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Peronospora variabilis on Chenopodium quinoa. a, b Conidiophores, c haustorium, d, e branches, f, g, h conidia. Scale bar is 100 lm for a, b, 10 lm for c, and 20 lm for d-h
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Downy mildew is an economically important and widespread disease in quinoa (Chenopodium quinoa) growing areas. Although in many studies Peronospora farinosa is most commonly regarded as the causal agent of the disease, identification and classification of the pathogen remain still uncertain due to its taxonomic confusion. Thirty-six Peronospora iso...
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... morphological features of the quinoa downy mildew pathogen are summarized as follows ( Fig. 1): Haustoria hyphal, often branched, without sheaths. Conidiophores emerging through stomata, colorless, straight to slightly curved, (320-)430-480-530(-600) lm long (n = 89); trunk substraight to slightly curved, (180-)270-315-360(-390) lm long (n = 81), basal end not differentiated, rarely bulbous, 12-17 lm wide at the base, 8-14 lm wide below the first branch, often slightly tapering upward, callose plugs rarely present; branches subdichoto- mously or monopodially branched in (4-)5-7 orders, slightly curved, elaborate, wall often thickening, callose plugs mostly absent; ultimate branchlets mostly in pair, with different lengths, (10-)14-19.5- 25(-32) lm long in axial (n = 60), (5-)10-12.0-14(- 17) lm in abaxial (n = 62), 2-3 lm wide at the base, from flexuous to curved, wall often thickening, apex obtuse or subtruncate. Conidia pale brown to oliva- ceous, varied in shape, mostly broadly ellipsoidal to ellipsoidal, sometimes appearing as obovoid or napi- form due to distinct pedicel, subglobose in young, greatest width median or submedian, (24.5-)28.7-30.7- 32.6(-35) lm long, (20.5-)22.3-23.8-25.3(-27.3) lm wide, length/width ratio = (1.18-)1.22-1.31-1.36(-1.56) (n = 96), tip rounded, base rounded or gradually narrowed; pedicel mostly present, short-conical or cylindrical, 1-1.5 lm long, 1-2 lm wide. Resting organ not seen. Peronospora from C. quinoa were easily distin- guished from P. boni-henrici on C. bonus-henricus and P. chenopodii-polyspermi on C. polyspermum by the broadly ellipsoidal to ellipsoidal conidia and its higher l/w ratio. The flexuous to curved ultimate branchlets and the pedicellated conidia allowed separation of the quinoa pathogen from P. chenopodii on C. hybridum and Peronospora sp. on C. ambro- sioides. The morphological comparison between Peronospora sp. from quinoa, Peronospora variabilis from C. album, and Peronospora farinosa s.l. from Atriplex patula were performed in more detail (Table 2). The quinoa pathogen was clearly distin- guished from P. farinosa on A. patula by larger size and higher l/w ratio in conidia. However, no morphological difference was found between Pero- nospora isolates from C. quinoa and P. variabilis from C. album. The present characteristics are also in agreement with previous records of the causal agent of quinoa downy mildew by Tewari and Boyetchko [7] and Danielsen and Ames [25] and of P. variabilis by Choi et al. [12]. The only significant difference in conidial size is found between the present observa- tions (av. 30.7 9 23.8 lm) and that of Danielsen et al. [9] (av. 22 9 18 ...
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... Previous studies have employed EF against plant pathogens and confirmed that EF can help to control or reduce the diseases caused by plant pathogens, such as Trichoderma asperellum against Fusarium wilt in banana [74], Penicillium citrinum and Aspergillus terreus against Table 1 The segments of reported downy mildews worldwide [20]. (54 %), followed by Pseudoperonospora cubensis on cucurbits (12 %), Bremia lactucae on lettuce (8 %), Peronospora spp. on leek and onion (6 %), on tobacco (4 %), on field crops such as peas, brassicas and sugar beet (each 3 %) and on soybeans and corn (each 2 %), Pseudoperonospora humuli on hops and Plasmopara halstedii on sunflower (each 1 %), and the systemic pathogens Peronosclerospora and Sclerophthora spp. in corn (1 %) (Syngenta internal data) [50,145]. ...
