Effect of climate change on sporulation of the teleomorphs of Leptosphaeria species causing stem canker of brassicas

Abstract

Leptosphaeria maculans and L. biglobosa are closely related sibling fungal pathogens that cause phoma leaf spotting, stem canker (blackleg) and stem necrosis of oilseed rape (Brassica napus). The disease is distributed worldwide, and it is one of the main causes of considerable decrease in seed yield and quality. Information about the time of ascospore release at a particular location provides important data for decision making in plant protection, thereby enabling fungicides to be used only when necessary and at optimal times and doses. Although the pathogens have been studied very extensively, the effect of climate change on the frequencies and distributions of their aerially dispersed primary inoculum has not been reported to date. We have collected a large dataset of spore counts from Poznan, located in central-west part of Poland, and studied the relationships between climate and the daily concentrations of airborne propagules over a period of 17 years (1998–2014). The average air temperature and precipitation for the time of development of pseudothecia and ascospore release (July–November), increased during the years under study at the rates of 0.1 °C and 6.3 mm per year. The day of the year (DOY) for the first detection of spores, as well as the date with maximum of spores, shifted from 270 to 248 DOY, and from 315 to 265 DOY, respectively. The acceleration of the former parameter by 22 days and the latter by 50 days has great influence on the severity of stem canker of oilseed rape.

Climate change accelerates local disease extinction rates in a long‐term wild host–pathogen association

“…Competing regional climate simulation models predict temperature increases in northern Fennoscandia of between 1.6-3.2 and 3.7-5.2°C by 2100 (Jacob et al, 2014). Analysis of changing climatic variables in the different Baltic Sea basins has also identified a time around the shift 1980/ 90s when there were almost synchronous changes, in large coupled to the North Atlantic Oscillation, with positive trends in temperature and precipitation, and negative trends in ice duration (BACC II Author Team, 2015;Diekmann & M€ ollmann, 2010). For example, the 1985-2015 extent of sea ice distribution differed from any other preceding 30-year winter period since ice observations started in 1720.…”

“…The potential for climate change to favour the dynamics of existing, new and emerging diseases thereby threatening global food security (Fisher et al, 2012), human (Altizer, Ostfeld, Johnson, Kutz, & Harvell, 2013;Equihua et al, 2017) and animal (Kalinda, Chimbari, & Mukaratirwa, 2017) health and biodiversity (Clare et al, 2016) has also attracted much attention (Fisher et al, 2012;Kaczmarek et al, 2016). With regard to fungal plant pathogens, concern has focused on the potential for climate change to increasingly favour agricultural pathogens within existing regions of host-pathogen associations (Chakraborty & Newton, 2011;Kaczmarek et al, 2016;Newbery, Qi, & Fitt, 2016) or to promote expansion of the geographic range of such pathogens (Bebber, Ramotowski, & Gurr, 2013;Fisher et al, 2012) into areas from which they are currently excluded by temperature and precipitation regimes.…”

“…The potential for climate change to favour the dynamics of existing, new and emerging diseases thereby threatening global food security (Fisher et al, 2012), human (Altizer, Ostfeld, Johnson, Kutz, & Harvell, 2013;Equihua et al, 2017) and animal (Kalinda, Chimbari, & Mukaratirwa, 2017) health and biodiversity (Clare et al, 2016) has also attracted much attention (Fisher et al, 2012;Kaczmarek et al, 2016). With regard to fungal plant pathogens, concern has focused on the potential for climate change to increasingly favour agricultural pathogens within existing regions of host-pathogen associations (Chakraborty & Newton, 2011;Kaczmarek et al, 2016;Newbery, Qi, & Fitt, 2016) or to promote expansion of the geographic range of such pathogens (Bebber, Ramotowski, & Gurr, 2013;Fisher et al, 2012) into areas from which they are currently excluded by temperature and precipitation regimes. Furthermore, consideration of these possibilitieswhether theoretical through various forms of simulation modelling (Kremer, Schluter, Racca, Fuchs, & Lang, 2016;Skelsey, Cooke, Lynott, & Lees, 2016), or empirically through assessments of the fit of temperature optima for pathogen growth (Chitarra, Siciliano, Ferrocino, Gullino, & Garibaldi, 2015;Sabburg, Obanor, Aitken, & Chakraborty, 2015;Yang et al, 2016) are largely focused on highly managed crop systems (Newbery et al, 2016;Shaw & Osborne, 2011) although forest trees receive some attention (Ghelardini, Pepori, Luchi, Capretti, & Santini, 2016;Sturrock et al, 2011).…”

“…Here, we use an ongoing 26-year study of the dynamics of a wild host-pathogen association to assess the potential impact of changing environmental conditions in northern latitudes where the effects of climate change in terms of rising temperatures, changing snow pack duration and increasing sea temperature conditions are already becoming apparent (Andersson et al, 2017;BACC II, 2015;Callaghan et al, 2010;Diekmann & M€ ollmann, 2010). Every year since 1990 we have assessed the epidemiology of the rust fungus…”

Climate change impacts on plant diseases

“…Elevated temperature and CO 2 concentration have impact on plant-disease interaction (Lopez et al, 2012) and posing a higher threat perception of late blight (Phytophthora infestans) of potato and blast (Magnaporthe grisea) and sheath blight (Rhizoctonia solani) of rice (Kobayashi et al, 2006). Effects of climate change on Phoma (Leptosphaeria maculans) in rape seed was observed through a model in combination with climate change that predict temperature and rainfall under CO 2 emission scenarios for the 2020 and 2050s in UK (Evans et al (2007); and sporulation of teleomorphs on climate change (Kaczmarek et al, 2016).…”