A Gene Expression Method for Evaluating Freshness of Spinach (Spinacia oleracea L.) Leaves

Abstract

　To date, the freshness of vegetables is evaluated mostly by appearance. In addition, several quality-related compounds are used to estimate the freshness; however, this approach is challenging because the initial amount of these compounds is affected by the cultivar or environmental conditions. In this study, we demonstrate a new method to evaluate the freshness of vegetables based on gene expression. Subtracted cDNA libraries were prepared from spinach (Spinacia oleracea L.) leaves before and after storage. Nucleotide sequences of these genes were determined. Expression of these genes was verified by northern blot analyses of RNA samples from leaves with different storage period. Specific marker genes, suitable for evaluating freshness, were selected. We developed a method of semi-quantitative multiplex PCR with combinations of these genes that can visualize the changes in freshness during storage. Using this technique, detection of the physiological changes in spinach was possible, even before the appearance of leaf yellowing. Application of this method enables the detection of differences in freshness under different packaging conditions based on gene expression.