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![Uromyces viciae-fabae hyphal development in the faba bean genotypes following treatment with ([(2-hydroxyphenyl) amino] sulphinyl) acetic acid, 1.1 dimethyl ester (OH-PAS) and D-mannose and in their appropriate controls. Light micrographs are of leaves at 5 days after inoculation. A, Susceptible VF-176. B, V-1271, characterized by the hypersensitive response. C, BPL-261, characterized by a high level of penetration resistance. D, V- 1271 treated with the cinnamyl acid dehydrogenase inhibitor OH-PAS. E, BPL-261 treated with OH-PAS. F, BPL-261 treated with the phosphate scavenger D-mannose.](profile/Diego-Rubiales/publication/23406452/figure/fig1/AS:310213585457160@1450972090710/Uromyces-viciae-fabae-hyphal-development-in-the-faba-bean-genotypes-following-treatment.png)
Uromyces viciae-fabae hyphal development in the faba bean genotypes following treatment with ([(2-hydroxyphenyl) amino] sulphinyl) acetic acid, 1.1 dimethyl ester (OH-PAS) and D-mannose and in their appropriate controls. Light micrographs are of leaves at 5 days after inoculation. A, Susceptible VF-176. B, V-1271, characterized by the hypersensitive response. C, BPL-261, characterized by a high level of penetration resistance. D, V- 1271 treated with the cinnamyl acid dehydrogenase inhibitor OH-PAS. E, BPL-261 treated with OH-PAS. F, BPL-261 treated with the phosphate scavenger D-mannose.
Source publication
ABSTRACT Effects on penetration and hypersensitive resistance of the cinnamyl acid dehydrogenase (CAD) suicide inhibitor ([(2-hydroxyphenyl) amino] sulphinyl) acetic acid, 1.1 dimethyl ester, which suppresses phenylpro-panoid biosynthesis, and of D-mannose, which sequesters phosphate and reduces energy available in host cells, were studied in faba...
Contexts in source publication
Context 1
... (Tables 1 and 2), the behavior of the lines to rust infection was similar. The susceptible line VF-176 was highly susceptible, with no early aborted colonies and more than 4.2 haustoria per colony (Tables 1 and 2). This, together with the lack of HR, explained the large colony size observed in this line (from 32.2 × 10 -2 to 39.1 × 10 -2 mm 2 ) (Fig. 1A). The lines 2N-34, 2N-52, V-1271, and V-1272 showed incomplete pre-and post- cell-penetration resistance. These lines had moderate levels of prepenetration resistance, with ≈5% early aborted colonies and low frequencies of haustorium formation (from 1.3 to 2.8 haus- toria per colony). In addition to low number of haustoria per colony, a ...
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... incomplete pre-and post- cell-penetration resistance. These lines had moderate levels of prepenetration resistance, with ≈5% early aborted colonies and low frequencies of haustorium formation (from 1.3 to 2.8 haus- toria per colony). In addition to low number of haustoria per colony, a high level of HR occurred in these lines (Tables 1 and 2; Fig. 1B). As previously reported (44,45), this HR was late acting and was evident 4 to 5 dai. In general, the number of haustoria per colony at 2 dai implicates penetration resistance. However, we cannot rule out the fact that incipient HR inhibits haustorium development before HR becomes visible, thus reducing the num- ber of haustoria per ...
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... line BPL-261 had a high level of partial resistance, mainly involving pre-cell penetration. BPL-261 had the highest propor- tion of early aborted colonies and the lowest number of haustoria per colony. Thus, BPL-261 had the smallest colony size (Fig. 1C). In BPL-261, the percentage of colonies associated with HR was extremely low (Tables 1 and 2) and HR was not a factor in its ...
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... Compared with controls, OH-PAS significantly increased the frequency of haus- toria per colony. Thus, OH-PAS-treated leaves reached the level of susceptibility observed in the susceptible line VF-176, where the inhibitor had no effect (Table 1). OH-PAS also reduced sig- nificantly the frequency of colonies with macroscopically visible (Table 1; Fig. ...
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... of haus- toria per colony were not different from the water controls (Table 1). The CAD inhibitor slightly but significantly reduced the macro- scopically visible cell death associated with colonies. However, the level of HR in this line was extremely low and, therefore, the reduction in visible cell death did not affect colony size (Table 1; Fig. ...
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... D-mannose completely suppressed early colony abortion and increased the frequency of haustoria per colony, raising it to the level observed in the susceptible line VF- 176. D-mannose also significantly reduced the already low per- centage of HR occurring in this line. Colony size also was in- creased dramatically by D-mannose treatment by >50% (Fig. ...
