A novel pathosystem between Aeschynomene evenia and Aphanomyces euteiches reveals new immune components in quantitative legume root-rot resistance.
Authors: Baker, M., Martinez, Y., Keller, J., Sarrette, B., Pervent, M., Libourel, C., Le Ru, A., Bonhomme, M., Gough, C., Castel, B., ARRIGHI, J.-F., Jacquet, C.
The study establishes Aeschynomene evenia as a new model for dissecting legume immunity against the soilborne pathogen Aphanomyces euteiches and its relationship with Nod factor-independent symbiosis. Quantitative resistance was assessed through inoculation assays, phenotypic and cytological analyses, and RNA‑seq identified thousands of differentially expressed genes, highlighting immune signaling and specialized metabolism, with mutant analysis confirming dual‑function kinases that modulate resistance. Comparative transcriptomics with Medicago truncatula revealed conserved and unique immune responses, positioning the A. evenia–A. euteiches system as a valuable platform for exploring quantitative resistance and symbiosis integration.
The authors used a bottom‑up thermodynamic modelling framework to investigate how plants decode calcium signals, starting from Ca2+ binding to EF‑hand proteins and extending to higher‑order decoding modules. They identified six universal Ca2+-decoding modules that can explain variations in calcium sensitivity among kinases and provide a theoretical basis for interpreting calcium signal amplitude and frequency in plant cells.
The study demonstrates that ELF4 is essential for recruiting ELF3 into hypocotyl nuclei at dusk, a process that enhances ELF3’s ability to repress target gene expression and limit hypocotyl elongation, especially under short‑day conditions. Subnuclear localization patterns of ELF3 differ between hypocotyl and root tissues, indicating tissue‑specific temporal regulation by ELF4.
The study genotyped 1,013 hard red spring wheat lines using SNP arrays and targeted KASP markers to track changes in genetic diversity and the distribution of dwarfing Rht alleles over a century of North American breeding. It found shifts from Rht‑D1b to Rht‑B1b dominance, identified low‑frequency dwarf alleles at Rht24 and Rht25 that have increased recently, and revealed gene interactions that can fine‑tune plant height, along with evidence of recent selection for photoperiod sensitivity.
The study investigates late‑stage effector genes of the fungus Leptosphaeria maculans that infect Brassica napus stems, assessing whether these effectors are more conserved than early‑stage ones and thus may confer more durable resistance. Six candidate late effectors were selected and screened across an expanded set of semi‑winter B. napus genotypes, revealing new resistance sources predominantly within this genetic pool, supporting the hypothesis of greater stability of late effectors.
The study employed deep learning–based image analysis to monitor 6,889 individual lesions caused by Zymoseptoria tritici on 14 wheat cultivars in field conditions, generating over 27,000 precise measurements of lesion growth. Lesion expansion was found to be a significant, moderately heritable component of quantitative resistance (QR) in most cultivars, and its variation correlated strongly with overall QR after exclusion of an outlier. These findings highlight lesion growth as a valuable target for breeding durable QR in wheat.
A biparental Vicia faba mapping population was screened under glasshouse conditions for resistance to a mixture of Fusarium avenaceum and Fusarium oxysporum, revealing several families with moderate to high resistance. Using the Vfaba_v2 Axiom SNP array, a high-density linkage map of 6,755 SNPs was constructed, enabling the identification of a major QTL on linkage group 4 associated with partial resistance to foot and root rot.