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Symptoms of Eucalyptus rust on different hosts. a Young lesions on E. grandis, the pustules are bright orange on young tissue. b Old lesions on E. grandis, grey discoloration on leaves and twigs and dead shoot tip. c,d Pustules on twigs, leaves and petioles of Myrrhinium atropurpureum var. octandrum appear bright orange. Trees also have dead shoot tips. Arrows show areas of dying shoot tips and location of orange urediniospores on infected branches.
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Eucalyptus or guava rust caused by Puccinia psidii is a serious disease of Eucalyptus and other Myrtaceae. In Uruguay, it has been previously found on Eucalyptus globulus and Psidium brasiliensis. Almost nothing is known regarding the occurrence of this pathogen on other Eucalyptus species or native Myrtaceae in that country. In this study, we dete...
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Context 1
... symptoms were observed on different hosts infected with P. psidii. Lesions were primarily observed on young tissues such as actively growing leaves and shoots (Fig. 1). Bright orange pustules with orange-yellow urediniospores were present on all evaluated hosts, but dark orange- brown teliospores were observed only on E. globulus and E. grandis. Gray discoloration of old lesions was observed on E. grandis, and shoot tips were dead on E. grandis and M. atropurpureum var. octandrum (Fig. 1). ...
Context 2
... leaves and shoots (Fig. 1). Bright orange pustules with orange-yellow urediniospores were present on all evaluated hosts, but dark orange- brown teliospores were observed only on E. globulus and E. grandis. Gray discoloration of old lesions was observed on E. grandis, and shoot tips were dead on E. grandis and M. atropurpureum var. octandrum (Fig. 1). Teliospores were similar to those reported by Walker (1983), roughly ellipsoidal to cylindrical to broadly clavate, one-septate, constricted at the central septum, 26-42 × 15-22 μm, with the upper cell generally slightly wider and shorter than the lower, wall pale golden yellow, pore apical in the upper cell and just below the septum ...
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Citations
... Host shifts. The negative impact of host-jump events from commercial settings to native forest ecosystems, and vice versa, has been recorded in the region [28,[51][52][53]. Funding to research native forest ecosystems is scarce in the region. ...
The plantation and natural forests of South America have been highly impacted by native and exotic pests in recent decades. The interaction of emerging invasive pests, climate change, and timber markets will define the region's forests, with significant but uncertain ecological changes and economic losses expected. The Southern Cone Forest Health Group (SCFHG), a joint ad hoc initiative run by forest health professionals from Argentina, Brazil, Chile, and Uruguay, aims to strengthen relationships between the forestry industry, stakeholders, academia, and government agencies across the region. Here, we highlight regional strengths, weaknesses, threats, and opportunities to address forest health issues in the region. A regional approach with a strong communication network is relevant for future actions. In the current global scenario of invasive species and climate change, the implementation of practices that incorporate the resilience of forest ecosystems and sustainable management needs to be prioritized in forest policy across the region. Understanding that pests and pathogens do not recognize borders, we call on governments and organizations to support joint actions with agreements and adequate resources to enhance our regional capabilities.
... Winter) Beenken [4,5,9]. This fungus, with a wide geographical distribution, is present in four of the five continents threatening Myrtaceae biodiversity, mainly in the Eucalyptus forestry industry [10,11]. ...
The fungus Austropuccinia psidii infects young tissues of Eucalyptus plants until they are two years old in the nursery and field, causing Myrtaceae rust. The characteristics making older eucalypt leaves resistant to A. psidii and the reason for the low levels of this pathogen in older plants need evaluations. The aim of this study was to evaluate the morphological differences between Eucalyptus grandis leaves of different growth stages and two plant ages to propose a visual phenological scale to classify E. grandis leaves according to their maturation stages and to evaluate the time of leaf maturation for young and adult plants. A scale, based on a morphological differentiation for E. grandis leaves, was made. The color, shape and size distinguished the leaves of the first five leaf pairs. Anatomical analysis showed a higher percentage of reinforced tissue, such as sclerenchyma-like tissue and collenchyma, greater leaf blade thickness, absence of lower palisade parenchyma in the mature leaves and a higher number of cavities with essential oils than in younger ones. Changes in anatomical characteristics that could reduce the susceptibility of older E. grandis leaves to A. psidii coincide with the time of developing leaf resistance. Reduced infection of this pathogen in older plants appears to be associated with a more rapid maturation of their leaf tissues.
... Puccinia psidii) species(Figure 3). The results of the present work are corroborated byPérez et al. (2010), who analyzed infection by Austropuccinia psidii in eucalyptus and native myrtaceae in Uruguay and reported infection of the pathogen in a guabiju plant in the municipality of Tacuarembó. ...
