Regeneration and characterization of somatic hybrid plants of Citrus sinensis (sweet orange) and Citrus micrantha, a progenitor species of lime

Most commercial citrus fruit species and cultivars are inter- and intra-specific hybrids. Conventional hybridization in citrus is largely handicapped by apomixis and long juvenility. As an alternative, somatic hybridization via protoplast fusion has been employed to create novel citrus germplasm. Witches' broom disease of lime (WBDL) emerged in Oman during the 1970s, which has been spreading to the neighboring countries. The disease is extremely destructive. A possible solution to the WBDL problem is to develop resistant hybrids. Resistance is available among the citrus relatives of lime i.e., sweet orange. Somatic hybrids combining sweet orange with lime have been produced but the fruit characteristics are different from lime. Herein, we report the development of somatic hybrids between a progenitor of lime (Citrus micrantha) and sweet orange (Citrus sinensis) in efforts to recreate a lime-like fruit using sweet orange as a donor of disease resistance gene(s). Successful somatic hybridization was verified by ploidy analyses using flow cytometry and RAPD analyses. This is the first report of using a progenitor species in somatic hybridization experiments in efforts to resynthesize an improved lime.