MoDUO1, a Duo1-like gene, is required for full virulence of the rice blast fungus Magnaporthe oryzae

Abstract

Duo1, a major component of the Dam1 complex which has been found in two species of yeast (the budding yeast Saccharomyces cerevisae and the fission yeast Schizosaccharomyces pombe), is involved in mitosis-related chromosome segregation, while its relevance to pathogenicity in filamentous fungi remains unclear. This report elucidated this very fact in the case of the rice blast fungus Magnaporthe oryzae. A gene designated MoDUO1 that encodes a Duo1-like homolog (MoDuo1) was discovered in the M. oryzae genome. Two types of MoDUO1 mutants were obtained using genetic approaches of Agrobacterium-mediated gene disruption and homologous recombination. Both disruption and deletion of MoDUO1 can exert profound effects on the formation pattern of conidiophores and conidial morphology, such as abnormal nucleic numbers in conidia and delayed extension of infectious hyphae. Intriguingly, plant infection assays demonstrated that inactivation of MoDUO1 significantly attenuates the virulence in its natural host rice leaves, and functional complementation can restore it. Subcellular localization assays showed that MoDuo1 is mainly distributed in the cytosol of fungal cells. Proteomics-based investigation revealed that the expression of four mitosis-related proteins is shut down in the MoDUO1 mutant, suggesting that MoDuo1 may have a function in mitosis. In light of the fact that Duo1 orthologs are widespread in plant and human fungal pathogens, our finding may represent a common mechanism underlying fungal virulence. To the best of our knowledge, this is the first example of linking a Duo1-like homolog to the pathogenesis of a pathogenic fungus, which might provide clues to additional studies on the role of Dam1 complex in M. oryzae and its interaction with rice.

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

“…However, the relationship between viability, DASH complex and the number of MTs is not clear in filamentous fungi, where single KT-MT attachment studies are currently lacking. Here, we show that the key members of the DASH complex, Dam1 and Ask1, like the previously studied MoDuo1 (Peng et al, 2011), are not essential in M . oryzae , suggesting that more than one MT likely binds to a KT in the blast fungus or other interactions stabilise this KT-MT attachment.…”

“…Another DASH complex protein in M . oryzae , MoDuo1, has previously been implicated in proper conidiation; however, its precise role in the process remained elusive (Peng et al, 2011). Defective septation, similar to the one during conidial development in the dam1 Δ mutant, has also been found in the absence of MoTea4 function, which is mainly involved in cell polarity in M .…”

“…The M . oryzae Duo1 plays a role in conidiation and full virulence in rice, but not much information is available regarding its function as a kinetochore protein in mitosis or its localisation during the cell cycle (Peng et al, 2011). In this study, we focussed on the role of DASH complex proteins in chromosome segregation, especially during the cell cycle-regulated morphological transitions in M .…”

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

“…However, the relationship between viability, the DASH complex and the number of MTs is not clear in filamentous fungi, where single kinetochore-MT attachment studies are currently lacking. Here, we show that the key members of the DASH complex, Dam1 and Ask1, like the previously studied M. oryzae Duo1 homolog, MoDuo1 (MGG_02484) (Peng et al, 2011), are not individually essential in M. oryzae, suggesting that more than one MT probably binds to a kinetochore in the blast fungus, or that other unknown protein interactions stabilise this kinetochore-MT attachment. The fact that we were able to generate deletion mutants of DAM1 and ASK1 implies that Dam1 and Ask1 are not essential for viability in Magnaporthe.…”

“…DASH complex proteins are not found in rice or other plant hosts making them potential candidates; however, within filamentous fungi, only the Duo1 subunit of Magnaporthe has been studied so far. The M. oryzae protein Duo1 plays a role in conidiation and full virulence in rice, but not much information is available regarding its function as a kinetochore protein in mitosis or its localisation during the cell cycle (Peng et al, 2011). In this study, we focused on the role of DASH complex proteins in chromosome segregation, especially during the cell cycle-regulated morphological transitions in M. oryzae.…”