Protoplast Fusion for Symmetric Somatic Hybrid Production in Brassicaceae

This chapter will focus on somatic hybridization in Brassicaceae. The results from a vast number of investigations have clearly shown that somatic hybridization in this family can overcome sexual barriers, and that the nuclear, mitochondrial, and chloroplast genomes from different sexually incompatible species can be combined. Reproducible protocols for protoplast culture and regeneration to plants have been established for a large number of crop species within this family, such as oilseed rape, turnip rape, cabbage, and Indian mustard (1 ). This has laid the foundation for the production of somatic hybrids (2 ,3 ). A substantial number of somatic hybrids have been produced between species within the genus Brassica , combining both diploid and allopolyploid Brassica species into hybrid plants. For example, the resynthesis of rapeseed (4 –7 ), but also a combination of all three Brassica genomes (A, B, and C) have been performed (8 ,9 ). To widen the gene pool of rapeseed, several intergenenc somatic hybrids combining Brassica napus with species from the genera Eruca (10 ), Sinapis (11 ,12 ), Raphanus (13 ), Moricandia (14 ,15 ), and Diplotaxis (16 ,17 ) have been made. Furthermore, it has even been possible to combine species from different tribes, by obtaining somatic hybrids, e.g., between rapeseed and Arabidopsis thahana (18 –21 ), rapeseed and Thlaspi perfoliatum (22 ), as well as rapeseed and Lesquerella fendleri (23 ).