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Roumaissa Barkat

 

Roumaissa Barkat

University of Angers, France

Abstract Title:

Alternaria species pathogenic to brassicaceae: molecular identification, phylogenomics and seed transmission

Biography:

Roumaissa Barkat is a PhD candidate in a joint doctoral program between University Oran 1 Ahmed Ben Bella (Algeria), where she specializes in Applied Microbiology, and the University of Angers (France), where she specializes in Molecular and Cellular Biology. She works at the Institut de Recherche en Horticulture et Seeds (IRHS, UMR 1345) under the supervision of Pr. Philippe Simoneau and Dr. Nabahat Bessadat. Her thesis addresses Alternaria species pathogenic to Brassicaceae: identification (multilocus sequence analysis, phylogenomics), Oxford Nanopore genome sequencing. She holds a Master's degree in applied microbiology.

Research Interests:

Alternaria leaf spot and blight are major diseases of Brassicaceae crops, caused mainly by Alternaria brassicae, A. brassicicola and A. japonica, in Algeria and worldwide. Alternaria telliensis, first described from Solanaceae in northwest Algeria, has since been reported on several wild and cultivated Brassicaceae, but its phylogenetic placement remains ambiguous. This study aimed to identify Alternaria species infecting wild and cultivated Brassicaceae, perform a phylogenomic analysis of A. japonica and A. telliensis, and compare their seed transmission. A total of 1,467 strains were isolated and more than 200 were purified. Phylogenetic analysis of the glyceraldehyde-3-phosphate dehydrogenase gene (gpd) grouped them into nine sections (Infectoriae, Chalastospora, Embellisioides, Embellisia, Eureka, Japonicae, Ulocladioides, Brassicicola, Alternaria) and one monophyletic lineage (A. brassicae). The genomes of A. telliensis CBS 145643 and A. japonica CBS 118390 strains were sequenced with Oxford Nanopore technology; assemblies of 34.4 and 33.5 Mb; 99.5% and 99.6% completeness of conserved single-copy genes (BUSCO), respectively. Phylogenomic analysis confirmed the placement of A. telliensis in section Japonicae with A. japonica (100% bootstrap support). Seed transmission was tested by inoculating Arabidopsis thaliana seed pods, and infection rates were analysed with a binomial generalized linear model (GLM). A. brassicicola showed the highest seed infection rate (55.8%; 95% confidence interval, CI: 50.1–61.4). A. japonica and A. telliensis strains (NB1050) showed intermediate rates (18–20.8%), and A. telliensis CBS 145643 from tomato the lowest (9.4%; 95% CI: 7.1–12.3), forming a distinct pathogenicity group. These results show a high diversity of Alternaria sections associated with Brassicaceae in Algeria, confirming the ability of A. telliensis in seeds transmission.