Genetic diversity and relationships in Corchorus olitorius (Malvaceae s.l.) inferred from molecular and morphological data

In this study, we investigated the genetic diversity and relationships in C. olitorius by analysing populations representing different distribution areas, and developed a hypothesis on the origin and spread of the species in the pantropics. We employed amplified fragment lengths polymorphism (AFLP) and morphometric analyses in a total of 101 C. olitorius accessions. Results of both data sets are mostly congruent. The molecular analysis indicated generally low genetic diversity within populations and the Nei's gene diversity (H-e) ranged from 0.0457 to 0.0955 with a mean of 0.0763. Qualitative traits, especially related to leaf morphology, branching habit and stipule color were the taxonomically most informative characters. The highest morphological variability occurred within African accessions, indicating that this species originally evolved in Africa. In both analyses, the Asian materials were nested within African populations, especially with those from North and East Africa. This indicates an African origin of the species and we hypothesise that dispersal occurred via the Mediterranean-Indian trade routes instead of natural migration along the coasts from western Africa to the Indian subcontinent. Both analyses revealed materials from Ethiopia to be quite distinct. The highest number of private bands (N = 35), percent polymorphism (29.29%), and gene diversity (0.0955) were also detected in wild accessions collected from Ethiopia, suggesting a long-term spatial isolation of C. olitorius populations in the country. Germplasm samples from this region could therefore be a useful source of genetic variation in jute breeding programs.