Genetic diversity and population structure of 18 Tunisians Orobanche foetida populations using RADseq

Orobanche foetida Poiret is a holoparasitic plant that lacks chlorophyll and totally depends on its host for its growth. It parasitizes host plant roots and extracts nutrients and water via a haustorium. The fetid broomrape is distributed in the Mediterranean region as a wild plant parasite. However, since 1992, it has become a real threat to faba bean in Tunisia causing serious damages which may reach 90% yield losses. Analysis of the genetic diversity of this parasite is important to better understand its evolution and spread.

In this work, we present the first study on genetic diversity and population structure using the robust technique Restriction-site-Associated DNA sequencing (RADseq) for Orobanche spp. We collected 244 samples of O. foetida from 18 faba bean fields in Tunisia. To overcome the difficulty of SNP discovery in the O. foetida genome as a non-model and tetraploid plant, we used three different informatics pipelines, namely UNEAK, pyRAD, and Stacks.

This study showed that genetic differentiation occurred in the Tunisian O. foetida emphasizing the isolation by distance effect. However, no strong population clustering was detected in this work based on the three data sets and clustering methods used. The present study traces the current real situation of the distribution of O. foetida populations in Tunisia and could be a valuable reference for the upcoming research projects focusing on this parasitic plant.