Abstract
BackgroundSweetpotato (Ipomoea batatas L.) is one of the seven major food crops grown worldwide. Cold stress often can cause protein expression pattern and substance contents variations for tuberous roots of sweetpotato during low-temperature storage. Recently, we developed proteometabolic profiles of the fresh sweetpotatoes (cv. Xinxiang) in an attempt to discern the cold stress-responsive mechanism of tuberous root crops during post-harvest storage.ResultsFor roots stored under 4 °C condition, the CI index, REC and MDA content in roots were significantly higher than them at control temperature (13 °C). The activities of SOD, CAT, APX, O2.- producing rate, proline and especially soluble sugar contents were also significantly increased. Most of the differentially expressed proteins (DEPs) were implicated in pathways related to metabolic pathway, especially phenylpropanoids and followed by starch and sucrose metabolism. L-ascorbate peroxidase 3 and catalase were down-regulated during low temperature storage. α-amylase, sucrose synthase and fructokinase were significantly up-regulated in starch and sucrose metabolism, while β-glucosidase, glucose-1-phosphate adenylyl-transferase and starch synthase were opposite. Furthermore, metabolome profiling revealed that glucosinolate biosynthesis, tropane, piperidine and pyridine alkaloid biosynthesis as well as protein digestion and absorption played a leading role in metabolic pathways of roots. Leucine, tryptophan, tyrosine, isoleucine and valine were all significantly up-regulated in glucosinolate biosynthesis.ConclusionsOur proteomic and metabolic profile analysis of sweetpotatoes stored at low temperature reveal that the antioxidant enzymes activities, proline and especially soluble sugar content were significantly increased. Most of the DEPs were implicated in phenylpropanoids and followed by starch and sucrose metabolism. The discrepancy between proteomic (L-ascorbate peroxidase 3 and catalase) and biochemical (CAT/APX activity) data may be explained by higher H2O2 levels and increased ascorbate redox states, which enhanced the CAT/APX activity indirectly. Glucosinolate biosynthesis played a leading role in metabolic pathways. Leucine, tryptophan, tyrosine, isoleucine and valine were all significantly up-regulated in glucosinolate biosynthesis.
Highlights
Sweetpotato (Ipomoea batatas L.) is one of the seven major food crops grown worldwide
This discrepancy between proteomic and biochemical data may be explained by higher H2O2 levels and increased ascorbate redox states, which enhanced the CAT/ascorbate peroxidase (APX) activity indirectly
In summary, our proteomic and metabolic profile analysis of sweetpotatoes reveal that the chilling injury (CI) index, relative electrical conductivity (REC) and MDA content in roots stored at 4 °C were much higher than them at 13 °C
Summary
Sweetpotato (Ipomoea batatas L.) is one of the seven major food crops grown worldwide. Cold stress often can cause protein expression pattern and substance contents variations for tuberous roots of sweetpotato during low-temperature storage. Xinxiang) in an attempt to discern the cold stress-responsive mechanism of tuberous root crops during post-harvest storage. Sweetpotato (Ipomoea batatas L.), a dicotyledonous plant which belongs to the Convolvulaceae family, ranks as the seventh-most important food crop in the world. Since soluble sugar content is very low in freshly harvested roots during general production process, a certain time of post-harvest storage at 13– 15°C is imperative to facilitate starch-sugar interconversion and boost the sweetness to increase the tuberous food quality before sale. A better understanding of biochemical and molecular response mechanisms to chilling stress is essential for extending tuberous crops storage time under low temperature condition
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