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The most serious foliar disease of perennial ryegrass (Lolium perenne L.) is crown rust (caused by Puccinia coronata Corda f.sp. lolii Brown). Progress in resistance breeding using recurrent selection has been slow, due to lack of genetic knowledge. Puccinia coronata is a basidiomycete fungus with a complex life‐cycle involving both asexual and sex...
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To assess the genetic diversity and population structure of Lolium species, we used 32 nuclear simple sequence repeat (SSR) markers and 7 cytoplasmic gene markers to analyze a total of 357 individuals from 162 accessions of 9 Lolium species. This survey revealed a high level of polymorphism, with an average number of alleles per locus of 23.59 and...
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... Fungal diseases, such as crown rust, can significantly reduce plant fitness, herbage yield quality, and seed yield and negatively impact seedling vigor in plants from rustinfected parents [57,58]. In this study, fungal disease symptoms were rather low, suggesting that climatic conditions are still unfavorable for the early spread of fungal infections in forage crops in Lithuania [31,33]. ...
Grasslands are important for sustainable milk and meat production as well as for providing other ecosystem services. One of the most productive components of short-term grasslands is Italian ryegrass (Lolium multiflorum subsp. italicum Lam.), offering high yield, excellent feed value, and high palatability to animals but low tolerance to abiotic stress. Global climate warming opens new opportunities and could be beneficial in increasing the potential of biomass production. In this study, we aimed to assess an Italian ryegrass cultivar of Lithuanian origin, ‘Ugnė’, for productivity and yield stability, with special emphasis on their relationship with climatic factors over a period of 14 years. The average winter temperatures and total spring precipitation explained 51% of the first-cut dry matter yield (DMY) variance. Second- and third-cut DMYs were associated with average temperature only. Italian ryegrass cv. ‘Ugnė’ demonstrated the potential to produce high dry matter yields after warm winters and withstand summer drought spells under Lithuanian conditions. However, mid-to-late-summer heat waves might reduce productivity and should be taken into consideration when breeding new Italian ryegrass cultivars.
... Conserved structural motifs and protein domains enable computational identification of R-genes by peptide sequence alignments and searching for structural similarity (Michelmore & Meyers, 1998). Thereby a large class of potential R-genes, known as Resistance Gene Analogs (RGAs), were predicted and mapped in rice (Miah et al., 2013;Sekhwal et al., 2015) and the orthologs of the rice RGAs were identified in wheat (Bouktila et al., 2014), maize (Xiao et al., 2007), rye (Dracatos et al., 2010) and finger millet (Reddy et al., 2011;Babu et al. 2014). The annotated rice genome and transcriptome data provide opportunities for the discovery of novel RGAs and these resources are increasingly investigated in search of RGAs as gene candidates for disease resistance. ...
... Resistance to crown rust in perennial ryegrass involves different mechanisms. Major genes, called resistance (R) genes, confer complete protection to a specific rust isolate, efficiently reducing pathogen growth [10]. Such resistance is controlled by one or a few genes, hence the name: qualitative resistance. ...
... Once inside the plant, infection hyphae grow to colonize the intercellular space [10]. At this stage, TMK proteins, the most well-known R proteins, might activate kinase enzymes following recognition of pathogen elicitors [42]. ...
A population of 239 perennial ryegrass (Lolium perenne L.) genotypes was analyzed to identify marker-trait associations for crown rust (Puccinia coronata f.sp. lolii) and brown rust (Puccinia graminis f.sp. loliina) resistance. Phenotypic data from field trials showed a low correlation (r = 0.17) between the two traits. Genotypes were resequenced, and a total of 14,538,978 SNPs were used to analyze population structure, linkage disequilibrium (LD), and for genome-wide association study. The SNP heritability (h2SNP) was 0.4 and 0.8 for crown and brown rust resistance, respectively. The high-density SNP dataset allowed us to estimate LD decay with the highest possible precision to date for perennial ryegrass. Results showed a low LD extension with a rapid decay of r2 value below 0.2 after 520 bp on average. Additionally, QTL regions for both traits were detected, as well as candidate genes by applying Genome Complex Trait Analysis and Multi-marker Analysis of GenoMic Annotation. Moreover, two significant genes, LpPc6 and LpPl6, were identified for crown and brown rust resistance, respectively, when SNPs were aggregated to the gene level. The two candidate genes encode proteins with phosphatase activity, which putatively can be induced by the host to perceive, amplify and transfer signals to downstream components, thus activating a plant defense response.
