Temporal dynamics of phenolics and lignin-related metabolism in sweet potato storage roots during post-curing storage

초록

Curing treatment is an effective post-harvest intervention for extending sweet potato storage longevity by promoting wound healing and preventing pathogenic infection. However, temporal dynamics of phenolic and lignin metabolism during post-curing storage remain poorly understood in sweet potato. This study characterized changes in phenolic accumulation and lignin metabolism in sweet potato storage roots during 56 days of post-curing storage at 13 degrees C. Sweet potato cultivar Pungwonmi was subjected to curing treatment (32 +/- 1 degrees C, 92 +/- 3% relative humidity for 3 days), followed by 56-day cold storage. Cured roots maintained superior physiological quality with minimal deterioration, while control roots exhibited progressive pathogenic infection. Cured roots maintained low and stable total phenolics and lignin contents throughout storage, whereas control roots showed dramatic progressive increases. Transcriptome-based expression analysis revealed coordinated down-regulation of phenylpropanoid pathway genes in cured roots throughout storage, contrasting with progressive induction in control roots. Peroxidase and polyphenol oxidase genes also showed sustained suppression in cured roots with markedly reduced enzyme activities, while control roots displayed elevated activities. These findings reveal that curing establishes a temperature-dependent regulatory program suppressing phenolic and lignin metabolism during cold storage, preventing excessive oxidative reactions and pathogenic-induced metabolite accumulation.

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