forename: Francine M
authors.initials: FM
authors.lastname: Perrine
authors.forename: Charles H
authors.initials: CH
authors.lastname: Hocart
authors.forename: Michael F
authors.initials: MF
authors.lastname: Hynes
authors.forename: Barry G
authors.initials: BG
authors.lastname: Rolfe
mesh_terms: D015169:Colony Count, Microbial; D003227:Conjugation, Genetic / Q000235:genetics; D023061:Gene Order; D008856:Microscopy, Fluorescence; D009566:Nitrates / Q000378:metabolism; D012275:Oryza; D018517:Plant Roots / Q000382:microbiology*; D010957:Plasmids / Q000235:genetics*; D036226:Seedlings / Q000254:growth & development* / Q000382:microbiology*; D016962:Sinorhizobium meliloti / Q000235:genetics*; D013559:Symbiosis
chemical_list: D009566:Nitrates