A lipid transfer protein has antifungal and antioxidant activity and suppresses Fusarium head blight disease and DON accumulation in transgenic wheat

Trichothecene mycotoxins such as deoxynivalenol (DON), are virulence factors of Fusarium graminearum, which causes Fusarium head blight (FHB), one of the most important diseases of small grain cereals. We previously identified a non-specific lipid transfer protein (nsLTP) gene, AtLTP4.4, which was overexpressed in an activation tagged Arabidopsis line resistant to trichothecin (Tcin), a type B trichothecene in the same class as DON. Here we show that overexpression of AtLTP4.4 in transgenic wheat significantly reduced F. graminearum growth in Bobwhite and RB07 lines in the greenhouse and reduced fungal lesion size in detached leaf assays. Hydrogen peroxide accumulation was attenuated upon exposure of transgenic wheat plants to DON, indicating that AtLTP4.4 may confer resistance by inhibiting oxidative stress. Field testing indicated that disease severity was significantly reduced in two transgenic Bobwhite lines expressing AtLTP4.4. DON accumulation was significantly reduced in four different transgenic Bobwhite lines expressing AtLTP4.4 or a wheat nsLTP, TaLTP3, which was previously shown to have antioxidant activity. Recombinant AtLTP4.4 purified from Pichia pastoris exhibited potent antifungal activity against F. graminearum. These results demonstrate that overexpression of AtLTP4.4 in transgenic wheat suppresses DON accumulation in the field. Suppression of DON induced reactive oxygen species by AtLTP4.4 might be the mechanism by which fungal spread and mycotoxin accumulation are inhibited in the transgenic wheat plants.

Pulsing and non-pulsing ULXs: the iceberg emerges

ABSTRACT We show that ultraluminous X-ray sources (ULXs) with coherent X-ray pulsing (PULXs) probably have neutron-star spin axes significantly misaligned from their central accretion discs. Scattering in the funnels collimating their emission and producing their apparent super-Eddington luminosities is the most likely origin of the observed correlation between pulse fraction and X-ray photon energy. Pulsing is suppressed in systems with the neutron-star spin closely aligned to the inner disc, explaining why some ULXs show cyclotron features indicating strong magnetic fields, but do not pulse. We suggest that alignment (or conceivably, field suppression through accretion) generally occurs within a fairly short fraction of the ULX lifetime, so that most neutron-star ULXs become unpulsed. As a result we further suggest that almost all ULXs actually have neutron-star accretors, rather than black holes or white dwarfs, reflecting their progenitor high-mass X-ray binary and supersoft X-ray source populations.