title: RNA interference-mediated repression of S6 kinase 1 impairs root nodule development in soybean.
abstract: Symbiotic nodule formation on legume roots is characterized with a series of developmental reprograming in root tissues, including extensive proliferation of cortical cells. We examined a possible involvement of the target of rapamycin (TOR) pathway, a central regulator of cell growth and proliferation in animals and yeasts, during soybean nodule development. Our results show that transcription of both GmTOR and its key downstream effector, GmS6K1, are activated during nodulation, which is paralleled with higher kinase activities of these gene products as well. RNAi-mediated knockdown of GmS6K1 impaired the nodule development with severely reduced nodule weight and numbers. In addition, expression of a few nodulins including leghemoglobin was also decreased, and consequently nitrogen fixation was found to be reduced by half. Proteomic analysis of the GmS6K1-RNAi nodules identified glutamine synthetase (GS), an essential enzyme for nitrogen assimilation in nodules, as one of the proteins that are significantly down regulated. These results appear to provide solid evidence for a functional link between GmS6K1 and nodule development.
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Um
authors.forename: Sunghan
authors.initials: S
authors.lastname: Kim
authors.forename: Yun-Kyoung
authors.initials: YK
authors.lastname: Kim
authors.forename: Seok-Bo
authors.initials: SB
authors.lastname: Song
authors.forename: Suk-Ha
authors.initials: SH
authors.lastname: Lee
authors.forename: Desh Pal S
authors.initials: DP
authors.lastname: Verma
authors.forename: Choong-Ill
authors.initials: CI
authors.lastname: Cheon
mesh_terms: D015870:Gene Expression; D055785:Gene Knockdown Techniques; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000235:genetics* / Q000378:metabolism; D053204:Root Nodules, Plant / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D034741:RNA, Small Interfering; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D058570:TOR Serine-Threonine Kinases