Guabiju tree (Myrcianthes pungens) belongs to the Myrtaceae family, with wide occurrence in Rio Grande do Sul (RS), southern Brazil, demonstrates great commercial potential regarding the consumption of its fresh fruit, which has a sweet taste and can be used in drinks, jellies and ice creams, in addition to its nutraceutical properties. As their main characteristic, rusts present the formation of orange pustules containing urediniospores of the pathogen on affected organs. The action of the pathogen causes deformation of stems, leaves, flowers and fruits, thus interfer-ing with the physiological processes of the plant. Thus, the present work aimed at presenting information on the occurrence and confirmation of the causal agent of guabiju rust, in addition to reporting the accessions most susceptible and resistant to Austropuccinia in the guabiju working collection of Eldorado do Sul, RS, Brazil. The diagnosis of the disease was based on symptoms, observation of fungal structures by light microscopy and molecular analyses. From microscopy, ellipsoid to ovoid and slightly equinulate urediniospores were observed, characteristic of Austropuccinia sp. The sequence of the internal transcribed spacer (ITS) region of the isolate showed 99.06% similarity with sequences from the same region of A. psidii deposited on the nucleotide database - GenBank (NCBI). This is the first report of rust associated with guabiju in the state of Rio Grande do Sul, Brazil. From the diagrammatic scale developed, it was possible to identify different levels of susceptibility to A. psidii in guabiju accessions under study.
... Eucalyptus rust, considered a major crop disease, is caused by the biotrophic fungus Austropuccinia psidii Winter, which causes severe damage to plantations in tropical and subtropical areas worldwide [7][8][9]. Such importance is due to damage caused and its influence on management of eucalyptus, which can even affect the conduction of sprouting in periods favorable to occurrence of the disease, considering susceptible clones [10]. ...
Eucalyptus is one of the most exploited forest genera on the planet. Eucalyptus has a variety of uses, mainly because of its great diversity and versatility. Brazil is among the main producers of cellulose, paper, and wood panels in the world. One of the factors limiting the production of Eucalyptus spp. is the occurrence of diseases such as rust caused by the fungus Austropuccinia psidii. This work aimed to map areas at risk of eucalyptus rust in the state of Espírito Santo, Brazil. The study was carried out in two stages: (i) mapping the rust risk areas in the state through the Geographic Information System (GIS) and (ii) applying fuzzy standardization to the infection index to generate a risk index. It was found through GIS and fuzzy standardization that most of the areas surveyed presented medium to high risk of rust occurrence. Thus, it becomes necessary to adopt complementary management measures to control the disease, especially for the months of April to November. The methodology used in this study can be implemented for other diseases and forest species in other parts of the world.
... Urediniospores are dikaryotic, onecelled and the mitotic spore stage that produces and disperses inocula. Teliospores are diploid, two-celled and the meiotic spore stage, produced on most hosts (da S. Machado et al., 2015;Ferreira, 1983;Glen et al., 2007;Pegg et al., 2014;Pérez et al., 2010). Basidiospores are the product of meiosis, contain two nuclei (Morin et al., 2014), and were experimentally shown to infect S. jambos (McTaggart et al., 2018a). ...
Austropuccinia psidii is the causal agent of myrtle rust, a fungal disease that infects over 480 species in the Myrtaceae. A. psidii is a biotrophic pathogen that reproduces sexually and asexually. Sexual reproduction has been previously shown on Syzygium jambos and little is known about its reproductive biology on other hosts or whether populations that were formerly structured by host range can outcross on universally susceptible hosts. We investigated if mating genes in three genomes of A. psidii were under selection as a proxy for whether different strains can reproduce sexually on a shared host. We examined three homologs of the STE3.2 gene, sequences of which were near-identical in the three genomes, and the homeodomain locus, which contained two alleles of two homeodomain genes in each genome. A. psidii likely uses tetrapolar mating. Pheromone/receptor loci were distal to homeodomain loci, and based on haplotypes of a phased assembly, mate compatibility is regulated by multiallelic HD genes and biallelic STE3.2 genes; the third homolog of STE3.2 (STE3.2-1) was present in both haplotypes, and our study supports hypotheses this gene does not regulate mate recognition. Populations of A. psidii formerly structured by host range could potentially outcross on universal hosts based on their related mating genes, however this hypothesis should remain theoretical given the implications for biosecurity. Additionally, we searched for core meiotic genes in genomes of A. psidii, four species of Puccinia, and Sphaerophragmium acaciae through comparative genomics based on 136 meiosis-related orthologous genes modeled from Mycosarcoma maydis. Meiotic genes are conserved in rust fungi at family rank. We analyzed the expression of two meiotic and four mitotic genes of A. psidii on E. grandis over a 28-day time course to validate that identified meiotic genes were upregulated in teliospores. Three mitotic genes were significantly downregulated in samples collected 28 days after inoculation (DAI) compared to 14 DAI. Expression of meiotic genes was significantly up-regulated in samples collected 28 DAI compared to 14 DAI, indicating a temporal switch from production of uredinia (mitotic stage) to telia in the life cycle, which we hypothesize may be in response to leaf ageing.
