Response to Temperature and Virulence Assessment of Fusarium circinatum Isolates in the Context of Climate Change

Abstract

With future global temperatures predicted to increase, the relationship between a host, pathogen, and environment, becomes less predictable and epidemics may pose a greater risk to forests worldwide. Resistance breeding is an important disease management tool, but because tree species require long breeding times, it is necessary to develop techniques for testing current pathogen isolates against their hosts. Pitch canker disease of pines, caused by the pathogen Fusarium circinatum, is no exception and represents a threat to pine forests and commercial plantations worldwide, as it thrives at warm temperatures and high humidity. We tested growth of 15 F. circinatum isolates in culture at three temperatures: 25, 27, and 31 • C. We also evaluated the sporulation and pathogenicity of eight of the isolates on two susceptible Pinus elliotti (slash pine) open-pollinated families and one tolerant open-pollinated Pinus taeda (loblolly pine) family. Our results showed significant differences among isolates in the temperature and pathogenicity tests. All isolates showed a significant decrease in growth at 31 • C, although some showed similar growth at 25 and 27 • C. Several of the new isolates tested were more pathogenic than the isolates that the USDA Forest Service Resistance Screening Center (RSC) had been using. The new isolates have now been incorporated into their operational screening program.Also, both pathogen and some of hosts have whole-genome drafts available [16][17][18] that would facilitate future projects designed to understand host-pathogen interactions at the genomic and molecular level.Due to the wide-scale planting of southern pines and their economic importance, there is an urgent need to understand, not only the genetics and host-pathogen interactions, but also interactions with the environment in order to develop practical strategies for the management of pitch canker and other diseases. Resistance to pitch canker is quantitative and heritable [19,20]; therefore, commonly used management strategies involve breeding and deployment of resistant host material. With future global temperatures predicted to increase [21][22][23], new climate variations and extreme weather events are predicted to increase [24][25][26][27][28], which may lead to increased disease incidence [29] and compromise the host's defense response [30][31][32][33]. These changes in environment may also alter the relationships between host, pathogen and environment [34]. This disruption may also change the geographical distribution of pathogens, bringing them into areas where they are currently absent. In the future, a larger number of outbreaks and possible pathogenic variants may be expected as new environmental conditions resulting from climate change may favor survival and fitness of some pathogens. In contrast, plant disease management strategies under new climate conditions are lagging [35].The USDA Forest Service Resistance Screening Center (RSC) in Asheville, North Carolina has been screening seedlings of pine and other forest tre...

Influence of Temperature and Moisture Duration on Pathogenic Life History Traits of Predominant Haplotypes of Fusarium circinatum on Pinus spp. in Spain

“…Mullet et al (2017) reported that the MGR at 25 ºC can depend on the isolate. Unlike some other studies (Quesada et al 2019), we found differences between 25 and 30ºC for two of the three isolates studied. In our study, isolate 9 had the highest MGR at all temperatures except 5ºC.…”

Next-generation fungal identification using target enrichment and Nanopore sequencing

“…A. rolfsii ( Curzi) C.C.Tu et Kimbr (Atheliaceae, Agaricomycotina) isolate 948 was kindly provided by Dr. Nicolas S. Dufault at the University of Florida. Pitch canker pathogen F. circinatum Nirenberg & O’Donnell (Nectriaceae, Pezizomycotina) isolate Volusia was isolated from loblolly pine [ 78 ]. For the purpose of DNA isolation, all fungal species were routinely maintained on PDA (Becton, Dickinson and Company, Franklin Lakes, NJ, USA) overlaid with a single-layer cellophane (Bio-Rad, Hercules, CA, USA), and the cultures were incubated at room temperature for seven days.…”

Trichoderma as a biostimulator and biocontrol agent against Fusarium in the production of cereal crops: Opportunities and possibilities

“…The exposure of plants to Fusarium species is determined by weather conditions during the flowering period of these cereal crops, in particular temperature and humidity. In addition, there is evidence that the weather conditions that promote colonization by pathogens can differ from those that are conducive to subsequent infections (Quesada et al, 2019). The occurrence of FHB is associated with moderate temperatures (25-30°C) with relatively high humidity and is promoted by rainfall during and following the flowering period in cereal crops (Vaughan et al, 2016).…”