Accumulation
and Molecular Regulation of Anthocyanin
in Purple Tumorous Stem Mustard (Brassica juncea var. <i>tumida</i> Tsen et Lee)
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Abstract
Tumorous stem mustard (Brassica juncea var. <i>tumida</i> Tsen
et Lee) is an economically and
nutritionally important dietary vegetable in Asian countries. Purple
tumorous stem mustard contains inflated tumorous stem and abundant
anthocyanin accumulation in leaves. Here, 20 anthocyanins were separated
and identified from the purple tumorous stem mustard by high-performance
liquid chromatography–electrospray ionization–tandem
mass spectrometry (HPLC–ESI–MS/MS). In order to investigate
the regulatory anthocyanin production in purple tumorous stem mustard, the expression of anthocyanin biosynthetic
and regulatory genes in leaves from purple and green cultivars were
examined. Regulatory gene <i>BjTT8</i> and all biosynthetic
genes were dramatically upregulated in the purple variety. Moreover,
the transcript level of <i>BjTT8</i> and all structural
genes, except <i>BjPAL</i>, were all significantly higher
in light-treated sprouts than in the dark. These results indicate
that transcriptional activation of <i>BjTT8</i> is associated
with upregulation of most anthocyanin biosynthetic genes, to produce
anthocyanins in purple tumorous stem mustard