RESUMEN
Plastid genome transformation offers an attractive methodology for transgene expression in plants, but for potato, only expression of gfp transgene (besides the selective gene aadA) has been published. We report here successful expression of ß-glucuronidase in transplastomic Solanum tuberosum (var. Desiree) plants, with accumulation levels for the recombinant protein of up to 41% of total soluble protein in mature leaves. To our knowledge, this is the highest expression level reported for a heterologous protein in S. tuberosum. Accumulation of the recombinant protein in soil-grown minitubers was very low, as described in previous reports. Interestingly, microtubers developed in vitro showed higher accumulation of ß-glucuronidase. As light exposure during their development could be the trigger for this high accumulation, we analyzed the effect of light on ß-glucuronidase accumulation in transplastomic tubers. Exposure to light for 8 days increased ß-glucuronidase accumulation in soil-grown tubers, acting as a light-inducible expression system for recombinant protein accumulation in tuber plastids. In this paper we show that plastid transformation in potato allows the highest recombinant protein accumulation in foliar tissue described so far for this food crop. We also demonstrate that in tubers high accumulation is possible and depends on light exposure. Because tubers have many advantages as protein storage organs, these results could lead to new recombinant protein production schemes based on potato.
Asunto(s)
Glucuronidasa/biosíntesis , Proteínas de Plantas/biosíntesis , Plastidios/enzimología , Plastidios/genética , Solanum tuberosum/enzimología , Solanum tuberosum/genética , Regulación de la Expresión Génica de las Plantas , Glucuronidasa/genética , Hojas de la Planta/enzimología , Hojas de la Planta/genética , Proteínas de Plantas/genética , Tubérculos de la Planta/enzimología , Tubérculos de la Planta/genética , Plantas Modificadas Genéticamente , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Nicotiana/enzimología , Nicotiana/genética , TransgenesRESUMEN
Chloroplast transformation has an extraordinary potential for antigen production in plants because of the capacity to accumulate high levels of recombinant proteins and increased biosafety due to maternal plastid inheritance in most crops. In this article, we evaluate tobacco chloroplasts transformation for the production of a highly immunogenic epitope containing amino acid residues 135-160 of the structural protein VP1 of the foot and mouth disease virus (FMDV). To increase the accumulation levels, the peptide was expressed as a fusion protein with the beta-glucuronidase reporter gene (uidA). The recombinant protein represented the 51% of the total soluble proteins in mature leaves, a level higher than those of the Rubisco large subunit, the most abundant protein in the leaf of a wild-type plant. Despite this high accumulation of heterologous protein, the transplastomic plants and wild-type tobacco were phenotypically indistinguishable. The FMDV epitope expressed in transplastomic plants was immunogenic in mice. These results show that transplastomic tobacco express efficiently the recombinant protein, and we conclude that this technology allows the production of large quantities of immunogenic proteins.