The chemical composition of 121 cultivars of Piper methysticum origina
ting from 51 Pacific islands, were investigated using HPLC. The result
s obtained for six major kavalactones (demethoxy-yangonin, dihydrokava
in, yangonin, kavain, dihydromethysticin and methysticin) were submitt
ed to cluster analysis and six distinct chemotypes were identified. Th
ree field experiments demonstrated that chemotypes are not affected by
environmental factors but are controlled genetically. Analysis of the
isozyme variation for eight enzyme systems, revealed that these culti
vars exhibited only three zymotypes. These are so similar that the dif
ferences in malate dihydrogenase and diaphorase could be explained as
mutations. Few genes are thought to be responsible for the chemotype v
ariation between cultivated clones. Because all cultivars are decaploi
ds and sterile, it is suggested that mutagenesis might be used to indu
ce genetic variability and to improve cultivar chemotypes. Copyright (
C) 1996 Elsevier Science Ltd.