Characterization of sugarcane response to Bipolaris sacchari: inoculations and host-specific HS-toxin

• Published in: Phytopathology Vol. 84; no. 7; pp. 672 - 676
• Main Authors: Bournival, B.L. (Hawaiian Sugar Planters' Association, Aiea, HI.), Ginoza, H.S, Schenck, S, Moore, P.H
• Format: Journal Article
• Language: English
• Published: St. Paul, MN American Phytopathological Society 01.07.1994
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; BIPOLARIS; CLONE; CLONES; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; MICOTOXINAS; MYCOTOXINE; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; PATHOTYPE; PATOTIPOS; Phytopathology. Animal pests. Plant and forest protection; PODER PATOGENO; POUVOIR PATHOGENE; RELACIONES HUESPED PARASITO; RELATION HOTE PARASITE; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; SACCHARUM; SINTOMAS; SYMPTOME; VARIACION GENETICA; VARIATION GENETIQUE; Saccharum; Monocotyledones; Plant pathogen; Mycosis; Pathogenesis; Cell biology; Biochemistry; Fungi; Characterization; Inoculation; Gramineae; Angiospermae; Fungi Imperfecti; Helminthosporium sacchari; Thallophyta; Pathophysiology; Phytotoxin; Host specificity; Tropical crop; Host agent relation; Sugar plant; Fungus resistance; Infection; Symptomatology; Experimental disease; Sensitivity resistance; Spermatophyta; Lesion
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/Phyto-84-672

Twenty-seven sugarcane clones inoculated with Bipolaris sacchari, causal agent of eyespot disease, were classified as susceptible or resistant based on the presence or absence of distinct chlorotic halos surrounding lesions on leaves. Under the inoculation conditions used in this study, all lesions on resistant plants were smaller than 3 mm; the proportion of lesions larger than 3 mm on susceptible clones ranged from 0.2 to 82.2%. The total number of lesions was not related to resistance or susceptibility. All clones classified as resistant to B. sacchari were insensitive to a host-specific toxin (HS-toxin) produced by the pathogen, whereas all susceptible plants produced a water-soaked streak when 1 microliter of partially purified HS-toxin was placed in a hole punched in a leaf segment. These results indicated that sensitivity to HS-toxin was an important factor in determining whether the pathogen could cause disease symptoms on the plant. Measurement of toxin-induced electrolyte leakage was not as reliable for differentiating between resistant and susceptible clones. In most susceptible individuals, the degree of disease severity was correlated with the level of sensitivity to HS-toxin; however, there were three clear exceptions, suggesting that in some clones, other factors besides sensitivity to HS-toxin might be involved in determining the extent of symptom expression