dieback in invasive plants due to a loss of protective microorganisms , or encounters with new pathogens ?

Parkinsonia aculeata L. (parkinsonia) is a Weed of National Significance. It impacts heavily on biodiversity, livestock and pasture management across northern Australia. Dieback in some parkinsonia populations has resulted in levels of control not previously achieved by other methods, and therefore raises the possibility of biological control of parkinsonia, using dieback. The composition of parkinsonia’s microbial endophyte communities, or ‘phytobiome’, suggests that multiple endophyte species may be responsible for dieback. Since dieback does not occur in the native range, we hypothesized that native-range parkinsonia hosts a different phytobiome that ‘protects’ its host against dieback-causing agents, whereas introduced parkinsonia does not. Hence, dieback may be caused by pathogens encountered by invasive parkinsonia upon its introduction to Australia. To test this hypothesis we compare microbial DNA from healthy parkinsonia sampled in the USA, to DNA from healthy and dieback-affected parkinsonia Is dieback in invasive plants due to a loss of protective microorganisms, or encounters with new pathogens?