Production and fitness of Fusarium pseudograminearum inoculum at elevated carbon dioxide in FACE

Abstract

Rising atmospheric carbon dioxide (CO 2 ) concentration is increasingly affecting food production but how plant diseases will influence production and quality of food under rising CO 2 is not well understood. With increased plant biomass at high CO 2 the stubble-borne fungal pathogen Fusarium pseudograminearum causing crown rot (CR) of wheat may become more severe. We have studied inoculum production by Fusarium using fungal biomass per unit wheat stubble, stem browning from CR and the saprophytic fitness of Fusarium strains isolated from two wheat varieties grown in 2007 and 2008 at ambient and elevated CO 2 in free-air CO 2 enrichment (FACE) with or without irrigation and once in a controlled environment. Fungal biomass, determined using primers for fungal ribosomal 18s and the TRI5 gene, increased significantly at elevated CO 2 in two of the three studies. Stem browning increased significantly at elevated CO 2 in the 2007 FACE study. At elevated CO 2 increased stem browning was not influenced by irrigation in a susceptible variety but in a resistant variety stem browning increased by 68% without irrigation. Wheat variety was significant in regression models explaining stem browning and Fusarium biomass but pathogen biomass at the two CO 2 levels was not significantly linked to stem browning. Fusarium isolates from ambient and elevated CO 2 did not differ significantly in their saprophytic fitness measured by the rate of colonization of wheat straw. We show that under elevated CO 2 Fusarium inoculum in stubbles will be amplified from increased crop and pathogen biomass while unimpeded saprophytic fitness will retain its effectiveness. If resistant varieties cannot completely stop infection, Fusarium will rapidly colonize stubble to further increase inoculum once the crop is harvested. Research should move beyond documenting the influence of elevated CO 2 to developing disease management strategies from improved knowledge of pathogen biology and host resistance under rising CO 2 .

Response of wheat fungal diseases to elevated atmospheric CO2level

“…In Mv Regiment, which was the least susceptible variety, a similar rate of infection was observed at both ambient and elevated CO 2 levels. The variation found here between wheat varieties was in accordance with previous results reported by Melloy et al (2010) on Fusarium pseudograminearum, which causes wheat crown rot. These authors found increased fungal biomass and/or increased stem browning in response to EC in some situations, which exhibited variety dependence.…”

Perspectives and Challenges for Sustainable Management of Fungal Diseases of Mungbean [Vigna radiata (L.) R. Wilczek var. radiata]: A Review

“…In South Asia, spot blotch in wheat (Cochliobolus sativus) has increased substantially in recent years and it is speculated that elevated night temperatures due to climate change has contributed to this (Sharma et al, 2007). In Australia, root and crown rot of wheat (Fusarium pseudograminearum) is expected to increase due to climate change as the disease was high with elevated CO 2 , temperature, and drought (Melloy et al, 2010). There is no information available on the impact of climate change on the dynamics of mungbean diseases.…”

“…Several soil-borne pathogens, such as Rhizoctonia, Fusarium etc. are common problem in rice and wheat (Kobayashi et al, 2006;Melloy et al, 2010). These fungal genera also infect mungbean, but more studies are required to determine if the same species and strains also infect mungbean.…”

Plant adaptation to climate change—opportunities and priorities in breeding

“…Changes in plant physiology at high CO 2 concentrations influence the life cycle of insect pests, weeds, and plant pathogens. The fecundity of many biotrophic (Hibberd et al 1996) and necrotrophic (Melloy et al 2010) pathogens increases at elevated CO 2 . The enlarged crop canopy from a CO 2 fertilisation effect increases the number of infection cycles to further boost pathogen population, potentially increasing the rate of evolution of new races (Chakraborty and Datta 2003).…”