Hanan Sela

Tandem kinases are emerging regulators of plant immunity, but the downstream defense programs they activate remain poorly understood. Stripe rust, caused by Puccinia striiformis f. sp. tritici ( Pst ), is a major constraint on global wheat production. The Yr15 resistance gene, derived from wild emmer wheat, encodes the tandem kinase protein WTK1. To define the temporal basis of this resistance, we analysed resistant and susceptible near‐isogenic lines across a 7‐day infection time course using histopathology, ROS phenotyping, RNA sequencing, co‐expression network analysis, and qRT‐PCR validation. WTK1‐mediated resistance limited fungal colonization, enhanced ROS accumulation, and triggered extensive transcriptional reprogramming. We identified 2509 pathogen‐responsive differentially expressed genes, including 1530 genes upregulated in the resistant line, revealing an early phase enriched for ROS and Ca ²⁺ signaling, autophagy‐related processes, and metacaspases consistent with hypersensitive cell death observed in pathogen‐invaded cells. This was followed by later defense reinforcement and metabolic reprogramming in later stages of infection, including pathogenesis‐related proteins, cell‐wall reinforcement, and phytoalexin biosynthesis, consistent with the confinement of Pst to localized necrotic lesions. Our results show that WTK1 triggers coordinated waves of transcriptional reprogramming and co‐expression network responses during infection, providing insight into tandem kinase‐mediated immunity and a framework for improving durable stripe rust resistance in wheat.

Seed weight (SW) and nutrient allocation are key determinants of yield and grain quality in wheat, yet the regulatory basis of naturally occurring variation in these traits remains poorly resolved. Wild emmer wheat ( Triticum dicoccoides ), the progenitor of modern wheat, retains extensive eco‐geographically structured genetic diversity that was largely eroded during domestication. Here, we identify a B3‐domain transcription factor (B3TF) as a key regulator of seed growth and metabolic partitioning in wheat. Genome‐wide association analysis of ~460 wild emmer accessions reveals a major locus on chromosome 2BL associated with SW, seed area and nitrogen (N) content, displaying pronounced climatic differentiation across environmental gradients. Introgression of the 2BL wild segment into the hexaploid wheat cultivars Chinese Spring and Bethlehem increases SW in cultivated backgrounds. Independent loss‐of‐function alleles generated by EMS mutagenesis in the tetraploid wheat cultivar Kronos produce larger seeds. Further, RNA‐seq of EMS mutants revealed metabolic reprogramming with upregulated fatty acid, nitrogen and phenylpropanoid pathways and downregulated carbohydrate metabolism and sugar transport. Metabolomic, lipidomic and ICP‐MS data showed increased essential amino acids, sugars, lipids, N content and minerals (Zn, Fe, Mo). Furthermore, CRISPR/Cas9‐mediated editing in the hexaploid wheat cultivar Fielder produced similar increases in SW and N content as observed in the EMS mutants, establishing this gene as a negative regulator of seed growth across ploidy levels. In addition, natural haplotypes show reciprocal climatic distributions, linking regulatory variation to environmental adaptation. Our findings uncover a TF underlying natural seed trait variation in wild wheat, providing a framework for exploiting regulatory alleles to enhance yield and nutritional quality in modern wheat.

Here we illuminate the evolutionary trajectory of domesticated wheat through genomic analysis of 3,000–6,000-year-old grains excavated in the southern Levant. Our results identify these specimens as an early domesticated form closely related to wheat accessions from Ethiopia, the Arabian Peninsula and India. Genomic evidence supports a multi-stage domestication model centred on the non-shattering spike, requiring mutations in both TtBtr1-A and TtBtr1-B genes. These mutations probably arose independently in northern and southern wild populations, respectively. The foundational domestication event was hybridization of these populations, uniting the required mutations to create domesticated wheat. Remarkably, this hybridization occurred at least twice, producing distinct domesticated lineages. Following this, ancient grain lineages acquired advantageous traits through gene flow from local wild emmer populations. These findings redefine wheat domestication as a prolonged, dynamic and regionally interconnected process, characterized by repeated independent hybridization events that were later diversified through human-led dispersal and local adaptation.

Our aim was to elucidate mechanisms underlying nitrogen (N)‐deficiency tolerance in bread wheat (cultivar Ruta), conferred by a wild emmer wheat QTL (WEW; IL99). We hypothesised that the tolerance in IL99 is driven by enhanced N‐uptake through modification of root system architecture (RSA) underscored by transcriptome modifications. Severe N‐deficiency (0.1 N for 26 days) triggered significantly higher plasticity in IL99 compared to Ruta by modifying 16 RSA traits; nine of which were IL99‐specific. The change in root growth in IL99 was collectively characterised by a transition in root orientation from shallow to steep, increased root number and length, and denser networks, enabling nutrient acquisition from a larger volume and deeper soil layers. Gene ontology and KEGG‐enrichment analyses highlighted IL99‐specific pathways and candidate genes elevated under N‐deficiency. This included Jasmonic acid metabolism, a key hormone mediating RSA plasticity (AOS1, TIFY, MTB2, MYC2), and lignification‐mediated root strengthening (CYP73A, 4CL). ‘N‐metabolism’ was identified as a main shared pathway to IL99 and Ruta, with enhanced nitrate uptake predominant in IL99 (NRT2.4), while remobilisation was the main strategy in Ruta (NRT2.3). These findings provide novel insights into wheat plasticity response underlying tolerance to N‐deficiency and demonstrate the potential of WEW for improving N‐uptake under suboptimal conditions.

