Biology subjects

Quilbe, J.

Publications and source records attributed to Quilbe, J..

4 recordsLinked to original sources

bioRxiv2025

RHD6LA regulates root hair responses to both symbionts and commensals

While intracellular symbiosis with rhizobia relies on Nod factor signaling through the conserved common symbiosis signaling pathway (CSSP), it remains unclear how legumes simultaneously manage interactions with commensal soil microbes. Using single cell RNA-sequencing, we show that commensal soil bacteria induce a Nod factor-independent transcriptional response in specific root hairs. This response is similar to the rhizobium response in the CSSP-deficient cyclops mutant, which is unable to accommodate rhizobia in root hair infection threads. Both responses include the nodulation gene NSP2 and a transcription factor, which we name ROOT HAIR DEFECTIVE 6 LIKE A (RHD6LA). We show that RHD6LA is required for facilitating infection thread formation in response to rhizobia and for preventing exaggerated root hair responses to commensal soil bacteria. The overlap between commensal and symbiotic signaling highlights the complexity of legume-microbe interactions at the root hair interface and suggests new mechanisms for microbial discrimination in rhizobium-responsive root hairs.

molecular biology↗

bioRxiv2024

A Receptor Like Cytoplasmic Kinase evolved in Aeschynomene legumes to mediate Nod-independent rhizobial symbiosis

Many plants interact symbiotically with arbuscular mycorrhizal (AM) fungi to enhance inorganic phosphorus uptake, and legumes also develop a nodule symbiosis with rhizobia for nitrogen acquisition. Establishment and functioning of both symbioses rely on a common plant signaling pathway activated by structurally related Myc- and Nod-factors. Recently, a SPARK Receptor-like-Kinase (RLK)/Receptor-like Cytoplasmic Kinase (RLCK) complex was shown to be essential for AM in both monocot and dicot plants. Here, we show that in Aeschynomene legumes the RLCK component of this receptor complex has evolved following a gene duplication event and mediates a unique nodule symbiosis that is independent of rhizobial Nod factors. In Aeschynomene evenia, AeRLCK2 is crucial for nodule initiation but not for AM. Additionally, AeRLCK2 physically interacts with and is phosphorylated by the Cysteine-rich RLK, AeCRK, also required for nodulation. This work reveals a novel evolutionary origin of this Nod-independent symbiosis from AM.

plant biology↗

bioRxiv2022

Genotype by microbiome interactions have large effects on growth in Lotus japonicus

Biological interactions between plants and their root microbiomes are pivotal for plant growth. Even though the plant genotype [G], soil microbiome [C], and growth conditions (environment) [E] are core factors shaping the root microbiome, their relationships remain unclear. We disentangled the effects of G, C, E, and their interactions on the Lotus root microbiome and plant growth using a cross-inoculation approach that reconstructed the interactions between nine Lotus accessions and four soil microbiomes under two different environmental conditions. We found that a large proportion of the root microbiome composition was determined by C and E and that G-related (G, G x C, and G x E) effects were significant but small. In contrast, the interactions between G and C had a more pronounced effect on plant shoot growth than C alone. Our findings indicate that most microbiome variations controlled by C have little effect on the plant phenotype, whereas G x C interactions have more significant effects. Plant genotype-dependent interactions with soil microbes warrant more attention in efforts to optimize crop yield and resilience.

plant biology↗

bioRxiv2020

Genetics of nodulation in Aeschynomene evenia uncovers new mechanisms of the rhizobium-legume symbiosis

Among legumes (Fabaceae) capable of nitrogen-fixing nodulation, several Aeschynomene spp. use a unique symbiotic process that is independent of Nod factors and infection threads. They are also distinctive in developing root and stem nodules with photosynthetic bradyrhizobia. Despite the significance of these symbiotic features, their understanding remains limited. To overcome such limitations, we conducted genetic studies of nodulation in Aeschynomene evenia, supported by the development of a genome sequence for A. evenia and transcriptomic resources for 10 additional Aeschynomene spp. Comparative analysis of symbiotic genes substantiated singular mechanisms in the early and late nodulation steps. A forward genetic screen also showed that AeCRK, coding a novel receptor-like kinase, and the symbiotic signaling genes AePOLLUX, AeCCamK, AeCYCLOPS, AeNSP2 and AeNIN, are required to trigger both root and stem nodulation. This work demonstrates the utility of the A. evenia model and provides a cornerstone to unravel new mechanisms underlying the rhizobium-legume symbiosis.

plant biology↗