FLAVANONE 3-HYDROXYLASE (F3H) EXPRESSION AND FLAVONOID LOCALIZATION IN NODULES OF 3 LEGUME PLANTS REVEAL DISTINCT TISSUE SPECIFICITIES

A fusion of the promoter of the Medicago sativa flavanone-3-hydroxylas e gene to the gus reporter gene was introduced into three leguminous p lants, M. truncatula, M. sativa subsp, varia, and Vicia hirsuta, Expre ssion of this fusion was detected in the parenchyma cells surrounding the vascular tissues in the nodules of the Medicago spp, plants, corre lating with the presence of flavonoid compounds detected in situ in th ese cells. In V. hirsuta nodules, the fusion was expressed in the meri stematic region, where high accumulation of flavonoids could also be d etected. Our results indicate that flavonoids of the dihydroflavonol p athway are not found in the same tissues of the nodules in these three species, where they may play different roles. In light of these resul ts, the possible roles of the F3H products in this organ are discussed .