Distribution, diversity and identification of hot spot of Fusarium spp. Associated whit onion (Allium cepa L.) in Burkina Faso

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Résumé

In Burkina Faso, onion (Allium cepa L.) crops are increasingly confronted with numerous biotic threats and
diseases caused by fungi are among the main factors constraining onion production. Observation of various Fusariumlike symptoms including seedling melt and basal rot, on onion, suggests the involvement of several species and underlines
the pressing need for additional information on their diversity, frequency and distribution. Three hundred thirty infected
onion samples were collected from north to south in the central region of Burkina Faso and two hundred and thirty-one
isolates of Fusarium species were recovered. The highest frequency of 86.66% was recorded in the Yatenga province
and the lowest in the Zoundwéogo with 53.33%. From North to South, a drop in the frequency of Fusarium infection has
been observed. Forty isolates were selected for molecular characterization based on the amplification of the translation
elongation factor 1α (TEF-1α) gene. Among them, 30 isolates contained an amplified region with approximately 420 bp
and showed 86.21% to 100% similarity to TEF-1α with NCBI reference strains. Twenty isolates were identified as Fusarium
oxysporum (3 isolates represented specialized form Fusarium oxysporum f.sp. cepae), Fusarium acutatum, Fusarium
falciforme, Fusarium solani, Fusarium proliferatum. Sequences with similarity rates ˂98% were not identified and were
named Fusarium sp. Fusarium solani and Fusarium falciforme were the most distributed species and corresponded to
30% of all identified isolates. Sanguié province shows the largest diversity of species.

Mots-clés

Burkina Faso, Fusarium spp., molecular characterization, onion (Allium cepa L.)