... Pada pengamatan lebih lanjut, spora A. psidii banyak ditemukan pada daun muda (Gambar 1) dan jarang ditemukan pada daun tua. Hal ini sesuai dengan ditemukan pada tanaman Eucalyptus (Glen et al., 2007;Pérez, Wingfield, Altier, Simeto, & Blanchette, 2011) yaitu infeksi ditemukan sebagian besar pada jaringan muda yang sedang tumbuh meskipun juga dapat ditemukan pada daun dewasa. Sebuah penelitian yang membandingkan perkecambahan urediniospora pada jaringan muda dan jaringan dewasa daun Eucalyptus grandis, menyimpulkan bahwa lapisan kutikula dan lapisan lilin yang lebih tebal berhubungan dengan lebih sedikitnya infeksi A. psidii pada daun tua dibandingkan pada daun yang lebih muda (Xavier et al., 2015). ...
... Namun upaya mencari kemiripan dengan metode BLAST tetap dilakukan. Satu sampel DNA dari spora pada pohon salam ulangan 1 yang memiliki 98% query cover menunjukkan adanya kemiripan tertinggi yaitu sebesar 94.27% (625/663) dengan sekuen ITS jamur A. psidii (EU348742) yang ditemukan pada Eucalyptus grandis dari Uruguay (Pérez et al., 2011). Suatu jenis jamur dapat dipastikan sebagai jamur A. psidii jika memiliki kemiripan lebih dari 98% (Rodas et al., 2015), oleh karena itu sampel spora tersebut meskipun teramplifikasi menggunakan penanda DNA ITS1F/ITS4 belum dapat dipastikan jenisnya. ...
... Perbedaan variasi genetik patogen serta tingkat patogenisitas tiap individu atau isolat perlu dipelajari untuk merencanakan upaya pengendalian penyakit. Adanya perbedaan variasi genetik dan tingkat patogenisitas A. psidii teramati di Uruguay meskipun dalam jumlah sampel yang sedikit (Pérez et al., 2011). ...
Austropuccinia psidii is a pathogenic fungus that causes rust in the Myrtaceae plant. The extensive plantation of the host of this fungus has increased the attack of fungal pathogen, therefore, will increase the threat tothe presence of Myrtaceae species around the globe including in Indonesia. This present study was aiming to detect and identify the presence of this pathogen by morphologicaland molecular observation. Morphological observationrevealed the presence of A. psidii urediniospores onsalam (Syzygium polyanthum) andkayuputih (Melaleuca cajuputi)leaves collected from the arboretum of the Indonesian Center for Forest Biotechnology and Tree Improvement (CFBTI), and the presence of teliospores on young Syzygium leaves. PCR amplification using specific primers of Ppsi1 / Ppsi6 succeeded in detecting the presence of A. psidii fungi Melaleuca and Syzygium showed by DNA amplicon length around 500bp. Efforts to obtain ITS DNA sequences to compare the molecular characteristics of fungi from two different hosts have been carried out, however, the sequencing electropherogram was unreadable, so the comparison can not be performed. This study reported that A. psidii is currently present in Myrtaceae species in Yogyakarta, therefore precaution efforts should be conducted to avoid economic and ecological impact from this pathogen.
... The pathogens considered in this study are Austropuccinia psidii, Dothistroma species, as well as species in the family Botryosphaeriaceae ( Figure 1). Austropuccinia psidii is the causal agent of myrtle rust on non-native Eucalyptus grown in commercial plantations in South America (Pérez et al. 2011;Rodas et al. 2015;Granados et al. 2017). Fusarium circinatum causes pitch canker on susceptible Pinus species and the fungus is considered one of the most important pathogens of pines (reviewed in Wingfield et al. 2008). ...
