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Abstract :

Root-knot nematodes are obligatory plant endoparasites that threaten the global food supply. These pests are one of the most devastating plant-parasitic nematodes worldwide due to their global distribution and wide host range. The most effective and common control approach consisted in deploying plant cultivars carrying resistant genes against Meloidogyne species. However, most resistance genes of these cultivated plants are inefficient against Meloidogyne enterolobii (M.e), which is now regulated as a quarantine species in Europe. To gain insight into the molecular characteristics underlying its parasitic success, it is essential to explore the host range compatibility and the genomic plasticity of M.e.
Part1: To understand the host range of M.e, a greenhouse study was conducted with 20 crop species testing 8 M.e populations, reared as single egg mass lines. Results showed that M.e was able to successfully reproduce on plant species which were earlier reported as non-hosts (phacelia, peanut, fodder radish & yellow mustard). In addition, the adaptive potential of M.e is also being tested toward poor-hosts such as A. thaliana, phacelia & cotton both in-vitro and in-vivo conditions. Preliminary results showed that M.e is also capable of adapting to a poor host in a given time.
Part2: For this study, we also produced a high-quality genome assembly of M.e using the PacBio HiFi long-reads sequencing approach, combined with a gap-aware sequence transformer, DeepConsensus. Consistent with flow cytometry estimates, the resulting genome assembly spans 273 Mbp with 556 contigs, and an N50 value of 2.11Mb, the highest reported so far for a root-knot nematode. In addition, we aligned PacBio Hi-Fi long-reads from the 8 different populations to the new reference genome to detect and genotype genomic structural variants (SVs). We found 7416 SVs spanning 3.46% of the reference genome. The most represented are deletions (57%) and insertions (35%). Using the same high-quality long reads, we will also detect SNPs in the different isolates.
Subsequently, correlation between genomic variations patterns (SNPs plus SVs) and geographical distribution along with differences in the host range compatibility will be investigated.

(The seminar will be in English)