Molecular characterization of the polyphenol oxidase gene in lulo (Solanum quitoense Lam.) var. Castilla

Abstract

Lulo (Solanum quitoense Lam.) is an exotic fruit from the Andes Mountains with a high export potential. However, the browning that is produced during harvest and the postharvest processes alters the organoleptic and nutritional properties of this fruit, which has made its management as a fresh fruit difficult. The browning processes are regulated by the enzyme family of the polyphenol oxidases (PPOs) located in the thylakoids of the chloroplast. When there is damage at the tissue level, the phenolic compounds found in the vacuoles enter into contact with the polyphenol oxidase. This enzyme produces polymerization among the phenolic compounds, as well as between them and the proteins and cell walls. This study analyzed the polyphenol oxidase in lulo var. Castilla at the genetic level, based on DNA and RNA samples. The results showed a high level of homology with other polyphenol oxidases from plants. The highest degree of homology was found with Solanum melongena L., which belongs to the same clade, Leptostemonum. The tyrosinase and two copper-binding domains, characteristic of the polyphenol oxidase, the conserved residues that maintain the natural environment, the sequence of a signal peptide for targeting chloroplast, and the UTRA domain of transcription regulation for recognizing small molecules were identified. Southern blot was used to analyze the number of gene copies, identifying at least eight ones in the lulo genome.

An optimized method for RNA extraction from the polyurethane oligomer degrading strain Pseudomonas capeferrum TDA1 growing on aromatic substrates such as phenol and 2,4-diaminotoluene

“…Some central intermediates of the biodegradation of aromatics such as phenols and catechols can be easily oxidized to yield the corresponding quinones. This reaction is regulated by the activity of enzymes known as polyphenol oxidases (PPOs) which are the principal basis of the browning reactions in plant tissues and extracts [ 13 – 16 ]. Such oxidases were also observed in Pseudomonas and other bacterial species [ 17 ].…”

“…To overcome these problems, reliable extraction methods such as commercial RNA extraction kits and organic solvents yield high quality RNA from different types of samples including cell lines, plant and mammalian tissues, bacteria, virus, etc. Nevertheless, phenolic compounds, polysaccharides, proteins and other secondary metabolites interfere with nucleic acids tend to co-precipitate or degrade RNA, restricting its yield and quality [ 13 , 23 – 27 ].…”

Evaluación agronómica de familias de medios hermanos de lulo de Castilla, Solanum quitoense Lam.

“…Por otro lado, la investigación en el cultivo de lulo ha girado en torno a estudios de filogenia y sus parientes silvestres (Bedoya-Reina & Barrero, 2009); caracterización morfológica de 39 genotipos de la colección de lulo (S. quitoense), de la Universidad de Nariño (Riascos et al 2012); caracterización molecular del gen de polifenolperoxidasa (Arias et al 2013); comportamiento agronómico de injertos de lulo de castilla en patrones de Solanum spp. A nivel internacional, algunas investigaciones, como la realizada por Silva et al (2016), en el Ecuador, se basaron en evaluar la variabilidad genética obtenida, tomando parámetros importantes para el mejoramiento del cultivo, como grados Brix, color de pulpa y peso promedio de fruto, entre otros.…”