Citations
... More detailed observations allowed to discern two types of incomplete resistance. The most common was non-hypersensitive resistance (Sillero et al. 2000;Herath et al. 2001) reducing hyphal growth and hampering haustoria formation Rojas-Molina et al. 2007) resulting in reduced epidemic progress despite a compatible interaction (high infection type, this is pustules well formed with no associated macroscopically visible necrosis). Attempts to identify alleles/QTLs (quantitative trait loci) for resistance and the development of DNA markers for nonhypersensitive resistance have been initiated, but no results are reported so far. ...
Faba bean (Vicia faba) is a grain legume crop widely cultivated in temperate areas for food and feed. Its productivity can be constrained by numerous diseases and pests that can be managed by a number of strategies, complemented with the deployment of resistant cultivars in an integrated manner. Few sources of resistance are available to some of them, although their phenotypic expression is usually insufficiently described, and their genetic basis is largely unknown. A few DNA markers have been developed for resistance to rust, ascochyta blight, and broomrape, but not yet for other diseases or pests. Still, germplasm screenings are allowing the identification of resistances that are being accumulated by classical breeding, succeeding in the development of cultivars with moderate levels of resistance. The adoption of novel phenotyping approaches and the unprecedented development of genomic resources along with speed breeding tools are speeding up resistance characterization and effective use in faba bean breeding.
... Inhibition of enzymes involved in the phenylpropanoid pathway (e.g., cinnamyl alcohol dehydrogenase, CAD), previously described to contribute to cell-wall reinforcement, lead to a suppression of HR in Vicia faba-U. fabae and consequently increase of haustoria per colony and colony size [55]. ...
Legume species are recognized for their nutritional benefits and contribution to the sustainability of agricultural systems. However, their production is threatened by biotic constraints with devastating impacts on crop yield. A deep understanding of the molecular and genetic architecture of resistance sources culminating in immunity is critical to assist new biotechnological approaches for plant protection. In this review, the current knowledge regarding the major plant immune system components of grain and forage legumes challenged with obligate airborne biotrophic fungi will be comprehensively evaluated and discussed while identifying future directions of research. To achieve this, we will address the multi-layered defense strategies deployed by legume crops at the biochemical, molecular, and physiological levels, leading to rapid pathogen recognition and carrying the necessary information to sub-cellular components, on-setting a dynamic and organized defense. Emphasis will be given to recent approaches such as the identification of critical components of host decentralized immune response negatively regulated by pathogens while targeting the loss-of-function of susceptibility genes. We conclude that advances in gene expression analysis in both host and pathogen, protocols for effectoromics pipelines, and high-throughput disease phenomics platforms are rapidly leading to a deeper understanding of the intricate host-pathogen interaction, crucial for efficient disease resistance breeding initiatives.
... Conner and Bernier (1982b) categorised faba bean rust reactions depending upon the colony size.On the basis of presence and absence of necrotic area, 16 races were identified (Emeran et al., 2001). Thesame set of differentials were used to group 27 Spanish and Portuguese isolates into 15 physiological races (Del Mar Rojas-Molina et al., 2007) with highest pathogenicity in Egyptian races.German botanist De Barry observed morphological and physiological alteration in faba bean rust pathogen after germination (Bary, 1866). The pathogen establishes infection structure to undertake decisive stages of pathogenesis: attachment, recognition, penetration, proliferation and nutrition. ...
Faba bean is one of the major cool season grain legumes and provides a good source of protein for human and animal consumption. It is considered as a staple food for Middle-East and North-African countries. It makes symbiotic association with the N-fixing bacteria and provides a natural source of fixed atmospheric nitrogen to the soil. Faba bean production is decreasing worldwide, due to various biotic (fungal and viral diseases) and abiotic (heat, frost and drought) factors. All of these factors are directly or indirectly related to seasonal shift due to fluctuating temperature and rainfall. Faba bean rust, Ascochyta blight and chocolate spot are the devastating diseases that can lead to the “no crop” losses. Good understanding on mechanism of disease resistance on host and pathogen virulence is needed to breed for disease resistance. Continuous crop breeding for developing better resistant cultivars is the only choice to ensure the sustainability in production. Environmental factors are the key elements that determine the epidemic development of disease. It is the reason why in some years a disease causes significant yield reduction, but negligible effect in other years. The aim of this review is to provide information on the current and past research on faba bean rust. Presence of different infection types, such as hypersensitive, slow-rusting and adult plant resistance provide good avenues for developing better resistance in the host. Proper utilisation of genetic factor of these responses combined with molecular markers will help in developing varieties with high level of rust resistance. Apart from host resistance, understanding on pathogen variation is equally important. Therefore, a routine survey of pathogen variation is required to prevent possible epidemics caused by the development of virulent pathotypes.
