Production of ipt-expressing white poplar lines (Populus alba L.) with abnormal root morphology.

Agrobacterium-mediated transformation of white poplar explants was performed using the pMAT-MT construct derived from the ipt-type MAT22 plasmid carrying the PsMTA1 cDNA encoding a pea metallothionein. In vitro shoot regeneration occurred on antibiotic-free medium and transformants were identified by visual selection. Beside the expected abnormal ipt-shooty phenotype, shoots with normal morphology were recovered. Interestingly, an additional phenotype characterised by a remarkable root development was also observed.