Forest pathogens are a major cause of forest disturbances and they have a significant economic impact on commercial forestry. Genomics is an important technology now available for studies concerning tree health, enabling researchers to better understand pathosystems and potentially to prevent future epidemics from occurring. Comparative genomics at the species level makes possible the identification of unique genomic regions and/or genes that influence the development of pathogens and their ability to cause disease. In addition, population genomics can reveal processes involved in the evolution of pathogens potentially showing how selection and/or environmental adaptation could have driven their emergence. Using these tools, important mechanisms involved in the evolution of pathogens and their hosts can be determined. Practical applications of such knowledge include the formulation of strategies for pathogen detection and surveillance, as well as breeding disease-resistant trees. These new and evolving technologies are set to ensure the long-term sustainability of plantation forestry in the Southern Hemisphere.
... Eucalyptus citriodora ;Joffily 1944). Considered to be of Neotropical origin, the rust has also been reported to infect diverse myrtaceous hosts elsewhere in South America, Central America, the Caribbean, Mexico, the United States (California, Florida, and Hawaii), Japan, Australia, China, and most recently South Africa and New Caledonia (Carnegie et al. 2010;Giblin 2013;Kawanishi et al. 2009;MacLachlan 1938;Marlatt and Kimbrough 1979;Mellano 2006;Pérez et al. 2011;Roux et al. 2013;Uchida et al. 2006;Zambino and Nolan 2011;Zhuang and Wei 2011). Given the rate at which the pathogen is spreading and its wide host range, the objectives of this study are to determine how much genetic diversity exists within populations across the species' putative native range as well as areas of recent introduction, evaluate possible pathways of spread, and predict the geographic area that is climatically suitable for the species to determine areas at risk of invasion. ...
... Eucalyptus citriodora; Joffily, 1944). Considered to be of neotropical origin, the pathogen has also been reported to infect other diverse myrtaceous hosts in South America (e.g., Granados et al., 2017;Kern & Toro, 1935;Mohali & Aime, 2016;Pérez, Wingfield, Altier, Simeto, & Blanchette, 2011;Simpson, Thomas, & Grgurinovic, 2006;Tommerup, Alfenas, & Old, 2003), the Caribbean (MacLachlan, 1938), California, USA (Mellano, 2006;Zambino & Nolan, 2011), Florida, USA (Marlatt & Kimbrough, 1979), Hawaii, USA (Uchida, Zhong, & Kilgore, 2006), Japan (Kawanishi et al., 2009), Australia (Carnegie et al., 2010), Hainan, China (Zhuang & Wei, 2011), and most recently South Africa (Roux, Greyling, Coutinho, Verleur, & Wingfield, 2013), New Caledonia (Giblin, 2013), Indonesia (McTaggart et al., 2016) and Singapore (de Plessis et al., 2017). In addition to rapid global spread of the myrtle rust pathogen in recent years, emergent natural epiphytotics (e.g., Rayachhetry, Elliott, & Van, 1997;Rayamajhi, Pratt, Klopfenstein, Ross-Davis, & Rodgers, 2013;Uchida & Loope, 2009) and new host reports (e.g., Pérez et al., 2011;Rodas et al., 2015;Telechea, Rolfo, Coutinho, & Wingfield, 2003;Zambino & Nolan, 2011) continue to be observed and documented within the Americas and Hawaii. ...
... Considered to be of neotropical origin, the pathogen has also been reported to infect other diverse myrtaceous hosts in South America (e.g., Granados et al., 2017;Kern & Toro, 1935;Mohali & Aime, 2016;Pérez, Wingfield, Altier, Simeto, & Blanchette, 2011;Simpson, Thomas, & Grgurinovic, 2006;Tommerup, Alfenas, & Old, 2003), the Caribbean (MacLachlan, 1938), California, USA (Mellano, 2006;Zambino & Nolan, 2011), Florida, USA (Marlatt & Kimbrough, 1979), Hawaii, USA (Uchida, Zhong, & Kilgore, 2006), Japan (Kawanishi et al., 2009), Australia (Carnegie et al., 2010), Hainan, China (Zhuang & Wei, 2011), and most recently South Africa (Roux, Greyling, Coutinho, Verleur, & Wingfield, 2013), New Caledonia (Giblin, 2013), Indonesia (McTaggart et al., 2016) and Singapore (de Plessis et al., 2017). In addition to rapid global spread of the myrtle rust pathogen in recent years, emergent natural epiphytotics (e.g., Rayachhetry, Elliott, & Van, 1997;Rayamajhi, Pratt, Klopfenstein, Ross-Davis, & Rodgers, 2013;Uchida & Loope, 2009) and new host reports (e.g., Pérez et al., 2011;Rodas et al., 2015;Telechea, Rolfo, Coutinho, & Wingfield, 2003;Zambino & Nolan, 2011) continue to be observed and documented within the Americas and Hawaii. ...
