Abstract
Various plant-derived promoters can be used to regulate ectopic gene expression in potato. In the present study, four promoters derived from the potato genome have been characterized by the expression of identical cassettes carrying the fusion with the reporter β-glucuronidase (gusA) gene. The strengths of StUbi, StGBSS, StPat, and StLhca3 promoters were compared with the conventional constitutive CaMV 35S promoter in various organs (leaves, stems, roots, and tubers) of greenhouse-grown plants. The final amount of gene product was determined at the post-transcriptional level using histochemical analysis, fluorometric measurements, and Western blot analysis. The promoter strength comparison demonstrated that the StUbi promoter generally provided a higher level of constitutive β-glucuronidase accumulation than the viral CaMV 35S promoter. Although the StLhca3 promoter was predominantly expressed in a green tissue-specific manner (leaves and stems) while StGBSS and StPat mainly provided tuber-specific activity, a “promoter leakage” was also found. However, the degree of unspecific activity depended on the particular transgenic line and tissue. According to fluorometric data, the functional activity of promoters in leaves could be arranged as follows: StLhca3 > StUbi > CaMV 35S > StPat > StGBSS (from highest to lowest). In tubers, the higher expression was detected in transgenic plants expressing StPat-gusA fusion construct, and the strength order was as follows: StPat > StGBSS > StUbi > CaMV 35S > StLhca3. The observed differences between expression patterns are discussed considering the benefits and limitations for the usage of each promoter to regulate the expression of genes in a particular potato tissue.
Highlights
The potato is an essential vegetable crop in various climate areas
Effective expression systems should be designed to increase the productivity of potato plants and alter their metabolic activity for both food-based agricultural and non-food industrial purposes
Owing to the increased demand for exploiting potato tubers as a production platform for nutrients with pharmaceutical or industrial interest, the choice of controllable promoter displaying tuber-specific expression is important for the creation of “factory” plants
Summary
The global production of potatoes takes first place among dicotyledonous species, second only to monocotyledonous cereal crops such as wheat, rice, and corn [1] It is generally consumed in fresh, frozen, and dehydrated food products and food ingredients but is used as animal feed and for industrial purposes as a source of starch, bio-ethanol, and other nutrients. The advanced methods of genetic modifications have become increasingly important in modern breeding programs. Such technologies as transgenesis and genome editing provide the specific alteration of potato genome that is not reached using conventional breeding methods [2]. The choice of an appropriate promoter is an important element in the accurate modification of gene function in engineered plants
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