Genetic transformation of the euploid Saccharum officinarum via direct and indirect embryogenesis

Abstract

The genetic nature of foreign gene transfer and integration into commercial sugarcane hybrids with complex genetic backgrounds is unclear and unpredictable. A pure genetic background in genetic engineering approaches might lead to more predictable results within Saccharum officinarum than in a hybrid genome. S. officinarum plants (Badila and Black Cheribon genotypes) expressing a reporter gene was regenerated from microprojectile-bombarded leaf disks and callus. The concentration of auxin added to the basal media, both prior to bombardment and during regeneration, significantly affected callus induction and somatic embryogenesis. A ten-fold decrease in 2,4-D concentration resulted in somatic embryos forming directly from sugarcane leaf disks. Somatic embryos were produced via direct embryogenesis from 7 days old Black Cheribon leaf disks on 0.5 mg/l 2,4-D. A callus interface initiated on 3 mg/l 2,4-D from Badila leaf disks was preferred for indirect embryogenesis to produce the maximum number of transgenic Badila plants. These approaches lead to the successful establishment of genetic transformation systems for two S. officinarum genotypes that could be used in the future for gene function studies and breeding purposes.