Since the myrtle rust pathogen (Austropuccinia psidii) was first reported (as Puccinia psidii) in Brazil on guava (Psidium guajava) in 1884, it has been found infecting diverse myrtaceous species. Because A. psidii has recently spread rapidly worldwide with an extensive host range, genetic and genotypic diversities were evaluated within and among A. psidii populations in its putative native range and other areas of myrtle rust emergence in the Americas and Hawaii. Microsatellite markers revealed several unique multilocus genotypes (MLGs), which grouped isolates into nine distinct genetic clusters [C1–C9 comprising C1: from diverse hosts from Costa Rica, Jamaica, Mexico, Puerto Rico, and USA-Hawaii, and USA-California; C2: from eucalypts (Eucalyptus spp.) in Brazil/Uruguay and rose apple (Syzygium jambos) in Brazil; C3: from eucalypts in Brazil; C4: from diverse hosts in USA-Florida; C5: from Java plum (Syzygium cumini) in Brazil; C6: from guava and Brazilian guava (Psidium guineense) in Brazil; C7: from pitanga (Eugenia uniflora) in Brazil; C8: from allspice (Pimenta dioica) in Jamaica and sweet flower (Myrrhinium atropurpureum) in Uruguay; C9: from jabuticaba (Myrciaria cauliflora) in Brazil]. The C1 cluster, which included a single MLG infecting diverse host in many geographic regions, and the closely related C4 cluster are considered as a “Pandemic biotype,” associated with myrtle rust emergence in Central America, the Caribbean, USA-Florida, USA-Hawaii, Australia, China-Hainan, New Caledonia, Indonesia and Colombia. Based on 19 bioclimatic variables and documented occurrences of A. psidii contrasted with reduced sets of specific genetic clusters (subnetworks, considered as biotypes), maximum entropy bioclimatic modelling was used to predict geographic locations with suitable climate for A. psidii which are at risk from invasion. The genetic diversity of A. psidii throughout the Americas and Hawaii demonstrates the importance of recognizing biotypes when assessing the invasive threats posed by A. psidii around the globe.
... In addition, this disease has been reported in many parts of the world such as the United States (Marlatt & Kimbrough, 1979;Mellano, 2006;Rayachhetry, Elliot, & Van, 1997;Uchida, Zhong, & Killgore, 2006;Zambino & Nolan, 2011), Mexico (Gallegos & Cummins, 1981), Japan (Kawanishi et al., 2009), Australia (Carnegie et al., 2010), China (Zhuang & Wei, 2011), South Africa (Roux, Greyling, Coutinho, Verleur, & Wingfield, 2013), New Caledonia (Giblin, 2013), Colombia (Rodas et al., 2015) and Indonesia . This global spread of P. psidii is indicative that phytosanitary measures are required to control its movement, especially in the tropical and subtropical regions where its occurrence and severity are more intense, as reported by recent studies in Uruguay (Pérez, Wingfield, Altier, Simeto, & Blanchette, 2011) and Brazil . ...
Brazilian forest-based industries are supported by more than 5.5 million hectares of Eucalyptus growing under different climatic conditions with different degrees of favourability for rust Puccinia psidii, including both traditional and expanding areas, where such disease is of major concern for the industry, foresters and scientists. The main objective of this study was to define favourable climatic zones for Eucalyptus rust in Brazil with the following aims: (i) to develop a spatial method for estimating the mean night-time temperature (Tng); (ii) to assess and validate a Eucalyptus rust model; and (iii) to map Eucalyptus rust favourability zones in Brazil based on the proposed model. A straightforward method, based only on latitude, day of the year, maximum and minimum air temperatures, was developed to estimate Tng, which is a key variable for a proper application of Ruiz rust model. Based on 37 field experiments with natural rust occurrence, it was observed that climatic conditions are determining factors for disease severity. Significant correlations between disease severity observed in the field and climatic conditions were found: a negative correlation with temperature (r = .50, p < .01) and a positive correlation with relative humidity (r = .89, p < .0001). A significant correlation (r = .81, p < .0001) between the normalized infection index, produced from Ruiz model, and the average rust score was also observed. Once the model was validated under field conditions, it was applied using historical average data of air temperature and leaf wetness duration to obtain monthly Eucalyptus rust favourability maps for the whole country. These final maps show that favourable climatic zones for Eucalyptus rust are extremely dynamic, with high temporal and spatial variability in Brazil and that climatic conditions should be considered for expansion of Eucalyptus to new areas, in breeding programmes, and for defining the most suitable seasons for forest establishment in each climate of the country. These results provide forestry managers with practical tools to reduce uncertainty about the expected severity of Eucalyptus rust in Brazil.
