Genetic diversity and oil quality of Guizotia Cass. (Asteraceae)

Abstract Genetic diversity of G. abyssinica (L.f) Cass., G. scabra (Vis.) Chiov. ssp. scabra; G. scabra (Vis.) Chiov. Ssp. schimperi (Sch. Bip.) Baagoe; G. villosa Sch. Bip., G. zavattarii Lanza and G. arborescens (I. Friis) collected from Ethiopia were studied using Inter Simple Sequence Repeat (ISSR) markers. Higher genetic diversity was revealed among the individuals belonging to the same population than among the populations of the different regions. Overall, greater variation was observed between the niger populations originating from Wollo and Hararghe on the one hand and those from the rest of the regions on the other. Among the wild Guizotia species, G. scabra ssp. Schimperi was found to be closer to G. villosa than to any of the wild Guizotia taxa. Likewise, G. zavattarii and G. arborescens are found to be more closely related to each other than to the rest of the wild taxa. Based on the ISSR results, revision of the previous classification that placed G. scabra ssp. Schimperi as a sub species of G. scabra was suggested. Both the field evaluation of agronomic characters as well as the ISSR analysis revealed variation among the niger populations grown in different regions of the country. Based on the agronomic characters, it was observed that the niger populations obtained from Wollo and Hararghe are of the early maturing types while the accessions originating from the rest of the regions are mostly of the late maturing types. The early maturing and the late maturing niger types differ in many of their agronomic characters notable among which are days to flower initiation, days to 50% flowering, plant height and seed size. Niger breeding experiment was undertaken in an attempt to elevate the oleic acid content in the seed oil. The objective to increase the oleic acid content in niger seed oil from what it is today, approximately 5-11% in the wild type niger of Ethiopian origin to over 80% in the strains improved for oleic acid content has been achieved. The increase in the oleic acid content of the seeds has been gradual. Niger strains that are true breeding for high oleic acid content of over 80% were obtained after three rounds of selection and breeding