Distribution of major clonal lineages EU_13_A2, EU_2_A1, and EU_23_A1 of Phytophthora infestans associated with potato late blight across crop seasons and regions in Algeria

Abstract

Potato is one of the most important agricultural crops in Algeria and worldwide.Each year, potato late blight, caused by Phytophthora infestans, is responsible for significant damage that leads to large production losses, and is thus a direct threat to food security in Algeria. In this study, 131 isolates of P. infestans and 92 DNA fingerprints captured on FTA cards were sampled from commercial and seed production fields in three major potato production regions (western, eastern, and central) during the main-season and late-season in Algeria over six cropping seasons (2010)(2011)(2012)(2013)(2014)(2015)(2016).Genotypes of P. infestans and population genetic diversity were analysed using a 17plex simple-sequence repeat (SSR) marker assay, and the mating type of all isolates was characterized. Both mating types (A1 and A2) were found, and often occurred in the same field. Differences in mating type proportion were observed between regions and between sampling periods. Analysis with SSR markers showed the prevalence of the EU_13_A2 lineage (70%) over EU_2_A1 (16%), EU_23_A1 (10%), and 4% of unknown multilocus lineage (MLL). The EU_13_A2 showed differentiation within the group. EU_23_A1 was found mainly in late-season crops. However, the cropping region did not influence the distribution of lineages due to the dispersal of the pathogen in Algeria by seeds. Genetic structure did not reveal a clear variation in distribution of the three lineages throughout the sampling regions. These data provide important new information on the composition and change over time of P. infestans populations in Algeria and open the way for a better understanding of the local epidemiology of this important pathogen.

Modelling the displacement and coexistence of clonal lineages of Phytophthora infestans through revisiting past outbreaks

“…subsequently declined and was not recovered later in 2016 (Beninal et al, 2022), which is consistent with the model output.…”

“…In the short‐term, the complete displacement of 2_A1 in the output appeared to be inconsistent with observations because 2_A1 was still very common in 2014 (Rekad et al., 2017). However, 2_A1 subsequently declined and was not recovered later in 2016 (Beninal et al., 2022), which is consistent with the model output.…”

Highly Diverse Phytophthora infestans Populations Infecting Potato Crops in Pskov Region, North-West Russia

“…This is also shown by a low genetic differentiation among these populations. High genotypic diversity through sexual reproduction and oospores’ formation is common in neighboring countries such as Finland and the Baltic region [ 26 , 32 , 68 ], but differs from essentially clonal populations in western regions of Europe [ 72 , 73 , 74 ], and in the United States and South America [ 75 , 76 ], Asia [ 61 , 77 ], and Africa [ 78 , 79 ]. However, recent rapid local and global genotype shifts have occurred due to pathogen migration with tuber trade [ 80 , 81 ].…”

Is there a trade-off between host generalism and aggressiveness across pathogen populations? A synthesis of the global potato and tomato blight lesion growth data

“…There are indications that aggressive generalists can co-occur with other strains, including specialists under specific conditions. For instance, 13_A2 and 23_A1 (genetically similar to US-23) co-occur in northern Africa (Beninal et al, 2022) and Pakistan (Belkhiter et al, 2019) where both crops are grown in proximity almost year round. In this case, controlled trials showed that 13_A2 was marginally less aggressive than 23_A1 with a moderate specificity on potato, while the latter was overall more aggressive on both hosts (Belkhiter et al, 2019).…”

“…Yet, the more aggressive ‘generalist’ 23_A1 is found predominantly on tomato. In Algeria, 23_A1 is similarly only dominant on tomato during late-season (Belkhiter et al, 2019; Beninal et al, 2021). Pathogenicity trials showed that US-23 in North America has specificity similar to that of 23_A1.…”