An acyltransferase-like gene obtained by differential gene expression profiles of quinolizidine alkaloid-producing and nonproducing cultivars of Lupinus angustifolius

Quinolizidine alkaloids (QAs) are one of the representative groups of plant alkaloids. To isolate genes involved in QA biosynthesis, we performed a differential gene expression analysis by PCR-select subtraction between a QA-producing bitter cultivar and a nonproducing sweet cultivar of Lupinus angustifolius. We obtained 71 and 43 clones specific to the bitter and sweet cultivars, respectively. Among the genes specifically expressed in the bitter cultivar, an acyltransferase-like gene (LaAT: Lupinus angustifolius acyltransferase) showing homology to the BAHD protein family was isolated. LaAT showed the strongest homology to the Arabidopsis thaliana BAHD acyltransferases involved in the formation of conjugated polyamines. Semi-quantitative RT-PCR revealed that LaAT expression was highest in the young leaves but barely detectable in the other organs of the bitter cultivar plant, whereas LaAT expression was undetectable in the sweet cultivar.