A new, highly aggressive race of <i>Austropuccinia psidii</i> infects a widely planted, myrtle rust‐resistant, eucalypt genotype in Brazil

Almeida, R. F.; Machado, Patrícia S.; Damacena, Michelle B.; Santos, Samuel A.; Guimarães, Lúcio Mauro da Silva; Klopfenstein, Ned B.; Alfenas, Acelino C.

doi:10.1111/efp.12679

Cited by 8 publications

(6 citation statements)

References 44 publications

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“…Combined with the pathogen's wide host range within the Myrtaceae [6,7], the spread of A. psidii has been facilitated by the long-distance dispersal of urediniospores either via wind or anthropogenic movement of spores and infected plant material. This pathogen is a major threat to Myrtaceae in native forest ecosystems as well as myrtle-related industries around the world [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Early Detection of Myrtle Rust on Pōhutukawa Using Indices Derived from Hyperspectral and Thermal Imagery

Watt,

Estarija,

Bartlett

et al. 2024

Remote Sensing

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Myrtle rust is a very damaging disease, caused by the fungus Austropuccinia psidii, which has recently arrived in New Zealand and threatens the iconic tree species pōhutukawa (Metrosideros excelsa). Canopy-level hyperspectral and thermal images were taken repeatedly within a controlled environment, from 49 inoculated (MR treatment) and 26 uninoculated (control treatment) pōhutukawa plants. Measurements were taken prior to inoculation and six times post-inoculation over a 14-day period. Using indices extracted from these data, the objectives were to (i) identify the key thermal and narrow-band hyperspectral indices (NBHIs) associated with the pre-visual and early expression of myrtle rust and (ii) develop a classification model to detect the disease. The number of symptomatic plants increased rapidly from three plants at 3 days after inoculation (DAI) to all 49 MR plants at 8 DAI. NBHIs were most effective for pre-visual and early disease detection from 3 to 6 DAI, while thermal indices were more effective for detection of disease following symptom expression from 7 to 14 DAI. Using results compiled from an independent test dataset, model performance using the best thermal indices and NBHIs was excellent from 3 DAI to 6 DAI (F1 score 0.81–0.85; accuracy 73–80%) and outstanding from 7 to 14 DAI (F1 score 0.92–0.93; accuracy 89–91%).

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Section: Introductionmentioning

confidence: 99%

Early Detection of Myrtle Rust on Pōhutukawa Using Indices Derived from Hyperspectral and Thermal Imagery

Watt,

Estarija,

Bartlett

et al. 2024

Remote Sensing

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“…Common controls of rusts include synthetic fungicides (Miles et al, 2007 ), deployment of resistant genotypes (Babu et al, 2020 ; Glen et al, 2007 ; Periyannan, 2018 ), and breeding for resistance (Ellis et al, 2014 ; Varshney et al, 2007 ). However, these short‐term solutions are limited by evolving pathogens (Drenth et al, 2019 ; McDonald & Linde, 2002 ), financial and environmental costs associated with agrichemicals (Lykogianni et al, 2021 ; Makinson, 2018 ; Makinson & Conn, 2014 ; Pegg et al, 2014 ), and the time required to breed improved crop varieties (Almeida et al, 2021 ). These traditional control strategies are also not viable in the conservation of non‐crop species.…”

Section: Introductionmentioning

confidence: 99%

Exogenous double‐stranded RNA inhibits the infection physiology of rust fungi to reduce symptoms in planta