... Downy mildew disease is caused by oomycetes of the Peronosporaceae family, and particularly in quinoa by Peronospora variabilis Gäum. [4,10,11]. P. variabilis has been found present in every continent where quinoa is cultivated [12][13][14][15][16] and its worldwide distribution has likely been expanded by commercial trade of infected seeds [17,18]. ...
... This is a major sterol in fungi [38], whereas Peronospora and other Peronosporales (Oomycetes) do not synthesize ergosterol [39]. Sequencing of the ITS region verified that the Kari strain, isolated from the Bolivian Andean plateau, belongs to the P. variabilis species [11,17]. ...
... Plants 2022,11, 2946 ...
Downy mildew disease, caused by the biotrophic oomycete Peronospora variabilis, is the largest threat to the cultivation of quinoa (Chenopodium quinoa Willd.) in the Andean highlands, and occurs worldwide. However, so far, no molecular study of the quinoa–Peronospora interaction has been reported. Here, we developed tools to study downy mildew disease in quinoa at the gene expression level. P. variabilis was isolated and maintained, allowing the study of downy mildew disease progression in two quinoa cultivars under controlled conditions. Quinoa gene expression changes induced by P. variabilis were analyzed by qRT-PCR, for quinoa homologues of A. thaliana pathogen-associated genes. Overall, we observed a slower disease progression and higher tolerance in the quinoa cultivar Kurmi than in the cultivar Maniqueña Real. The quinoa orthologs of putative defense genes such as the catalase CqCAT2 and the endochitinase CqEP3 showed no changes in gene expression. In contrast, quinoa orthologs of other defense response genes such as the transcription factor CqWRKY33 and the chaperone CqHSP90 were significantly induced in plants infected with P. variabilis. These genes could be used as defense response markers to select quinoa cultivars that are more tolerant to P. variabilis infection.
... chenopodii Byford. However, further studies demonstrated that P. variabilis Gäum is the causal agent of this disease (Choi et al. 2010;Testen et al. 2014). Downy mildew can cause up to 99% yield losses in susceptible quinoa cultivars (Danielsen et al. 2000). ...
... Molecular diversity of P. variabilis isolates has previously been analyzed using the internal transcribed spacer (ITS) ribosomal DNA (rDNA) and cytochrome c oxidase subunit 2 (cox2) regions and by using a universally primed PCR (UP-PCR) approach. Choi et al. (2010) studied the molecular diversity of 36 Peronospora isolates from quinoa with different geographic origins, including Argentina, Bolivia, Denmark, Ecuador, and Peru, analyzing the ITS region of the rDNA. They found two base substitutions between the majority of the Danish isolates and South American isolates. ...
... Our results show, in agreement with other studies performed in other countries (Choi et al. 2010;Testen et al. 2014), that P. variabilis is able to infect both C. quinoa and C. album in southern Spain. The ITS and cox2 sequences obtained from isolates collected in Spain shared at least 99.7% similarity with ITS and cox2 sequences from other isolates of this species present in the GenBank database (data not shown). ...
Quinoa is an expanding crop in southern Spain. Downy mildew, caused by Peronospora variabilis, is the most important quinoa disease in Spain and worldwide. In Spain, this disease has also been observed on the weed Chenopodium album. The objectives of this study were to unravel the origin of the P. variabilis isolates currently infecting quinoa in southern Spain and to study their genetic diversity. We hypothesized that P. variabilis isolates infecting quinoa in Spain could have been introduced through the seeds of the quinoa varieties currently grown in the country or, alternatively, that these isolates are endemic isolates, originally infecting C. album, that jumped to quinoa. In order to test these hypotheses, we sequenced the internal transcribed spacer (ITS), cytochrome c oxidase subunit 1 (cox1), and cox2 regions of 33 P. variabilis isolates infecting C. quinoa and C. album in southern Spain and analyzed their phylogenetic relationship with isolates present in other countries infecting Chenopodium spp. cox1 gene sequences from all of the Spanish P. variabilis isolates were identical and exhibited nine single-nucleotide polymorphisms (SNPs) compared with a single P. variabilis cox1 sequence found at GenBank. Phylogenetic analyses based on the ITS ribosomal DNA region were not suitable to differentiate isolates according to their geographical origin or host. The cox2 sequences from P. variabilis Spanish isolates collected from C. quinoa and C. album were all identical and had a distinctive SNP in the last of four polymorphic sites that distinguished Spanish isolates from isolates from other countries. These results suggest that P. variabilis infecting quinoa in southern Spain could be native isolates that originally infected C. album.
