Analysis of Wheat Disease Resistance Data Originating from Screenings of Gatersleben Genebank Accessions during 1933 and 1992

Abstract

Series of 10,348 accessions belonging to 21 species (hexaploid, tetraploid, diploid) of the genus Triticum and 489 accessions belonging to 20 species of the genus Aegilops were scored for disease resistance during a period of 60 years. Tests were performed at the seedling stage for powdery mildew (Erysiphe graminis DC. f. sp. tritici March.), leaf rust (Puccinia recondita Rob. ex Desm. f. sp. tritici Erikss.), stripe rust (Puccinia striiformis West. f. sp. tritici Erikss.) and eyespot (Pseudocercosporella herpotrichoides (Fron.) Deight.) but also at the adult plant stage considering powdery mildew, leaf rust, stripe rust, eyespot and glume blotch (Septoria nodorum Berk.). About 150,000 disease scores recorded on index cards using different scoring scales were transferred to the computer, converted into a 1-9 scale and used to summarise the results. Within the genus Triticum 20% of the material analysed was classified as heterogeneous. For the accessions without detectable segregation a large variability for resistance/susceptibility was detected. At the adult plant stage resistant accessions without visible infections were identified for all diseases. The percentages of resistant accessions at that growth stage were always higher than the ones found in the material tested at the seedling stage. The probability for finding resistant material was shown to be highest in the diploid species (>50%) but decreased with increasing ploidy level to about 10% in the hexaploids. For Aegilops it was shown that most of the accessions were homogeneous and highly resistant against powdery mildew (seedling and adult plant stage), leaf rust (adult plant stage) and eyespot (seedling and adult plant stage/ natural infection).

NGS technologies for analyzing germplasm diversity in genebanks*

“…Therefore, most evaluation efforts were focused to combine i.e. disease resistance and important morphological characters (yield components) [8, 17]. Deep genetic and phenotypic characterization of genetic resources by HT techniques, including resequencing of enriched candidate genes and low-coverage full-genome resequencing will increasingly become available.…”

“…Prior to the advent of molecular characterization, accessions in germplasm collections were mainly examined based on morphological characters and phenotypic traits [8]. The development of molecular techniques now allows a more accurate analysis of large collections.…”

Distribution and characterization of Aegilops and Triticum species from the Bulgarian Black Sea coast

“…cylindrica samples were the most susceptible to powdery mildew. Börner et al [4] investigated 489 samples belonging to 20 species of the genus Aegilops and most of them were homogeneous and highly resistant against powdery mildew and leaf rust in adult plant stage. Similarly to powdery mildew resistance, most of T. monococcum ssp.…”

“…There have been large efforts to evaluate, document and store many Triticeae landraces and wild relatives for breeding purposes [4,5]. As there is concern among breeders that the narrow genetic base of wheat might limit future breeding advances, there is an urgent need to explore the genetic diversity in natural populations of wild species and use those with valuable traits for wheat breeding.…”

Resistance of winter wheat cultivars to eyespot and characterisation of causal agents of the disease

“…Cappelle-Desprez. Börner et al (2006) detected resistance among Gatersleben genebank accessions of wheat collected from 1933 to 1992. These accessions may carry already known genes/alleles as well as new loci.…”