Degnan

McTaggart

Shuey³

et al. 2022

Molecular Plant Pathology

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Rust fungi (Pucciniales) are a diverse group of plant pathogens in natural and agricultural systems. They pose ongoing threats to the diversity of native flora and cause annual crop yield losses. Agricultural rusts are predominantly managed with fungicides and breeding for resistance, but new control strategies are needed on non-agricultural plants and in fragile ecosystems. RNA interference (RNAi) induced by exogenous double-stranded RNA (dsRNA) has promise as a sustainable approach for managing plant-pathogenic fungi, including rust fungi. We investigated the mechanisms and impact of exogenous dsRNA on rust fungi through in vitro and whole-plant assays using two species as models, Austropuccinia psidii (the cause of myrtle rust) and Coleosporium plumeriae (the cause of frangipani rust). In vitro, dsRNA either associates externally or is internalized by urediniospores during the early stages of germination. The impact of dsRNA on rust infection architecture was examined on artificial leaf surfaces. dsRNA targeting predicted essential genes significantly reduced germination and inhibited development of infection structures, namely appressoria and penetration pegs. Exogenous dsRNA sprayed onto 1-year-old trees significantly reduced myrtle rust symptoms. Furthermore, we used comparative genomics to assess the wide-scale amenability of dsRNA to control rust fungi. We sequenced genomes of six species of rust fungi, including three new families (Araucariomyceaceae, Phragmidiaceae, and Skierkaceae) and identified key genes of the RNAi pathway across 15 species in eight families of Pucciniales. Together, these findings

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“…However, it is only possible to screen for resistance to this pathogen by growing seedlings of Western Australian species in the eastern states and using the pandemic strain of the pathogen from eastern Australia. This pandemic strain or other strains more aggressive to eucalypts could eventually be introduced into WA (Almeida et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Resistance to quambalaria shoot blight and myrtle rust in Corymbia calophylla seedlings

Duong

Pegg

Mazanec³

et al. 2022

Forest Pathology

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Corymbia calophylla (marri), an endemic keystone tree species in southwest Western Australia, is increasingly impacted by the introduced basidiomycete smut Quambalaria pitereka. The basidiomycete rust Austropuccinia psidii (myrtle rust), an invasive pathogen recently introduced to Eastern Australia, is expected to spread to the southwest of Western Australia eventually. Austropuccinia psidii has similar epidemiology to Q. pitereka, and there is concern that C. calophylla may be susceptible. Preliminary pathogenicity tests showed significant differences in aggressiveness between twelve Q. pitereka isolates, and there was evidence of interactions between isolates and C. calophylla provenances. Seedlings from 59 open‐pollinated families from 11 provenances covering the natural range of marri were screened for resistance to Q. pitereka and A. psidii under controlled glasshouse conditions. Resistance of seedlings within provenances to Q. pitereka and A. psidii differed significantly. There was no significant correlation between resistance to Q. pitereka and resistance to A. psidii. Seedlings of provenances from wetter regions were more resistant to both pathogens, but the correlation coefficients were insignificant. Seedlings of four families in three provenances (Serpentine, Chidlow, and Kingston) showed 100% resistance to Q. pitereka. Narrow‐sense heritability estimates were 0.07 for quambalaria shoot blight resistance and 0.34 for myrtle rust resistance. The results indicate the potential to use selected families/individuals resistant to Q. pitereka and A. psidii for tree improvement programs and adaptive management strategies.

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A new, highly aggressive race of Austropuccinia psidii infects a widely planted, myrtle rust‐resistant, eucalypt genotype in Brazil

Abstract: Austropuccinia psidii (G. Winter) Beenken, first reported as Puccinia psidii on guava (Psidium guajava) in southern Brazil (Winter, 1884), is an obligate biotrophic pathogen that causes myrtle rust (MR), and threatens numerous Myrtaceae species around the world (Beresford

Cited by 8 publications

References 44 publications

Early Detection of Myrtle Rust on Pōhutukawa Using Indices Derived from Hyperspectral and Thermal Imagery

Early Detection of Myrtle Rust on Pōhutukawa Using Indices Derived from Hyperspectral and Thermal Imagery

Exogenous double‐stranded RNA inhibits the infection physiology of rust fungi to reduce symptoms in planta

Resistance to quambalaria shoot blight and myrtle rust in Corymbia calophylla seedlings

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