Involvement of polyamines in root development at low temperature in the subantarctic cruciferous species Pringlea antiscorbutica.

Polyamine involvement in root development at low temperature was studied in seedlings of Pringlea antiscorbutica R. Br. This unique endemic cruciferous species from the subantarctic zone is subjected to strong environmental constraints and shows high polyamine contents.

Attenuation of the Phenotype Caused by the Root-Inducing, Left-Hand, Transferred DNA and Its rolA Gene (Correlations with Changes in Polyamine Metabolism and DNA Methylation).

We present four examples of attenuation of the transformed phenotype caused by the root-inducing, left-hand, transferred DNA from Agrobacterium rhizogenes in tobacco (Nicotiana tabacum). The first was associated with a genetic variable (homozygosity for the T-DNA), and the second was induced at the physiological level by putrescine and tyramine, suggesting that the transformed phenotype depends on defective polyamine metabolism. Physiological attenuation is further illustrated in the third example, in which the inhibition of flowering caused by P35S-rolA, a gene from the root-inducing, left-hand, transferred DNA driven by a strong viral promoter, was attenuated by grafting the transformed shoot onto non-transformed rootstock that had been induced to flower.