Biology subjects

Ried-Lasi, M. K.

Publications and source records attributed to Ried-Lasi, M. K..

5 recordsLinked to original sources

bioRxiv2026

Evolutionary diversification of the SymRK receptor family in land plants

Plant receptor-like kinases (RLKs) are involved in diverse processes, ranging from growth and reproduction to interactions with microbes. Variation in the extracellular domains delineates several RLKs subfamilies, including the malectin-like domain leucine-rich repeat receptor-like kinases (MLD-LRR-RLKs). Symbiosis Receptor-like Kinase (SymRK) is the prototypical member of MLD-LRR-RLKs and is required for microbial accommodation in host roots during root endosymbiosis. Yet, comparative phylogenetic analysis of SymRK orthologs in the broader context of MLD-LRR-RLK subfamily evolution remains limited. In this study, we examined the inventory, phylogeny and clade-specific evolutionary and transcriptional characteristics of this receptor group. SymRK and its closest homologs are present in most land plant lineages and group into four major clades and six additional species-specific clades. These clades can be distinguished by their evolutionary characteristics as either conserved with reduced gene copy number changes (including SymRK) or expanded and diversified, as observed in clade IV. Clade IV dynamics are largely driven by tandem gene duplications, which often arise within gene clusters. We further analysed the evolutionary characteristics of MLD-LRR-RLKs at the population level in Arabidopsis thaliana accessions. We found that some genes are conserved across accessions and are therefore likely to be functionally important, whereas a subset of genes, often located within tandem clusters, are highly diverse and likely contribute to accession-specific adaptations. Finally, most MLD-LRR-RLKs in the A. thaliana Col-0 accession are expressed in roots and respond broadly to biotic stimuli at the transcriptional level. Notably, clustered genes frequently exhibited divergent expression profiles, suggesting transcriptional diversification. Together, we revealed two contrasting evolutionary characteristics among members of the MLD-LRR-RLK subfamily, potentially associated with their functions in plants.

plant biology↗

bioRxiv2026

Sequence adaptations in the intracellular domain of Symbiosis receptor-like kinase (SymRK) promoted infection thread progression in root nodule primordia

The uptake of nitrogen-fixing bacteria into living plant cells and the intracellular accommodation of arbuscular mycorrhiza (AM) fungi requires the plasma membrane-localised Symbiosis Receptor-like Kinase (SymRK). AM is widespread across terrestrial vascular plant lineages, while the nitrogen-fixing root nodule symbiosis (RNS) is restricted to one clade within the eurosids. This distribution led to the concept that SymRK was adopted during evolution to mediate RNS. Comparative analyses revealed that SymRK orthologs from the eurosid clade support RNS while SymRK from the phylogenetically distant species Solanum lycopersicum (tomato) does not. To dissect the molecular basis for this different functionality, we carried out complementation analyses of the Lotus japonicus symrk-3 mutant which is unable to form AM or RNS. Domains swap chimera from the tomato and L. japonicus SymRK orthologs revealed that the intracellular domain of L. japonicus SymRK is necessary and for cortical infection thread (IT) and symbiosome development at 21 days post inoculation. Notably, this signalling specificity could be overcome by ectopic expression of tomato SymRK, pointing to altered protein dosage as a potential determinant of function. Consistent with this idea, SINA family E3 ubiquitin ligases interacted with and ubiquitinylated L. japonicus SymRK, but not tomato SymRK. In yeast two hybrid analysis, the interaction of SymRK with SINA2 and SINA4 depended on the C-terminal intrinsically disordered tail region of L. japonicus SymRK. We conclude that the SymRK intracellular domain evolved interaction capabilities with SINA E3 ligases which correlates with its ability to support RNS.

plant biology↗

bioRxiv2026

Karrikin and strigolactone signalling affect pattern-triggered immunity and resistance to specific pathogens