[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .
... Data on measurements are described as maxima and minima in parentheses, and the mean plus and minus the standard deviation of a number of measurements is provided in parentheses. The means are presented in italics in the center of the data (between two values), as previously described (Choi et al. 2010). Deoxyribonucleic acid (DNA) extraction, PCR, and sequencing For genomic DNA extraction, approximately 100 mg of symptomatic leaf tissue was ground in a 2 mL Eppendorf tube containing 1 mL of CTAB buffer (2% CTAB, 100 mmol/L Tris HCl pH 8.0, 20 mmol/L EDTA, and 1.4 mol/L NaCl) (Doyle 1991). ...
... MEGA 11 (Tamura et al. 2021) was used for alignment and phylogenetic reconstruction. An alignment was constructed using the MUSCLE aligner (Edgar 2004) and reference sequences from the genus Peronospora (Choi et al. 2008(Choi et al. , 2010Lee et al. 2020). The sequence of Peronospora lamii D104 was used as an outgroup. ...
... Five samples of C. berlandieri from Sinaloa, Mexico, with downy mildew symptoms indicated a constant association with an oomycete from the genus Peronospora (Webster and Weber 2007). Despite some differences in the dimensions of the conidiophores, conidia, and oospores, the morphological characteristics of our specimens correspond to those of P. variabilis (formerly known as P. farinosa) infecting C. quinoa in Argentina, Bolivia, Denmark, Ecuador, and Peru (Choi et al. 2010), the USA (Testen et al. 2012), South Korea (Choi et al. 2014), and Turkey (Kara et al. 2020). ...
Peronospora variabilis was observed to be consistently associated with downy mildew of pitseed goosefoot (Chenopodium berlandieri). Morphological characteristics of the conidiophores, conidia and oospores of the oomycete corresponded to those of P. variabilis. The morphological identification was complemented by a phylogenetic analysis of the ITS region. To our knowledge, this is the first report of P. variabilis on C. berlandieri in Mexico.
... They were found in Arabidopsis rice, maize, and wheat. Downy mildew is the most acute disease for quinoa, caused by the fungus Peronospora variabili (Choi et al., 2010). A recent study attempted the identification of genes based on a GWAS analysis in quinoa. ...
Quinoa germplasm preserves useful and substantial genetic variation, yet it remains untapped due to a lack of implementation of modern breeding tools. We have integrated field and sequence data to characterize a large diversity panel of quinoa. Whole-genome sequencing of 310 accessions revealed 2.9 million polymorphic high confidence SNP loci. Highland and Lowland quinoa were clustered into two main groups, with F ST divergence of 0.36 and LD decay of 6.5 and 49.8 Kb, respectively. A genome-wide association study using multi-year phenotyping trials uncovered 600 SNPs stably associated with 17 traits. Two candidate genes are associated with thousand seed weight, and a resistance gene analog is associated with downy mildew resistance. We also identified pleiotropically acting loci for four agronomic traits important for adaptation. This work demonstrates the use of re-sequencing data of an orphan crop, which is partially domesticated to rapidly identify marker-trait association and provides the underpinning elements for genomics-enabled quinoa breeding.
... Among the adverse biotic factors, the downy mildew disease caused by Peronospora variabilis Gäum (formerly P. farinosa f. sp. chenopodii Byford) (Choi et al., 2010) stands out. ...
