Phytophthora Diseases Worldwide

Wheller, Terri; Erwin, D. C.; Ribeiro, O. K.

doi:10.2307/3761286

Cited by 78 publications

(164 citation statements)

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“…These species were only detected with the ITS primers and not with COI. They are host specific and have been described mainly on Castanea, Solanaceae, and Eucalyptus, respectively [90,91]. Confirmation of their presence at the sites is recommended.…”

Section: Discussionmentioning

confidence: 99%

Diversity of Phytophthora Species Detected in Disturbed and Undisturbed British Soils Using High-Throughput Sequencing Targeting ITS rRNA and COI mtDNA Regions

Landa

Arias-Giraldo

Henricot

et al. 2021

Forests

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Disease outbreaks caused by introduced Phytophthora species have been increasing in British forests and woodlands in recent years. A better knowledge of the Phytophthora communities already present in the UK is of great importance when developing management and mitigation strategies for these diseases. To do this, soils were sampled in “disturbed” sites, meaning sites frequently visited by the public, with recent and new plantings or soil disturbances versus more “natural” forest and woodland sites with little disturbance or management. Phytophthora diversity was assessed using high-throughput Illumina sequencing targeting the widely accepted barcoding Internal Transcribed Spacer 1 (ITS1) region of rRNA and comparing it with the mitochondrial cytochrome c oxidase I (COI) gene. Isolation of Phytophthora was run in parallel. Nothophytophthora spp. and Phytophthora spp. were detected in 79 and 41 of the 132 locations of the 14 studied sites when using ITS or COI, respectively. A total of 20 Phytophthora amplicon sequence variants (ASVs) were assigned to known Phytophthora species from eight clades (1a, 2, 2b, 3a, 5, 6b, 7a, 8b, 8c, 8d, 10a, and 10b) and 12 ASVs from six clades (1a, 2c, 3a, 3b, 6b, 7a, 8b, 8c, and 8d) when using ITS or COI, respectively. Only at two locations were the results in agreement for ITS, COI, and isolation. Additionally, 21 and 17 unknown Phytophthora phylotypes were detected using the ITS and COI, respectively. Several Phytophthora spp. within clades 7 and 8, including very important forest pathogens such as P. austrocedri and P. ramorum, were identified and found more frequently at “disturbed” sites. Additionally, eight ASVs identified as Nothophytophthora spp. were detected representing the first report of species within this new genus in Britain. Only three species not known to be present in Britain (P. castaneae, P. capsici, and P. fallax) were detected with the ITS primers and not with COI. To confirm the presence of these or any potential new Phytophthora species, sites should be re-sampled for confirmation. Additionally, there is a need to confirm if these species are a threat to British trees and try to establish any eradication measures required to mitigate Phytophthora spread in Britain.

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Section: Discussionmentioning

confidence: 99%

Diversity of Phytophthora Species Detected in Disturbed and Undisturbed British Soils Using High-Throughput Sequencing Targeting ITS rRNA and COI mtDNA Regions

Landa

Arias-Giraldo

Henricot

et al. 2021

Forests

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“…The UEX1 strain of P. cinnamomi used in the present study was isolated in 2008, in Valverde de Mérida (Badajoz, Spain), as described by [ 7 ], and the pathogenicity and virulence were demonstrated by [ 95 ]. The strain was maintained on V8-agar medium [ 96 , 97 ] at 25 °C in darkness and subcultured at 2-week intervals. The isolates were passaged through chestnut or avocado leaves two weeks prior to the first test, as a precautionary measure against loss of pathogenicity through continuous subculturing [ 96 , 97 ].…”

Section: Methodsmentioning

confidence: 99%

“…The strain was maintained on V8-agar medium [ 96 , 97 ] at 25 °C in darkness and subcultured at 2-week intervals. The isolates were passaged through chestnut or avocado leaves two weeks prior to the first test, as a precautionary measure against loss of pathogenicity through continuous subculturing [ 96 , 97 ].…”

Section: Methodsmentioning

confidence: 99%

Efficient Transformation of Somatic Embryos and Regeneration of Cork Oak Plantlets with a Gene (CsTL1) Encoding a Chestnut Thaumatin-Like Protein