Hormone signalling is important for plant adaptation to biotic stress. Karrikins (KARs), smoke-derived compounds, and strigolactones (SLs), endogenous plant hormones, are families of butenolide mole-cules, sharing a convergent perception and signalling pathway to regulate a plethora of developmental processes and plant-symbiont relationships. Perception of KARs and SLs is mediated by the /{beta}-hydro-lase KARRIKIN INSENSITIVE 2 (KAI2) and DWARF14 (D14), respectively, each resulting in the for-mation of an E3 ubiquitin ligase complex with the F-Box protein MORE AXILLIARY GROWTH 2 (MAX2) to target transcriptional repressors of the SUPPRESSOR OF MAX2 (SMAX)/SMAX-LIKE (SMXL) family for degradation. Most likely, KAI2 additionally perceives a still elusive endogenous ligand (KAI2-ligand, KL). Recent reports suggest a role of KL/SL signalling in plant immunity, but how these pathways are involved in defence, while balancing appropriate symbiont interactions remains largely unknown. Here, we report that KL and SL signalling quantitatively modulate plant immune responses and pathogen re-sistance. In Arabidopsis thaliana (hereafter Arabidopsis), disrupting or de-repressing KL or SL signalling affects plant susceptibility to a variety of plant pathogens. Furthermore, we describe a previously un-known role for KL and SL signalling in modulating pattern-triggered immunity (PTI). Interfering with KL and SL perception in Arabidopsis had similar effects on microbe-associated molecular pattern (MAMP)-triggered reactive oxygen species production, but transcriptomic profiling suggests a predominant role for KL signalling in regulating the extent of PTI. Importantly, KAI2- and D14-mediated regulation of MAMP-triggered ROS production extends to Lotus japonicus and, in the case of KAI2, to Nicotiana benthamiana, indicating conserved immuno-modulatory roles across dicotyledonous lineages. Together our data identify KL and SL signalling, with a predominant role for the KL pathway, as a conserved modulatory layer of plant immunity and provides a framework for understanding how developmental pathways intersect with immune regulation.

plant biology↗

bioRxiv2025

Lateral root formation is stimulated by common symbiosis genes and NIN in Lotus japonicus

Lateral roots (LR) and the root nodules (RN) of legumes are structurally related and the decision processes leading to RN formation involve signal exchange with the shoot. In order to disentangle these processes, we established a quantitative assay for LR formation in hairy root liquid cultures (HRLC) for the legume Lotus japonicus. In HRLC, ectopic expression of SymRK, or deregulated, auto-active versions of CCaMK and Cyclops stimulated LR formation in a NIN-dependent manner, but spontaneous RN were never observed. It appears that the previously described spontaneous RN formation induced by these versions requires the presence of the shoot. Interestingly, CCaMKT265D increased LR number in a cyclops mutant, revealing the presence of additional CCaMK targets mediating LR formation. Constitutive and ectopic expression of NIN under the ubiquitin promoter resulted in a significant increase in LR number. We compared the responsiveness of two Rosaceae that have either retained NIN (Dryas drummondii) or lost it (Fragaria vesca) to stimulation with the constitutively active variant CCaMK1-314. Intriguingly, CCaMK1-314 was able to increase LR formation in Dryas but not in Fragaria, pointing to consequences of the evolutionary loss of NIN on root architecture. Taken together our data provide evidence for NIN as a molecular link between symbiosis-signaling and LR formation. Non-inoculated nsp1 and nsp2 mutant plants as well as HRLC of these mutants exhibited increased LR densities that were no further increased by expression of CCaMK1-314. We propose a model in which LR density is balanced by the activation of NIN expression by SymRK and CCaMK and the LR suppressing activity of NSP1 and NSP2.

plant biology↗

bioRxiv2024

Lotus japonicus VIH2 is an inositol pyrophosphate synthase that regulates arbuscular mycorrhiza

Plant yield is often maximized by the extensive use of mineral fertilizers, which, however, has severe environmental consequences. Phosphate is particularly problematic, as it represents a globally limited resource, and its runoff and soil erosion threaten open water bodies. Many crops engage in arbuscular mycorrhizal (AM) symbiosis with nutrient-acquiring fungi, aiding in the uptake of phosphate and other mineral nutrients. However, AM colonization is strongly reduced under high soil phosphate levels. A mechanistic understanding of phosphate sensing, phosphate starvation responses, and their connection to AM remains enigmatic. Here, we show that in Lotus japonicus, low-abundant, energy-rich inositol pyrophosphates act as master regulators of AM, orchestrating the crosstalk between phosphate starvation responses and plant root endosymbiosis. These findings hold promise for breeding nutrient-efficient crops.

plant biology↗