Thermal inactivation of Phytophthora capsici oospores

Etxeberria, Aitzol; Mendarte, S.; Larregla, Santiago

doi:10.1016/j.riam.2011.01.004

Cited by 19 publications

(15 citation statements)

References 30 publications

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“…Year 2011, where both inbred and F 1 isolates were observed in the field, signified a generational shift in the population. The absence of F 1 in the following years (2012–2013) is consistent with previous reports of oospore declines in viability over time (Bowers, 1990), and negligible oospore survival after four years in field conditions (Babadoost and Pavon, 2013). While we did not quantify disease incidence in the field, observation of predominantly F 1 isolates in 2010–2011 suggests that highly productive years contributed disproportionately to population structure, in accordance with theoretical predictions for populations in which sexual propagules require a dormancy period, e.g., plant species with seed banks (Templeton and Levin, 1979; Nunney, 2002).…”

Section: Discussionsupporting

confidence: 91%

“…Clones did not appear in multiple years, consistent with the inability of asexual propagules to survive the winter (Hausbeck and Lamour, 2004; Babadoost and Pavon, 2013). After clone-correction, the A2 mating type was more represented in the field (A1:A2 = 65:94; χ 2 test, P -value = 0.02), a phenomenon also observed in the in vitro F 1 (A1:A2 = 16:25; χ 2 test, P -value = 0.16; Figure 1 ).…”

Section: Resultsmentioning

confidence: 77%

“…Therefore, it was not surprising that year distributions of the ME statistic were consistent with F , with increased MEs in years 2012–2013 ( Figure 5A ). Because asexual propagules do not survive the winter (Hausbeck and Lamour, 2004; Babadoost and Pavon, 2013), it can be assumed that all F 1 isolates in the field, in any year, were derived from oospores in the year of the initial field inoculation (2008). Applying a threshold of 5.58% MEs (3 SD from the in vitro F 1 mean) to characterize F 1 versus non-F 1 , we observed exclusively F 1 in 2009-10, a mixture of F 1 and inbred isolates in 2011 (ratio of F 1 to inbred = 29:16) and all inbred isolates in 2012–2013 ( Figure 5B ).…”

Section: Resultsmentioning

confidence: 99%

“…First, unlike asexual propagules, oospores survive exposure to cold temperatures (Hausbeck and Lamour, 2004; Babadoost and Pavon, 2013). Thus, in regions with cold winter conditions, oospores are the primary source of overwintering inoculum (Bowers, 1990; Lamour and Hausbeck, 2003; Granke et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…While asexual reproduction can increase the prevalence of a specific genotype within a sexually reproducing population, the inability of asexual propagules to survive cold winters (Hausbeck and Lamour, 2004; Babadoost and Pavon, 2013) implies that each year meiosis disrupts linkage between the particular combination of alleles observed within a clone (Kondrashov, 1988). As a consequence, sexual reproduction mediates the effects of clonal propagation on P. capsici population structure (Lamour and Hausbeck, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Temporal Genetic Dynamics of an Experimental, Biparental Field Population of Phytophthora capsici

et al. 2017

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Defining the contributions of dispersal, reproductive mode, and mating system to the population structure of a pathogenic organism is essential to estimating its evolutionary potential. After introduction of the devastating plant pathogen, Phytophthora capsici, into a grower’s field, a lack of aerial spore dispersal restricts migration. Once established, coexistence of both mating types results in formation of overwintering recombinant oospores, engendering persistent pathogen populations. To mimic these conditions, in 2008, we inoculated a field with two P. capsici isolates of opposite mating type. We analyzed pathogenic isolates collected in 2009–2013 from this experimental population, using genome-wide single-nucleotide polymorphism markers. By tracking heterozygosity across years, we show that the population underwent a generational shift; transitioning from exclusively F1 in 2009–2010, to multi-generational in 2011, and ultimately all inbred in 2012–2013. Survival of F1 oospores, characterized by heterozygosity excess, coupled with a low rate of selfing, delayed declines in heterozygosity due to inbreeding and attainment of equilibrium genotypic frequencies. Large allele and haplotype frequency changes in specific genomic regions accompanied the generational shift, representing putative signatures of selection. Finally, we identified an approximately 1.6 Mb region associated with mating type determination, constituting the first detailed genomic analysis of a mating type region (MTR) in Phytophthora. Segregation patterns in the MTR exhibited tropes of sex-linkage, where maintenance of allele frequency differences between isolates of opposite mating type was associated with elevated heterozygosity despite inbreeding. Characterizing the trajectory of this experimental system provides key insights into the processes driving persistent, sexual pathogen populations.

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