Histopathological study of compatible and incompatible interactions between barley and the spot blotch fungus Bipolaris sorokiniana
S. SHRESTHA (1), R. Sharma Poudel (1), P. Borowicz (1), S. Zhong (1) (1) North Dakota State University, U.S.A.

Spot blotch, caused by Bipolaris sorokiniana, is an important foliar disease of barley. However, few studies have been done to understand the host-pathogen interaction in this pathosystem. The objective of this study was to investigate the histopathological events of compatible and incompatible interactions between barley and B. sorokiniana. Four B. sorokiniana isolates (ND93-1, ND85F, ND90Pr and ND4008 representing Pathotype 0, 1, 2, and 7, respectively) were transformed with a vector (pCA56) harboring a gene for red fluorescent protein (RFP). The transformants expressing RFP were used to inoculate seedling plants of four barley genotypes (Bowman, ND5883, PI235186 and PI356746). Leaf samples were collected at 4, 8, 12, 16, 20, 24, 36, 48, 72, 168 hours post inoculation (HPI) for fluorescent microscopy. Significant differences were observed between compatible and incompatible interactions after 8 HPI. The pathotype 0, 1 and 7 induced hypersensitive reaction (HR) on resistant barley genotype at the time of fungal penetration (12 HPI). HR was not observed until 16 HPI in susceptible genotypes, except for the pathotype 2-infected Bowman which had cell death at 12 HPI. Our study suggests that the fungus changes from biotrophic to necrotrophic within 12-16 HPI depending on the fungal pathotypes and barley genotypes involved. 3,3′-Diaminobenzidine staining and qPCR are being used to further understand the molecular mechanism of resistance and susceptibility to spot blotch.

Abstract Number: P7-211
Session Type: Poster