HAIRY ROOTS OF BRASSICA-NAPUS .1. APPLIED GLUTAMINE OVERCOMES THE EFFECT OF PHOSPHINOTHRICIN TREATMENT

Hairy roots of Brassica napus (rape cv. Giant) were produced by cocult ivating leaf and cotyledon explants with Agrobacterium rhizogenes stra in A4T. The hairy roots grew prolifically on solid and in liquid media . Incorporation of ammonium sulphate or phosphinothricin (PPT) into th e media reduced growth. PPT treatment reduced glutamine synthetase (GS ) activity and increased the ammonia content of the hairy roots. We ha ve found that PPT treatment also induces a loss of glutamine from the roots and this may influence root growth. To test this we grew hairy r oots in a liquid medium containing 10 mM glutamine. This glutamine tre atment overcame the PPT-induced suppression of growth but also signifi cantly increased GS activity, reduced ammonia accumulation and increas ed the levels of glutamate and asparagine.