High resolution mapping of a novel late blight resistance gene Rpi-avll, from the wild Bolivian species Solanum avilesii

Both Mexico and South America are rich in Solanum species that might be valuable sources of resistance (R) genes to late blight (Phytophthora infestans). Here, we focus on an R gene present in the diploid Bolivian species S. avilesii. The genotype carrying the R gene was resistant to eight out of 10 Phytophthora isolates of various provenances. The identification of a resistant phenotype and the generation of a segregating population allowed the mapping of a single dominant R gene, Rpi-avl1, which is located in an R gene cluster on chromosome 11. This R gene cluster is considered as an R gene “hot spot”, containing R genes to at least five different pathogens. High resolution mapping of the Rpi-avl1 gene revealed a marker co-segregating in 3890 F1 individuals, which may be used for marker assisted selection in breeding programs and for further cloning of Rpi-avl

SolRgene: an online database to explore disease resistance genes in tuber-bearing Solanum species

Background The cultivated potato (Solanum tuberosum L.) is an important food crop, but highly susceptible to many pathogens. The major threat to potato production is the Irish famine pathogen Phytophthora infestans, which causes the devastating late blight disease. Potato breeding makes use of germplasm from wild relatives (wild germplasm) to introduce resistances into cultivated potato. The Solanum section Petota comprises tuber-bearing species that are potential donors of new disease resistance genes. The aim of this study was to explore Solanum section Petota for resistance genes and generate a widely accessible resource that is useful for studying and implementing disease resistance in potato. Description The SolRgene database contains data on resistance to P. infestans and presence of R genes and R gene homologues in Solanum section Petota. We have explored Solanum section Petota for resistance to late blight in high throughput disease tests under various laboratory conditions and in field trials. From resistant wild germplasm, segregating populations were generated and assessed for the presence of resistance genes. All these data have been entered into the SolRgene database. To facilitate genetic and resistance gene evolution studies, phylogenetic data of the entire SolRgene collection are included, as well as a tool for generating phylogenetic trees of selected groups of germplasm. Data from resistance gene allele-mining studies are incorporated, which enables detection of R gene homologs in related germplasm. Using these resources, various resistance genes have been detected and some of these have been cloned, whereas others are in the cloning pipeline. All this information is stored in the online SolRgene database, which allows users to query resistance data, sequences, passport data of the accessions, and phylogenic classifications. Conclusion Solanum section Petota forms the basis of the SolRgene database, which contains a collection of resistance data of an unprecedented size and precision. Complemented with R gene sequence data and phylogenetic tools, SolRgene can be considered the primary resource for information on R genes from potato and wild tuber-bearing relatives

Partial resistance to late blight (Phytophthora infestans) in hybrid progenies of four South American Solanum species crossed with diploid S. Tuberosum

Resistant genotypes of the diploid tuber-bearing South American species Solanum arnezii × hondelmannii, S. berthaultii, S. leptophyes and S. microdontum were crossed with three diploid genotypes of S. tuberosum that varied in resistance and maturity type. The progenies were field tested for 2 years for resistance to a complex race of Phytophthora infestans. A wealth of genetic variation for resistance was found in most of the progenies. At least two susceptibility groups could be distinguished in some progenies of S. microdontum. This could be explained by the presence of several major resistance genes in the wild parent and, unexpectedly, in the susceptible parent SH 82-44-111. In most of the wild parents and in the Susceptible parent SH 77-114-2988 there appeared to be minor resistance genes. General combining ability effects were predominant; small specific combining ability effects were detected in some crosses of S. microdontum. Gene action appeared dominant in some crosses.

Vierjarig Phytophthora-onderzoek afgerond : wordt Phytophthora een beheersbare factor in de biologische aardappelteelt? : deel 2: resistente rassen

Tweede artikel van een serie van drie over een vierjarig onderzoek van het Louis Bolk Instituut en Plant Research International naar Phytophthora infestans. In veldproeven werden een groot aantal Phytophthora-resistente rassen geteeld onder sterke infectiedruk en beoordeeld op opbrengst en kwaliteit, en de relatie tussen groeiduur en opbrengst. Ook werd gekeken naar de mogelijkheden om de resistentie te versterken door sturing van het stikstofaanbod en door toepassing van endofytische bacterieën die de schimmel kunnen remme

Vierjarig Phytophthora-onderzoek afgerond : wordt Phytophthora een beheersbare factor in de biologische aardappelteelt? : deel 2: resistente rassen

Tweede artikel van een serie van drie over een vierjarig onderzoek van het Louis Bolk Instituut en Plant Research International naar Phytophthora infestans. In veldproeven werden een groot aantal Phytophthora-resistente rassen geteeld onder sterke infectiedruk en beoordeeld op opbrengst en kwaliteit, en de relatie tussen groeiduur en opbrengst. Ook werd gekeken naar de mogelijkheden om de resistentie te versterken door sturing van het stikstofaanbod en door toepassing van endofytische bacterieën die de schimmel kunnen remme

Leaf position prevails over plant age and leaf age in reflecting resistance to late blight in potato

The effects of plant age, leaf age, and leaf position on race-nonspecific resistance against Phytophthora infestans were investigated in a series of field and controlled environment experiments with five different potato (Solanum tuberosum) cultivars. Leaf position proved to be the most significant factor; apical leaves were far more resistant to late blight than basal leaves. Plant age and leaf age had only minor effects; therefore, the resistance of a specific leaf remained about the same during its entire lifetime. The gradual increase in late blight resistance from basal leaves to apical leaves appeared to be a general effect, irrespective of cultivar, growing conditions, or resistance test. Therefore, it is important to consider leaf position in tests for late blight resistance, because contrasts in resistance may be ascribed erroneously to differences between genotypes or treatments. whereas they are actually caused by differences in leaf position

Ultraviolet, optical and infra-red observations of the wolf-rayet contact-eclipsing binary CQ cephei

SIGLELD:8053.4155(RAL--84-005) / BLDSC - British Library Document Supply CentreGBUnited Kingdo