Detection of pectolytic activity andpel homologous sequences inFrankia

Using a cup-plate pectin agar assay, pectolytic activity was detected in nodule filtrates obtained fromAlnus rugosa (DuRoi) Spreng,A. glutinosa (L.) Gaertn andA. crispa (Ait.) Pursh seedlings after infection with twoFrankia strains (ACN1 AG , CpI1). Pectolytic activity was also detected in cultures filtrates of the same twoFrankia isolates afterin vitro-cultivation on Qmod pectin liquid medium. When Southern blots of Frankia total DNAs from 3 isolates ofF. alni subsp.Pommerii (ACN1 AG , ArI3, and CPX32b) and 3 isolates ofF. elaeagni (EUN1 pec, SCN 10a and TX31e HR ) were hybridized withPelBDA probes fromErwinia chrysanthemi, positive signals were found in all 7 Frankiae tested.