Lack of gene flow between Phytophthora infestans populations of two neighboring countries with the largest potato production

Abstract

Gene flow is an important evolutionary force that enables adaptive responses of plant pathogens in response to changes in the environment and plant disease management strategies. In this study, we made a direct inference concerning gene flow in the Irish famine pathogen Phytophthora infestans between two of its hosts (potato and tomato) as well as between China and India. This was done by comparing sequence characteristics of the eukaryotic translation elongation factor 1 alpha (eEF-1α) gene, generated from 245 P. infestans isolates sampled from two countries and hosts. Consistent with previous results, we found that eEF-1α gene was highly conserved and point mutation was the only mechanism generating any sequence variation. Higher genetic variation was found in the eEF-1α sequences in the P. infestans populations sampled from tomato compared to those sampled from potato. We also found the P. infestans population from India displayed a higher genetic variation in the eEF-1α sequences compared to China. No gene flow was detected between the pathogen populations from the two countries, which is possibly attributed to the geographic barrier caused by Himalaya Plateau and the minimum cross-border trade of potato and tomato products. The implications of these results for a sustainable management of late blight diseases are discussed. K E Y W O R D Selongation factor-1α (eEF-1α), haplotype network, phylogenetic analysis, Phytophthora infestans, population connectivity, population genetic structure | 319 WANG et Al.

The dynamics of Phytophthora infestans populations in the major potato‐growing regions of Asia – A review

“…Recently, Wang et al (2020) reported a lack of gene flow between the P . infestans populations in China and India, but the significance of their findings is difficult to interpret as it appears that the populations compared belonged to different clonal lineages and mating types.…”

“…Recently, Wang et al (2020) reported a lack of gene flow between the P. infestans populations in China and India, but the significance of their findings is difficult to interpret as it appears that the populations compared belonged to different clonal lineages and mating types. A lack of direct gene flow is not unexpected in view of the natural Himalayan barrier, restricted trade in agricultural commodities, and strict border surveillance between these countries.…”

Mixed-Mating Model of Reproduction Revealed in European Phytophthora cactorum by ddRADseq and Effector Gene Sequence Data

“…Preferences of particular isolates to produce either antheridia or oogonia in heterothallic species have been recorded; however, bisexuality is hypothesised in homothallic species [ 29 ], therefore, the possibility of the mating of two isolates of homothallic species cannot be excluded. Outbreeding was documented in either heterothalic P. infestans [ 30 , 31 , 32 ] or P. ramorum [ 33 ], or in homothallic species such as P. sojae and P. porri . In homothallic Phytophthora spp., outbreeding was reported as a possible mechanism generating new pathotypes able to overcome host resistance [ 34 , 35 , 36 , 37 ].…”

Evidence for a synergistic effect of post‐translational modifications and genomic composition of eEF‐1α on the adaptation of Phytophthora infestans

“…Second, although there are a low number of amino acid isoforms, as many as 10 nucleotide haplotypes and some reticulation structures were detected in the haplotype network (Figure 2). Intra-gene recombination was not detected in both the current or previous sequences (Wang et al, 2020) in the eEF-1α gene and in the eEF-1α gene the reticulation structures are likely caused by convergent mutations. Intra-gene recombination events have been detected in effector and fungicide target genes of the same pathogen collection (Chen et al, 2018;Yang et al, 2020;Yang et al, 2018).…”

“…Strains were purified by three serial transfers of mycelia to fresh rye B media. Details of the pathogen collection and isolation are described in previous publications (Qin et al., 2016; Wang et al., 2020). Only one isolate was secured from each infected leaf and a total of 1,473 isolates were secured from the samples.…”