title: A sweetpotato SRD1 promoter confers strong root-, taproot-, and tuber-specific expression in Arabidopsis, carrot, and potato.
abstract: Harvestable, starch-storing organs of plants, such as fleshy taproots and tubers, are important agronomic products that are also suitable target organs for use in the molecular farming of recombinant proteins due to their strong sink strength. To exploit a promoter directing strong expression restricted to these storage organs, we isolated the promoter region (3.0 kb) of SRD1 from sweetpotato (Ipomoea batatas cv. 'White Star') and characterized its activity in transgenic Arabidopsis, carrot, and potato using the β-glucuronidase (GUS) gene (uidA) as a reporter gene. The SRD1 promoter conferred root-specific expression in transgenic Arabidopsis, with SRD1 promoter activity increasing in response to exogenous IAA. A time-course study of the effect of IAA (50 μM) revealed a maximum increase in SRD1 promoter activity at 24 h post-treatment initiation. A serial 5' deletion analysis of the SRD1 promoter identified regions related to IAA-inducible expression as well as regions containing positive and negative elements, respectively, controlling the expression level. In transgenic carrot, the SRD1 promoter mediated strong taproot-specific expression, as evidenced by GUS staining being strong in almost the entire taproot, including secondary phloem, secondary xylem and vascular cambium. The activity of the SRD1 promoter gradually increased with increasing diameter of the taproot in the transgenic carrot and was 10.71-fold higher than that of the CaMV35S promoter. The SRD1 promoter also directed strong tuber-specific expression in transgenic potato. Taken together, these results demonstrate that the SRD1 promoter directs strong expression restricted to the underground storage organs, such as fleshy taproots and tubers, as well as fibrous root tissues.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Seoul, 136-701, Korea.
authors.forename: Seol Ah
authors.initials: SA
authors.lastname: Noh
authors.forename: Haeng-Soon
authors.initials: HS
authors.lastname: Lee
authors.forename: Gyung Hye
authors.initials: GH
authors.lastname: Huh
authors.forename: Mi-Joung
authors.initials: MJ
authors.lastname: Oh
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Paek
authors.forename: Jeong Sheop
authors.initials: JS
authors.lastname: Shin
authors.forename: Jung Myung
authors.initials: JM
authors.lastname: Bae
mesh_terms: D020121:5' Untranslated Regions; D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D018552:Daucus carota / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology; D027723:Ipomoea batatas / Q000235:genetics* / Q000378:metabolism; D054883:Oxylipins / Q000494:pharmacology; D052585:Phloem / Q000166:cytology / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D035281:Plant Tubers / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011198:Solanum tuberosum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013194:Staining and Labeling; D013997:Time Factors; D024363:Transcription Initiation Site; D014170:Transformation, Genetic; D052584:Xylem / Q000166:cytology / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D003470:Culture Media; D003517:Cyclopentanes; D018744:DNA, Plant; D007210:Indoleacetic Acids; D054883:Oxylipins; C011006:jasmonic acid; C030737:indoleacetic acid; D005966:Glucuronidase