... A number of reports indicate a close relationship between the activity of enzymes involved in lignin biosynthesis such as PAL and disease resistance in plants ( Parlevielet 1995). Inhibition of enzymes involved in the phenylpropanoid pathway, such as cinnamyl alcohol dehydrogenase (CAD), leads to disruption of resistance and hypersensitivity against rust in various lines of faba bean with exception of line BPL-261 which remained unaffected ( Rojas-Molina et al. 2007;Prats et al. 2007). However, the resistance in BPL-261 was prehaustorial in nature, indicating that the phenylpropanoid pathway might not be directly associated with prehaustorial forms of resistance. ...
Ten recombinant inbred lines (RILs) of pea were selected, on the basis of rust (Uromyces fabae) reaction under screenhouse conditions and molecular makers associated with rust resistance, to study the association of lignification and early abortive fungal colonies in response to attack of U. fabae. The present investigation indicated that partial resistance to rust in pea, as measured by the area under disease progress curve (AUDPC), is negatively influenced by lignification (r = −0.48). Histological studies indicated a higher number of early abortive fungal colonies and delayed development of colonies in resistant RILs than susceptible ones. Furthermore, investigations into the association of phenylalanine ammonia lyase activity and total phenolics during the partial resistance reaction to U. fabae in pea revealed a very low correlation with AUDPC in the RILs. This study infers that lignification plays a major role and is the best indicator of partial resistance towards U. fabae in pea, by influencing colony size and the number of early abortive colonies.
... Legumes utilize flavonoids, notably isoflavones and isoflavanones, to defend themselves against physical injury and pathogens. Many of these effects appear to be related to their ability to modulate cell-signaling pathways [75]. ...
Faba bean is an important food crop worldwide. However, progress in faba bean genomics lags far behind that of model systems due to limited availability of genetic and genomic information. Using the Illumina platform the faba bean transcriptome from leaves of two lines (29H and Vf136) subjected to Ascochyta fabae infection have been characterized. De novo transcriptome assembly provided a total of 39,185 different transcripts that were functionally annotated, and among these, 13,266 were assigned to gene ontology against Arabidopsis . Quality of the assembly was validated by RT-qPCR amplification of selected transcripts differentially expressed. Comparison of faba bean transcripts with those of better-characterized plant genomes such as Arabidopsis thaliana , Medicago truncatula and Cicer arietinum revealed a sequence similarity of 68.3%, 72.8% and 81.27%, respectively. Moreover, 39,060 single nucleotide polymorphism (SNP) and 3,669 InDels were identified for genotyping applications. Mapping of the sequence reads generated onto the assembled transcripts showed that 393 and 457 transcripts were overexpressed in the resistant (29H) and susceptible genotype (Vf136), respectively. Transcripts involved in plant-pathogen interactions such as leucine rich proteins (LRR) or plant growth regulators involved in plant adaptation to abiotic and biotic stresses were found to be differently expressed in the resistant line. The results reported here represent the most comprehensive transcript database developed so far in faba bean, providing valuable information that could be used to gain insight into the pathways involved in the resistance mechanism against A . fabae and to identify potential resistance genes to be further used in marker assisted selection.
... Genes involved in secondary metabolism were also detected. Legumes utilize flavonoids, notably isoflavones and isoflavanones, for defence against pathogens and as signalling molecules, with a number of phenylpropanoids having antimicrobial activity and restricting pathogen growth and disease symptoms [69]. In group G, we identified a "reticuline oxidase-like protein", up regulated in non-race-specific resistance to stripe rust in wheat [70], an "isoflavone 2′-hydroxylase" from the isoflavonoid pathway [71] and a "dihydroflavonol-4-reductase" catalysing the first enzymatic step in anthocyanin biosynthesis, in the flavonoid pathway [72]. ...
