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Local adaptation to temperature in populations and clonal lineages of the Irish potato famine pathogen Phytophthora infestans

View Article: PubMed Central - PubMed

ABSTRACT

Environmental factors such as temperature strongly impact microbial communities. In the current context of global warming, it is therefore crucial to understand the effects of these factors on human, animal, or plant pathogens. Here, we used a common‐garden experiment to analyze the thermal responses of three life‐history traits (latent period, lesion growth, spore number) in isolates of the potato late blight pathogen Phytophthora infestans from different climatic zones. We also used a fitness index (FI) aggregating these traits into a single parameter. The experiments revealed patterns of local adaptation to temperature for several traits and for the FI, both between populations and within clonal lineages. Local adaptation to temperature could result from selection for increased survival between epidemics, when isolates are exposed to more extreme climatic conditions than during epidemics. We also showed different thermal responses among two clonal lineages sympatric in western Europe, with lower performances of lineage 13_A2 compared to 6_A1, especially at low temperatures. These data therefore stress the importance of thermal adaptation in a widespread, invasive pathogen, where adaptation is usually considered almost exclusively with respect to host plants. This must now be taken into account to explain, and possibly predict, the global distribution of specific lineages and their epidemic potential.

No MeSH data available.


Temperature responses of 14 Phytophthora infestans isolates belonging to the 13_A2 clonal lineage sampled in two geographical areas for latent period (A), lesion growth rate (B), sporangia production (C), and sporangia size (D). SE were omitted for clarity. Significant differences between the geographical areas at a given temperature, as revealed by Wilcoxon rank‐sum tests or lsmeans: *P < 0.05, **P < 0.01.
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ece32282-fig-0003: Temperature responses of 14 Phytophthora infestans isolates belonging to the 13_A2 clonal lineage sampled in two geographical areas for latent period (A), lesion growth rate (B), sporangia production (C), and sporangia size (D). SE were omitted for clarity. Significant differences between the geographical areas at a given temperature, as revealed by Wilcoxon rank‐sum tests or lsmeans: *P < 0.05, **P < 0.01.

Mentions: The LPs were generally similar among the 14 isolates tested belonging to the 13_A2 clonal lineage but coming from different geographic areas (WE and MB). This was true over the whole temperature range, except at 18°C where west European isolates had a significantly shorter LP (Wilcoxon rank‐sum tests, P = 0.041; Fig. 3A). Significant effects of origin × temperature interaction were observed for LGR, SP, and FI (Table 3). Indeed, west European isolates grew faster than Mediterranean isolates at low temperatures (10 and 14°C; Fig. 3B), whereas Mediterranean isolates performed better at high temperatures, especially at 18°C (Wald's test, lsmeans post hoc comparison; P = 0.049; Fig. 3B). These temperature‐dependent differences were also observed for SP with more sporangia produced by the west European isolates at 14°C compared to the Mediterranean isolates (Wald's test, lsmeans post hoc comparison; P = 0.007; Fig. 3C), while the opposite was observed at 18 and 24°C (Wald's test, lsmeans post hoc comparison; P < 0.05–<0.01; Fig. 3C). Finally, west European isolates had a significantly higher FI than Mediterranean isolates at 14°C, while the reverse trend was found at 18°C (Wald's test, lsmeans post hoc comparison; P < 0.05–<0.01; Fig. 3D).


Local adaptation to temperature in populations and clonal lineages of the Irish potato famine pathogen Phytophthora infestans
Temperature responses of 14 Phytophthora infestans isolates belonging to the 13_A2 clonal lineage sampled in two geographical areas for latent period (A), lesion growth rate (B), sporangia production (C), and sporangia size (D). SE were omitted for clarity. Significant differences between the geographical areas at a given temperature, as revealed by Wilcoxon rank‐sum tests or lsmeans: *P < 0.05, **P < 0.01.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC5016652&req=5

ece32282-fig-0003: Temperature responses of 14 Phytophthora infestans isolates belonging to the 13_A2 clonal lineage sampled in two geographical areas for latent period (A), lesion growth rate (B), sporangia production (C), and sporangia size (D). SE were omitted for clarity. Significant differences between the geographical areas at a given temperature, as revealed by Wilcoxon rank‐sum tests or lsmeans: *P < 0.05, **P < 0.01.
Mentions: The LPs were generally similar among the 14 isolates tested belonging to the 13_A2 clonal lineage but coming from different geographic areas (WE and MB). This was true over the whole temperature range, except at 18°C where west European isolates had a significantly shorter LP (Wilcoxon rank‐sum tests, P = 0.041; Fig. 3A). Significant effects of origin × temperature interaction were observed for LGR, SP, and FI (Table 3). Indeed, west European isolates grew faster than Mediterranean isolates at low temperatures (10 and 14°C; Fig. 3B), whereas Mediterranean isolates performed better at high temperatures, especially at 18°C (Wald's test, lsmeans post hoc comparison; P = 0.049; Fig. 3B). These temperature‐dependent differences were also observed for SP with more sporangia produced by the west European isolates at 14°C compared to the Mediterranean isolates (Wald's test, lsmeans post hoc comparison; P = 0.007; Fig. 3C), while the opposite was observed at 18 and 24°C (Wald's test, lsmeans post hoc comparison; P < 0.05–<0.01; Fig. 3C). Finally, west European isolates had a significantly higher FI than Mediterranean isolates at 14°C, while the reverse trend was found at 18°C (Wald's test, lsmeans post hoc comparison; P < 0.05–<0.01; Fig. 3D).

View Article: PubMed Central - PubMed

ABSTRACT

Environmental factors such as temperature strongly impact microbial communities. In the current context of global warming, it is therefore crucial to understand the effects of these factors on human, animal, or plant pathogens. Here, we used a common&#8208;garden experiment to analyze the thermal responses of three life&#8208;history traits (latent period, lesion growth, spore number) in isolates of the potato late blight pathogen Phytophthora infestans from different climatic zones. We also used a fitness index (FI) aggregating these traits into a single parameter. The experiments revealed patterns of local adaptation to temperature for several traits and for the FI, both between populations and within clonal lineages. Local adaptation to temperature could result from selection for increased survival between epidemics, when isolates are exposed to more extreme climatic conditions than during epidemics. We also showed different thermal responses among two clonal lineages sympatric in western Europe, with lower performances of lineage 13_A2 compared to 6_A1, especially at low temperatures. These data therefore stress the importance of thermal adaptation in a widespread, invasive pathogen, where adaptation is usually considered almost exclusively with respect to host plants. This must now be taken into account to explain, and possibly predict, the global distribution of specific lineages and their epidemic potential.

No MeSH data available.