A mixture of six Georgia isolates of Phytophthora capsici (Leon.), the causal agent of phytophthora blight, were used for greenhouse mass screening of over 700 accessions of Capsicum annuum for both stem blight and fo...A mixture of six Georgia isolates of Phytophthora capsici (Leon.), the causal agent of phytophthora blight, were used for greenhouse mass screening of over 700 accessions of Capsicum annuum for both stem blight and foliar blight. From this screening, it was determined that resistance to both forms of the disease were relatively common in the germplasm, but resistance to one form of the disease was not strongly correlated to resistance to the other form. Ten accessions previously shown to possess root rot resistance were tested for resistance to stem rot and leaf blight, and were found to also be highly resistant to these forms of the disease. It appears that single accessions have resistance to foliar, stem and root rot caused by P. capsici, which may simplify breeding for resistance to all three forms of the disease.展开更多
A field study was undertaken to ascertain the effects of elicitors viz. benzothiadiazole （BTH） and salicylic acid （SA） on defense related enzymes viz. peroxidase, phenylalanine ammonia lyase, superoxide dismutase,...A field study was undertaken to ascertain the effects of elicitors viz. benzothiadiazole （BTH） and salicylic acid （SA） on defense related enzymes viz. peroxidase, phenylalanine ammonia lyase, superoxide dismutase, chitinase and 13-1,3-glucanase, and phenols in rice （Pusa Basmati I） plants. First foliar spray of BTH （50 mg/kg） and SA （50 mg/kg） was done at the maximum tillering stage and inoculation with Rhizoctonia solani was carried 24 h after elicitor treatment. Elicitors were further sprayed at every growth stage. Time course analysis showed peak accumulation of defense related enzymes and phenols in the rice leaves treated with BTH and SA, and accumulation was the highest at the flowering stage. Higher enzymatic activity was observed in elicitor treated plants inoculated with R. solani. Compared to the untreated control plants, application of elicitors before R. solani inoculation significantly elicited the defense related enzymes and phenols. Moreover, application of elicitors had a positive effect on yield and disease reduction. It is suggested that pretreatment of rice leaves with BTH and SA could be used to enhance the level of protection against sheath blight and to improve rice yield in the fields.展开更多
Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phyto...Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phytophthora capsici. Differences in root rot, stem blight and foliar blight severities among accessions were significant. The accessions consistently differentiated into two groups across the three disease syndromes. Simple sequence repeat (SSR) markers showed variability both within and between accessions of California Wonder. The variability in the responses to the three forms of Phytophthora blight does not warrant its usefulness as a standard susceptible control in studies involving the Capsicum-P. capsici patho-system.展开更多
Exserohilum turcicum and Puccinia sorghi cause foliar fungal diseases that affect maize crop in Argentina. These diseases, northern leaf blight and common rust respectively, are presented each year with different leve...Exserohilum turcicum and Puccinia sorghi cause foliar fungal diseases that affect maize crop in Argentina. These diseases, northern leaf blight and common rust respectively, are presented each year with different levels of severity affecting significantly the yield in susceptible hybrids. Disease control usually consists in the use of resistant cultivars and chemical control. Biological control as a preventive method is a viable alternative to evaluate. The aims of this study were to evaluate the natural incidence of both foliar diseases in maize after application of two antagonists, to determine the survival of the antagonists in the maize phyllosphere and to evaluate the effect of inoculation on grain yield at harvest. Plants treated with both biological control agents showed significant reductions in the incidence of both foliar diseases. In northern leaf blight the reduction was higher than 50% during 40 days in plants treated with Bacillus spp. Moreover, grain yield was significantly higher as compared to control treatments.展开更多
文摘A mixture of six Georgia isolates of Phytophthora capsici (Leon.), the causal agent of phytophthora blight, were used for greenhouse mass screening of over 700 accessions of Capsicum annuum for both stem blight and foliar blight. From this screening, it was determined that resistance to both forms of the disease were relatively common in the germplasm, but resistance to one form of the disease was not strongly correlated to resistance to the other form. Ten accessions previously shown to possess root rot resistance were tested for resistance to stem rot and leaf blight, and were found to also be highly resistant to these forms of the disease. It appears that single accessions have resistance to foliar, stem and root rot caused by P. capsici, which may simplify breeding for resistance to all three forms of the disease.
基金supported by the University Grants Commission Rajiv Gandhi National Fellowship(RGNF) of India
文摘A field study was undertaken to ascertain the effects of elicitors viz. benzothiadiazole （BTH） and salicylic acid （SA） on defense related enzymes viz. peroxidase, phenylalanine ammonia lyase, superoxide dismutase, chitinase and 13-1,3-glucanase, and phenols in rice （Pusa Basmati I） plants. First foliar spray of BTH （50 mg/kg） and SA （50 mg/kg） was done at the maximum tillering stage and inoculation with Rhizoctonia solani was carried 24 h after elicitor treatment. Elicitors were further sprayed at every growth stage. Time course analysis showed peak accumulation of defense related enzymes and phenols in the rice leaves treated with BTH and SA, and accumulation was the highest at the flowering stage. Higher enzymatic activity was observed in elicitor treated plants inoculated with R. solani. Compared to the untreated control plants, application of elicitors before R. solani inoculation significantly elicited the defense related enzymes and phenols. Moreover, application of elicitors had a positive effect on yield and disease reduction. It is suggested that pretreatment of rice leaves with BTH and SA could be used to enhance the level of protection against sheath blight and to improve rice yield in the fields.
文摘Greenhouse studies were performed to determine the reactions of 10 “California Wonder” (Capsicum annuum) accessions to the three forms of Phytophthora blight (root rot, stem blight and foliar blight) caused by Phytophthora capsici. Differences in root rot, stem blight and foliar blight severities among accessions were significant. The accessions consistently differentiated into two groups across the three disease syndromes. Simple sequence repeat (SSR) markers showed variability both within and between accessions of California Wonder. The variability in the responses to the three forms of Phytophthora blight does not warrant its usefulness as a standard susceptible control in studies involving the Capsicum-P. capsici patho-system.
文摘Exserohilum turcicum and Puccinia sorghi cause foliar fungal diseases that affect maize crop in Argentina. These diseases, northern leaf blight and common rust respectively, are presented each year with different levels of severity affecting significantly the yield in susceptible hybrids. Disease control usually consists in the use of resistant cultivars and chemical control. Biological control as a preventive method is a viable alternative to evaluate. The aims of this study were to evaluate the natural incidence of both foliar diseases in maize after application of two antagonists, to determine the survival of the antagonists in the maize phyllosphere and to evaluate the effect of inoculation on grain yield at harvest. Plants treated with both biological control agents showed significant reductions in the incidence of both foliar diseases. In northern leaf blight the reduction was higher than 50% during 40 days in plants treated with Bacillus spp. Moreover, grain yield was significantly higher as compared to control treatments.