Background
Grass pea (Lathyrus sativus L.) is a valuable resource for potentially durable partial resistance to rust. To gain insight into the resistance mechanism and identify potential resistance genes, we generated the first comprehensive transcriptome assemblies from control and Uromyces pisi inoculated leafs of a susceptible and a partially rust-resistant grass pea genotype by RNA-seq.Results134,914 contigs, shared by both libraries, were used to analyse their differential expression in response to rust infection. Functional annotation grouped 60.4% of the contigs present in plant databases (37.8% of total) to 33 main functional categories, being ¿protein¿, ¿RNA¿, ¿signalling¿, ¿transport¿ and ¿stress¿ the most represented. Transcription profiles revealed considerable differences in regulation of major phytohormone signalling pathways: whereas Salicylic and Abscisic Acid pathways were up-regulated in the resistant genotype, Jasmonate and Ethylene pathways were down-regulated in the susceptible one. As potential Resistance-genes we identified a mildew resistance locus O (MLO)-like gene, and MLO-related transcripts. Also, several pathogenesis-related genes were up-regulated in the resistant and exclusively down regulated in the susceptible genotype. Pathogen effectors identified in both inoculated libraries, as e.g. the rust Rtp1 transcript, may be responsible for the down-regulation of defence-related transcripts. The two genotypes contained 4,892 polymorphic contigs with SNPs unevenly distributed between different functional categories. Protein degradation (29.7%) and signalling receptor kinases (8.2%) were the most diverged, illustrating evolutionary adaptation of grass pea to the host/pathogens arms race.Conclusions
The vast array of novel, resistance-related genomic information we present here provides a highly valuable resource for future smart breeding approaches in this hitherto under-researched, valuable legume crop.
... A relatively high proportion of germlings failing to form any haustoria in mesophyll cells causing "early aborted colonies" has been observed in some pea accessions (Table 2). Probably, epidermal cells developed papillae and/or cell wall strengthening under the site of the attempted attack avoiding the fungus penetration, as described previously in other plant-rust interactions (Prats et al. 2007b;Rojas-Molina et al. 2007). Further studies are currently carried out to study host cell (Sillero et al. 2012) and U. viciaefabae (Sillero et al. 2000;Sillero & Rubiales 2002), respectively. ...
Pea is the second most important food legume crop in the world. Rust is a pea disease widely distributed, particularly in regions with warm, humid weather. Pea rust can be incited by Uromyces viciae-fabae and by U. pisi. U. viciae-fabae prevails in tropical and subtropical regions such as India and China, while U. pisi prevails in temperate regions. Chemical control of rust is possible, but the use of host plant resistance is the most desired means of rust control. In this paper we revise and discuss the occurrence and incidence of both pathogens on peas, the availability of resistance sources and the present state of the art in pea breeding against this disease.
... The accumulation of plant autofluorescent compounds in response to the penetration of plant cells by pathogenic fungi is known to occur in several interactions between plants and pathogens, with fluorescence being attributed to the presence of phenolic compounds that, when accumulated in mesophyll cells, can lead to lignification of plant cell walls, cell death and papillae formation (Rojas-Molina et al. 2007;Bozkurt et al. 2010). In the resistant genotypes assessed in our study we found that there was an increase in the production of plant autofluorescent compounds over time, with the autofluorescence we observed in Toropi cells resembling that described for autofluorescent cells associated with broad bean (Viciae faba) plants partially-resistant to infection with Uromyces viciae-fabae (Rojas-Molina et al. 2007). ...
... The accumulation of plant autofluorescent compounds in response to the penetration of plant cells by pathogenic fungi is known to occur in several interactions between plants and pathogens, with fluorescence being attributed to the presence of phenolic compounds that, when accumulated in mesophyll cells, can lead to lignification of plant cell walls, cell death and papillae formation (Rojas-Molina et al. 2007;Bozkurt et al. 2010). In the resistant genotypes assessed in our study we found that there was an increase in the production of plant autofluorescent compounds over time, with the autofluorescence we observed in Toropi cells resembling that described for autofluorescent cells associated with broad bean (Viciae faba) plants partially-resistant to infection with Uromyces viciae-fabae (Rojas-Molina et al. 2007). Similar autofluorescent compounds have been reported in oat genotypes partially-resistant to P. coronata and powdery mildew caused by Erysiphe graminis f. sp. ...
Leaf rust, caused by the fungus Puccinia triticina is a major disease of wheat (Triticum aestivum) worldwide. This disease is prevalent in southern South America where the environmental conditions and high genetic variability of P. triticina favour epidemics. The primary means of controlling pathogenic P. triticina races has been through using wheat varieties containing race-specific resistance genes. The defence mechanisms involved in durable race non-specific resistance to P. triticina are probably distinct from those involved in non-durable race-specific resistance. We investigated the histological components of resistance to P. triticina present in three wheat genotypes: the race non-specific resistant Brazilian variety Toropi; the race-specific resistant line RL6010 Lr9; and the susceptible Brazilian variety BRS 194. Plants of these three genotypes were inoculated with P. triticina race MFP and tissue samples excised from flag leaves at various times after inoculation to assess the number of infective structures, frequency of cell death and the accumulation of autofluorescent cells and hydrogen peroxide. The genotypes showed different resistance mechanisms active at different times during the infection process. Our results for Toropi indicate that there was a reduction in the extent of formation of stomatal appressoria and all subsequent structures. During attempted penetration we also observed the production of autofluorescent compounds and late cell death, but not peroxide formation. This non-specific resistance to P. triticina involves both pre-haustorial and post-haustorial mechanisms which may be responsible for maintaining the low disease severity observed in this variety even under high inoculum pressure.
