Stem Rust Resistance in 1BL.1RS and 2RL.2BS Double Wheat-Rye Translocation Lines

The wheat stem rust pathogen, Puccinia graminis f.sp. tritici, is a significant and devastating disease of wheat crops worldwide. Wheat has many wild relatives in which to source new resistance genes, including the cereal crop of rye in the tertiary genepool. The aim of this study was to assess the reaction of 1BL.1RS and 2RL.2BS double wheat-rye translocation lines to virulent stem rust races from Africa and North America. BC1F3 and BC1F4 populations from a cross between the line KR99-139 (a double wheat-rye translocation line with 1BL.1RS and 2RL.2BS) and the bread wheat cultivar Topper were used in the study. Several of the populations homozygous for 1BL.1RS and heterozygous for 2RL.2BS showed resistance and low severity adult plant resistance (20RMR-50MSS) to the African stem rust race TTKSK in the field. None of the tested populations with varying chromosome combinations showed seedling resistance to any of the tested stem rust races. Thus, these resistant populations likely carry gene/s effective at the adult plant stage since all stage resistance genes with major effect appear to be absent based on the seedling assays. Resistant lines combined three chromosomes (1RS, 2RS and 2BS) which make their direct use in breeding more complicated. Mapping studies followed by potential transfer of genes between 2R and 2B will make the identified minor genes more useful in wheat breeding

Cultivar fingerprinting and SNP-based pedigree reconstruction in Danish heritage apple cultivars utilizing genotypic data from multiple germplasm collections in the world

Heirloom Danish apple cultivars are historically and pomologically important, part of the cultural heritage, and have valuable adaptation to regional climate conditions. However, lack of information about their genetic identity and pedigree relatedness with other cultivars hampers proper cultivar identification, germplasm curation, genebank management, and future regional breeding efforts. Many Danish apple cultivars are maintained in the national collection “The Pometum”, maintaining around 850 apple accessions. Additional material is maintained in public or private Danish collections. However, no information exists regarding genotypic duplicates between these collections and germplasm collections in other countries, pedigree inferences across collections, and genotypically unique accessions at the genebank level. To provide such information, 976 accessions from Denmark were genotyped with simple sequence repeat (SSR) markers and the Illumina Infinium 20K single nucleotide polymorphism (SNP) array. The resulting genotypic data were compared to large databases of genotypic data from germplasm collections in multiple countries to identify genotypic duplicates and conduct pedigree reconstruction. The germplasm maintains 305 unique genotypic profiles which were not found in other germplasm collections. The study exposed previously unknown synonyms, accessions not true-to-type, and novel pedigree relationships involving accessions from multiple collection sites. The most frequent parents of Danish germplasm were ‘Hvid Vinter Pigeon’ and ‘Cox’s Orange Pippin’ whereas ‘Reinette Franche’ was the most common grandparent. The accession-level information will benefit germplasm curation, cultivar identification, genebank management, and future breeding efforts, and shed new light on cultivar history and origi

Molecular and morphological diversity in the plant genus Chaenomeles

In this paper, five studies on diversity in the plant genus Chaenomeles are summarised. Genetic resources in the genus Chaenomeles were evaluated using molecular markers and morphological characters. Population differentiation and diversity were estimated in cultivated and wild plant material. In agreement with studies on cultivated Chaenomeles material, native material of C. japonica was strongly differentiated from C. speciosa, C. cathayensis and C. thibetica. Populations of C. japonica and C. speciosa were considerably more diverse than populations of C. cathayensis and C. thibetica. Furthermore, evidence of spontaneous hybridisation in native populations between C. cathayensis and C. speciosa was obtained. Random amplified polymorphic DNA markers and morphological characters revealed concordant patterns of genetic relatedness among the offspring families studied. To increase diversity in breeding populations and collections, different strategies for sampling of wild plant material are proposed for C. japonica and C. speciosa on the one hand, and C. cathayensis and C. thibetica on the other

