Abstract
Chamomile (Matricaria chamomilla) is an important medicinal plant whose beneficial activities partly rely on certain
flavonoids. The first dedicated step in flavonoid biosynthesis is chalcone synthase
(CHS, EC 2.3.1.74). The genomic DNA of CHS was studied in six chamomile specimens
from different genotypes to describe interspecimen, as well as interspecific, variability.
One specimen of M. discoidea was included as an outgroup. The two exons of CHS of M. chamomilla (McCHS) and M. discoidea (MdCHS) were 188 bp and 1,011 bp long, separated by an intron of variable length
between 192 and 199 bp in McCHS and 201 bp in MdCHS, respectively. The two exons with
5.3 and 6.2 mutations per 100 bp, respectively, were more conserved than the intron
with 11.5 mutations per 100 bp. In total, 96 SNPs were detected in both species, of
which 12 SNPs were only present in MdCHS and 80 SNPs only in McCHS. Overall, 70 haplotypes
(multilocus genotypes, MLGs) were
detected. The samples could be classified into two groups, a ʼcompactʼ group of a
low number and diversity of haplotypes and a ʼvariableʼ group of a high number and
diversity of haplotypes. Of the 74 SNPs in McCHS, only six SNPs were non-synonymous.
However, the amino acid changes did not affect critical areas of the enzyme. The combination
of the six SNPs resulted in nine translated amino acid MLGs. The CHS network located
MdCHS, due to the crossing barrier, quite distant from chamomile. MdCHS docked to
McCHS at a position from where McCHS divergently evolved into two directions.
Key words
Chamomile -
Matricaria chamomilla
- Asteraceae - chalcone synthase - flavonoids
