Biology subjects

Wulff, B. B. H.

Publications and source records attributed to Wulff, B. B. H..

14 recordsLinked to original sources

bioRxiv2026

Direct effector recognition by a tandem kinase triggers non-canonical immunity in wheat

Tandem kinase proteins (TKPs) are an important class of disease resistance genes in cereal crops alongside nucleotide-binding (NB-ARC) leucine-rich repeat (LRR) (NLR) receptors. Here, we cloned the wheat (Triticum aestivum) resistance gene Lr41, which encodes a TKP with a C-terminal fusion, and its paired effector gene AvrLr41 from the rust pathogen Puccinia triticina. AvrLr41 is unusually large and highly divergent from most fungal effectors and is directly recognized by Lr41 through its pseudokinase domain. Immune activation mediated by Lr41 require auxiliary helper proteins, including either a minimal coiled-coil (CC) helper protein or its full-length NLR ortholog. These findings reveal a non-canonical immune system in which a kinase-type receptor directly recognizes an effector and recruits either CC or NLR helpers, demonstrating that full-length NLRs are not strictly required for NLR-linked immune execution and expanding the functional repertoire of disease resistance proteins in crops.

plant biology↗

bioRxiv2025

An HMA-like integrated domain in the wheat tandem kinase WTK4 recognises an RNase-like pathogen effector

Proteins with a tandem kinase structure have recently emerged as new players in race-specific resistance in cereal crops. However, the molecular understanding of these novel immune receptors resistance mechanisms is limited by the lack of knowledge about the pathogen effectors that they recognise. In this work, we identify AvrWTK4, the wheat powdery mildew RNase-like effector recognised by the wheat tandem kinase immune receptor WTK4, through a combination of bi-parental genetic mapping and mutagenesis. We demonstrate that mutations in the AvrWTK4 gene or a reduction of its expression lead to virulence on WTK4. Transfection of AvrWTK4 specifically induced cell death in WTK4-containing Aegilops tauschii protoplasts. The avirulent AvrWTK4 variant interacts more strongly than the virulent variant with the N-terminal heavy metal-associated (HMA)-like domain of WTK4. These findings further highlight that integrated domains in tandem kinase proteins serve as decoys for pathogen effectors, which could be leveraged to design novel recognition specificities.

molecular biology↗

bioRxiv2025

An extended β-finger motif is a near-universal feature of kinase fusion proteins

Kinase fusion proteins (KFPs) are immune receptors that confer disease resistance in wheat (Triticum aestivum) and barley (Hordeum vulgare). We discovered that KFPs with a confirmed function share an extended {beta}-finger motif, a Poaceae-specific feature that originated [~]98 million years ago. The genes encoding these receptors are among the most highly expressed within the plant KFP repertoire, suggesting that elevated transcript abundance is a hallmark of their disease resistance function.

plant biology↗

bioRxiv2024

Population genomics uncover loci for trait improvement in the indigenous African cereal tef (Eragrostis tef)

Tef (Eragrostis tef) is an indigenous African cereal that is gaining global attention as a gluten-free "superfood" with high protein, mineral, and fibre contents. However, tef yields are limited by lodging and by losses during harvest owing its small grain size (150x lighter than wheat). Breeders must also consider a strong cultural preference for white-grained over brown-grained varieties. Tef is relatively understudied with limited "omics" resources. Here, we resequenced 220 tef accessions from an Ethiopian diversity collection and also conducted multi-locational phenotyping for 25 agronomic and grain traits. Grain metabolome profiling revealed differential accumulation of fatty acids and flavonoids between white and brown grains. We conducted k-mer and SNP-based genome wide association and uncovered novel marker-trait associations. A significant 70 kb peak for panicle morphology contained the tef orthologue of rice qSH1, a transcription factor regulating inflorescence morphology in cereals. We also observed a previously unknown relationship between grain size, colour, and fatty acids. These traits were highly associated with retrotransposon insertions in homoeologues of TRANSPARENT TESTA 2, a known regulator of grain colour. Our study provides valuable resources for tef research and breeding, facilitating the development of improved cultivars with desirable agronomic and nutritional properties.

genomics↗

bioRxiv2024

A wheat tandem kinase sensor activates an NLR helper to trigger immunity

Most plant resistance genes encode membrane-anchored receptor-like proteins or intracellular nucleotide-binding and leucine-rich repeat (NLR) receptors. In wheat and barley, tandem kinases (TKs) have emerged as a new class of resistance determinants. To understand the modus operandi of the wheat stem rust resistance protein Sr62TK, we identified two genetic interactors-- a host gene required for Sr62TK function and the corresponding fungal AvrSr62 effector. We discovered that the SR62 locus consists of a digenic module encoding Sr62TK and an NLR (Sr62NLR). AvrSr62 binds to the N-terminal kinase of Sr62TK. This triggers displacement of the C-terminal kinase allowing it to recruit Sr62NLR for activation of immune responses. Understanding the mechanism of this two-component resistance complex will help engineering and breeding for durable resistance.

