Objective: The objective of the study was to clone a root-specific promoter from tomato fOr future use in generating new tomato materials through genetic engineering. Method: Genomic walking technique was used to amplify the upstream regulatory sequence of LeGRP2 (glycine-rich protein), a tomato root-specific expression gene. To investigate the tissue expression pattern of the cloned regulatory sequence, an expression vector containing this sequence fused with GUS was constructed for transfonnation into Arabidopsis by using agrobacterium-mediated method. Result: Using tomato genomic DNA as a template, a regulatory sequence (GenBank accession number: EU262719) 1 959 bp upstream of the LeGRP2 ATG site was amplified by two consecutive genomic walking steps. Sequence analyses revealed that it contained 9 copies of ROOTMOTIFTAPOX1, a known cis-acting element related to root-specific expression. Histochemical staining of transgenic Arabidopsis showed that GUS reporter gene was predominantly expressed in root in both 7 d seedlings and 40 d adult plants. Conclusion: The LeGRP2 promoter was cloned, which displayed a strong root-specific expression pattern in Arabidopsis transformed with LeGRP1 promoter fused with gene GUS.
Scientia Agricultura Sinica Vol. 43, Issue 9, p. 1877-1882