The impact of microbial communities on the incidence of foliar fungal disease symptoms in wheat

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The study of plant diseases in controlled environments offers several advantages in terms of controlling / or minimising additional factors which might influence the outcome of the disease interaction. This includes limiting exposure to various environmental stresses as well as minimising interactions with other organisms including natural microbial communities. However these experiments may not translate completely into real field situations where the additional stresses including negative and positive interactions will almost certainly alter the outcome of a plant pathogen interaction, and this may ultimately affect crop yield.In natural field systems plant pathogens cause disease in heterogeneous environments where variable microbial communities may impact negatively or positively upon symptom severity and / or nutrient acquisition. Very few efforts have been made to address the interactions between organisms which can cause major foliar diseases of wheat within environments of variable above and below ground microbial communities.This project aims to understand how two major global disease-causing fungi on wheat leaves, Zymoseptoria tritici (Zt), the causal agent of Septoria tritici blotch (STB) and Parastagonospora nodorum (Pn), the causal agent of Septoria nodorum blotch (SNB), affect wheat-associated microbial communities and vice versa. The project will use both controlled environment experiments and field samples to monitor changes in microbial communities throughout fungal infection and changes in foliar diseases in response to distinct microbial communities. Antagonistic and agonistic interactions will be studied and microbes or microbial communities identified which can alter the outcome or severity of wheat disease caused by either or both fungi.A secondary objective will be to identify and engineer a wheat leaf associated endophytic fungus to produce fungal effector proteins via manipulation of Type 2 secretion to enhance the rate of screening for effector sensitivities in diverse wheat germplasm.The hypotheses to be tested in this project include1- That under controlled conditions STB and SNB have different impacts on associated below and above ground microbial communities2- That artificial manipulation of above and/or below ground microbial communities influences foliar disease symptomology caused by STB and SNB3- That particular mutants of Zt and Pn defective in different components of pathogenicity and virulence have distinct effects on microbial communities present within the infected leaf4- That wheat plants artificially inoculated by each fungal pathogen in the field will have different disease symptomology and microbial associations compared to controlled environments5- That we can identify and engineer a new fungal effector delivery system in a wheat leaf-associated endophytic microbe.The study of plant diseases in controlled environments offers several advantages in terms of controlling / or minimising additional factors which might influence the outcome of the disease interaction. This includes limiting exposure to various environmental stresses as well as minimising interactions with other organisms including natural microbial communities. However these experiments may not translate completely into real field situations where the additional stresses including negative and positive interactions will almost certainly alter the outcome of a plant pathogen interaction, and this may ultimately affect crop yield.In natural field systems plant pathogens cause disease in heterogeneous environments where variable microbial communities may impact negatively or positively upon symptom severity and / or nutrient acquisition. Very few efforts have been made to address the interactions between organisms which can cause major foliar diseases of wheat within environments of variable above and below ground microbial communities.