... There is frequent sexual reproduction in downy mildew (an oomycete), which generates new pathogen genetic diversity and probably new pathotype development Peterson et al., 2015). Choi et al. (2010), based on phylogeny of the internal transcribed spacer (ITS) region of the ribosomal RNA genes (rDNA), showed differences between the populations from Europe and South America. Using COX2 phylogeny, Danielsen and Lubeck (2010) observed differences between US and South American samples of downy mildew. ...
... Analyses were restricted to the type host/a single host to avoid perpetuating potential errors in identification (e.g., the reports of Sclerophthora cryophila on Heteropogon contortus and Dichanthium annulatum [Farr and Rossman 2021] that are likely Peronosclerospora heteropogonis and Peronosclerospora dichanthiicola, respectively, which are species described after the initial reports were made) and potential pseudoreplication. Such an approach is justified because most phylogenetically defined downy mildew species have a narrow plant host range with either one host or a few closely related hosts (e.g., Choi et al. 2008Choi et al. , 2009aChoi et al. , 2009bChoi et al. , 2010Choi et al. , 2015Choi et al. , 2020Cunnington 2006;García-Blázquez et al. 2008;Görg et al. 2017;Petrželová et al. 2017;Rouxel et al. 2014;Runge and Thines 2012;Runge et al. 2011;Thines 2011;Thines and Choi 2016;Voglmayr et al. 2014b). Peronospora species infecting hosts in the Brassicales were considered to be members of Hyaloperonospora, even in the absence of formal transfers, based on the trends observed by Constantinescu and Fahtei (2002), Göker et al. (2003Göker et al. ( , 2004Göker et al. ( , 2009aGöker et al. ( , 2009b, Voglmayr et al. (2014a), andSalgado-Salazar et al. (2020). ...
There are approximately 700 obligate biotrophic species grouped into 20 genera (Oomycota, Peronosporaceae) that cause downy mildew diseases. In 2001, Dick hypothesized that diversification of downy mildew species was driven in part by host plant secondary metabolites. Dick further speculated that this was driven by the transition of host plants away from mycorrhizal associations or the evolution of C 4 photosynthesis. Specifically, loss of mycorrhizal associations or the use of C 4 photosynthesis would result in more free carbon that the plants could then use to produce more secondary metabolites. If true, then there should be more downy mildew species that infect hosts from plant lineages that lack mycorrhizal associations or use C 4 photosynthesis. However, analysis of 677 downy mildew species for host plant mycorrhizal associations and host plant photosynthetic pathway type shows that this is not what occurred. Seventy percent of downy mildew species parasitize hosts that form mycorrhizal associations, and 94% of downy mildew species parasitize hosts that use C 3 photosynthesis. From this, it is concluded that the diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of C 4 photosynthesis. However, 85% of downy mildew species that parasitize Poaceae (grasses) parasitize C 4 hosts. Thus, it is possible that C 4 photosynthesis plays a role in the diversification of these genera.
[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2022.
... Among the adverse biotic factors, the downy mildew disease caused by Peronospora variabilis Gäum (formerly P. farinosa f. sp. chenopodii Byford) (Choi et al., 2010) stands out. ...
... There is frequent sexual reproduction in downy mildew (an oomycete), which generates new pathogen genetic diversity and probably new pathotype development Peterson et al., 2015). Choi et al. (2010), based on phylogeny of the internal transcribed spacer (ITS) region of the ribosomal RNA genes (rDNA), showed differences between the populations from Europe and South America. Using COX2 phylogeny, Danielsen and Lubeck (2010) observed differences between US and South American samples of downy mildew. ...
This book presents reviews on the application of the technology for crop improvement towards food and nutrition security, and research status on mutation breeding and associated biotechnologies in both seed crops and vegetatively propagated crops. It also presents perspectives on the significance of next-generation sequencing and bioinformatics in determining the molecular variants underlying mutations and on emerging biotechnologies such as gene editing. Reviews and articles are organized into five sections in the publication: (1) Contribution of Crop Mutant Varieties to Food Security; (2) Mutation Breeding in Crop Improvement and Climate-Change Adaptation; (3) Mutation Induction Techniques for Enhanced Genetic Variation; (4) Mutation Breeding in Vegetatively Propagated and Ornamental Crops; and (5) Induced Genetic Variation for Crop Improvement in the Genomic Era. The contents of this volume present excellent reference material for researchers, students and policy makers involved in the application of induced genetic variation in plants for the maintenance of biodiversity and the acceleration of crop adaptation to climate change to feed a growing global population in the coming years and decades.
