Biology subjects

Brauer, E. K.

Publications and source records attributed to Brauer, E. K..

3 recordsLinked to original sources

bioRxiv2024

Identification of novel loci regulating dormancy in barley and association with hypoxia sensitivity

Low seed dormancy is an essential trait in malting barley since malting involves rapid and uniform induction of germination. At least two major QTLs on chromosome 5H, SD1 and SD2, regulate dormancy in multiple barley populations, and additional genetic regions are thought to be involved. To identify novel genetic loci that might be associated with dormancy, a panel of genotypes from diverse agro-ecosystems were evaluated alongside two Canadian biparental populations for germination rate. Association mapping revealed QTLs within the SD1 and SD2 loci in the Canadian populations, while neither of these loci were linked to dormancy in the diversity panel. The diversity panel identified 14 additional marker-trait associations, including novel genetic loci. An alanine aminotransferase (AlaAT1) underlies dormancy regulation at the SD1 allele and is thought to help mitigate the suppressive effects of hypoxia on respiration during grain fill. Additional testing with four genotypes carrying either dormant or non-dormant AlaAT1 alleles revealed that dormant alleles had increased hypoxia sensitivity and hypoxia-responsive gene expression during grain fill. Together, this work indicates that multiple genetic regions influence dormancy and suggests that hypoxia influences dormancy establishment in barley. HighlightDormancy is regulated by distinct genetic regions in North American barley compared to African barley. The SD1 locus influences dormancy in North American lines and genotypes with the dormant SD1 allele are more sensitive to hypoxia.

plant biology↗

bioRxiv2023

Resolving the haplotypes of arbuscular mycorrhizal fungi highlights the role of two nuclear populations in host interactions

Arbuscular mycorrhizal fungi (AMF) are prominent root symbionts with a multinucleate cytoplasm that can carry thousands of nuclei deriving from two parental strains and varying in relative abundance in a large syncytium. Here, we set out to improve our understanding of such remarkable genetics by resolving the nuclear genomes of all publicly available AMF heterokaryons using PacBio HiFi and Hi-C sequencing. We find that all AMF heterokaryons carry two sets of homologous chromosomes, where genes associated with plant colonization reside in gene-sparse, repeat-rich compartments. The co-existing nuclear genomes are phylogenetically related but differ significantly in content and epigenetics, resulting in nucleus-specific regulatory programs during mycorrhizal interactions. AMF heterokaryons carry signatures of past genetic exchange indicative of sexual reproduction, followed by clonal haplotype evolution. This work uncovers the contribution and origin of nuclear genomes present in AMF heterokaryons and opens avenues for improvement and environmental application of these strains.

genomics↗

bioRxiv2022

Back from the dead: the atypical kinase activity of a pseudokinase regulator of cation fluxes during inducible immunity

While most pseudokinases lack phosphotransfer activity due to altered catalytic residues within their kinase domain, a subset of pseudokinases maintain kinase activity through atypical mechanisms. The Arabidopsis ILK1 is a pseudokinase from the Raf-like MAP3K family and is the only known plant pseudokinase with confirmed kinase activity. ILK1 activity promotes microbial pattern-induced root growth inhibition through its stabilization of the HAK5 potassium transporter with the calmodulin-like protein CML9. ILK1 also has a kinase-independent function in salt stress suggesting that it interacts with additional proteins. We determined that members of the ILK subfamily are the sole pseudokinases within the Raf-like MAP3K family and identified 179 novel putative ILK1 protein interactors. We also identified 70 novel peptide targets for ILK1, the majority of which were phosphorylated in the presence of Mn2+ instead of Mg2+ in line with modifications in ILK1s DFG cofactor binding domain. Overall, the ILK1-targeted or interacting proteins included diverse protein types including transporters (HAK5, STP1), protein kinases (MEKK1, MEKK3), and a cytokinin receptor (AHK2). The expression of 31 genes encoding putative ILK1-interacting or phosphorylated proteins, including AHK2, were altered in the root and shoot in response to molecular patterns suggesting a role for these genes in immunity. We describe a potential role for ILK1 interactors in the context of cation-dependent immune signaling responses, highlighting the importance of K+ in MAMP responses. This work further supports the notion that ILK1 is an atypical kinase with an unusual cofactor dependence that may interact with multiple proteins in the cell.

plant biology↗