Abstract BACKGROUND The growth and yield of Helianthus annuus (sunflower) are severely constrained by the root‐parasitic plant Orobanche cumana in China. Translocated RNAs from stocks via heterografting can act as mobile signals to modulate physiological processes in scions, including defense and stress responses. Because the interaction between parasitic plants and their host plants can be seen as a form of ‘perfect graft’, it is necessary to investigate the trans‐species movement of RNAs between O. cumana and its host sunflower, to understand their interaction in search for new strategies to control this parasitic weed. RESULTS Using RNA sequencing and functional analyses, we demonstrated dynamic, stage‐specific RNA transfer during key parasitic stages (haustorium penetration and vascular connection). A significant proportion of reads (≤5.4% from O. cumana to sunflower and 1.8% in reverse) were identified as mobile, with enriched functional categories such as translation, protein folding and translational elongation. Gene silencing of OcPar1 —a highly abundant mobile gene derived from O. cumana —in sunflower led to a reduction in infection, whereas overexpression of this gene enhanced the parasitism of O. cumana on sunflower, demonstrating the critical role of mobile transcripts during the invasion of O. cumana into sunflower. Additionally, mobile lncRNAs were identified, and the function of the O. cumana‐ originated lncRNAs in sunflower was predicted, suggesting cross‐species regulatory potential. CONCLUSION These findings reveal that trans‐species RNA mobility is not merely passive, but a regulated process with functional significance, shaping both parasitic adaptation and host defense mechanisms. This study provides foundational insights into RNA‐mediated communication between parasitic and host plants, offering potential strategies for controlling parasitic weeds. © 2026 Society of Chemical Industry.
Yang et al. (Sun,) studied this question.