Mycorrhizal symbiosis as a strategy for root parasitic weed control

Abstract: Parasitic weeds of the genera Striga and Orobanche spp. cause severe damage toimportant agricultural crops worldwide. Although some promising control methods against theseparasitic plants have been developed, new strategies for integrated approaches are still relevant.The lifecycle of root parasitic weeds is intimately associated with their host and is a suitabletarget to develop such new control strategies. Of particular interest are approaches directed atearly stages of the host-parasitic interaction. Strigolactones were first described as germinationstimulants for the seeds of these root parasitic plants. In addition, they also act as host detectionsignals for arbuscular mycorrhizal (AM) fungi. It is well known that AM fungi have a positiveeffect on plant fitness and on the induction of plant defence responses, conferring resistance tobiotic and abiotic stresses. In relation to parasitic plants, it has been recently shown that AMfungal inoculation of maize and sorghum lead to a reduction in Striga hermonthica infection.Moreover, we previously showed that a tomato mutant with a reduced production ofstrigolactones was less susceptible to Orobanche aegythiaca infection. Here we show that tomatoplants colonized by the AM fungus Glomus mosseae induce less germination of Orobancheramosa seeds than non-mycorrhizal plants. The results indicate that AM fungi may be used as asuitable tool for controlling root parasitic weeds by reducing strigolactone production by the hostplant.