Asmmetry in Somatic Hybrids for Gene Transfer,Elimination of Chromosomes,Hybridization,Fragmentation,Agricultural Production

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	Asmmetry in Somatic Hybrids for Gene Transfer - As discussed above, in many somatic hybrids, the chromosome number has been found to be abnormal, often fewer than expected. For instance, in Erucobrassica about 60% plants had fewer than the expected chromosome number. Variability was also observed in Moricandiobrassica and other hybrids. In many of these cases, chromosomes are eliminated or translocated thus facilitating limited alien gene transfer. An important example of use of such asymmetric hybrids in gene transfer, is the transfer of black leg resistance to rapeseed.
The disease blackleg, caused by the fungus Phoma lingam, is a world wide problem for agricultural production of rapeseed and turnip rape: Fungal mycelia enter into stem, such that stem rots and plant dies by Wilting. A toxin (sirodesmin PI) isolated from fungus can be used to select resistant material. To promote limited gene transfer, resistant donor lines were irradiated prior to fusion and hybridization, causing fragmentation and elimination of chromosomes, thus facilitating integration of resistance gene into the recipient line. The fusion products were allowed to develop into colonies before exposing them to selective toxin. Calli resistant to toxin were regenerated into, plants and tested for resistance. Most of these plants exhibited resistance suggesting transfer during somatic hybridization.