Cytokinins as an alternative suicidal Striga germination compound

The witchweed Striga hermonthica, an obligate and noxious root-parasitic plant, remains a persistent threat to cereal production and poses a great challenge to small-holder farmers in Sub-Saharan Africa. Inducing suicidal germination of Striga seeds by applying strigolactone analogs is a promising strategy to deplete the Striga seed bank of infested soils. Nevertheless, there is a need to increase the efficiency and improve the applicability of this strategy, which may be achieved by testing further Striga germination stimulants. Herein, we explored the potential of cytokinins in inducing Striga seed germination. We investigated their activity as a suicidal germination agent along with fluridone that inhibits carotenoid biosynthesis and hence reduces abscisic acid formation and facilitates breaking of seed dormancy. Under lab conditions, application of fluridone (at 100 mu M) or cytokinins (at 100 mu M) showed 19% and 63% Striga germination, respectively, while combining different cytokinins with fluridone led to above 93% germination of treated seeds, with thidiazuron as the most active cytokinin. Using rice (cv IAC-165), we also show that co-application of fluoridone and thidiazuron to Striga infested pots before planting the host led to up to 86%-100% reduction in Striga emergence. In summary, cytokinins, particularly thidiazuron, could be useful suicidal agents to induce Striga seed germination and ultimately deplete the seedbank in Striga-infested regions.

Automated summary

The root-parasitic plant Striga hermonthica poses a significant threat to cereal production in Sub-Saharan Africa. Inducing suicidal germination of Striga seeds is a promising strategy to deplete the seed bank in infested soils. This study explores the potential of cytokinins as germination agents and demonstrates the efficacy of thidiazuron in inducing Striga seed germination.