... This HR, associated with late-acting programmed cell death, has also been reported in other interactions between plants and biotrophic fungi, such as that between faba bean and U. viciae-fabae or between barley and Blumeria graminis f.sp. hordei (Rojas-Molina et al., 2007;Prats et al., 2010). According to the macroscopic assessment the combination of both early and late cell death was the most efficient response reducing IF, whereas the late cell death observed in cv. ...
... Primula, which affected only some of the mesophyll cells penetrated by the fungus, delayed the time of sporulation but did not greatly reduce the IF. This limited effect of late-acting cell death was also observed in faba bean and barley attacked by rust and powdery mildew, respectively (Rojas-Molina et al., 2007;Prats et al., 2010). As the isolate used here was avirulent against Pc52 and Pc59, this effect could be due to the result of the presence of either of these genes, or unidentified ones. ...
An isolate of Puccinia coronata f.sp. avenae with virulence against the oat crown rust resistance gene Pc94 was discovered in oat fields in Córdoba, Spain. In order to identify alternative sources of resistance to this virulent isolate, a collection of 159 Avena accessions, including 107 A. sativa and 29 A. byzantina landraces and 23 commercial A. sativa and A. strigosa cultivars, was screened. Eight resistant landraces and four cultivars were selected according to macroscopic assessment to further characterize the operative defence mechanisms. Histological studies showed a range of defence mechanisms, acting alone or in combination, which impeded fungal development at different stages. Some accessions allowed reduced fungal growth before mesophyll penetration. In others, the fungus was arrested at the penetration stage by mesophyll cell wall strengthening and/or papilla deposition. Mesophyll cells of several accessions were penetrated by the fungus, but then the hypersensitive response (HR) leading to cell death hampered fungal development. In some cases cell death was very fast and colonies aborted early, whereas in other cases necrosis was observed later and associated with numerous secondary hyphae, suggesting a slow HR. Characterization of defence mechanisms will be useful for breeding programmes and for further cellular and molecular studies to unravel the bases of resistance. Commonalities with the resistance of the same oat collection to powdery mildew are discussed.
... Microscopically it is seen as reduced hyphal growth that hampers the formation of haustoria, resulting in a significant proportion of infection units failed to form any haustoria and in those that successfully form some, they are of smaller size (Sillero and Rubiales, 2002;Rubiales and Sillero, 2003). This penetration resistance is reduced by application of disruptors of energy metabolism such as D-mannose, but not by inhibition of cinnamyl acid dehydrogenase (CAD), involved in the lignin synthesis pathway (Rojas-Molina et al., 2007) what resembles resistance to penetration in mlo-barleys (Lyngkjaer et al., 1997). ...
... Isolation of haustoria confirmed that both the number and the size of haustoria were reduced in resistant lines, irrespective of whether the resistance was associated with hypersensitivity or not . The importance of the lignin metabolic pathway in hypersensitive resistance is supported by the suppression of hypersensitivity expression by CAD inhibition (Rojas-Molina et al., 2007). The existence of races of U. viciae-fabae reinforces the need to look for additional genes and to implement strategies to increase durability of the resistance. ...
Faba bean is a major grain legume widely cultivated in many countries for food and feed purposes. A number of aerial fungi, together with soil-borne pathogens associated with foot and root rot complexes, nematodes, parasitic weeds and viruses may cause severe diseases in faba bean crops. The use of genetic resistance is the most economical and environmentally friendly control method. However, to date no efficient sources of resistance have been described to some diseases, or it is scarce and of complex nature, making necessary the implementation of other control measures. Phenotypic expression of resistance is usually poorly described. As a consequence of this, and of the poorly developed genomic resources available, the genetic basis of resistances is, in most cases, largely unknown. Effectiveness of MAS might soon increase with the adoption of new improvements in marker technology together with the integration of comparative mapping and functional genomics. In this paper we will review and critically discuss current and future strategies on breeding faba bean for disease resistance.
