AB-QTL analysis in winter wheat: II. Genetic analysis of seedling and field resistance against leaf rust in a wheat advanced backcross population

The present study aimed to localize exotic quantitative trait locus (QTL) alleles for the improvement of leaf rust (P.triticina) resistance in an advanced backcross (AB) population, B22, which is derived from a cross between the winter wheat cultivar Batis (Triticumaestivum) and the synthetic wheat accession Syn022L. The latter was developed from hybridization of T.turgidum ssp. dicoccoides and T.tauschii. Altogether, 250 BC2F3 lines of B22 were assessed for seedling resistance against the leaf rust isolate 77WxR under controlled conditions. In addition, field resistance against leaf rust was evaluated by assessing symptom severity under natural infestation across multiple environments. Simultaneously, population B22 was genotyped with a total of 97 SSR markers, distributed over the wheat A, B and D genomes. The phenotype and genotype data were subjected to QTL analysis by applying a 3-factorial mixed model analysis of variance including the marker genotype as a fixed effect and the environments, the lines and the marker by environment interactions as random effects. The QTL analysis revealed six putative QTLs for seedling resistance and seven for field resistance. For seedling resistance, the effects of exotic QTL alleles improved resistance at all detected loci. The maximum decrease of disease symptoms (−46.3%) was associated with marker locus Xbarc149 on chromosome 1D. For field resistance, two loci had stable main effects across environments and five loci exhibited marker by environment interaction effects. The strongest effects were detected at marker locus Xbarc149 on chromosome 1D, at which the exotic allele decreased seedling symptoms by 46.3% and field symptoms by 43.6%, respectively. Some of the detected QTLs co-localized with known resistance genes, while others appear to be as novel resistance loci. Our findings indicate, that the exotic wheat accession Syn022L may be useful for the improvement of leaf rust resistance in cultivated wheat

Advanced backcross QTL mapping of resistance to Fusarium head blight and plant morphological traits in a Triticum macha × T. aestivum population

While many reports on genetic analysis of Fusarium head blight (FHB) resistance in bread wheat have been published during the past decade, only limited information is available on FHB resistance derived from wheat relatives. In this contribution, we report on the genetic analysis of FHB resistance derived from Triticum macha (Georgian spelt wheat). As the origin of T. macha is in the Caucasian region, it is supposed that its FHB resistance differs from other well-investigated resistance sources. To introduce valuable alleles from the landrace T. macha into a modern genetic background, we adopted an advanced backcross QTL mapping scheme. A backcross-derived recombinant-inbred line population of 321 BC2F3 lines was developed from a cross of T. macha with the Austrian winter wheat cultivar Furore. The population was evaluated for Fusarium resistance in seven field experiments during four seasons using artificial inoculations. A total of 300 lines of the population were genetically fingerprinted using SSR and AFLP markers. The resulting linkage map covered 33 linkage groups with 560 markers. Five novel FHB-resistance QTL, all descending from T. macha, were found on four chromosomes (2A, 2B, 5A, 5B). Several QTL for morphological and developmental traits were mapped in the same population, which partly overlapped with FHB-resistance QTL. Only the 2BL FHB-resistance QTL co-located with a plant height QTL. The largest-effect FHB-resistance QTL in this population mapped at the spelt-type locus on chromosome 5A and was associated with the wild-type allele q, but it is unclear whether q has a pleiotropic effect on FHB resistance or is closely linked to a nearby resistance QTL

Genetic analysis of artificial Triticinae amphidiploid Aurotica based on the glaucousness trait

Changes in plant genomes of hybrid origin which become apparent on different levels of phenotypic manifestation of genetic and epigenetic changes are an important object of cytogenetics and molecular genetics. The changes in expression of the glaucousness trait in the artificial Triticinae amphidiploid Aurotica (AABBTT) were investigated; haplotypes of plants with the appearance of glaucous and non-glaucous genes were determined by hybridization experiments. It was suppoted that the changes in expression can be explained by (epi)mutations abolishing the efficiency of dominant alleles of orthologous series of glaucous inhibitor gene Iw. Analysis of F2 population with SSR markers specific to 2B and 2D wheat chromosomes and 2T chromosome of Aegilops mutica manifested associated inheritance of the Wms 102 and Wms 702 loci, which mapped to the short arm of chromosome 2D. The Wms 702 marker was linked to the Iw2(T) gene and can now be used to detect that gene.Изменения в геноме растений гибридного проис-хождения, которые проявляются на разных фенотипических уровнях реализации генетических и эпигенетических изменений, интенсивно исследуются цитогенетикой и молекулярной генетикой. Изучали изменения экспрессии признака наличие/отсутствие воскового налета у искусственного амфидиплоида Авротика (Triticinae, AABBTT). Гибридологическим анализом установлены гаплотипы растений с контрастными фенотипами и показано, что изменение экспрессии признака связано с (эпи)мутацией, которая приводит к утрате активности доминантного аллеля ортологической серии генов Iw —ингибиторов воскового налета у пшеницевых. Микросателлитный анализ расщепляющихся популяций по SSR-локусам, специфичным для 2B и 2D хромосом пшеницы и 2T хромосомы эгилопса, показал сцепленное наследование локусов Wms 102 и Wms 702, локализованных на плече 2DS, а локус Wms 702 сцеплен с геном Iw2(T) и может быть использован для определения этого гена.Зміни у геномі рослин гібридного походження, які виявляються на різних фенотипних рівнях реалізації генетичних та епігенетичних змін, інтенсивно досліджуються цитогенетикою та молекулярною генетикою. Вивчали зміни експресії ознаки наявність/відсутність воскової осуги у штучного амфідиплоїда Авротика (Triticinae, AABBTT). Гібридологічним аналізом встановлено гаплотипи рослин з контрастними фенотипами та показано, що зміна експресії ознаки пов’язана з (епі)мутацією, яка призводить до втрати активності домінантного алеля ортологічної серії генів Iw — інгібіторів воскової осуги у пшеницевих. Мікросателітний аналіз популяций, що розщеплюються, за SSR-локусами, специфічними для 2B та 2D хромосом пшениці та 2T хромосоми егілопсу, показав зчеплене успадкування локусів Wms 102 та Wms 702, локалізованих на плечі 2DS, а локус Wms 702 зчеплений з геном Iw2(T) та може бути використаний для визначення цього гена