... Crown rust (caused by Puccinia coronata f. sp. lolli) is a foliar disease that disrupts photosynthesis and accumulation of water-soluble carbohydrates, impairing yield-related traits such as tillering, root growth, and regrowth after cutting [14], as well as persistency [15]. In some perennial ryegrass cultivars, it can reduce yields by up to 30% [16]; moreover, it damages forage quality, potentially leading to health problems in grazing cattle [17] and liver damage in dairy calves [18]. ...
... In some perennial ryegrass cultivars, it can reduce yields by up to 30% [16]; moreover, it damages forage quality, potentially leading to health problems in grazing cattle [17] and liver damage in dairy calves [18]. The effect of crown rust on reproductive capacity of the plants is also well documented; infected plants produce fewer tillers and smaller, lighter seeds, reducing seed yield [14,19,20]. Because the disease also reduces the vigour of perennial ryegrass and lowers its competitiveness, the composition of plant mixtures gradually changes in long-term swards [15,19]. ...
The market success of perennial ryegrass (Lolium perenne L.) cultivars depends on sufficient seed production, as they are propagated by seed. However, breeding for high quality forage production reduces seed yield, and breaking the negative correlation would help to overcome the problem. The foliar disease crown rust is another factor affecting reproductive capacity and thereby seed yield. We evaluated seed yield-related traits and resistance to crown rust in a collection of commercial cultivars and ecotypes of perennial ryegrass and identified genome-wide markers associated with the traits. The study revealed high variation between the ecotype and cultivar groups as well as between years. A genome-wide association study identified 17 DNA single-nucleotide polymorphisms (SNPs) of which eight were associated with crown rust and nine with flag-leaf length. The SNP markers were located within or near predicted genes functioning in defense against pathogens. The identified genes are strong candidates for a further in-depth functional study to continue unravel determination of leaf architecture and crown rust resistance in perennial ryegrass.
... Foliar diseases of ryegrasses caused by fungi belonging to the genus Puccinia are the most damaging, causing a reduction in tillering, root and shoot biomass, and plant regrowth [1]. Consequently, the infection reduces the quality of pastures used for meat, milk, and wool production and damages turf used for recreation [2]. ...
Climate change calls for novel approaches to include environmental effects in future breeding programs for forage crops. A set of ryegrasses (Lolium) varieties was evaluated in multiple European environments for crown rust (Puccinia coronata f. sp. lolii) and stem rust (P. graminis f. sp. graminicola) resistance. Additive Main Effect and Multiplicative Interaction (AMMI) analysis revealed significant genotype (G) and environment (E) effects as well as the interaction of both factors (G × E). Genotypes plus Genotype-by-Environment interaction (GGE) analysis grouped the tested environments in multiple mega-environments for both traits suggesting the presence of an environmental effect on the ryegrasses performances. The best performing varieties in the given mega-environments showed high resistance to crown as well as stem rust, and overall, tetraploid varieties performed better than diploid. Furthermore, we modeled G × E using a marker x environment interaction (M × E) model to predict the performance of varieties tested in some years but not in others. Our results showed that despite the limited number of varieties, the high number of observations allowed us to predict both traits’ performances with high accuracy. The results showed that genomic prediction using multi environmental trials could enhance breeding programs for the crown and stem rust in ryegrasses.
... During infection, the synthesis of several classes of antimicrobial molecules is induced, such as reactive oxygen species (ROS), phytoalexins, phytoanticipins and pathogenesis-related (PR) proteins. Therefore, the plant implements a downstream response to a pathogen-specific attack in an attempt to inhibit colonization by the rust [118]. ...
Flowering time, abiotic stress tolerance and disease resistance are important agronomic traits of forage species like Lolium spp. Understanding the genetic control of these traits is enabled by the combination of genomic tools with conventional breeding techniques. Flowering time in this genus represents a complex trait due to the differences in the primary induction requirements among the species. In total, 36 QTLs (Quantitative Trait Locus) were identified across all seven linkage groups of Italian and perennial ryegrass involved in the flowering pathways, with several putative orthologous/homologous genes that have been characterized in other major crops. From the perspective of climate change, abiotic stress tolerance has become an essential feature; many QTLs that are involved in the control of plant responses have been identified, and transcriptional studies focusing on drought tolerance reported several DEGs (Differentially Expressed Genes) involved in carbon and lipid metabolism and signal transduction. Due to the incidence of microbial diseases, QTLs useful to developing cultivars resistant to bacterial wilt (Xanthomonas translucens pv. graminis), ryegrass crown rust (Puccinia coronata f. sp. Lolii) and gray leaf spot (Magnaporthe grisea/oryzae) have been mapped in both L. perenne and L. multiflorum populations. Due to the great importance of Lolium species, especially as forage crops, additional information about the three aforementioned agronomic traits is needed.
