Review on Somatic Hybridization and Its Role in Crop Improvement

Abstract

Somatic hybridization is one of the most important uses of protoplast culture. This is particularly significant for hybridization between species or genera, which cannot be made to cross by conventional methods of sexual hybridization. The aim of somatic hybridization is to transfer traits which are desired and generate a beneficial crop plants without genetic engineering and as well as facilitate conventional breeding through providing novel crop lines. Somatic hybridization broadens the base of accessible germplasm and offers additional opportunities for introgression of desirable traits into cultivars. Plant protoplasts can be fused and the fusion products cultured to produce somatic hybrid plants. This technique has been used to produce germplasm previously unavailable to the plant breeder. Several researchers have emphasized production of hybrids between distantly related, sexually incompatible species, but many of these hybrids are sterile, precluding incorporation into a breeding program. Hence, to transfer traits such as disease and herbicide resistance, emphasis has shifted to production of hybrids between more closely related species. Novel variation has been observed in such somatic hybrids due to segregation of mixed organelles, cytoplasmic and nuclear gene recombination, and somaclonal variation. The unique gene combinations made possible by protoplast fusion ensure that new plant varieties will soon be derived from somatic hybridization. Even though measurable success of somatic hybridization in terms of cultivar release may still be limited, the potential for their use in plant breeding remains great. In general, somatic hybridization provides excellent opportunities for research on plant improvement, first by exploring genetic variations among the existing crops and then by attempting to transfer the available genetic information from one species to another through fusion of protoplasts isolated from somatic tissues of these crops. Somatic hybridization is contributing to plant breeding in overcoming common crossing barriers among plant species. Some of the problems could be overcome by somatic hybridization are: sexual incompatibility, nucellar embryogenesis, male or female sterility, transfer of resistance genes for biotic and abiotic stresses, to create novel hybrids with increased yields. Several steps are involved in the somatic hybridization process. Some of them are: identification of the source of protoplasts, isolation of protoplasts, planting of protoplasts, regeneration of plants, fusion of protoplasts, selection procedures, identification and characterization of somatic hybrid plants. Generally somatic hybridization is playing a key role in the production of novel interspecific and intergeneric hybrids and transfer of genes for diseases resistance, abiotic stress resistance, herbicide resistance and many other quality characters. Besides being of value for the transfer of unidentified genes, somatic hybridization is a tool for the modification and improvement of polygenic traits. Furthermore, the modification of organellar genetic material is possible via somatic hybridization since a mixture of the two fusion partners is obtained in the hybrid cell Production of hybrid plants through the fusion of protoplasts of two different plant species/varieties. Keywords: Somatic; Hybridization; Protoplast; Fusion. DOI: 10.7176/JBAH/10-11-04 Publication date: June 30 th 2020