Vascular expression driven by the promoter of a gene encoding a high-affinity potassium transporter HAK5 from <Emphasis Type="Italic">Eucalyptus grandis</Emphasis> |
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Authors: | Carolina S Costa Juliana P Bravo Cíntia L Ribeiro Adriana S Soprano Flávio T Sassaki Ivan G Maia |
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Institution: | 1.Departamento de Genética, Instituto de Biociências,UNESP,Botucatu,Brazil;2.Monsanto Company,Chesterfield,USA;3.Instituto de Genética e Bioquímica,Universidade Federal de Uberlandia,Monte Carmelo,Brazil;4.Departamento de Genética, Instituto de Biociências,UNESP,Botucatu,Brazil |
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Abstract: | The construction of expression cassettes harboring tissue-specific promoters is a viable alternative to limit transgene expression to specific organs and cell types. In this study, we have functionally characterized the promoter of a Eucalyptus grandis gene encoding a putative high-affinity HAK5-like potassium (K+) transporter (designated EgHAK5) showing root-specific expression. The ability of the EgHAK 5′-flanking region (~1.3 kb) to drive root-specific expression of a reporter gene (β-glucuronidase; GUS) was examined using transgenic tobacco plants. Histochemical analysis revealed enhanced GUS staining in the vasculature of leaves, hypocotyls and roots, which was also confirmed in histological cross-sections. Moreover, the relative expression of GUS in the roots of the generated transgenic lines was increased in response to K+ starvation. Overall, our results indicate that, in a heterologous system, the EgHAK5 promoter shows expression in vascular tissues, mainly within the phloem, and is up-regulated upon potassium deprivation. |
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