Production of Three New Grapefruit Cybrids to Improve Citrus Canker Resistance

The production of cybrids, combining nucleus of a species with alien cytoplasmic organelles, is a valuable method used for improvement of various crops. Moreover, this technology considers a non-GMO biotechnology strategy. In citrus, Cybrid plants can be produced as a by-product of somatic fusion. Several citrus cybrids have been created by somatic hybridization. Through the cell fusion between nucellar callus cells Meiwa kumquat, Fortunella crassifolia Swingle (believed to contain a gene(s) for canker resistance) and mesophyll cells in three Citrus combinations of commercial grapefruit (Marsh grapefruit, Citrus paradisi Macfadyen, Flame grapefruit, Citrus paradisi Macfadyen, and N11-11 somaclone grapefruit), we obtained and regenerated putative cybrid-like grapefruit plants resembling mesophyll parent. The mtDNA analysis is underway to confirm that the generated clones that resembled mesophyll parents has identical mtDNA fragment patterns to those of the nuclear callus parent. The results from this test will confirm that these regenerated clones resembling mesophyll parents are cybrids. The confirmed generated cybrids will be propagated for greenhouse and field disease resistance assays. Those plants may have a great potential to improve citrus canker residence in commercial grapefruit varieties.