Strain‐related pathogenicity in Diplodia corticola

Abstract

Diplodia corticola is one of the most aggressive fungal pathogens of Quercus species and is involved in the decline of Mediterranean cork oak forests and Californian oaks.Information regarding variation in virulence between strains is scarce. We hypothesize that D. corticola strains differ in virulence and consequently induce different symptoms in infected plants. To test this, infection assays were carried out on Quercus suber half-sib seedlings with seven strains of D. corticola. Visual symptoms of infection (external lesions, leaf wilting, exudation and others) were recorded in parallel with physiological and biochemical parameters. All strains were able to cause lesions but at differing levels of aggressiveness. We show that internal lesion length did not correlate directly with strain aggressiveness and this agrees with physiological parameters that should be taken into account to infer about strain pathogenicity. Infection by all strains induced an overall negative impact on the net photosynthetic rate and an increase in the oxidative stress status of plants; however, significant differences were found when the effects of different strains were compared. Results also suggest that being under optimum growth conditions, prior to and during infection, allowed plants to respond to the pathogen. At the end of the experiment, some strains of D. corticola established a latent pathogen-like relationship with cork oak. This is the first study to show that D. corticola virulence is strain-dependent.

Impact of Botryosphaeria, Diplodia and Neofusicoccum species on two Eucalyptus species and a hybrid: From pathogenicity to physiological performance

“…The same was reported for the pathosystem Diplodia corticola/Quercus suber (Félix et al, 2017). The results obtained here suggest that lesion size is not directly related to physiological disorders, and cannot be taken as a direct measure of pathogen aggressiveness.…”

“…Félix et al, 2017). Variability in pathogenicity/aggressiveness at the isolate level has been reported previously in Botryosphaeriaceae (e.g.…”

“…The unclear differentiation concerning fungal species pathogenicity (effects on plant physiology rather than length of lesions produced) may have resulted from the use of a single pathogen isolate per species, since it is recognized that different isolates from the same species may have differing virulence (Félix et al, 2017;Mohali et al, 2009;Piškur et al, 2011). The unclear differentiation concerning fungal species pathogenicity (effects on plant physiology rather than length of lesions produced) may have resulted from the use of a single pathogen isolate per species, since it is recognized that different isolates from the same species may have differing virulence (Félix et al, 2017;Mohali et al, 2009;Piškur et al, 2011).…”

“…It is recognized that tolerance to stress factors such as drought differs among and within Eucalyptus species (Correia et al, 2014;Granda et al, 2014;McKiernan et al, 2016). Félix et al, 2017;Barradas et al, 2018). Previous studies assessed pathogenicity/aggressiveness of Botryosphaeriaceae species based on traits such as lesion length (Barradas et al, 2016;Li et al, 2018;Pavlic, Slippers, Coutinho, & Wingfield, 2007;Pérez, Wingfield, Slippers, Altier, & Blanchette, 2010;Rodas, Slippers, Gryzenhout, & Wingfield, 2009;Smith, Kemp, & Wingfield, 1994), while the physiological status of the infected plants remains poorly studied (e.g.…”

“…Previous studies assessed pathogenicity/aggressiveness of Botryosphaeriaceae species based on traits such as lesion length (Barradas et al, 2016;Li et al, 2018;Pavlic, Slippers, Coutinho, & Wingfield, 2007;Pérez, Wingfield, Slippers, Altier, & Blanchette, 2010;Rodas, Slippers, Gryzenhout, & Wingfield, 2009;Smith, Kemp, & Wingfield, 1994), while the physiological status of the infected plants remains poorly studied (e.g. Félix et al, 2017;Barradas et al, 2018). Morpho-physiological parameters that include growth, gas exchange and photosynthetic efficiency, among others, represent good indicators of plant responses to biotic factors (Berger, Sinha, & Roitsch, 2007;Linaldeddu, Sirca, Spano, & Franceschini, 2009).…”