Growth and ultrastructural modifications to chestnut calli induced by culture filtrates of virulent and hypovirulent Cryphonectria parasitica strains

Abstract

Gallus cultures of two susceptible Castanea sativa cultivars, 'Garrone rosso' and 'Glone 71' were grown on culture medium supplemented to 50% with culture filtrates (GEs) from E4 virulent (E4-V) or E13 hypovirulent (E13-H) Cryphonectria parasitica strain, respectively. E13-H GEs caused a reduction in fresh weight and an increase in dry weight on calli of both genotypes. E4-V GEs did not induce any modification of these parameters compared with the control, but fresh weight of 'Glone 71' was reduced. Eight and electron microscopy observation showed the presence of large osmiophilic aggregates in the vacuoles and, sometimes, the ruptured tonoplast in the E4-V treated calli. Galli grown on E13-H GEs had a meristematic-like appearance, with small, scarcely vacuolated cells containing altered mitochondria and plasmaletnma proliferations.

The Use of Interactions in Dual Cultures in vitro to Evaluate the Pathogenicity of Fungi and Susceptibility of Host Plant Genotypes

“…Changes involving the reduction of matter of living callus while increasing the share of dead callus were observed in tissue cultures of sweet chestnut (Castanea sativa) affected by the virulent strain of Cryphonectria parasitica. In this case, the research in dual cultures fully confirmed the in vivo observations [25]. Many studies show that virulent pathogens are stimulated by the callus in dual cultures, while saprotrophic fungi or fungi that re-colonize wood are inhibited by the callus [5,3,13,33].…”

Growth and physiological responses of chestnut calli to crude extracts of virulent and hypovirulent strains of Cryphonectria parasitica

“…1997). In contrast, the absence of necrotic symptoms on tomato seedlings treated with H‐E13 CEs suggests that the inhibition of callus growth due to these CEs could be attributed to secondary metabolites with a growth‐regulation effect rather than a toxic action, as implied by the suppression of root differentiation observed during the phytoxicity assay and the meristematic‐like appearance of callus cells treated with culture filtrates of H‐E13 ( P IAGNANI et al. 1997).…”

“…Growth inhibition of chestnut calli caused by V‐E4 CEs can be attributed to their toxic activity, as detected on tomato seedlings during the phytotoxicity test. A reduced concentration of phytotoxic substances is likely to explain the lack of inhibitory effect observed in callus growth exposed to V‐E4 culture filtrates ( P IAGNANI et al. 1997).…”

“…1994), a particularly useful technique, when the infection process takes place in bark or woody tissues. On chestnut calli of two susceptible cultivars of C. sativa , culture filtrates (CFs) of a hypovirulent strain of C. parasitica caused a significant reduction in fresh weight, whereas CFs of a virulent isolate caused only a small decrease in fresh weight ( P IAGNANI et al. 1997).…”

Cryphonectric Acid and Other Minor Metabolites from a Hypovirulent Strain of Cryphonectria parasitica

“…The results are in agreement with the interference with cell differentiation shown by the culture filtrates of E13 C. parasitica strain on chestnut calli of C. sativa and C. mollissima. 10 Further work is required in order to characterize the physiological effects of the compounds produced by E13 on the cultured cells of both susceptible and resistant Castanea species.…”