Infection biology and defence responses in sorghum against Colletotrichum sublineolum

• Published in: Journal of applied microbiology Vol. 107; no. 2; pp. 404 - 415
• Main Authors: Basavaraju, P, Shetty, N.P, Shetty, H.S, de Neergaard, E, Jørgensen, H.J.L
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.08.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Biological and medical sciences; Colletotrichum; Colletotrichum - pathogenicity; Colletotrichum sublineolum; Fundamental and applied biological sciences. Psychology; Glycoproteins - metabolism; hemibiotrophy; Host-Pathogen Interactions; HRGPs; Hydrogen Peroxide - metabolism; infection biology; Microbiology; Plant Diseases - microbiology; Plant Leaves - cytology; Plant Leaves - metabolism; Plant Leaves - microbiology; Plant Proteins - metabolism; reactive oxygen species; Sorghum; Sorghum - metabolism; Sorghum - microbiology; sorghum anthracnose; Sorghum bicolor; Spores, Fungal - pathogenicity; hemibiotrophy; Monocotyledones; Oxygen; Applied microbiology; Biology; Colletotrichum; Fungi; Infection; infection biology; sorghum anthracnose; Sorghum bicolor; Gramineae; Angiospermae; reactive oxygen species; Spermatophyta; Fungi Imperfecti; Sorghum (food); HRGPs
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2009.04234.x

To investigate the infection biology of Colletotrichum sublineolum (isolate CP2126) and defence responses in leaves of resistant (SC146), intermediately resistant (SC326) and susceptible (BTx623) sorghum genotypes. Infection biology and defence responses were studied quantitatively by light microscopy, H₂O₂ accumulation by DAB staining and HRGP accumulation by immunological methods. Inhibition of conidial germination and appressorium formation may represent prepenetration defence responses on the leaf surface. Inducible defence responses in the resistant genotypes included decreases in formation of appressoria as well as accumulation of H₂O₂, HRGPs and phytoalexins. Concomitant with these inducible responses, fungal growth was stopped during or just after penetration in genotypes SC146 and SC326. High levels of H₂O₂ accumulating at late infection stages (5 days after inoculation) in the susceptible genotype BTx623 correlated with necrosis and tissue degeneration. The early accumulation of H₂O₂ and HRGPs indicates roles in defence whereas the late accumulation in genotype BTx623 correlated with successful pathogenesis. The fact that there is a significant correlation between induced accumulation of H₂O₂, papilla formation and cell wall cross-linking, as evidenced by HRGP accumulation, and cessation of pathogen growth in resistant genotypes may help exploit host resistance in sorghum.