... Cereal grains and forage grasses within the Poaceae are grown on almost every continent on earth and are important sources of nutrition for both humans and grazing ruminants in both developed and developing countries. Rust pathogens (Puccinia spp.) spread from host to host by wind, rain, or human-aided spore migration and are some of the most damaging diseases of cereals (wheat, barley, and oats) and forage grasses (brome grass, ryegrass, and fescue) (Dean et al. 2012;Dracatos et al. 2010). Breeding for genetic resistance is a cost-effective and environmentally responsible method of rust disease control. ...
Barley is an intermediate or near-nonhost to many cereal rust pathogens that infect grasses, making it a highly suitable model to understand the evolution and genetic basis of nonhost resistance (NHR) in plants. To characterise the genetic architecture of NHR in barley, we used the Oregon Wolfe Barley doubled haploid (DH) and Morex x SusPtrit RIL mapping populations. To elicit a wide array of NHR responses, we tested 492 barley accessions and both mapping populations with pathogenically diverse cereal rust isolates representing distinct formae speciales adapted to Avena, Hordeum, Triticum and Lolium spp.: P. coronata f. sp. avenae (Pca; oat crown rust pathogen) and f. sp. lolii (Pcl; ryegrass crown rust pathogen); P. graminis f. sp. avenae (Pga; oat stem rust pathogen) and f. sp. lolii (Pgl; the ryegrass stem rust pathogen); and P. striiformis f. sp. tritici (Pst; wheat stripe rust pathogen) and f. sp. pseudo-hordei (Psph; barley grass stripe rust pathogen). With the exception of Pcl and Pca, susceptibility and segregation for NHR was observed in the barley accessions and both mapping populations. QTLs for NHR were mapped on all seven chromosomes. NHR in barley to the heterologous rusts tested was due to a combination of QTLs with either or both overlapping and distinct specificities. Across both mapping populations, broadly effective NHR loci were also identified that likely play a role in host specialisation.
... Perennial ryegrass (Lolium perenne L.) is cultivated as seed crop in temperate regions 49 of the world. The seeds are typically used for growing forage grass due to its high 50 nutrient content, digestibility, and rapid establishment and regrowth after grazing 51 (Dracatos et al., 2010;Potter, 1987 can also affect leaves laminas, glumes, and awns. Stem rust provokes reductions in the 57 photosynthetic plant area and disruption of nutrient and water transport to the 58 developing inflorescence leading to the production of shriveled seeds. ...
... Error bars306 indicate the standard error of the mean (SEM) (DBI: days before inoculation, caused by rust fungi, e.g. stem rust and crown rust may lead to 311 significant seed yield losses of perennial ryegrass, thus compromising the stability of 312 seed production and yield(Dracatos et al., 2010;Mattner and Parbery, 2007; Pfender, 313 2001;Potter et al., 1990). Fungicides such as azoles, strobilurins, and SDHIs have been 314 widely used to control rust fungi infecting perennial ryegrass(Pfender, 2006(Pfender, , 2009 315 Rijckaert, 2016;Rolston et al., 2009;Welty and Azevedo, 1993). ...
