Global biogeography and invasion risk of the plant pathogen genus Phytophthora

Scott, P. M.; Bader, Martin K.‐F.; Burgess, Treena I.; Hardy, G.E.St.J.; Williams, N.

doi:10.1016/j.envsci.2019.08.020

Cited by 73 publications

(72 citation statements)

References 34 publications

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“…bark beetle outbreaks, alone or in interaction with drought ( Gaylord et al , 2013 ; Anderegg et al , 2015 ; Arango-Velez et al , 2016 ), and leaf-feeding insects ( Krause and Raffa, 1992 ; Quentin et al , 2010 ; Eyles et al , 2011 a ; Stone et al , 2013 ; Chen et al , 2017 ). However, there is a remarkable lack of studies on the impact of pathogen-induced defoliation on tree productivity and resilience through mechanistic approaches despite persistent increases in invasive pathogen alerts and predictions of future increases ( Anderson et al , 2004 ; Fisher et al , 2012 ; Scott et al , 2019 ). This knowledge gap challenges the establishment of process-based growth loss models and their inclusion in a wider framework of tree death, accounting for the interaction with other stressors ( McDowell et al , 2011 ; Dietze and Matthes, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

No carbon limitation after lower crown loss in Pinus radiata

et al. 2020

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Background and Aims Biotic and abiotic stressors can cause different defoliation patterns within trees. Foliar pathogens of conifers commonly prefer older needles and infection with defoliation that progresses from the bottom crown to the top. The functional role of the lower crown of trees is a key question to address the impact of defoliation caused by foliar pathogens. Methods A 2 year artificial defoliation experiment was performed using two genotypes of grafted Pinus radiata to investigate the effects of lower-crown defoliation on carbon (C) assimilation and allocation. Grafts received one of the following treatments in consecutive years: control–control, control–defoliated, defoliated–control and defoliated–defoliated. Results No upregulation of photosynthesis either biochemically or through stomatal control was observed in response to defoliation. The root:shoot ratio and leaf mass were not affected by any treatment, suggesting prioritization of crown regrowth following defoliation. In genotype B, defoliation appeared to impose C shortage and caused reduced above-ground growth and sugar storage in roots, while in genotype A, neither growth nor storage was altered. Root C storage in genotype B decreased only transiently and recovered over the second growing season. Conclusions In genotype A, the contribution of the lower crown to the whole-tree C uptake appears to be negligible, presumably conferring resilience to foliar pathogens affecting the lower crown. Our results suggest that there is no C limitation after lower-crown defoliation in P. radiata grafts. Further, our findings imply genotype-specific defoliation tolerance in P. radiata.

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Section: Introductionmentioning

confidence: 99%

No carbon limitation after lower crown loss in Pinus radiata

et al. 2020

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“…Phytophthora lateralis Port Orford Cedar root rot (Jules et al 2002), Phytophthora kernoviae (Brasier et al 2005). The continued introduction of economically and environmentally damaging forest pathogens and their establishment in novel areas has highlighted the need for forest pathologists to look to invasion science for insights on how to better understand the processes leading to invasion and spread of IFPs (Brasier 2008;Loo 2008;Santini et al 2013;Scott et al 2019).…”

