In planta selfing and oospore production of Phytophthora cinnamomi in the presence of Acacia pulchella

Jayasekera, A.U.; McComb, J.; Shearer, B. L.; Hardy, G.

doi:10.1016/j.mycres.2006.11.003

Cited by 16 publications

(18 citation statements)

References 32 publications

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“…can also stimulate selfing within heterothallic oomycetes (Brasier 1971(Brasier , 1978Jayasekera et al 2007;Jung et al 2013;Lamour and Kamoun 2009). Differences between forest and nursery systems in terms of these environmental factors could cause different rates of selfing which, in turn, could affect genetic differences between the two systems.…”

Section: Discussionmentioning

confidence: 99%

Genotypic Diversity of Phytophthora cinnamomi and P. plurivora in Maryland’s Nurseries and Mid-Atlantic Forests

2017

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Genetic diversity of two Phytophthora spp.-P. cinnamomi (102 isolates), commonly encountered in Maryland nurseries and forests in the MidAtlantic United States, and P. plurivora (186 isolates), a species common in nurseries-was characterized using amplified fragment length polymorphism. Expected heterozygosity and other indices suggested a lower level of diversity among P. cinnamomi than P. plurivora isolates. Hierarchical clustering showed P. cinnamomi isolates separated into four clusters, and two of the largest clusters were closely related, containing 80% of the isolates. In contrast, P. plurivora isolates separated into six clusters, one of which included approximately 40% of the isolates. P. plurivora isolates recovered from the environment (e.g., soil and water) were genotypically more diverse than those found causing lesions. For both species, isolate origin (forest versus nursery or among nurseries) was a significant factor of heterozygosity. Clonal groups existed within P. cinnamomi and P. plurivora and included isolates from both forest and nurseries, suggesting that a pathway from nurseries to forests or vice versa exists.The genus Phytophthora includes numerous species that are among the most significant plant pathogens worldwide. As a result, the genus has been the focus of many population biology studies (Bhat and Browne

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Section: Discussionmentioning

confidence: 99%

Genotypic Diversity of Phytophthora cinnamomi and P. plurivora in Maryland’s Nurseries and Mid-Atlantic Forests

2017

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“…P. cinnamomi is ostensibly heterothallic although sexual reproduction through selfing does occur in the A2 mating type in the presence of external agents such as Trichoderma spp. (Brasier, , ,b; Pratt, Sedgley, Heather, & Shepherd, ) and in Acacia roots (Jayasekera, McComb, Shearer, Hardy, & St, ). Crone, McComb, O'Brien, and Hardy () showed that the A2 mating type formed abundant selfed oospores in naturally infected roots of several herbaceous plants showing no symptoms of disease and postulated that the formation of selfed oospores in plant roots was probably common and widespread on asymptomatic hosts.…”

Section: What Does Genetic Variation In A1 Phytophthora Cinnamomi Telmentioning

confidence: 99%

Phytophthora cinnamomi A1: An ancient resident of New Guinea and Australia of Gondwanan origin?

Arentz¹

2017

Forest Pathology

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Summary This article re‐examines the hypothesis, first proposed by Shepherd (Search, 6(11‐12), 1975, 484), that Phytophthora cinnamomi is an ancient organism in Australia and New Guinea. It further evaluates data that suggest the A1 mating type is Gondwanan in origin and may have been present in New Guinea for up to 10 million years. It is postulated that there has been a mating type change in P. cinnamomi from A1 to A2 in relatively recent times as a result of genetic transformation of the A1 mating type.

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“…Although P. cinnamomi is a heterothallic species, it can be difficult to get oospores to form when pairing isolates of opposite mating type and, when oospores do form, they can be difficult to germinate (16)(17)(18)32,44). However, Linde et al (23) and Dobrowolski et al (7) were successful in obtaining oospores from sexual outcrosses with sufficient germination frequency to allow analysis of the progeny.…”

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confidence: 99%

“…The ability of isolates to self and form oospores in single culture in response to different environmental stimuli has been reported but, again, the oospores are difficult to germinate (32,41,48). Interestingly, Jayasekera et al (16) observed selfing of isolates in colonized roots of Lupinus angustifolis when placed in soil underneath Acacia pulchella. The occurrence of sexual recombination in populations of P. cinnamomi is important because this could assist with long-term survival of the pathogen in the form of persistent oospores as well as increasing the potential for genetic diversity of the pathogen.…”

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confidence: 99%

Mitochondrial Haplotype Analysis for Differentiation of Isolates of Phytophthora cinnamomi

Martin

Coffey²

2012

Phytopathology®

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Although Phytophthora cinnamomi is heterothallic, there are few instances of successful crossing in laboratory experiments, and analysis of field populations indicates a clonally reproducing population. In the absence of sexual recombination, the ability to monitor mitochondrial haplotypes may provide an additional tool for identification of clonal isolates and analysis of population structure. To determine mitochondrial haplotypes for this species, seven mitochondrial loci spanning a total of 6,961 bp were sequenced for 62 isolates representing a geographically diverse collection of isolates with A1 and A2 mating type. Three of the regions were primarily intergenic regions between trnG and rns, rns and nad3, and nad6 and cox1, while the remaining loci spanned cox2, nad9, rps10, and secY coding regions and some of the flanking spacer regions. In total, 45 mitochondrial haplotypes were identified (75% of the total isolates examined) with differences due to single-nucleotide polymorphisms (SNPs, totaling 152 bp) and length mutations (17 indels >2 bp representing a total of 910 bp in length). SNPs were the predominate mutation in the four coding regions and their flanking intergenic regions, while both SNPs and length mutations were observed in the three primarily intergenic regions. Some of the length mutations in these regions were due to addition or loss of unique sequences while others were due to variable numbers of subrepeats (in the trnG-rns region, there were 3 to 12 copies of a 24-bp subrepeat sequence that differentiated 17 haplotypes). Network analysis of the haplotypes identified eight primary clades, with the most divergent clade representing primarily A1 isolates collected from Papua New Guinea. The isolate grouping in the network corresponded to mating type and previously published isozyme classifications, with three exceptions: a haplotype representing an A1 mating type (H29) was placed well within the A2 mating type haplotype grouping, one haplotype (H26) had isolates with two isozyme classifications, and one isozyme group was represented on separate network clades, suggesting that recombination has occurred in the past. Among the 62 isolates examined, several examples were identified of isolates recovered from different geographic regions having the same mitochondrial haplotype, suggesting movement of isolates via plant material. Analysis of the data set to determine whether fewer loci could be sequenced to classify haplotypes indicated that the trnG-rns and rns-nad6 loci would classify 87% of the haplotypes identified in this study, while additional sequencing of the nad9 or secY loci would further differentiate the remaining six haplotypes. Based on conservation of gene order in Phytophthora spp., the trnG-rns locus should be useful for mitochondrial haplotype classification in other species, as should the cox2, nad9, rps10, and secY loci. However, the rns-nad3 and nad6-cox1 loci span regions that can have a different gene order in some Phytophthora spp.

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In planta selfing and oospore production of Phytophthora cinnamomi in the presence of Acacia pulchella

Cited by 16 publications

References 32 publications

Genotypic Diversity of Phytophthora cinnamomi and P. plurivora in Maryland’s Nurseries and Mid-Atlantic Forests

Genotypic Diversity of Phytophthora cinnamomi and P. plurivora in Maryland’s Nurseries and Mid-Atlantic Forests

Phytophthora cinnamomi A1: An ancient resident of New Guinea and Australia of Gondwanan origin?

Mitochondrial Haplotype Analysis for Differentiation of Isolates of Phytophthora cinnamomi

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