Case study on high sucrose synthesis, drought tolerant and virus resistant
Bambang Sugiharto
Center for Development of Advanced Science and Technology (CDAST) and Department of Biology Faculty of Mathematic and Natural Sciences, Jember University, Jl. Kalimantan No. 37 Kampus Tegalboto, Jember, 68121 Indonesia Email: [email protected] and [email protected]
Abstract
Sugarcane is one of the most important crops for sugar production in the tropical and sub-tropical regions. The conventional breeding has greatly contributed to sugarcane improvement, but the limitation of the breeding make sugarcane is good candidate for the improvement through genetic transformation approach. There are several genetic transformation methods and the Agrobacterium-mediated transformation is the most commonly used method. We have successfully developed an efficient method for sugarcane transformation using Agrobacterium vector.
Sucrose-phosphate synthase (SPS) is a key enzyme controlling photosynthetic carbon flux into sucrose. Molecular study on gene for SPS found presence of two isogene for SPS in sugarcane leaves, photosynthetic (SoSPS1) and non-photosynthetic (SoSPS2) types. Genetic transformation of SoSPS1 showed the increase of SPS activity and sucrose content in leaves of transgenic tomato. Therefore, the SoSPS1 was overexpressed in sugarcane and resulted in the increases of sucrose content and cane yield. At present time, the transgenic sugarcane line have been submitted for biosafety assessment.
Plants are subjected to a variety of abiotic and biotic stresses, which reduces and limits agricultural crop productivity. Plants adapt to water stress with various strategies include change in the gene expression and accumulation of organic compounds called compatible solutes. Drought inducible protein (SoDip22) has been identified and the expression was significantly induced by water and osmotic stresses in sugarcane. However, the function of the SoDip22 protein is still unclear and remain to be elucidated. The drought tolerant sugarcane was developed using betA gene encoding for choline dehydrogenase in bacteria. Genetic transformation of betA gene elevated glycine-betaine content as an osmoprotectant and resulted in water stress tolerant of transgenic sugarcane. The drought tolerant of sugarcane was already approved and released by Indonesian Government for commercialization.
Sugarcane mosaic virus (ScMV) is a pathogenic virus from the family Potyviridae and caused chlorosis, stunting and significantly reduced sugar productivity in sugarcane. Gene encoding for coat protein (CP) from the virus is widely used for inducing resistance in plants. This gene (CpScMV) was cloned from the virus infected sugarcane leaves and used to develop resistances by pathogen derived resistance (PDR) and RNA interference (RNAi) methods. The ScMV resistant transgenic sugarcane lines were successfully developed by PDR and RNAi method, but comparison of both methods indicated that RNAi method targeting the gene for CP effectively produces more resistances against the SCMV infection in sugarcane.
Keywords: biotechnology, transgenic sugarcane, sucrose synthesis, drought tolerant, virus resistant.