Aspects of fusion combining ability of dihaploid Solanum tuberosum L.: influence of the cytoplasm
 Potato Research (1998) 41: 155-162
Frei U., Stattmann M.*, Lössl A, Wenzel G
 TU München-Weihenstephan, 85350 Freising, Germany
* Bioplant GmbH, 29574 Ebstorf, Germany


Summary: In potato increasing numbers of  4x clones originating from cell fusion of 2x clones are evaluated, and it became obvious that besides the combined nuclear genome the composition of the cytoplasm influences significantly the phenotypic traits of the hybrid clones. In order to analyze the influence of the parental cytoplasm on the success of the protoplast fusion and the regeneration of hybrids itself, data of 50 dihaploid clones used in 74 fusion combinations were analyzed. The majority of dihaploid breeding clones belonged to the cytoplasm types Wa , Tb and Wg.
When the mt types a, b and g were involved, fusion combinations showed a better general combining ability compared to incorporation of the more distantly related cytoplasms d and e. A superiority of fusions containing the same mt type (homofusions) over the fusion of different types could not be proved. Whereas homofusions of cytoplasm type Wa yielded significantly more hybrids than homofusions of the type Tb. There are indications for a specific combining ability of the cytoplasm types Wa and Wg.  In general the influence of the parental cytoplasm types on the fusion combining behaviour showed to be of minor importance.
Thus the knowledge of the cytoplasm type of the fusion parents is no suitable criteria for selecting fusion parents. It has to be seen as an additional information in order to use the whole potential of protoplast fusion in creating new valuable cytoplasm types.

Andreas Lössl
Acknowledgements: The authors are grateful to Mr. A. Barth, Mrs. E. Gerick, Mr. C. Kornbauer and Mrs. Ammerseder for technical assistance. This work was supported by grants of the BMBF under the number 0310768.
Last Update: Jan, 2010