Lupine leghemoglobin I: expression in transgenic Lotus and tobacco tissues

The proximal parts of the promoters of the genes for symbiotic-type hemoglo bins are generally conserved, but the promoter of the lbI gene of lupine (L ulbI) shows some unusual structural features. It lacks typical organ-specif ic elements characteristic of all the leghemoglobin gene promoters describe d thus far. We have analysed its functional activity in transgenic Lotus co rniculatus. A fusion construct between the lbI promoter and the GUS reporte r gene was expressed mainly in the central zone of the root nodule, but the product was also detected in the non-nodule root zone and in roots in tiss ue culture. In roots of transgenic tobacco, the activity of the promoter wa s only 24% lower than in Lotus nodules. LulbI promoter activity was also de tected in tobacco leaves. Lupine hemoglobin I has a higher sequence identit y to symbiotic-type hemoglobins and thus it groups within the "Class II" he moglobins.