Browsing by Person "Pitz, Marion"

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Expanding the BonnMu sequence‐indexed repository of transposon induced maize (Zea mays L.) mutations in dent and flint germplasm
(2024) Win, Yan Naing; Stöcker, Tyll; Du, Xuelian; Brox, Alexa; Pitz, Marion; Klaus, Alina; Piepho, Hans‐Peter; Schoof, Heiko; Hochholdinger, Frank; Marcon, Caroline
The BonnMu resource is a transposon tagged mutant collection designed for functional genomics studies in maize. To expand this resource, we crossed an active Mutator (Mu) stock with dent (B73, Co125) and flint (DK105, EP1, and F7) germplasm, resulting in the generation of 8064 mutagenized BonnMu F2‐families. Sequencing of these Mu‐tagged families revealed 425 924 presumptive heritable Mu insertions affecting 36 612 (83%) of the 44 303 high‐confidence gene models of maize (B73v5). On average, we observed 12 Mu insertions per gene (425 924 total insertions/36 612 affected genes) and 53 insertions per BonnMu F2‐family (425 924 total insertions/8064 families). Mu insertions and photos of seedling phenotypes from segregating BonnMu F2‐families can be accessed through the Maize Genetics and Genomics Database (MaizeGDB). Downstream examination via the automated Mutant‐seq Workflow Utility (MuWU) identified 94% of the presumptive germinal insertion sites in genic regions and only a small fraction of 6% inserting in non‐coding intergenic sequences of the genome. Consistently, Mu insertions aligned with gene‐dense chromosomal arms. In total, 42% of all BonnMu insertions were located in the 5′ untranslated region of genes, corresponding to accessible chromatin. Furthermore, for 38% of the insertions (163 843 of 425 924 total insertions) Mu1, Mu8 and MuDR were confirmed to be the causal Mu elements. Our publicly accessible European BonnMu resource has archived insertions covering two major germplasm groups, thus facilitating both forward and reverse genetics studies.
Nonadditive gene expression contributing to heterosis in partially heterozygous maize hybrids is predominantly regulated from heterozygous regions
(2025) Pitz, Marion; Baldauf, Jutta A.; Piepho, Hans‐Peter; Hochholdinger, Frank
Hybrids often perform better than their homozygous parents, a phenomenon that is commonly referred to as heterosis. Heterosis is widely utilized in modern agriculture, although its molecular basis is not very well understood. In this study, we backcrossed an intermated recombinant inbred line population of maize ( Zea mays L.) with its parental inbred lines B73 and Mo17. The resulting hybrids exhibited different degrees of heterozygosity and heterosis. We identified nonadditively expressed genes, which are expressed differently from their mid‐parental level. In addition, we surveyed their regulation by investigating expression quantitative trait loci (eQTL). Nonadditively expressed genes explain up to 27% of heterotic variance in the backcross hybrids. Furthermore, nonadditively expressed genes are regulated almost exclusively from heterozygous regions of the genome. We observed that nonadditive expression patterns are distinctly regulated depending on the genetic origin of the higher expressed parent. As a consequence, these regulatory regimes lead to higher gene activity in most nonadditively expressed genes in the hybrids. We demonstrated that nonadditive expression patterns contribute to heterosis and their mode of regulation might translate phylogenetic distance into vigorous hybrids. Based on our results, we hypothesize that diverging regulatory preferences in inbred lines are beneficial for selecting parental combinations for hybrid breeding.