title: Expression of an expansin gene is correlated with root elongation in soybean.
abstract: Expansin is a family of proteins that catalyze long-term expansion of cell walls and has been considered a principal protein that affects cell expansion in plants. We have identified the first root-specific expansin gene in soybean (Glycine max), GmEXP1, which may be responsible for root elongation. Expression levels of GmEXP1 were very high in the roots of 1- to 5-d-old seedlings, in which rapid root elongation takes place. Furthermore, GmEXP1 mRNA was most abundant in the root tip region, where cell elongation occurs, but scarce in the region of maturation, where cell elongation ceases, implying that its expression is closely related to root development processes. In situ hybridization showed that GmEXP1 transcripts were preferentially present in the epidermal cells and underlying cell layers in the root tip of the primary and secondary roots. Ectopic expression of GmEXP1 accelerated the root growth of transgenic tobacco (Nicotiana tabacum) seedlings, and the roots showed insensitivity to obstacle-touching stress. These results imply that the GmEXP1 gene plays an important role in root development in soybean, especially in the elongation and/or initiation of the primary and secondary roots.
authors.affiliation: School of Agricultural Biotechnology and Crop Functional Genomics Center, Seoul National University, Suwon 441-744, Korea.
authors.forename: Dong-Keun
authors.initials: DK
authors.lastname: Lee
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Ahn
authors.forename: Sang-Kee
authors.initials: SK
authors.lastname: Song
authors.forename: Yang Do
authors.initials: YD
authors.lastname: Choi
authors.forename: Jong Seob
authors.initials: JS
authors.lastname: Lee
mesh_terms: D002455:Cell Division / Q000235:genetics / Q000502:physiology; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D005810:Multigene Family; D019441:Plant Epidermis / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D030262:Soybean Proteins / Q000235:genetics / Q000378:metabolism; D013025:Glycine max / Q000235:genetics* / Q000254:growth & development; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D012333:RNA, Messenger; D030262:Soybean Proteins; C095825:expansin protein, plant