Biology subjects

Oldach, K.

Publications and source records attributed to Oldach, K..

3 recordsLinked to original sources

bioRxiv2025

Partial cross-resistance of oats to different Fusarium species and the role of trichomes in susceptibility

Resistance of oats to FHB, caused by different Fusarium species, is important for grain quality and yield. In this study, 25 oat genotypes were evaluated for resistance to Fusarium graminearum (FG), F. sporotrichioides (FS) and F. poae (FP) in field trials across Germany to assess the presence of cross-resistance and to analyse the role of trichomes on the hulls during Fusarium infection. Infection severity was quantified by Fusarium species-specific qPCR and showed the highest fungal biomass for FP, followed by FS and FG. Variability due to environmental effects was very high, resulting in rather low heritabilities for FG (0.50) and FS (0.36), and no significant genotype effect for FP. A significant positive correlation was found between FP and FS infection, whereas FG infection was not correlated with either FP or FS. Microscopic analyses revealed important genotype-specific differences in trichome size and density on lemma and palea with very high heritability (0.97). FG biomass was positively correlated with trichome size and density, and FG hyphae were observed in close interaction with trichomes and stomata. These results indicate the presence of partial cross-resistance in addition to mostly species-specific resistance and suggest a role for trichomes in susceptibility to FG.

plant biology↗

bioRxiv2024

VRS5 (HvTB1) binds to the promoter of tillering and floral homeotic genes to regulate their expression

Variation in shoot architecture, or tillering, is an important adaptive trait targeted during the domestication of crops. A well-known regulatory factor in shoot architecture is TEOSINTE BRANCHED 1 (TB1). TB1 and its orthologs have a conserved function in integrating environmental signals to regulate axillary branching, or tillering in cereals. The barley ortholog of TB1, VULGARE ROW-TYPE SIX 5 (VRS5) does not only regulate tillering, but is also involved in regulating row-type by inhibiting lateral spikelet development. These discoveries predominantly come from genetic studies, but how VRS5 regulates these processes on a molecular level remains largely unknown. By combining transcriptome analysis between vrs5 and wild type at different developmental stages and DAP-sequencing to locate the genome-wide DNA binding sites of VRS5, we identified bona fide targets of VRS5. We found that VRS5 targets abscisic acid related genes, potentially to inhibit tillering in a conserved way. While later in inflorescence development, row-type gene VRS1 and several known floral development genes, like MIKCc type MADS-box genes, are targeted. This study identifies several significant genes for mutational analysis, representing a selection of bona fide targets that will contribute to a deeper understanding of the VRS5 network and its role in shaping barley development.

plant biology↗

bioRxiv2023

High-resolution mapping of Ryd4Hb, a major resistance gene to Barley yellow dwarf virus from Hordeum bulbosum

Virus diseases are causing high yield losses in crops worldwide. The Barley yellow dwarf virus (BYDV) complex is responsible for one of the most widespread and economically important viral diseases of cereals. While no complete resistance gene has been uncovered in the primary genepool of barley, sources of resistance were identified in the wild relative Hordeum bulbosum, representing the secondary genepool of barley. One such locus, Ryd4Hb, has been previously introgressed into barley, and was allocated to chromosome 3H, but is tightly linked to a sublethality factor that prevents the incorporation and utilization of Ryd4Hb in barley varieties. To solve this problem, we fine-mapped Ryd4Hb and separated it from this negative factor. We narrowed the Ryd4Hb locus to a 66.5 kbp physical interval in the barley Morex reference genome. The region comprises one complete and one partial gene from the nucleotide-binding and leucine-rich repeat immune receptor family, typical of dominant virus resistance genes. The closest homolog to these two Ryd4Hb candidate genes is the wheat Sr35 stem rust resistance gene. In addition to the fine mapping, we reduced the sublethality factor interval to 600 kbp in barley. Aphid feeding experiments demonstrated that Ryd4Hb provides a direct resistance to BYDV rather than a resistance to its vector. The presented results, including the high-throughput molecular markers, will permit a more targeted selection of the resistance in breeding, enabling the use of Ryd4Hb in barley varieties. Key messageWe mapped Ryd4Hb in a 66.5 kpb interval in barley and dissociated it from a sublethality factor. These results will enable a targeted selection of the resistance in barley breeding.

plant biology↗