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Site‐directed mutagenesis of the organ‐specific element in the soybean leghemoglobin Ibc 3 gene promoter
Author(s) -
Ramlov Karsten Bak,
Laursen Niels Bech,
Stougaard Jens,
Marcker Kjeld A.
Publication year - 1993
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1993.04030577.x
Subject(s) - leghemoglobin , biology , gene , promoter , genetics , mutagenesis , consensus sequence , point mutation , regulatory sequence , site directed mutagenesis , gene expression , microbiology and biotechnology , mutation , mutant , base sequence , root nodule , symbiosis , bacteria
The expression of a soybean leghemoglobin 5′ Ibc 3–GUS‐3′ nos chimeric gene was analyzed in Lotus corniculatus after site‐specific mutagenesis of the nodulin consensus sequences, AAAGAT and CTCTT, present in the organ‐specific element (OSE) (−139 to −102). Full‐length promoters (−1956,+46) carrying clustered point mutations in the CTCTT sequence or in both the AAAGAT and the CTCTT sequences were inactive. Point mutations in the AAAGAT sequence had only minor effects on the expression level. Substitution of the ATTG sequence between the AAAGAT and the CTCTT sequences in the OSE reduced the activity in nodules to 10%. This, together with the conservation of the ATTGT sequence in the same position of leg‐hemoglobin genes from other legumes, indicates that these sequences, in addition to the nodulin consensus sequences of the OSE, are important for high‐level nodule‐specific expression. Substitution of the CTCTT sequences outside the OSE (−44,−40 and −79,−75) results in promoter activities of approximately 50%.