Cano

Martínez

Couselo

et al. 2021

IJMS

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We present a reproducible procedure for transforming somatic embryos of cork oak with the CsTL1 gene that codes for a thaumatin-like protein, in order to confer tolerance to Phytophthora cinnamomi. Different concentrations/combinations of the antibiotics carbenicillin and cefotaxime, as bacteriostatic agents, and kanamycin, as a selective agent, were tested. A lethal dose of 125 mg/L kanamycin was employed to select transgenic somatic embryos, and carbenicillin was used as a bacteriostatic agent at a concentration of 300 mg/L, which does not inhibit somatic embryo proliferation. The transformation efficiency was clearly genotype-dependent and was higher for the TGR3 genotype (17%) than for ALM80 (4.5%) and ALM6 (2%). Insertion of the transgenes in genomic DNA was confirmed by PCR analysis, whereas expression of the CsTL1 gene was evaluated by semi-quantitative real-time PCR (qPCR) analysis. A vitrification treatment successfully cryopreserved the transgenic lines generated. The antifungal activity of the thaumatin-like protein expressed by the gene CsTL1 was evaluated in an in vitro bioassay with the oomycete P. cinnamomi. Of the eight transgenic lines analyzed, seven survived for between one or two times longer than non-transgenic plantlets. Expression of the CsTL1 gene and plantlet survival days were correlated, and survival was generally greater in plantlets that strongly expressed the CsTL1 gene.

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“…The identification of the pathogenic oomycetes was initially based on visual observation of the forming colony (color and shape), mycelial growth, and sporulation. Under the light microscope, colony and hyphal morphology, and the production and morphological traits of sporangia, oogonium, antheridia, oospores and chlamydospores were examined accordingly [4,[26][27][28][29]. To induce the formation of sporangia, mycelial plugs of 1 cm in diameter were cut from the edges of 5-day old growing cultures on V8 agar medium and then placed in Petri dishes previously filled with 10 mL of non-sterile soil extract [4].…”

Section: Morphological Identificationmentioning

confidence: 99%

“…They are divided into several more or less virulent genera and species; the most devastating of which are the species belonging to Pythium and Phytophthora [3]. Root rot is the most common disease caused by these pathogens [4]. Phytophthora and Pythium species can survive for a long time in the soil and in diseased plants.…”

Section: Introductionmentioning

confidence: 99%

Phytopythium vexans Associated with Apple and Pear Decline in the Saïss Plain of Morocco

et al. 2021

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An extensive survey conducted in the Saïss plain of Morocco during the 2017–2018 growing season revealed that 35 out of 50 apple and pear orchards were infested with a pathogen that causes the decline disease. Morphological and phylogenetic tree analyses using the cox II gene allowed us to identify the pathogen as Phytopythium vexans. Interestingly, no Phytophthora and Pythium species were isolated. The occurrence and prevalence of the disease varied between locations; the most infested locations were Meknes (100%), Imouzzer (83%), and Sefrou (80%). To fulfill Koch’s postulate, a greenhouse pathogenicity test was performed on the stem and collar of one-year-old healthy seedlings of apple rootstock M115. Symptoms similar to those observed in the field were reproduced in less than 4 months post-inoculation with root rot disease severity ranging from 70 to 100%. The survey results evidenced that apple rootstocks, soil type, and irrigation procedure may contribute significantly to the occurrence of the disease. The disease was most prevalent in drip water irrigation and sandy-clay soil on wild apple rootstock. Accordingly, a rational drip advanced watering system and good sanitation practices could eliminate water stagnation and help prevent the onset of this disease. It was concluded that Pp. vexans occurrence may be strongly influenced by irrigation mode and type of soil. Therefore, the obtained findings of this study could help to better understand the recurrence of this disease and to develop a reliable integrated strategy for its management.

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Phytophthora Diseases Worldwide

Cited by 78 publications

References 0 publications

Diversity of Phytophthora Species Detected in Disturbed and Undisturbed British Soils Using High-Throughput Sequencing Targeting ITS rRNA and COI mtDNA Regions

Diversity of Phytophthora Species Detected in Disturbed and Undisturbed British Soils Using High-Throughput Sequencing Targeting ITS rRNA and COI mtDNA Regions

Efficient Transformation of Somatic Embryos and Regeneration of Cork Oak Plantlets with a Gene (CsTL1) Encoding a Chestnut Thaumatin-Like Protein

Phytopythium vexans Associated with Apple and Pear Decline in the Saïss Plain of Morocco

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