Evolution of HMA-integrated tandem kinases accompanied by expansion of target pathogens
Authors: Asuke, S., Tagle, A. G., Hyon, G.-S., Koizumi, S., Murakami, T., Horie, A., Niwamoto, D., Katayama, E., Shibata, M., Takahashi, Y., Islam, M. T., Matsuoka, Y., Yamaji, N., Shimizu, M., Terauchi, R., Hisano, H., Sato, K., Tosa, Y.
The study cloned the resistance genes Rmo2 and Rwt7 from barley and wheat, revealing them as orthologous tandem kinase proteins (TKPs) with an N‑terminal heavy metal‑associated (HMA) domain. Domain‑swapping experiments indicated that the HMA domain dictates effector specificity, supporting a model of TKP diversification into paralogs and orthologs that recognize distinct pathogen effectors.
The authors introduce the ENABLE(R) Gene Editing in planta toolkit, a streamlined two‑step cloning system for creating CRISPR/Cas9 knockout vectors suitable for transient or stable transformation. Validation was performed in Oryza sativa protoplasts and Arabidopsis thaliana plants, and the toolkit includes low‑cost protocols aimed at facilitating adoption in the Global South.
The study examined how tricarboxylic acid (TCA) cycle metabolites influence drought tolerance in grapevine and Arabidopsis, finding that malate uniquely triggers stomatal closure via elevations in cytosolic Ca2+ and activation of the SLAC1 anion channel. G-proteins were shown to be essential for malate‑mediated signaling, linking metabolic changes to drought response through a second‑messenger cascade.
The study introduces Transposase-Accessible Chromosome Conformation Capture (TAC-C), which combines ATAC‑seq and Hi‑C to map fine‑scale chromatin interactions in rice, sorghum, maize, and wheat, revealing genome‑size‑correlated loop structures and distinct C3 vs. C4 patterns. Integration with population genetics shows that loops link distal regulatory elements to phenotypic variation, and SPL transcription factors (TaSPL7/15) modulate photosynthesis‑related genes via these interactions, enhancing photosynthetic efficiency and starch content in wheat mutants.