Epsilon Open Archive

Abstract

The genus Guizotia belongs to the tribe Heliantheae in the family Asteraceae. It has been placed under different subtribes. The genus has its center of origin, distribution and genetic diversity in Ethiopia, where G. abyssinica (niger) has been domesticated. Amplified Fragment Length Polymorphism (AFLP), Random Amplified Polymorphic DNA (RAPD) and DNA sequencing were applied to study the genetic diversity, phylogenetics, and molecular systematics of this genus. A large number of niger populations, representing all regions in Ethiopia where this crop is grown, was investigated using AFLP and RAPD molecular marker techniques. The extent of genetic variation in niger is distributed throughout its growing regions, regardless of the extent and altitude of cultivation. Despite the fact that most of the variation was within populations, significant population differentiation was obtained (AMOVA; P < 0.001) in all guizotias. It is concluded that both G. abyssinica and its wild and/or weedy relatives have wide genetic bases that need to be conserved and utilized for the improvement of G. abyssinica. Further collection of niger germplasm and exploration and conservation of highly localized guizotias are recommended. Most of the diagnostic markers generated from AFLPs and RAPDs in this study were specific to G. arborescens and G. zavattarii. Phylogenetic analyses of the genus Guizotia were undertaken based on molecular sequence data from the internal transcribed spacers (ITS) and five chloroplast DNA regions. The analyses revealed a close phylogenetic relationship between G. abyssinica and G. scabra ssp. schimperi and support the previous suggestion that the latter is the progenitor of the former. According to this study, G. scabra ssp. scabra, G. scabra ssp. schimperi, and the Chelelu and Ketcha populations are best viewed at present as separate species within the genus Guizotia. Those perennial guizotias with highly localized geographic distribution appears to have evolved first during the evolutionary history of the genus. This study supports the placement of the genus Guizotia within the subtribe Milleriinae. It is suggested that the present species composition of Guizotia and the subtribal placement of the genus need to be redefined.