När pesten kommer till fruktodlingarna

En av de mest fruktade sjukdomarna på fruktträd är päronpest, som på engelska har det mera passande namnet ‘fire blight’. Denna sjukdom orsakas av den nordamerikanska bakterien Erwinia amylovora som attackerar - och dödar - olika medlemmar av växtfamiljen Rosaceae, rosväxter. Angreppen börjar ofta i blommorna, sprider sig snabbt ner i grenverket och kan döda ett helt fruktträd på några veckor. Sålunda tog päronpesten livet av nära en tredjedel av den amerikanska äpplegenbanken i Geneva, staten New York, i början av 2000-talet. Dessvärre emigrerade några exemplar av denna bakterie till Europa redan ett halvt århundrade tidigare. Här har sjukdomen på senare tid spridit sig från Europas sydliga och västliga delar till mera nordostliga områden. I vårt grannland Danmark har sjukdomen varit synlig av och till sedan 1968. Nyligen blev den danska pärongenbanken på Pometet i Tåstrup utanför Köpenhamn så illa angripen att man bestämde sig för att hugga ner alla träden! Kraftiga angrepp har även noterats i Baltstaterna under senare år

Konsten att särskilja olika sorter av körsbär

Vildväxande fågelbär brukar väl inte smaka så märkvärdigt, men långvarigt urval i denna art har resulterat i dagens betydligt mumsigare sötkörsbär. I Sverige var klosterträdgårdarna först med att odla ‘fina’ körsbär från utlandet men snart fick även ägarna till diverse slott och herresäten upp ögonen för dessa delikatesser. Här etablerades både odlingar och plantskolor redan på 1500-talet. Under 1700- och första hälften av 1800-talet var speciellt Östergötland känt för sina omfattande körsbärsodlingar. Några av den tidens sortnamn är olika former av amareller, moreller och bigarråer (röda, gula, markbrés, svarta), Maikirschen, Spanska kirsebär, Brysselska Bruna, Oranienkirschen, Prinzenkirschen, Prinzessinkirschen, Kentiska röda, May Dukes, Pragiska muskateller, van der Natt, Weichsel von Montmorency och Doctor-Kirsche (Fernqvist, 1988). Även brunkörsbär och klarbär nämns i Nilssons (1989) pomologi och anses ha spridit sig från gård till gård som rotäkta plantor. Flera av dagens körsbärssorter är alltså mycket gamla. Ofta används dessutom samma namn på sorter som faktiskt är genetiskt olika (Fernqvist, 1988; Nilsson, 1989). Betydande variation i både utseende och DNA-profiler har man exempelvis hittat i surkörsbärssorterna Sumadinka och Stevnsbaer, och i sötkörsbärssorten Sam (Pedersen, 2006). Skillnaderna mellan de olika klonerna av samma sort var betydligt större än vad skillnader orsakade av mutationer brukar vara. Uppenbarligen härstammar dessa kloner alltså istället från olika fröplantor. Och då borde de INTE ha samma sortnamn! Samma problem, dvs olika DNA-profiler hos träd med samma sortnamn samt även det motsatta problemet (olika namn men samma DNA-profil) förekom mycket frekvent i en stor undersökning av körsbärsgenbanker i Schweiz (Frei m.fl., 2010). Sortnamnet Napoleon visade sig till exempel vara synonymt med sju andra namn! I Sverige har 29 sorter (både sötkörsbär och surkörsbär) tilldelats status som mandatsorter, och dessa ska alltså bevaras inom landet (Hjalmarsson, 2007). Med finansiering från Jordbruksverket har forskare på Balsgård nyligen utvecklat DNA-baserade fingeravtryck för merparten av dessa mandatsorter. Avsikten är att genbankskuratorer, forskare, växtförädlare, yrkesodlare och allmänheten, nu och i framtiden, ska kunna särskilja sorterna och använda korrekta namn

Rätt namn på päronen med hjälp av DNA-markörer

Många länder har numera inrättat program för att samla in, bevara och karaktärisera genetiska resurser av viktiga nyttoväxter. Har de intressanta egenskaper, kan de ju komma till användning i framtiden, antingen som de är eller som föräldrar i ett korsningsprogram inom växtförädlingen. I Sverige bevarar man därför ‘mandatsorter’ av exempelvis frukt och bär, dvs sorter som uppkommit i Sverige eller som har haft en lång och viktig odlingshistoria här. Hittills har 57 olika päronsorter fått status av mandatsort. Flertalet av dessa bevaras i något av de 11 klonarkiven runt om i landet. Den största samlingen av päronsorter finns dock på Balsgård-SLU, med drygt ett 100-tal namngivna sorter varav 30 mandatsorter. För många av de äldre sorterna är ursprunget okänt, och man vet ibland inte ens vilket land de kommit från

Problem med fruktsättningen på dina äppleträd?

