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Sucrose is the main form of higher plant photosynthesis product transport,which provides carbon and energy source and plays a decisive role in the process of plant growth and metabolism. There are three types of sugar metabolism related enzymes in plants and sugarcane, including invertase or G - furan fruit glycosidase (Inv), sucrose phosphate synthesis Enzyme (SPS) and sucrose synthase (SUSy),among which sucrose synthetase is one of the key enzymes catalyzing sucrose metabolism.Sucrose is the control factor of the cell metabolism and participates in the plants adapting to adversity stress reaction.Sugar have signal function, which can be induced to express some special protein coding genes.
Years of research show that the main physiological function of plant sucrose synthetase in the following aspects: 1.affecting the ability of sink and regulating the amount of fruit input and ordinary sugar metabolism ability. The fruit of sugar is the basic component of a very important index for the quality evaluation.In general, for the most part of sugar accumulation in fruit is soluble total sugar, in addition is the fructose and glucose. Due to the synthesis of sucrose synthase and invertase regulating sucrose and decomposition, make sink of plant organs and phloem maintain appropriate sucrose concentration gradient, which is advantageous for the sugar into the cells. 2.affect the synthesis of starch. Starch is the main storage form of carbohydrate in plants and is an important part of the plant storage organs. 3.sucrose synthetase participates in the building of various tissues and cells. For example, in the process of biological growth and development using sucrose synthetase of sucrose degradation UDPG building cell walls or callose synthesis. Sucrose synthase can break sucrose up into glucose and fructose, make its osmotic pressure increase in the cell,which is advantageous to the quick protuberance and elongation of the epithelial cells of cotton integument. 4.improve plant resistance.Sucrose is the main carbon source of plants,and when plants subjected to external environment stress, plant sucrose accumulation occurs in the body. This phenomenon is a kind of feedback regulating plants adapt to the environment.
Systematic searches using the complete genome se-quence of rice (Oryza sativa) identified OsSUS7, a new member of the rice sucrose synthase (OsSUS) gene family,which shows only nine single nucleotide substitutions in the OsSUS5 coding sequence. Comparative genomic analysis revealed that the synteny between OsSUS5 and OsSUS7 is conserved, and that significant numbers of transposable elements are scattered at both loci. In particular, a 17.6-kb genomic region containing transposable elements was identified in the 5′upstream sequence of the OsSUS7 gene. In our present study, we isolated a new member of the Os-SUS gene family, OsSUS7, through analysis of the complete genome sequence of rice. OsSUS7 is nearly identical to Os-SUS5 except for nine single nucleotide differences. We first investigated the evolutionary relationship between OsSUS7 and the previously reported SUS genes including OsSUS5. We then compared the expression and subcellular localization of OsSUS7 with that of OsSUS5 and other Os-SUS genes by RT-PCR analysis and transient expression assays using promoter-luciferase (LUC) fusion and GFP fusion constructs. Finally, we discuss the duplication of OsSUS5 and OsSUS7 genes and their function in rice.
Labs working on this gene
Systemic blast searches of the rice genome, using nucleotide and amino acid sequences of previously reported rice SUS genes, identified seven genes encoding sucrose synthase enzymes. Thus, our analysis enabled the detection of a previously uncharacterized sucrose synthase gene, named OsSUS7. An in-depth examination further found that the genomic sequence of OsSUS7 is nearly identical to that of OsSUS5, which are located near to each other on chro-mosome 4. Comparative analysis of both genomic region revealed an insertion region of a 17.6 kb in the promoter of OsSUS7, which was absent in the corresponding region of OsSUS5 . Further analysis of the OsSUS5 and OsSUS7 genomic regions using BAC clones provided an interesting insight into the evolutionary history of both genes . We found that several genes located at the periphery of OsSUS5 and OsSUS7 were nearly identical to each other.In addition, we found that a number of transposable elements are scattered among the OsSUS5 and OsSUS7 genes .These data suggest that the OsSUS7 chromosomal region might have been duplicated from the OsSUS5 genomic region,which was followed by transposition events involving transposable elements. Alternatively, the OsSUS5 genomic segment may have been duplicated from that of OsSUS7 via an excision of the 17.6-kb insertion region.
1.Jung-Il Cho;Hyun-Bi Kim;Chi-Yeol Kim;Tae-Ryong Hahn;Jong-Seong Jeon Identification and characterization of the duplicate rice sucrose synthase genes OsSUS5 and OsSUS7 which are associated with the plasma membrane Molecules and Cells, 2011, 31(6): 553-561 2.The Rice Annotation Project Database (RAP-DB): 2008 update. Rice Annotation Project, et al. Nucleic Acids Res, 2008 Jan. 3. Curated genome annotation of Oryza sativa ssp. japonica and comparative genome analysis with Arabidopsis thaliana. Rice Annotation Project, et al. Genome Res, 2007 Feb. 4.The Rice Annotation Project Database (RAP-DB): hub for Oryza sativa ssp. japonica genome information. Ohyanagi H, et al. Nucleic Acids Res, 2006 Jan 1. 5.The map-based sequence of the rice genome. International Rice Genome Sequencing Project. Nature, 2005 Aug 11.