Impacts on the metabolome of down-regulating polyphenol oxidase in potato tubers

Abstract

Tubers of potato (Solanum tuberosum L. cv. Estima) genetically modified to reduce polyphenol oxidase (PPO) activity and enzymatic discolouration were assessed for changes in the metabolome using Liquid Chromatography-Mass Spectrometry (LC-MS) and Gas Chromatography (GC)-MS. Metabolome changes induced over a 48 hour (h) period by tuber wounding (sliced transverse sections) were also assessed using two PPO antisense lines (asPPO) and a wild-type (WT) control. Data were analysed using Principal Components Analysis and Analysis of Variance to assess differences between genotypes and temporal changes post-tuber wounding (by slicing). The levels of 15 metabolites (out of a total of 134 that were detected) differed between the WT and asPPO lines in mature tubers at harvest. A considerably higher number (63) of these metabolites changed significantly over a 48 h period following tuber wounding. For individual metabolites the magnitude of the differences between the WT and asPPO lines at harvest were small compared with the impacts of tuber wounding on metabolite levels. Some of the observed metabolite changes are explicable in terms of pathways known to be affected by wound responses. Whilst some statistically significant interactions (11 metabolites) were observed between line and time after wounding, very few profiles were consistent when comparing the WT with both asPPO lines, and the underlying metabolites appeared to be random in terms of the pathways they occupy. Overall, mechanical damage to tubers has a considerably greater impact on the metabolite profile than any potential unintended effects resulting from the down-regulation of PPO gene expression.

An R1R2R3 MYB Transcription Factor, MnMYB3R1, Regulates the Polyphenol Oxidase Gene in Mulberry (Morus notabilis)

“…Additionally, silencing the walnut PPO genes via RNA interference technology reportedly increases the chances that the resulting plants develop necrotic plaques [8]. Many other studies have confirmed the relationship between PPOs and plant defense [9,10,11,12,13,14,15,16,17]. Studies regarding the overexpression or silencing of PPO genes have clearly demonstrated the key role of PPOs in plant defense responses.…”

Optimization and Characterization of Tyrosinases from Multi-enzyme Producing Fusarium solani and Fumago sp.

“…Tyrosinase is a copper containing enzyme present in both plant and animal tissues that catalyzes the production of melanin and other pigments from tyrosine by oxidation. A typical illustration is the blackening of a peeled or sliced tuber crop, during exposure to air [5]. From a mechanistic perspective, tyrosinases oxidize their substrates through hydroxylation of monophenol to o-diphenol (monophenolase or cresolase activity) and the oxidation of diphenol to o-quinones (diphenolase or catecholase activity), both using molecular oxygen, followed by a series of non-enzymatic steps, which may result in the formation of melanin [6].…”

Early prediction of internal bruising in potatoes by biospeckle laser technique

“…In potatoes, the losses by mechanical injuries occur during every stage of production, from harvest to consumption. However, as the injuries are cumulative, the whole process should be monitored, and there should be actions to prevent damages (Shepherd et al, 2015). Ferreira and Netto (2007) reported that in potatoes the superficial damages and internal bruising can get to 40% of the whole production, reducing the sale price and even causing the rejection of the product.…”