Phomopsis stem blight (PSB) caused by Diaporthe toxica is a major disease in narrow-leafed lupin ( Lupinus angustifolius L.). The F(2) progeny and the parental plants from a cross between a breeding line 75A:258 (containing a single dominant resistance gene Phr1 against the disease) and a commercial cultivar Unicrop (susceptible to the disease) were used for development of molecular markers linked to the disease resistance gene. Two pairs of co-dominant DNA polymorphisms were detected using the microsatellite-anchored fragment length polymorphism (MFLP) technique. Both pairs of polymorphisms were isolated from the MFLP gels, re-amplified by PCR, sequenced, and converted into co-dominant, sequence-specific and PCR-based markers. Linkage analysis by MAPMAKER suggested that one marker (Ph258M2) was 5.7 centiMorgans (cM) from Phr1, and the other marker (Ph258M1) was 2.1 cM from Ph258M2 but further away from Phr1. These markers are suitable for marker-assisted selection (MAS) in lupin breeding.
The distinctness of, and overlap between, pea genotypes held in several Pisum germplasm collections has been used to determine their relatedness and to test previous ideas about the genetic diversity of Pisum. Our characterisation of genetic diversity among 4,538 Pisum accessions held in 7 European Genebanks has identified sources of novel genetic variation, and both reinforces and refines previous interpretations of the overall structure of genetic diversity in Pisum. Molecular marker analysis was based upon the presence/absence of polymorphism of retrotransposon insertions scored by a high-throughput microarray and SSAP approaches. We conclude that the diversity of Pisum constitutes a broad continuum, with graded differentiation into sub-populations which display various degrees of distinctness. The most distinct genetic groups correspond to the named taxa while the cultivars and landraces of Pisum sativum can be divided into two broad types, one of which is strongly enriched for modern cultivars. The addition of germplasm sets from six European Genebanks, chosen to represent high diversity, to a single collection previously studied with these markers resulted in modest additions to the overall diversity observed, suggesting that the great majority of the total genetic diversity collected for the Pisum genus has now been described. Two interesting sources of novel genetic variation have been identified. Finally, we have proposed reference sets of core accessions with a range of sample sizes to represent Pisum diversity for the future study and exploitation by researchers and breeders.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-012-1839-1) contains supplementary material, which is available to authorized users.
A total of 298 bacterial isolates were collected from pea cultivars, landraces and breeding lines in North-Central Spain over several years. On the basis of biochemical-physiological characteristics and molecular markers, 225 of the isolates were identified as Pseudomonas syringae, either pv. pisi (110 isolates) or pv. syringae (112), indicating that pv. syringae is as frequent as pv. pisi as causal agent of bacterial diseases in pea. Most strains (222) were pathogenic on pea. Further race analyses of P. syringae pv. pisi strains identified race 4 (59.1% of the isolates of this pathovar), race 2 (20.0%), race 6 (11.8%), race 5 (3.6%) and race 3 (0.9%). Five isolates (4.6%) showed a not-previously described response pattern on tester pea genotypes, which suggests that an additional race 8 could be present in P. syringae pv. pisi. All the isolates of P. syringae pv. syringae were highly pathogenic when inoculated in the tester pea genotypes, and no significant pathogenic differences were observed. Simultaneous infections with P. syringae pv. pisi and pv. syringae in the same fields were observed, suggesting the importance of resistance to both pathovars in future commercial cultivars. The search for resistance among pea genotypes suitable for production in this part of Spain or as breeding material identified the presence of resistance genes for all P. syringae pv. pisi races except for race 6. The pea cultivars Kelvendon Wonder, Cherokee, Isard, Iceberg, Messire and Attika were found suitable sources of resistance to P. syringae pv. syringae.
