Cutinase is not required for fungal pathogenicity on pea.

Abstract

Cutinase, a fungal extracellular esterase, has been proposed to be crucial in the early events of plant infection by many pathogenic fungi. To test the long-standing hypothesis that cutinase of Nectria haematococca (Fusarium solani f sp piso is essential to pathogenicity, we constructed cutinase-deficient mutants by transformation-mediated gene disruption of the single cutinase gene of a highly virulent N. haematococca strain. Four independent mutants were obtained lacking a functional cutinase gene, as confirmed by gel blot analyses and enzyme assays. Bioassays of the cutinasedeficient strains showed no difference in pathogenicity and virulence on pea compared to the wild type and a control transformant. We conclude that the cutinase of N. haematococca is not essential for the infection of pea.

Cutinase Gene Disruption in Fusarium solani f sp pisi Decreases Its Virulence on Pea

“…The wild-type 77-2-3 showed a single major hybridizing band with EcoRI, Hindlll, Pstl, and Sstl, and the location of the band was shifted as expected as a result of the gene disruption (data not shown). Figure 7 shows the results obtained with Kpnl, which demonstrates gene disruption as has been previously reported (Stahl and Schafer, 1992) and shows that the isolates used for inoculation were the same as those present at the end of the experiment. As seen previously , isolate T-8 showed multiple cutinase bands, including a band corresponding to that found in the wild-type isolate 77-2-3 (Figure 7).…”

“…However, the amount of 3H-DipF labeling of extracellular proteins showed that 77-2-3 produced only 5 to 11% of extracellular active serine enzymes produced by T-8. With the cutinase gene-disrupted mutant, 3H-DipF-labeled cutinase could not be detected, although after 10 days small amounts of label were found in higher molecular weight components as previously found (Stahl and Schafer, 1992). Because the amount of extracellular fluid from the mutant used for SDS-PAGE was 10 times that from the wild type, these higher molecular weight proteins are only minor components.…”

“…This decreased virulence was clearly demonstrated by the assays used in this study; these assays involved different assays can detect differences in virulence. In a previous evaluation of virulence of this mutant, multiple spore levels were not tested and microscopic examination of the progression of lesions was not reported (Stahl and Schafer, 1992). There was no evidence presented to indicate that the assay conditions and methods used by these investigators to test for virulence would have detected decreased virulence.…”

“…Because the highly virulent strains of F: s. pisi have multiple cutinase genes , strain 77-2-3, with one cutinase gene, was used to generate cutinase gene-disrupted transformants (Stahl and Schafer, 1992). It was reported that these transformants retained virulence, and therefore, it was concluded that cutinase did not play a significant role in pathogenesis.…”

The Potato Late Blight Pathogen Phytophthora infestans and Other Pathogenic Oomycota

“…), Fusarium solani f. sp. pisi (Stahl and Schafer 1992), and Magnaporthe grisea (Sweigard et al 1992;Chap. 3, this Vol.…”