Fusarium oxysporumf. sp.orthoceras, a Potential Mycoherbicide, Parasitizes Seeds ofOrobanche cumana(Sunflower Broomrape): a Cytological Study

Fusarium oxysporum f. sp. orthoceras , a potential agent for biological control of the root-parasitic weed Orobanche cumana in sunflower, attacks underground developmental stages, such as shoots, tubercles and seed germ tubes. The germination of inoculated seed was significantly reduced, and cytological investigation showed that F. oxysporum had penetrated and colonized dormant seeds of O. cumana . Germ tubes of microconidia penetrated all parts of the thick, complex seed testa, and seed contents were completely destroyed. Hyphae dissolved the endosperm cell walls and metabolized the cytoplasm which was rich in lipid- and protein-bodies. Thus, the inoculation of soils with F. oxysporum may be used to reduce the Orobanche seed bank.