The two best-known species of marigolds are the African
and French marigolds (The plant list, 2010; Taylor, 2011),
while in Thailand there are landraces belonging to
T. erecta L. Therefore, the molecular phylogeny was analysed
in these three populations belonging to two species,
namely commercial varieties of African marigold, Thai
landraces of African marigold and French marigold. The
dendrogram constructed based on the UPGMA cluster
using Nei’s (1972) genetic distance separated the 26 marigold
samples into two main clusters according to
taxonomic classification, including species of African
marigold and French marigold (Fig. 2). The genetic
distance between the African marigold and the French
marigold is 0.79. The cluster of African marigold was also
further divided into two clusters (commercial varieties
and Thai landraces) with a genetic distance of 0.33 according
to originating regions. The highest divergence was
observed between FM05 and MKU54017, whereas the
highest similarity was observed between FM04 and
FM05, with genetic distances of 0.99 and 0.00, respectively.
Bootstrap values at each node are also shown in Fig. 2, the
highest value was at the node that separated the African
marigold cluster from the French marigold cluster.