2025/03/24 by Guillaume Brun, Estelle Billard, Adéla Hýlová +9 · 1 voice
Agricultural and Biological Sciences · #Legume Nitrogen Fixing Symbiosis #Plant Parasitism and Resistance #Plant and animal studies
paper · doi:10.1093/pcp/pcaf032
openalex publication_date 2025/03/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Broomrapes (Phelipanche and Orobanche spp.) and witchweeds (Striga spp.) are parasitic weeds that are increasingly threatening crops worldwide. Seeds of these species rely on host-derived signals such as strigolactones (SL) to germinate. While cytokinins (CKs) were also reported as germination inducers of witchweeds, their role during the germination of broomrapes remains unexplored. Our study shows that some but not all CKs stimulate Striga hermonthica germination independently of SL and that high concentrations of bioactive CKs trigger Striga seedlings to differentiate into fully extruded embryo-like structures. In contrast, CK-free bases but not ribosylated or glycosylated conjugates are extremely potent inhibitors of broomrapes germination. Germination inhibition upon the CK signaling inhibitor PI-55 and inhibitor of CK degradation INCYDE suggest that the CK perception and degradation machinery is conserved in parasitic weeds. In Phelipanche ramosa, gene expression analyses combined with targeted quantification of CK contents revealed that SL first induce an increase in abscisic acid catabolism, then a modification of the CK endogenous pool in favor of inactive conjugates. Overall, this study provides valuable insights into the hormonal interplay governing seed germination in broomrapes and witchweeds, paving the way for future studies aimed at developing novel strategies for parasitic weed control.