... Among the adverse biotic factors, the downy mildew disease caused by Peronospora variabilis Gäum (formerly P. farinosa f. sp. chenopodii Byford) (Choi et al., 2010) stands out. ...
... There is frequent sexual reproduction in downy mildew (an oomycete), which generates new pathogen genetic diversity and probably new pathotype development Peterson et al., 2015). Choi et al. (2010), based on phylogeny of the internal transcribed spacer (ITS) region of the ribosomal RNA genes (rDNA), showed differences between the populations from Europe and South America. Using COX2 phylogeny, Danielsen and Lubeck (2010) observed differences between US and South American samples of downy mildew. ...
The main goals of this study were to evaluate the agronomic performance of wheat mutant lines; to detect the effect of genotype, location and different fertilizer levels on analysed traits; to assess seed and feed quality; and to select best performing mutant lines for dual-purpose growing. Ten wheat mutant lines were sown on two loca�tions in Macedonia, for evaluation of their agronomic performance. At both locations, grain yield, straw mass, harvest index, nitrogen use efficiency, nitrogen and protein content in seed and straw, neutral detergent fibre and acid detergent fibre in the straw were determined. In order to classify the genotypes based on all analysed traits, two-way cluster analysis was applied. According to their overall performance, at both locations and with the three different fertilization treatments, the mutant lines were classified in two main groups. The first cluster con�sisted of mutants 5/1-8, 2/2-21, 4/2-56 and 2/1-51, characterized by very high values for seed yield, straw yield and harvest index, and high to moderate values for all other traits. Only 4/2-56 had very low values for N and protein content in the seed. One mutant line, 6/2-2, did not belong to any of the groups and differed from all other genotypes based on its very low seed and straw yield and very high values for nitrogen and protein content in the straw and neutral detergent fibre. All other mutants belonged to the second group, with low to moderate yield and moderate to high values for the other traits. Mutant lines with the highest seed and straw yield, as well as the best quality of seed and straw under different management systems, were identified and after additional evalu�ation will be submitted for official variety registration.
... Several studies have provided evidence of a high degree of specialization within Peronospora strains that infect Chenopodium spp. (Belbahri et al. 2005;Choi et al. 2008Choi et al. , 2010Thines and Choi 2016). Byford (1967) reported that Peronospora spp. on Chenopodium hosts are limited by host range and should be differentiated as such. ...
Quinoa is a potential new crop for New England; however, its susceptibility to downy mildew, caused by Peronospora variabilis, is a key obstacle for cultivation. The objectives of this study were to: 1.) evaluate differential resistance within the Chenopodium genus; 2.) identify novel sources of resistance for use in future genetic studies and/or breeding programs; and 3.) investigate phylogenetic relationships of P. variabilis isolates from different Chenopodium hosts. The long-term goal of this research is to develop a resistant variety of quinoa to be grown in New England. Field trials conducted at UNH evaluated downy mildew disease severity on ten Chenopodium accessions representing four species. Disease severity for each treatment was compared and significant differences in disease severity were observed among accessions. C. berlandierivar. macrocalycium ecotypes collected from Rye Beach, NH and Appledore Island, ME exhibited the lowest disease severity over the growing season. P. variabilis was isolated from each accession and COX2 sequences were compared. Phylogenetic analyses suggest no effect of host species on P. variabilis sequence similarity; however, isolates are shown to cluster by geographic location. This research provides the first step in identifying potential New England native sources of resistance to downy mildew within the genus Chenopodium, and provides preliminary information needed to further investigate resistance at the genomic level in Chenopodium spp.