plant biology↗

bioRxiv2023

Septoria tritici blotch resistance gene Stb15 encodes a lectin receptor-like kinase

Septoria tritici blotch (STB), caused by the Dothideomycete fungus Zymoseptoria tritici, is of one of the most damaging diseases of bread wheat (Triticum aestivum)1 and the target of costly fungicide applications2. In line with the fungus apoplastic lifestyle, STB resistance genes isolated to date encode receptor-like kinases (RLKs) including a wall-associated kinase (Stb6) and a cysteine-rich kinase (Stb16q)3,4. Here, we used genome-wide association studies (GWAS) on a panel of 300 whole-genome shotgun-sequenced diverse wheat landraces (WatSeq consortium) to identify a 99 kb region containing six candidates for the Stb15 resistance gene. Mutagenesis and transgenesis confirmed a gene encoding an intronless G-type lectin RLK (LecRK) as Stb15. The characterisation of Stb15 exemplifies the unexpected diversity of RLKs conferring Z. tritici resistance in wheat.

genetics↗

bioRxiv2022

A wheat kinase and immune receptor form the host-specificity barrier against the blast fungus

Since emerging in Brazil in 1985, wheat blast has spread throughout South America and recently appeared in Bangladesh and Zambia. We show that two wheat resistance genes, Rwt3 and Rwt4, acting as host-specificity barriers against non-Triticum blast pathotypes encode a nucleotide-binding leucine-rich repeat immune receptor and a tandem kinase, respectively. Molecular isolation of these genes allowed us to develop assays that will ensure the inclusion of these two genes in the wheat cultivars to forestall the recurrence of blast host jumps.

plant biology↗

bioRxiv2019

LYS3 encodes a prolamin-box-binding transcription factor that controls embryo growth in barley and wheat

Mutations at the LYS3 locus in barley have multiple effects on grain development, including an increase in embryo size and a decrease in endosperm starch content. The gene underlying LYS3 was identified by genetic mapping and mutations in this gene were identified in all four barley lys3 alleles. LYS3 encodes a transcription factor called Prolamin Binding Factor (PBF). Its role in controlling embryo size was confirmed using wheat TILLING mutants. To understand how PBF controls embryo development, we studied its spatial and temporal patterns of expression in developing grains. The PBF gene is expressed in both the endosperm and the embryos, but the timing of expression in these organs differs. PBF expression in wild-type embryos precedes the onset of embryo enlargement in lys3 mutants, suggesting that PBF suppresses embryo growth. We predicted the down-stream target genes of PBF in wheat and found them to be involved in a wide range of biological processes, including organ development and starch metabolism. Our work suggests that PBF may influence embryo size and endosperm starch synthesis via separate gene control networks. HIGHLIGHTSO_LILYS3 encodes a transcription factor called Prolamin Binding Factor (PBF) that is expressed in grains only. C_LIO_LIWheat and barley LYS3/PBF mutants have enlarged embryos suggesting that this gene suppresses embryo growth. C_LIO_LIThe down-stream target genes of PBF in wheat are predicted to be involved in a wide range of biological processes including organ development and starch metabolism. C_LI

plant biology↗

bioRxiv2018

The wheat Sr22, Sr33, Sr35 and Sr45 genes confer resistance against stem rust in barley

In the last 20 years, stem rust caused by the fungus Puccinia graminis f. sp. tritici (Pgt), has re-emerged as a major threat to wheat and barley cultivation in Africa and Europe. In contrast to wheat with 82 designated stem rust (Sr) resistance genes, barleys genetic variation for stem rust resistance is very narrow with only seven resistance genes genetically identified. Of these, only one locus consisting of two genes is effective against Ug99, a strain of Pgt which emerged in Uganda in 1999 and has since spread to much of East Africa and parts of the Middle East. The objective of this study was to assess the functionality, in barley, of cloned wheat Sr genes effective against Ug99. Sr22, Sr33, Sr35 and Sr45 were transformed into barley cv. Golden Promise using Agrobacterium-mediated transformation. All four genes were found to confer effective stem rust resistance. The barley transgenics remained susceptible to the barley leaf rust pathogen Puccinia hordei, indicating that the resistance conferred by these wheat Sr genes was specific for Pgt. Cloned Sr genes from wheat are therefore a potential source of resistance against wheat stem rust in barley.

plant biology↗

bioRxiv2018

Speed breeding in growth chambers and glasshouses for crop breeding and model plant research

