Using amplicon sequencing to identify pathogens causing eggplant wilt in Tanzania and Uganda. Amplicon sequences of eggplant wilt in Tanzania and Uganda

African eggplant (Solanum aethiopicum L.) is one of the most common traditional vegetables in Tanzania and Uganda but its productivity is severely affected by the wilt disease caused by a number of pathogens. Through amplicon-sequencing of many neighbouring diseased and healthy plants in several fields of Tanzania and Uganda, we identified candidate causal pathogens. The present study suggested that wilting of S. aethiopicum is most likely to result from a bacterial pathogen (Ralstonia solanacearum) in Uganda [the Shum type plants) whereas from a fungal pathogen in Tanzania (the Gilo type plants), most likely infection of roots by Macrophomina phaseolina. Controlled inoculation suggested that M. phaseolina strain can cause the typical witling symptoms on several Gilo type genotypes. Furthermore, wilt symptoms on the Gilo type plants (Tanzania) may also have resulted from infection of both stems (by Fusarium solani) and roots (by M. phaseolina). This difference in causal agents demonstrates the need for aetiological studies before developing and implementing effective control methods. Further research is needed to understand whether the differences in wilt causal agents between Tanzania and Uganda is related to pathogen host specialisation with regard to the Shum/Gilo type.