A total of 122 accessions of different wild and cultivated Pisum sp. were analysed using retrotransposon-based insertion polymorphisms (RBIP) markers. The Pisum materials included wild and cultivated (landraces and cultivars) materials from the World core collection of the John Innes Centre (JI) representing all generally recognized Pisum taxa, landraces materials from the Spanish core collection, and commercial pea cultivars largely sown in Spain. The overall polymorphism detected by RBIP marker was high and all accessions, except two pairs, could be distinguished by their marker pattern. Principal component and phylogenetic analyses clearly discriminated P. fulvum and P. abyssinicum samples from both each other and P. sativum, while P. elatius and P. humile samples were scattered among the other taxa clusters, supporting the existence of three well defined taxa in the genus Pisum (P. abyssinicum, P. fulvum and P. sativum). These results also suggest that the Spanish pea core collection of landraces maintains a relatively high variability which is only partially represented in cultivars generally sown in Spain. Thus, Spanish landraces are still a source of genetic variability for breeding new pea cultivars.Additional key words: genetic resources, Pisum abyssinicum, Pisum fulvum, Pisum sativum, RBIP markers. ResumenDiversidad genética en variedades locales y cultivares españoles de guisante (Pisum sativum L.) y en la colección nuclear mundial de Pisum estimada mediante polimorfismo de inserción de retrotransposones (RBIP)Se ha estudiado un total de 122 accesiones silvestres y cultivadas de Pisum sp. usando marcadores basados en polimorfismos de inserción de retrotransposones (RBIP). Las accesiones de Pisum incluyen materiales silvestres y cultivados (cultivares y variedades locales) de la colección nuclear mundial del John Innes Centre (JI) representando a todos los taxones generalmente reconocidos de Pisum, variedades locales de la colección nuclear española, y por úl-timo algunas variedades comerciales de guisante ampliamente cultivadas en España. Para el análisis genético se usaron 18 loci RBIP. El polimorfismo general detectado con los marcadores RBIP fue alto y todas las muestras, excepto dos pares, pudieron ser identificadas por un patrón particular de marcadores. Análisis de componentes principales y filogenéticos discriminaron claramente P. fulvum y P. abyssinicum entre ellas y de P. sativum, mientras que las muestras de P. humile y P. elatius se mezclaban con las de otros taxones en distintos grupos. Esto apoya la existencia de tres especies en el género Pisum (P. abyssinicum, P. fulvum y P. sativum). Los resultados indican que la colección nuclear española de guisante mantiene una variabilidad relativamente elevada que está sólo parcialmente representada en los cultivares generalmente sembrados en España. Por tanto, las variedades locales españolas representan aún una fuente de variabilidad genética para la mejora de nuevos cultivares.
BackgroundFrost is one of the main abiotic stresses limiting plant distribution and crop production. To cope with the stress, plants evolved adaptations known as cold acclimation or chilling tolerance to maximize frost tolerance. Cold acclimation is a progressive acquisition of freezing tolerance by plants subjected to low non-freezing temperatures which subsequently allows them to survive exposure to frost. Lentil is a cool season grain legume that is challenged by winter frost in some areas of its cultivation.ResultsTo better understand the genetic base of frost tolerance differential gene expression in response to cold acclimation was investigated. Recombinant inbred lines (RILs) from the cross Precoz x WA8649041 were first classified as cold tolerant or cold susceptible according to their response to temperatures between −3 to −15 °C. Then, RILs from both extremes of the response curve were cold acclimated and the leaf transcriptomes of two bulks each of eight frost tolerant and seven cold susceptible RILs were investigated by Deep Super-SAGE transcriptome profiling. Thus, four RNA bulks were analysed: the acclimated susceptible, the acclimated tolerant and the respective controls (non-acclimated susceptible and non-acclimated tolerant). Approximately 16.5 million 26 nucleotide long Super-SAGE tags were sequenced in the four sets (between ~3 and 5.4 millions). In total, 133,077 different unitags, each representing a particular transcript isoform, were identified in these four sets. Tags which showed a significantly different abundance in any of the bulks (fold change ≥4.0 and a significant p-value <0.001) were selected and used to identify the corresponding lentil gene sequence. Three hundred of such lentil sequences were identified. Most of their known homologs coded for glycine-rich, cold and drought-regulated proteins, dormancy-associated proteins, proline-rich proteins (PRPs) and other membrane proteins. These were generally but not exclusively over-expressed in the acclimated tolerant lines.ConclusionsThis set of candidate genes implicated in the response to frost in lentil represents an useful base for deeper and more detailed investigations into this important agronomic trait in future.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-017-1057-8) contains supplementary material, which is available to authorized users.
Pseudomonas syringae pv. syringae causes extensive yield losses in the pea crop worldwide, although there is little information on its host specialization and its interactions with pea. A collection of 88 putative P. syringae pv. syringae strains (including 39 strains isolated from pea) was characterized by repetitive polymerase chain reaction (rep-PCR), multilocus sequence typing (MLST), and syrB amplification and evaluated for pathogenicity and virulence. rep-PCR data grouped the strains from pea into two groups (1B and 1C) together with strains from other hosts; a third group (1A) was formed exclusively with strains isolated from non-legume species. MLST data included all strains from pea in the genomospecies 1 of P. syringae pathovars defined in previous studies; they were distributed in the same three groups defined by rep-PCR. The inoculations performed in two pea cultivars showed that P. syringae pv. syringae strains from groups 1A and 1C were less virulent than strains from group 1B, suggesting a possible pathogenic specialization in this group. This study shows the existence of genetically and pathogenically distinct P. syringae pv. syringae strain groups from pea, which will be useful for the diagnostic and epidemiology of this pathogen and for disease resistance breeding.
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