Three major chlorotype lineages in chamomile (Matricaria chamomilla L., Asteraceae)

Abstract

Chamomile (Matricaria chamomilla L., Asteraceae) is one of the most important medicinal plants with antiphlogistic, spasmolytic, carminative, antibacterial and antimycotic properties. Thirty-one chloroplast markers were developed, optimised for high-resolution melting analysis. Subsequently, 23 M. chamomilla accessions (247 individuals) complemented with 2 individuals of the closely related species M. discoidea were analysed with this marker set. The marker set can practically be reduced to 20 markers without information loss due to the linkage of 16 markers. In total, 20 chlorotypes (multilocus genotypes) were identified, organised in three evolutionary main lineages. Only 8 accessions were monomorphic, the other 15 accessions had between 2 and 6 chlorotypes per accession. The high number of polymorphic accessions and the high number of chlorotypes within many accessions indicate already a high degree of variability within accessions, confirmed by the 66% variation within by AMOVA. Gene diversity of the polymorphic accessions ranged between 0.069 and 0.261. Since many cultivars had their origin in wild populations of the countries where breeding took place, a first hypothetical indication of the geographic origin of chamomile could point to Albania and adjacent countries. The ‘ancient chlorotype’ was identified by comparing published plastome sequences of Artemisia annua and Lactuca sativa. The ‘ancient chlorotype’ was present only in the closely related M. discoidea but not in any of the M. chamomilla accessions. Two commercially important tetraploid cultivars proofed to be unrelated to their presumed diploid parents.