Fig. 1.

Silencing of a root-expressed type III polyketide synthase reduces tropane and pyrrolidine alkaloid levels. a The tropane and pyrrolidine alkaloid biosynthetic pathway in the Solanaceae starting from putrescine (1). Experimentally validated enzymes are shown in blue, AbPYKS is noted in red, and unknown reactions are noted with question marks. Enzyme abbreviations are as follows: PMT; putrescine methyltransferase, MPO; methylputrescine oxidase, TRI; tropinone reductase I, TRII; tropinone reductase II; CYP80F1; littorine mutase, H6H; hyoscyamine-6-hydroxylase. b Abundance of tropane and pyrrolidine alkaloids together with selected precursors in TRV2 empty vector control lines (cyan bars) and TRV2:ab1322 (AbPYKS) VIGS lines (green bars). Data are presented as the mean n = 24 biological replicates for TRV2 empty vector control lines and n = 23 for TRV2:ab1322 (AbPYKS) VIGS lines. Asterisks denote significant differences (***p < 0.001) as determined by Student’s t test. This experiment was replicated twice. For each box plot, the lower and upper bounds of the box indicate the first and third quartiles, the line indicates the median value, and the whiskers extend to the minimum and maximum data points. Source Data are provided as a Source Data file