Plant pathogens pose a continuous threat to global food production. Recent discoveries in plant immunity research unveiled a unique protein family characterized by an unusual resistance protein structure that combines two kinase domains. This study demonstrates the widespread occurrence of tandem kinase proteins (TKPs) across the plant kingdom. An examination of 104 plant species’ genomes uncovered 2,682 TKPs. The majority (95.6%) of these kinase domains are part of the receptor-like kinase–Pelle family, which is crucial for cell surface responses in plant immunity. Notably, 90% of TKPs comprise dual kinase domains, with over 50% being pseudokinases. Over 56% of these proteins harbor 127 different integrated domains, and over 47% include a transmembrane domain. TKP pseudokinases and/or integrated domains probably serve as decoys, engaging with pathogen effectors to trigger plant immunity. The TKP Atlas we created sheds light on the mechanisms of TKP convergent molecular evolution and potential function.

Nucleotide-binding leucine-rich repeat (NLR) disease resistance genes typically confer resistance against races of a single pathogen. Here, we report that Yr87/Lr85, an NLR gene from Aegilops sharonensis and Aegilops longissima, confers resistance against both P. striiformis tritici (Pst) and Puccinia triticina (Pt) that cause stripe and leaf rust, respectively. Yr87/Lr85 confers resistance against Pst and Pt in wheat introgression as well as transgenic lines. Comparative analysis of Yr87/Lr85 and the cloned Triticeae NLR disease resistance genes shows that Yr87/Lr85 contains two distinct LRR domains and that the gene is only found in Ae. sharonensis and Ae. longissima. Allele mining and phylogenetic analysis indicate multiple events of Yr87/Lr85 gene flow between the two species and presence/absence variation explaining the majority of resistance to wheat leaf rust in both species. The confinement of Yr87/Lr85 to Ae. sharonensis and Ae. longissima and the resistance in wheat against Pst and Pt highlight the potential of these species as valuable sources of disease resistance genes for wheat improvement.

This paper is dedicated to the memory of the APS Fellow Prof. Yehoshua Anikster (1934 -2023). A total of 336 urediniospore isolates of Puccinia graminis f. sp. tritici (Pgt) were derived from samples collected in Israel from 2009 to 2019 and analyzed for virulence with the standard set of 20 differentials. Seventy-four virulence phenotypes were identified during the survey. Two Pgt phenotypes (TKTTF, TTTTF) were found in nine annual populations while 57 appeared in only one year, in most of the cases (51) only once. The yearly pathogen collections of 2009 – 2014 differed from the collections of 2015-2018, and the 2019 collection diverged from all others. No virulence to Sr24 and Sr31 indicators of UG99 was detected. When comparing the 2009 – 2014 and 2015 – 2018 periods, virulence frequencies declined for Sr17, 30, and 38 genes from 0.85—0.98 to 0.31 – 0.59, while the frequency for Sr36 rose (0.42 vs. 0.87). The average relative virulence complexity of Pgt phenotypes decreased from 0.83 (2009—2014) and 0.79 (2015 – 2018) to 0.67 in 2019. Variability within the annual populations gradually increased over time. The Pgt collections of isolates in 2009 – 2014 and 2015 – 2018 were significantly different (p = 0.01). The effective number of different annual populations in 2009 – 2018 was 2.04 (β-variation = 0.12). Since Pgt does not over-summer in Israel, the northern source of inoculum from Turkey and Russia seems the most probable.

Plant pathogens pose a continuous threat to global food production. Recent discoveries in plant immunity research unveiled a unique protein family characterized by an unusual resistance protein structure that combines two kinase domains (KD). This study demonstrates the widespread occurrence of tandem-kinase proteins (TKPs) across the plant kingdom. An examination of 104 plant species' genomes uncovered 2,682 TKPs. The majority (95.6%) of these KDs are part of the RLK-Pelle receptor-like kinase family, which is crucial for cell surface responses in plant immunity. Notably, 90% of TKPs comprise dual KDs, with over 50% being pseudokinases. Over 56% of these proteins harbor 127 different integrated domains, and over 47% include a transmembrane domain. TKP pseudokinases and/or integrated domains probably serve as decoys, engaging with pathogen effectors to trigger plant immunity. The TKP Atlas we created sheds light on the mechanisms of TKP convergent molecular evolution and potential function.

Nucleotide-binding site leucine-rich repeat (NLR) disease-resistance genes typically confer resistance against races of a single pathogen. We report that Lr/Yr548, an NLR gene from Aegilops sharonensis and Aegilops longissima, confers specific resistance against Puccinia triticina (Pt) and P. striiformis tritici (Pst) that cause leaf and stripe rust, respectively. Lr/Yr548 prevented disease development in wheat introgression as well as transgenic wheat lines. Comparative analysis of Lr/Yr548 and all cloned Triticeae NLR disease-resistance genes showed that Lr/Yr548 contains a distinctive coiled-coil domain and that it is unique to Ae. sharonensis and Ae. longissima. A phylogenetic analysis indicated multiple events of gene flow of Lr/Yr548 between the two species, and suggested loss of resistance in susceptible isolates. The confinement of Lr/Yr548 to Ae. longissima and Ae. sharonensis and the cross resistance that it confers against Pt and Pst in wheat highlight the potential of these species as sources of novel disease-resistance genes for wheat improvement.

A total of 353 urediniospore isolates of Puccinia striiformis f. sp. tritici (Pst) collected in Israel during 2001 to 2019 were analyzed. Pst pathogenicity was studied with a set of 20 differential...