Cold storage reveals distinct metabolic perturbations in processing and non-processing cultivars of potato (Solanum tuberosum L.)

Abstract

Cold-induced sweetening (CIS) causes considerable losses to the potato processing industry wherein the selection of potato genotypes using biochemical information has found to be advantageous. Here, 1 H NMR spectroscopy was performed to identify metabolic perturbations from tubers of five potato cultivars (Atlantic, Frito Lay-1533, Kufri Jyoti, Kufri Pukhraj, and PU1) differing in their CIS ability and processing characteristics at harvest and after cold storage (4 °C). Thirty-nine water-soluble metabolites were detected wherein significantly affected metabolites after cold storage were categorized into sugars, sugar alcohols, amino acids, and organic acids. Multivariate statistical analysis indicated significant differences in the metabolic profiles among the potato cultivars. Pathway enrichment analysis revealed that carbohydrates, amino acids, and organic acids are the key players in CIS. Interestingly, one of the processing cultivars, FL-1533, exhibited a unique combination of metabolites represented by low levels of glucose, fructose, and asparagine accompanied by high citrate levels. Conversely, non-processing cultivars (Kufri Pukhraj and Kufri Jyoti) showed elevated glucose, fructose, and malate levels. Our results indicate that metabolites such as glucose, fructose, sucrose, asparagine, glutamine, citrate, malate, proline, 4-aminobutyrate can be potentially utilized for the prediction, selection, and development of potato cultivars for long-term storage, nutritional, as well as processing attributes. Potato (Solanum tuberosum L.)-an important staple non-grain vegetable food crop-is used globally for both processing and table purposes. In order to ensure the year-round supply of quality tubers for consumption, cold storage of potato tubers after harvesting is mandatory to reduce sprouting, prevent diseases, avoid losses due to shrinkage, and extend post-harvest shelf life 1,2. Usually 8-10 °C is the recommended storage temperature for potato tubers along with sprout suppressants, such as isopropyl N-(3-chlorophenyl) carbamate. The use of such chemical suppressants-due to their environmental safety and toxicity issues-are being replaced and reliance on storage of potatoes at colder temperatures even below 4 °C has been increased gradually 3-5. During cold storage, potato tubers undergo cold-induced sweetening (CIS), wherein rapid degradation of starch and sucrose hydrolysis leads to the accumulation of reducing sugars (RS)-such as glucose and fructose 6. During the frying process, these RS react with free amino acids in a Maillard reaction to generate dark-pigmented products that are bitter and unsightly to consumers. In addition to this, one of the products of the Maillard reaction is acrylamide-a potent neurotoxin and carcinogen 4,7. Hence, CIS is considered as one of the critical parameters in potato production as well as in processing; therefore, the identification and development of potato tubers

Metabolic changes associated with chilling injury tolerance in tomato fruit with hot water pretreatment

“…Tryptophan decreased in the control fruit but increased in the HWT fruit (Tables 2 and S2). In potato tuber, cold storage decreases the levels of tryptophan (Datir et al, 2020),…”

“…They observed an increase in the levels of tyrosine, isoleucine, and valine, whereas those of glutamic acid decreased, suggesting that higher levels of amino acids are contributing to cold tolerance. However, the amino acids associated with cold tolerance vary among different potato cultivars (Datir et al, 2020). Carbon dioxide-treated tomato fruit improved its cold tolerance, such tolerance was associated with increased levels of alanine, valine, lysine, glutamic acid, serine, glycine, and tyrosine after cold storage at 4°C for 14 days (Park et al, 2021).…”

“…Then, GABA is transported from cytosol to mitochondria where is converted to succinate, which provides electrons to the Krebs cycle and improves the energetic status of the cells (Morteza Soleimani Aghdam et al, 2018). Potato tubers of five cultivars were exposed to cold storage at 4°C, one of them showed higher levels of GABA, and the five cultivars increased their levels of adenosine (Datir et al, 2020). Another study showed the GABA levels were also increased in cold-stored potato tubers of two cultivars (S. acaule and S. tuberosum) (Kou et al, 2018).…”

“…Metabolomic analysis of Micro-Tom tomato fruit by GC-MS showed that chilling changes the profile of key metabolites of glycolysis and pentose phosphate pathway (i.e., glucose-6-phosphate and fructose-6phosphate), increases the levels of arabinose, citric acid, dehydroascorbic acid, and valine; and it decreases the levels of glutamic and shikimic acids . NMR studies of the effect of cold stress in tubers of five potato cultivars showed evidence that the cold response is associated with adjustments in the biochemical pathways of carbohydrates, amino acids, and organic acids (Datir et al, 2020). Transcriptome and metabolome analyses showed that putrescine is important in the cold tolerance of the potato tuber of Solanum acaule, showing also an accumulation of saccharides, amino acids, γ-aminobutyric acid (GABA), among other metabolites (Kou et al, 2018).…”

“…Imperial) has been associated with changes in the expression of genes encoding heat shock proteins and enzymes of the antioxidant system and the energy metabolism (Cruz-Mendivil et al, 2015;Salazar-Salas et al, 2017); however, the metabolites associated with such tolerance have not been identified. In this regard, the CI tolerance induction has been associated with a range of metabolites and depends on the species, varieties of the same species, and developmental stage, among other factors (Aghdam et al, 2019;Albornoz et al, 2019;Datir et al, 2020;Gonzalez et al, 2019;Jannatizadeh et al, 2019;Loayza et al, 2021;Zhang et al, 2019).…”