<i>BcACS6</i> overexpression promotes the accumulation of L-cysteine and L-tyrosine and improves the quality of Wucai

At present, the research on the quality of Wucai (<i>Brassica campestris</i> L. ssp. <i>chinensis</i> var. <i>rosularis</i> Tsen et Lee.) is still in its infancy. The content and type of amino acids play a pivotal role in determining the quality of Wucai. This study employed widely targeted metabolomics technology to examine the changes in metabolites associated with the quality transformation of Wucai, identifying amino acids as prominent differentially accumulated metabolites during this process. Electronic tongue analysis revealed that the primary taste attributes of Wucai before and after quality transformation are saltiness, astringency, and umami. To elucidate the relationship between amino acid composition and taste, we analyzed the correlation between electronic tongue response values and the reaction intensity data of flavor amino acids. The results showed that the absolute value of the correlation coefficient was highest between L-cysteine and umami, as well as between astringency and L-aspartic acid. Moreover, the values for L-phenylalanine, L-tyrosine, and γ-aminobutyric acid with saltiness were identical and surpassed those for all other amino acids. Transcriptomic analysis further revealed that <i>BcACS6</i> was significantly positively correlated with changes in amino acid content, and its overexpression in <i>Arabidopsis</i> significantly increased the content of five amino acids associated with the primary taste attributes of Wucai, before and after its quality transformation. Additionally, <i>BcCOR413PM1</i>, <i>BcBcDnaJ</i>, and <i>BcPCR8</i> were found to interact with <i>BcACS6</i>, suggesting that <i>BcACS6</i> may be involved in protein synthesis and degradation during low-temperature acclimation, thereby regulating amino acid content and influencing flavor development in Wucai.