The maize transcription factor Sn alters proanthocyanidin synthesis in transgenic Lotus corniculatus plants

Lotus corniculatus L. plants were transformed with Agrobacterium rhizogenes binary vector carrying the maize Sn regulatory gene driven by the 35S prom oter. These plants showed modifications in the pattern of accumulation of p roanthocyanidin (PA). All the transformed plants but one showed an increase in PA content in the root relative to control untransformed and control gu s gene transformed plants (C). With respect to the PA accumulation in leave s, Sn transgenic plants were grouped in two classes: suppressed (S), that s howed a consistent reduction of foliar PA content, and unsuppressed (U) tha t did not differ significantly from controls. Dihydroflavanol reductase (DF R) and leucocyanidin reductase (LAR) enzyme activities in S and U plant lea ves mirrored the changes seen with foliar PA accumulation. LAR activity in the roots was consistent with the root PA levels. Mature Sn mRNA accumulate d in the leaves of U plants, but not in leaves of S plants; however, leaves of both S and U plants were able to initiate Sn transcription. All Sn-tran sformed plants accumulated Sn message in root tissue. A possible negative i nteraction of Sn and an unidentified homologous endogene is proposed for ex plaining the behaviour of S plants.