alpha-Amanitin resistance is developmentally regulated in carrot
L Pitto1, F L Schiavo, M Terzi
1Istituto di Mutagenesi e Differenziamento, Consiglio Nazionale delle Richerche, Via Svezia, 10, I-56100 Pisa, Italy.
Summary
Carrot cells normally inactivate alpha-amanitin only during embryogenesis. A specific mutation (a3) allows this inactivation during vegetative growth, indicating broader developmental control.
Area of Science:
- Plant molecular biology
- Cellular differentiation
- Biochemistry
Background:
- Carrot cells exhibit conditional inactivation of alpha-amanitin, restricted to embryogenic states.
- Understanding the genetic and biochemical basis of this conditional inactivation is crucial for plant regeneration studies.
Purpose of the Study:
- To investigate the genetic basis of alpha-amanitin inactivation in carrot cells.
- To determine the biochemical mechanism underlying drug inactivation.
- To explore the pleiotropic effects of the identified mutation.
Main Methods:
- Comparative analysis of wild-type and mutant (a3) carrot cell lines.
- Somatic hybridization to assess dominance of the mutation.
- Biochemical assays to identify the enzyme responsible for inactivation.
Main Results:
- The mutant line a3 demonstrates alpha-amanitin inactivation in both embryogenic and non-embryogenic (vegetative) conditions.
- The mutation conferring this ability is dominant in somatic hybrids.
- The mutation is pleiotropic, enabling other embryonal functions during vegetative growth.
- Tyrosinase enzyme's oxidative activity was identified as the mechanism for alpha-amanitin inactivation.
Conclusions:
- A specific mutation enables constitutive alpha-amanitin inactivation in carrot cells, independent of developmental stage.
- This mutation is dominant and pleiotropic, linking drug inactivation to broader embryonal functions.
- Tyrosinase is the key enzyme mediating alpha-amanitin detoxification in carrot cells.