1.To meet the challenge of feeding a growing population, breeders and scientists are continuously looking for ways to increase genetic gain in crop breeding. One way this can be achieved is through \"speed breeding\" (SB), which shortens the breeding cycle and accelerates research studies through rapid generation advancement. The SB method can be carried out in a number of ways, one of which involves extending the duration of a plants daily exposure to light (photoperiod) combined with early seed harvest in order to cycle quickly from seed to seed, thereby reducing the generation times for some long-day (LD) or day-neutral crops. Here we present glasshouse and growth chamber-based SB protocols with supporting data from experimentation with several crop species. These protocols describe the growing conditions, including soil media composition, lighting, temperature and spacing, which promote rapid growth of spring and winter bread wheat, durum wheat, barley, oat, various members of the Brassica family, chickpea, pea, grasspea, quinoa and the model grass Brachypodium distachyon. Points of flexibility within the protocols are highlighted, including how plant density can be increased to efficiently scale-up plant numbers for single seed descent (SSD) purposes. Conversely, instructions on how to perform SB on a small-scale by creating a benchtop SB growth cabinet that enables optimization of parameters at a low cost are provided. We also outline the procedure for harvesting and germinating premature wheat, barley and pea seed to reduce generation time. Finally, we provide troubleshooting suggestions to avoid potential pitfalls.

plant biology↗

bioRxiv2018

BED-domain containing immune receptors confer diverse resistance spectra to yellow rust

Introductory paragraph Introductory paragraph Main Methods Author contributions Data availability Competing interests References Crop diseases reduce wheat yields by ~25% globally and thus pose a major threat to global food security1. Genetic resistance can reduce crop losses in the field and can be selected for through the use of molecular markers. However, genetic resistance often breaks down following changes in pathogen virulence, as experienced with the wheat yellow (stripe) rust fungus Puccinia striiformis f. sp. tritici (Pst)2. This highlights the need to (i) identify genes that alone or in combination provide broad-spectrum resistance and (ii) increase our understanding of the underlying molecular mod ...

plant biology↗

bioRxiv2018

Chromosome-scale comparative sequence analysis unravels molecular mechanisms of genome evolution between two wheat cultivars

BackgroundRecent improvements in DNA sequencing and genome scaffolding have paved the way to generate high-quality de novo assemblies of pseudomolecules representing complete chromosomes of wheat and its wild relatives. These assemblies form the basis to compare the evolutionary dynamics of wheat genomes on a megabase-scale.\n\nResultsHere, we provide a comparative sequence analysis of the ~700-megabase chromosome 2D between two bread wheat genotypes - the old landrace Chinese Spring and the elite Swiss spring wheat line CH Campala Lr22a. There was a high degree of sequence conservation between the two chromosomes. Analysis of large structural variations revealed four large insertions/deletions (InDels) of >100 kb. Based on the molecular signatures at the breakpoints, unequal crossing over and double-strand break repair were identified as the evolutionary mechanisms that caused these InDels. Three of the large InDels affected copy number of NLRs, a gene family involved in plant immunity. Analysis of single nucleotide polymorphism (SNP) density revealed three haploblocks of ~8 Mb, ~9 Mb and ~48 Mb with a 35-fold increased SNP density compared to the rest of the chromosome.\n\nConclusionsThis comparative analysis of two high-quality chromosome assemblies enabled a comprehensive assessment of large structural variations. The insight obtained from this analysis will form the basis of future wheat pan-genome studies.

genomics↗

bioRxiv2018

Resistance gene discovery and cloning by sequence capture and association genetics

Genetic resistance is the most economic and environmentally sustainable approach for crop disease protection. Disease resistance (R) genes from wild relatives are a valuable resource for breeding resistant crops. However, introgression of R genes into crops is a lengthy process often associated with co-integration of deleterious linked genes1, 2 and pathogens can rapidly evolve to overcome R genes when deployed singly3. Introducing multiple cloned R genes into crops as a stack would avoid linkage drag and delay emergence of resistance-breaking pathogen races4. However, current R gene cloning methods require segregating or mutant progenies5-10, which are difficult to generate for many wild relatives due to poor agronomic traits. We exploited natural pan-genome variation in a wild diploid wheat by combining association genetics with R gene enrichment sequencing (AgRenSeq) to clone four stem rust resistance genes in <6 months. RenSeq combined with diversity panels is therefore a major advance in isolating R genes for engineering broad-spectrum resistance in crops.

genomics↗

bioRxiv2017

Speed breeding: a powerful tool to accelerate crop research and breeding

The growing human population and a changing environment have raised significant concern for global food security, with the current improvement rate of several important crops inadequate to meet future demand [1]. This slow improvement rate is attributed partly to the long generation times of crop plants. Here we present a method called speed breeding, which greatly shortens generation time and accelerates breeding and research programs. Speed breeding can be used to achieve up to 6 generations per year for spring wheat (Triticum aestivum), durum wheat (T. durum), barley (Hordeum vulgare), chickpea (Cicer arietinum), and pea (Pisum sativum) and 4 generations for canola (Brassica napus), instead of 2-3 under normal glasshouse conditions. We demonstrate that speed breeding in fully-enclosed controlled-environment growth chambers can accelerate plant development for research purposes, including phenotyping of adult plant traits, mutant studies, and transformation. The use of supplemental lighting in a glasshouse environment allows rapid generation cycling through single seed descent and potential for adaptation to larger-scale crop improvement programs. Cost-saving through LED supplemental lighting is also outlined. We envisage great potential for integrating speed breeding with other modern crop breeding technologies, including high-throughput genotyping, genome editing, and genomic selection, accelerating the rate of crop improvement.

plant biology↗