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Isolation and Characterization of Root‐Specific Phosphate Transporter Promoters from Medicago truncatula
Author(s) -
Xiao K.,
Liu J.,
Dewbre G.,
Harrison M.,
Wang Z.Y.
Publication year - 2006
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2005-873053
Subject(s) - medicago truncatula , biology , promoter , gus reporter system , green fluorescent protein , reporter gene , transgene , gene , arabidopsis thaliana , gene expression , microbiology and biotechnology , genetically modified crops , medicago , beta glucuronidase , arabidopsis , botany , genetics , symbiosis , bacteria , mutant
Abstract: Promoters of phosphate transporter genes MtPT1 and MtPT2 of Medicago truncatula were isolated by utilizing the gene‐space sequence information and by screening of a genomic library, respectively. Two reporter genes, β‐glucuronidase (GUS) and green fluorescent protein (GFP) were placed under the control of the MtPT1 and MtPT2 promoters. These chimeric transgenes were introduced into Arabidopsis thaliana and transgenic roots of M. truncatula, and expression patterns of the reporter genes were assayed in plants grown under different phosphate (Pi) concentrations. The expression of GUS and GFP was only observed in root tissues, and the levels of expression decreased with increasing concentrations of Pi. GUS activities in roots of transgenic plants decreased 10‐fold when the plants were transferred from 10 μM to 2 mM Pi conditions, however, when the plants were transferred back to 10 μM Pi conditions, GUS expression reversed back to the original level. The two promoters lead to different expression patterns inside root tissues. The MtPT1 promoter leads to preferential expression in root epidermal and cortex cells, while MtPT2 promoter results in strong expression in the vascular cylinder in the center of roots. Promoter deletion analyses revealed possible sequences involved in root specificity and Pi responsiveness. The promoters are valuable tools for defined engineering of plants, particularly for root‐specific expression of transgenes.