Section: Recognition Of Invasion Science By Forest Pathologistsmentioning

confidence: 99%

Harmonising the fields of invasion science and forest pathology

Paap¹,

Wingfield²,

Burgess³

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Invasive alien species are widely recognised as significant drivers of global environmental change, with far reaching ecological and socio-economic impacts. The trend of continuous increases in first records, with no apparent sign of saturation, is consistent across all taxonomic groups. However, taxonomic biases exist in the extent to which invasion processes have been studied. Invasive forest pathogens have caused, and they continue to result in dramatic damage to natural forests and woody ecosystems, yet their impacts are substantially underrepresented in the invasion science literature. Conversely, most studies of forest pathogens have been undertaken in the absence of a connection to the frameworks developed and used to study biological invasions. We believe this is, in part, a consequence of the mechanistic approach of the discipline of forest pathology; one that has been inherited from the broader discipline of plant pathology. Rather than investigating the origins of, and the processes driving the arrival of invasive microorganisms, the focus of pathologists is generally to investigate specific interactions between hosts and pathogens, with an emphasis on controlling the resulting disease problems. In contrast, central to the field of invasion science, which finds its roots in ecology, is the development and testing of general concepts and frameworks. The lack of knowledge of microbial biodiversity and ecology, speciation and geographic origin present challenges in understanding invasive forest pathogens under existing frameworks, and there is a need to address this shortfall. Advances in molecular technologies such as gene and genome sequencing and metagenomics studies have increased the “visibility” of microorganisms. We consider whether these technologies are being adequately applied to address the gaps between forest pathology and invasion science. We also interrogate the extent to which the two fields stand to gain by becoming more closely linked.

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“…The worldwide importance of Phytophthora (Stramenopiles: Oomycetes: Peronosporales) species as plant pathogens in agriculture, horticulture, and natural ecosystems (Scott et al ., 2019) makes it imperative that these pathogens can be isolated and cultured to study their biology, epidemiology and management. The number of described Phytophthora species is increasing rapidly (Martin et al ., 2014).…”

Section: Introductionmentioning

confidence: 99%

“…In 1995 there were around 50 described species and most of them were associated with diseases of crops (Erwin and Ribeiro, 1996). At present, the number has increased to more than 180, and is expected to rise further, through the investigation of previously unexplored natural ecosystems (Scott et al ., 2019). In addition to these described species, even more putative new species have been detected using high‐throughput sequencing (Burgess et al ., 2017; Bose et al ., 2018; Khaliq et al ., 2018) but have not yet been cultured.…”

Section: Introductionmentioning

confidence: 99%

Antimicrobials in Phytophthora isolation media and the growth of Phytophthora species

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Many recently described Phytophthora species detected using high‐throughput sequencing have never been isolated into culture. NARH is a commonly used isolation medium containing cornmeal agar with nystatin 22.72 ppm, ampicillin 100 ppm, rifampicin 10 ppm, and hymexazol 50 ppm. We investigated whether the antimicrobial compounds in this medium selectively inhibit growth of some Phytophthora species. Growth of 10 Phytophthora species from 10 Phytophthora clades was tested in NARH medium with antimicrobials in a range of concentrations, singly and in combination: nystatin 12.5–100 ppm, ampicillin 62.5–500 ppm, rifampicin 5–40 ppm, hymexazol 12.5–100 ppm and in addition, chloramphenicol 5–40 ppm. Two combinations of antimicrobials that supported good growth of the greatest number of species were selected: (a) nystatin 12.5 ppm, ampicillin 250 ppm, rifampicin 10 ppm, and hymexazol 12.5 ppm, and (b) these compounds with the addition of chloramphenicol 5 ppm. Subsequently the growth of 47 Phytophthora species from all clades was tested in media with these two combinations and standard NARH, both in aseptic culture and in plates with leaf baits infected from soils known to be infested with Phytophthora. Although growth of some Phytophthora species was better with the new combinations of antimicrobials in aseptic culture, suppression of competing microorganisms was best in standard NARH. Sensitivity to the NARH antimicrobials is not the reason for the difficulty or failure of isolating many species detected using high‐throughput sequencing. NARH is a robust and appropriate medium for isolation of Phytophthora species from all clades.

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Global biogeography and invasion risk of the plant pathogen genus Phytophthora

Cited by 73 publications

References 34 publications

No carbon limitation after lower crown loss in Pinus radiata

No carbon limitation after lower crown loss in Pinus radiata

Harmonising the fields of invasion science and forest pathology

Antimicrobials in Phytophthora isolation media and the growth of Phytophthora species

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