Äppleträd dignande av vacker och välsmakande frukt…. ja, detta ser nog alla framför sig när de planterar nyinköpta äppleträd. Men det finns många fallgropar. Förutom alla de vanliga problemen med olämplig jord, torka, vårfrost, otrevliga insektsangrepp och ännu otrevligare svampsjukdomar, så finns det ytterligare ett besvärande faktum. Nämligen att blommorna måste pollineras! Och detta pollen måste komma från en annan äpplesort – annars kan inte pollenslangen växa ner genom blommans pistill och utföra en befruktning (Nybom m.fl. 2007a)

Phenotypic Diversity of Date Palm Cultivars (Phoenix dactylifera L.) from Sudan Estimated by Vegetative and Fruit Characteristics

The aim of this study was to apply some of the vegetative and fruit traits which are easily recognised to identify the variation and the diversity level of the most famous Sudanese date palm cultivars grown on farm in the northern region of Sudan. Sixteen phenotypic traits consisting of ten quantitative and six qualitative characteristics were used for describing the vegetative and fruit characteristics. The principal components analysis (PCA) and UPGMA clustering were used to analyse the data set. The results revealed high variability among the cultivars according to PCA. Fourteen out of the sixteen quantitative and qualitative traits investigated showed a strong discriminating factor suggesting their possible uses in the initiation of Sudanese date palm morphological descriptor list. UPGMA clustering exhibited strong relationship between some cultivars according to their fruit and vegetative characteristics similarity. Based on morphological traits, cultivars Wad-laggi (Lag) and Wad-khateeb (Kha) formed a distinct group suggesting their close relatedness. Similarly, the cultivars sharing the dry fruit texture such as Gondaila (Gon), Tamoda (Tam), Kolmah (Kol), and Barkawi (Bar) were grouped together according to their vegetative traits. Further investigations on Sudanese date palm using more phenotypic characteristics are recommended in order to shape and complete the set of the morphological descriptor list

A systematic review of rye (Secale cereale L.) as a source of resistance to pathogens and pests in wheat (Triticum aestivum L.)

Abstract Wheat is globally one of the most important crops. With the current human population growth rate, there is an increasing need to raise wheat productivity by means of plant breeding, along with development of more efficient and sustainable agricultural systems. Damage by pathogens and pests, in combination with adverse climate effects, need to be counteracted by incorporating new germplasm that makes wheat more resistant/tolerant to such stress factors. Rye has been used as a source for improved resistance to pathogens and pests in wheat during more than 50 years. With new devastating stem and yellow rust pathotypes invading wheat at large acreage globally, along with new biotypes of pest insects, there is renewed interest in using rye as a source of resistance. Currently the proportion of wheat cultivars with rye chromatin varies between countries, with examples of up to 34%. There is mainly one rye source, Petkus, that has been widely exploited and that has contributed considerably to raise yields and increase disease resistance in wheat. Successively, the multiple disease resistances conferred by this source has been overcome by new pathotypes of leaf rust, yellow rust, stem rust and powdery mildew. However, there are several other rye sources reported to make wheat more resistant to various biotic constraints when their rye chromatin has been transferred to wheat. There is also development of knowledge on how to produce new rye translocation, substitution and addition lines. Here we compile information that may facilitate decision making for wheat breeders aiming to transfer resistance to biotic constraints from rye to elite wheat germplasm

On-Farm Diversity of Date Palm (Phoenix dactylifera L) in Sudan: A Potential Genetic Resources Conservation Strategy

Although the main goal of traditional farming is to produce food, it can play an important role in conservation of genetic resources. This paper reports a study, which explored the diversity of date palm (Phoenix dactylifera L.) cultivars grown by farmers and their preferences for different cultivars. The possibilities of using farms as sites for conserving genetic resources are discussed. The data for the study were collected from personal interviews that involved randomly selected date palm farmers in the Northern State and River Nile State, Sudan. Ordered and binary logit models were used to account for possible factors influencing the diversity of cultivars grown by farmers and preferences for different cultivars, respectively. The results showed that the cultivars grown by the respondents vary widely. On average, the Northern State respondents grew twice the number of cultivars as those in the River Nile State. Of all the date palm cultivars, the Barakawi was the most preferred. The diversity of the cultivars grown by the respondents and their preferences were mainly influenced by factors, such as farm location, drought, uses of date palm, years of farming experience, education, income from date palm and household size. The findings will help in designing a more sustainable date palm breeding program, as well as a genetic resources conservation strategy