Author
Koki Nagao
nakouki_v5@s.okayama-u.ac.jp
Okayama Uni
Okayama
Coauthors
Taku Takahashi, Okayama Uni, Okayama, Japan
Ryusuke Yokoyama, Tohoku Uni, Miyagi, Japan
Abstract
Cuscuta is a holoparasite causing significant crop damage. Control is challenged by a persistent soil seed bank (viable >10 years). Mycoherbicides (e.g., Fusarium oxysporum f. sp. cuscutae) are known to be effective against vulnerable Cuscuta seedlings. However, their field efficacy is limited because sporadic seed germination prevents uniform targeting. A strategy is needed to induce mass germination, exposing the entire vulnerable seedling population.
To identify a physiological “trigger” for such a strategy, we investigated environmental effects on C. campestris germination. Our physiological study revealed that far-red light induced germination and shoot elongation more than red light. Moreover, a reversible response to red and far-red light was observed, indicating a phytochrome-mediated pathway opposite to that in many non-parasitic plants.
Furthermore, we discovered that methyl jasmonate (MeJA) significantly promotes both germination and shoot elongation. RT-PCR analysis also revealed that a putative RbcS gene did not respond to light.
These physiological findings offer a practical solution to this biocontrol challenge. The application of “triggers” could be used to induce mass “suicidal germination” of the soil seed bank. This synchronization strategy, which we suggest as a new concept, would allow a single application of an existing mycoherbicide to target the entire vulnerable population simultaneously, dramatically enhancing the efficacy of biological control.
Keywords
Cuscuta
parasitic plants
jasmonic acid
Highlights
Cuscuta shows a unique light response: far-red light, not red, promotes germination.
Methyl jasmonate, in addition to gibberellic acid, promotes germination and shoot elongation.
Cuscuta retains plant responses but has uniquely adapted signalling for its parasitic lifestyle.