Laohavisit, A. | Search bioRxiv

bioRxiv2025

A copper-dependent, redox-based hydrogen peroxide perception in plants

Redox-related molecules, such as quinones and reactive oxygen species (ROS), are important signaling molecules for all living organisms. A plant-specific leucine rich-repeat receptor-like kinase (LRR-RLK) CANNOT RESPOND TO DMBQ 1 (CARD1), also known as HYDROGEN-PEROXIDE-INDUCED Ca2+ INCREASES (HPCA1), perceives both quinones and ROS, but knowledge on key structural features is unknown. Here, we determine the structure of the CARD1 ectodomain and uncover its unique features. Structural studies, coupled with genetics and biochemical analysis, demonstrated that previously identified unique cysteine residues are not essential for signal perception in CARD1. Interestingly, CARD1 harbors a copper ion on the surface of the ectodomain via histidine-coordination that is crucial for hydrogen peroxide signaling. Our work reports the first copper-dependent redox receptor and highlights a unique perspective between a receptor and non-peptide stimuli during their perception.

plant biology↗

bioRxiv2025

Neofunctionalized RGF pathways drive haustorial organogenesis in parasitic plants

Parasitic plants initiate rapid de novo organogenesis of a specialized feeding structure called a haustorium upon contact with their hosts. Currently, little is known about the internal signals regulating haustorium development. Here, we identify root meristem growth factor (RGF) peptides in Phtheirospermum japonicum as endogenous inducers of prehaustorium formation. Treatment with specific RGF peptides in the absence of hosts triggered prehaustoria and induced expression of PjYUC3, a gene required for auxin biosynthesis and prehaustorium formation. CRISPR-mediated knockouts showed that PjRGFR1 and PjRGFR3, receptors activated by the haustorium specific RGF peptides PjRGF2 and PjRGF5, are essential for prehaustorium formation, revealing functional redundancy. Phylogenic analyses indicate that PjRGF2 is broadly conserved among Orobanchaceae, whereas PjRGF5 appears to have recently evolved through tandem multiplication and neofunctionalization. Our findings establish RGF peptides and their corresponding receptors as critical components of haustorium developmental signaling and provide insights into the evolutionary trajectories that shape plant parasitism. TeaserPlant peptide hormones regulate and induce the parasitic plant specialized organ for connecting to and feeding from the host.

plant biology↗