Genotypic and Phenotypic Structure of the Population of Phytophthora infestans in Egypt Revealed the Presence of European Genotypes

Abstract

Late blight disease of potato and tomato, caused by Phytophthora infestans, results in serious losses to Egyptian and global potato and tomato production. To understand the structure and dynamics of the Egyptian population of P. infestans, 205 isolates were collected from potato and tomato plants during three growing seasons in 2010–2012. The characterization was achieved by mating-type assay, metalaxyl sensitivity assay, and virulence pattern. Additionally, genotyping of 85 Egyptian isolates and 15 reference UK isolates was performed using 12 highly informative microsatellite (SSR) markers David E. L. Cooke and five effector (RxLR) genes. Mating-type testing showed that 58% (118 of 205) of the isolates belonged to mating type A1, 35% (71 isolates) to mating type A2, and the rest 8% (16 isolates) were self-fertile. The phenotype of metalaxyl response was represented as 45% resistant, 43% sensitive, and 12% as intermediate. Structure analysis grouped the 85 identified genotypes into two main clonal lineages. The first clonal lineage comprised 21 isolates belonging to A2 mating type and 8 self-fertile isolates. This clonal lineage was identified as Blue_13 or EU_13_A2. The second main clonal lineage comprised 55 isolates and was identified as EU_23_A1. A single isolate with a novel SSR genotype that formed a distinct genetic grouping was also identified. The effector sequencing showed good correspondence with the virulence data and highlighted differences in the presence and absence of loci as well as nucleotide polymorphism that affect gene function. This study indicated a changing population of P. infestans in Egypt and discusses the findings in the context of late blight management.

Population Dynamics of Phytophthora infestans in Egypt Reveals Clonal Dominance of 23_A1 and Displacement of 13_A2 Clonal Lineage

“…Most of the known avirulence (AVR) effector genes are of RxLR type, which is a unique class of host-translocated proteins consisting of an RxLR domain following a signal peptide at the N-terminal [ 12 ]. Thus, studying the repertoire of RxLR effectors may provide molecular insights into the interaction between emerging P. infestans lineages and the host plants with R-genes leading to the improved deployment of cultivar resistance for integrated management of late blight [ 13 ].…”

“…The P. infestans strain 2_A1 is a dominating A1 mating type in the east African countries Burundi, Kenya, Rwanda, Tanzania and Uganda [ 21 ]. Whereas, the population structure of P. infestans in the North African countries is mostly newly emerging A2 mating types of European origin [ 13 , 22 ]. This might be due to a high import of seed potato into this region from European countries [ 19 ].…”

“…Egypt is a significant exporter of potatoes with exports worth USD 221.9 million in 2020. Phytophthora infestans was presumably present in the agro-ecological regions of Egypt since 1941 [ 23 ] and some reports mentioned the presence of both the A1 and A2 mating types and additionally self-fertile isolates of P. infestans [ 13 , 24 , 25 ]. Although, in Egypt both mating types have been reported earlier.…”

“…Differences in the virulence profiles on differential potato clones ( Solanum demissum ) carrying the R genes (R1-R11), metalaxyl sensitivity and SSR markers have been used to characterize isolates of P. infestans in Egypt and have identified two European clonal lineages 13_A1 and 23_A1. Differences in virulence profiles were observed within the clonal lineages 13_A2 and 23_A1 [ 13 ].…”

Leaf Extracts from Resistant Wild Tomato Can Be Used to Control Late Blight (Phytophthora infestans) in the Cultivated Tomato

“…de Bary. Late blight has led to significant economic losses in the production of tomato and potato crops, and has caused global food security concerns [ 6 ]. P. infestans is an oomycete pathogen that is highly destructive and has the capacity to destroy tomato plants within 7 to 10 days under cool and humid conditions [ 7 , 8 ].…”