Rust epidemics may have detrimental effects on seed yield in perennial ryegrass (Lolium perenne L.). Field trials comprising two cultivars of perennial ryegrass were established to evaluate the impact of stem rust (Puccinia graminis subsp. graminicola) and crown rust (Puccinia coronata f.sp. lolii) on seed yields. Two or three applications of a mixture of fungicides (epoxiconazole plus boscalid mixed with pyraclostrobin) provided effective control of both stem rust and crown rust and positive seed yield responses, although differences were observed between cultivars. For stem rust, two fungicide applications led to variable levels of disease control (from 86% to 100% for cv. Esquire and from 15% to 98% for cv. Calibra), whereas three applications resulted in 100% disease control in both cultivars. Two fungicide applications were sufficient for an appropriate control of crown rust on both cultivars (approx. 98–100% disease control). Generally, two fungicide applications resulted in an increase in seed yield for both cultivars. On average, an increment of 4% and 15% was observed in Esquire and Calibra equivalent to 86 kg/ha and 352 kg/ha, respectively. Three fungicide applications provided an increase of 2% and 17% in Esquire and Calibra equivalent to 45 kg/ha and 434 kg/ha, respectively. On average, significant differences were only observed in Calibra after two or three fungicide applications. Additionally, results from semi-open field trials testing for preventive and curative effects showed that tebuconazole, pyraclostrobin, picoxystrobin, azoxystrobin, and a mixture of epoxiconazole, pyraclostrobin, and boscalid fungicides resulted in high efficacy in reducing stem rust occurrence, the latter resulted in the largest preventive and curative effect. Experiences from field and semi-open field trials indicated that fungicide mixtures with contrasting modes of actions, e.g., triazoles, strobilurins, and SDHIs, and applied close to the time of inoculation provided an effective control of rust fungi and increased seed yield in perennial ryegrass.
... A clear effect of host origin was observed as only the samples from F. alnus were split into two genetic clusters (Fig. 1), possibly caused by a large number of missing values due to the markers' inability to amplify the targeted regions within that particular group of samples. Several formae speciales may simultaneously infect the same alternate hosts (Dracatos et al. 2010). The 12 microsatellite markers selected in our study were developed for P. coronata f. sp. ...
... This genetic link was not detected in this study, indicating that the importance of R. cathartica in the epidemiology of oat crown rust is unclear. The absence of a genetic link between the samples from oats and R. cathartica underlines that R. cathartica is host also for other formae speciales of P. coronata (Dracatos et al. 2010;Gäumann 1959). Both R. cathartica and F. alnus are prevalent within the studied agricultural area (Mossberg and Stenberg 2003), contributing to the possibility for the fungus to perform its sexual cycle between seasons. ...
The fungus Puccinia coronata Corda. is the causal agent of crown rust on oats (Avena sativa) and grasses and the disease is a major problem in oat production causing devastating yield losses. The population biology of P. coronata in oat fields and on the aecial host in central Sweden was studied to get a deeper understanding of the role of the aecial hosts in the epidemiology of the disease. Samples were collected from the aecial hosts common buckthorn (Rhamnus cathartica) and alder buckthorn (Frangula alnus), and three adjacent spring oat (Avena sativa) fields. Microsatellite markers were used to evaluate the relationships between populations sampled from the different hosts. According to our results F. alnus can be excluded as a part of the oat crown rust disease cycle. The results further show that samples collected from the aecial host were genetically separate from the population sampled in adjacent oat fields. Concurrently, the genotypic variation of P. coronata observed within oat fields was high. No population differentiation was observed within or between samples collected from different fields within the region, suggesting that airborne spores from other than the sampled specimens of the aecial hosts were contributing to the genetic diversity of P. coronata f. sp. avenae in the selected oat fields.
... The correlation between WSC and fructan concentration is expected, as WSC concentration is predominantly made up of sucrose and fructans (Turner et al. 2002). Crown rust resistance in perennial ryegrass is controlled by a range of genes, some of which are race specific (Dracatos et al. 2010) and the prevalence of races varies from environment to environment (Dracatos et al. 2009). Although rust susceptibility is not related to WSC carbohydrate concentration, it has been shown that genotypes with high WSC concentrations are not able to express this potential when heavily infected with crown rust (Smith et al. 1998c). ...
Perennial ryegrass is the most important forage grass used in temperate agriculture. Transgenic perennial ryegrass events with altered fructan biosynthesis have the potential not only to increase animal production by improving digestibility of the grasses, but also to increase pasture intake by the animal due to lower neutral detergent fibre (NDF) concentrations. Transgenic perennial ryegrass plants were shown to have increased (P < 0.05) in fructan concentrations of leaf blades in transgenic T0 events and have thus an increase in water-soluble carbohydrate and in vivo dry matter digestibility concentrations as well as a decrease in the NDF concentration within the plant in spring and summer. These changes in nutritive value have led to an increase in metabolisable energy of up to 1.7 MJ ME·kg DM−1 in selected T0 events compared to FLp418-20 during spring and summer, with no differences in autumn or winter. The field evaluation of these events and the further development of these events using molecular breeding technologies are described in this paper.
