Spatiotemporal regulation of arbuscular mycorrhizal symbiosis at cellular resolution
Authors: Chancellor, T., Ferreras-Garrucho, G., Akmakjian, G. Z., Montero, H., Bowden, S. L., Hope, M., Wallington, E., Bhattacharya, S., Korfhage, C., Bailey-Serres, J., Paszkowski, U.
The study applied dual-species spatial transcriptomics at single-cell resolution to map plant and fungal gene activity in rice roots colonized by Rhizophagus irregularis, revealing transcriptional heterogeneity among morphologically similar arbuscules. By pioneering an AM-inducible TRAP-seq using stage‑specific promoters, the authors uncovered stage‑specific reprogramming of nutrient transporters and defence genes, indicating dynamic regulation of nutrient exchange and arbuscule lifecycle.
The authors created a fast‑cycling, isogenic barley line (GP‑rapid) by introgressing the wild‑type Ppd‑H1 allele from Igri into the Golden Promise cultivar and performing two backcrosses to limit the donor genome, achieving a 25% reduction in generation time under speed‑breeding conditions while retaining high transformation efficiency. CRISPR/Cas9‑mediated editing of Ppd‑H1 showed regeneration and transformation rates comparable to the original Golden Promise, establishing GP‑rapid as a rapid platform for transgenic and gene‑edited barley research.
The study applied CRISPR/Cas9 gene editing to Physalis peruviana to modify plant‑architecture genes and create a compact growth ideotype. This compact phenotype is intended to increase per‑plot yield and support future breeding efforts for this nutritionally valuable minor crop.
The study characterizes the single-copy S-nitrosoglutathione reductase 1 (MpGSNOR1) in the liverwort Marchantia polymorpha, showing that loss-of-function mutants generated via CRISPR/Cas9 exhibit marked morphological defects and compromised SNO homeostasis and immune responses. These findings indicate that GSNOR-mediated regulation of S‑nitrosylation is an ancient mechanism linking development and immunity in early land plants.
The study used CRISPR/Cas9 to edit the downstream region of the Arabidopsis thaliana FLOWERING LOCUS T (FT) gene, identifying a 2.3‑kb segment containing the Block E enhancer as crucial for normal FT expression and flowering. Fine‑scale deletions pinpointed a 63‑bp core module with CCAAT‑ and G‑boxes, and revealed a cryptic CCAAT‑box that becomes active when repositioned, highlighting the importance of local chromatin context and motif arrangement for enhancer function.
The study optimized three wheat transformation methods—immature embryo, callus, and in planta injection—by systematically adjusting Agrobacterium strain, bacterial density, acetosyringone concentration, and incubation conditions, achieving transformation efficiencies up to 66.84%. Using these protocols, CRISPR/Cas9 knockout of the negative regulator TaARE1-D produced mutants with increased grain number, spike length, grain size, and a stay‑green phenotype, demonstrating the platform’s potential to accelerate yield and stress‑tolerance improvements in wheat.
The study applied spatial transcriptomics to map the transcriptional landscape of wheat (Triticum aestivum) inflorescences during spikelet development, revealing two distinct regions—a RAMOSA2‑active primordium and an ALOG1‑expressing boundary. Developmental assays showed that spikelets arise from meristematic zones accompanied by vascular rachis formation, identifying key regulators that could be targeted to improve spikelet number and yield.
The authors introduced a polycistronic tRNA‑gRNA array for CRISPR/Cas9 editing in Physcomitrium patens that doubled the frequency of large, targeted deletions compared with conventional single‑gRNA constructs. Using dual‑gRNA targeting, they achieved simultaneous deletion of two to four genes (katanin and TPX2 families) in a single transformation, reaching up to 42% efficiency per gene, though efficiency depended on gRNA pair design.
An optimized workflow was developed to apply the Xenium in situ sequencing platform to formalin‑fixed paraffin‑embedded (FFPE) sections of Medicago truncatula roots and nodules, incorporating customized tissue preparation, probe design, and imaging to overcome plant‑specific challenges such as cell wall autofluorescence. The protocol was validated across nodule developmental stages using both a 50‑gene panel for mature cell identity and an expanded 480‑gene panel covering multiple cell types, providing a scalable high‑resolution spatial transcriptomics method adaptable to other plant systems.
The study used CRISPR/Cas9 to generate rice snrk1 mutants and performed integrated phenotypic, transcriptomic, proteomic, and phosphoproteomic analyses under normal and starvation conditions, revealing SnRK1’s dual role in promoting growth and mediating stress responses. Findings indicate sub-functionalization of SnRK1 subunits and identify novel phosphorylation targets linked to membrane trafficking, ethylene signaling, and ion transport.