Dual role for fungal-specific outer kinetochore proteins during cell cycle and development in Magnaporthe oryzae

The outer kinetochore DASH complex (also known as the Dam1 complex) ensures proper spindle structure and chromosome segregation. While DASH complex protein requirement diverges among different yeasts, its role in filamentous fungi has not yet been investigated. We studied the dynamics and role of middle (Mis12) and outer (Dam1 and Ask1) kinetochore proteins in the filamentous fungal pathogen, Magnaporthe oryzae, which undergoes multiple cell cyclelinked developmental transitions. While Mis12 was constitutively present in the nucleus, Dam1 and Ask1 were recruited only during mitosis. Although Dam1 was not required for viability, loss of its function (dam1 Delta) delayed mitotic progression, resulting in impaired conidial and hyphal development. Both Dam1 and Ask1 also localised to the hyphal tips, in the form of punctae oscillating back and forth from the growing ends, suggesting that Magnaporthe DASH complex proteins may play a non-canonical role in polarised growth during interphase, in addition to their function in nuclear segregation during mitosis. Impaired appressorial (infection structure) development and host penetration in the dam1. mutant suggest that fungus-specific Dam1 complex proteins could be an attractive target for a novel anti-fungal strategy.