HAIRY ROOT CULTURES OF HYOSCYAMUS-MUTICUS - EFFECT OF POLYAMINE BIOSYNTHESIS INHIBITORS

The effect of several inhibitors of polyamine synthesis on root growth and morphology and on polyamine titres in normal and Agrobacterium rhizogenes-transformed hairy root cultures of Hyoscyamus muticus was investigated. Five millimolar cyclohexylamine (CHA) and 1 mM methylglyoxal-bis-guanylhydrazone (MGBG) significantly inhibited both root growth and lateral root formation. One millimolar alpha-difluoromethylarginine (DFMA) significantly reduced while 1 mM alpha-difluoromethylornithine (DFMO) stimulated elongation growth of primary and lateral roots without affecting lateral root number. Both normal and hairy roots treated with DFMO, alone or in combination with DFMA, displayed a very evident lack of root hairs. Free polyamines constituted only a small part of the total polyamines present in hairy roots; of these, spermidine was the most abundant. A conspicuous accumulation of trichloracetic acid-soluble and -insoluble conjugated putrescine was also found. Although DFMO did not significantly alter total putrescine content, DFMA reduced it dramatically. This effect was further accentuated when DFMO and DFMA were supplied together. CHA and MGBG did not provoke the expected depletion in spermidine and/or spermine, but both inhibitors caused a marked accumulation in free and conjugated putrescine.