The susceptibility of different regions in Dioscorea rotundata (white yam) tuber to rot infecting fungi was investigated. Isolation was made from the periphery of the rotted tuber tissues, followed by a pathogenicity ...The susceptibility of different regions in Dioscorea rotundata (white yam) tuber to rot infecting fungi was investigated. Isolation was made from the periphery of the rotted tuber tissues, followed by a pathogenicity test and identification of isolates. Three fungi associated with D. rotundata (white yam) were isolated;they include Penicillium oxalicum, Aspergillus niger and Rhizopus stolonifer. Each of the isolates from pure cultures were inoculated on the head, middle and tail regions of healthy yam tubers. The three fungi were found to be pathogenic at different rates at the head, middle and tail ends of the yam tuber respectively. The head region was less susceptible to the three fungi with the following rot depths (P. oxalicum 25 mma, A. niger 18.2 mma and R. stolenifer 12.7 mmb). Rot depth in the middle region was (P. oxalicum 15 mma, A. niger 10.6 mma and R. stolenifer 8.8 mmb). While the tail region of the yam tuber recorded rot depth of (P. oxalicum 32.0 mma, A. niger 26.4 mma and R. stolenifer 20.8 mmb) respectively. Generally, the tail region of D. rotundata was more susceptible to fungal attack and the rot recorded in the tail region was significantly different from rot at the middle and the head. It was recommended that yam tubers should be stacked with their head on the ground to reduce incidence of rotting in stock-piled yam tubers.展开更多
Ten isolates of Erwinia carotovora ssp. carotovora (Ecc) were isolated from infected potato tubers of Picasso, Sante, and Nevskiy varieties collected from different regions in Kyrgyzstan. Isolates were identified as E...Ten isolates of Erwinia carotovora ssp. carotovora (Ecc) were isolated from infected potato tubers of Picasso, Sante, and Nevskiy varieties collected from different regions in Kyrgyzstan. Isolates were identified as Erwinia carotovora ssp. carotovora (Ecc) by standard bacteriological techniques and pathogenicity tests on tubers and also by PCR analyses. Tests on the pathogenicity of E. carotovora ssp. carotovora (Ecc) strains to host plants by artificial inoculation have shown a high sensibility of the Picasso variety. As a result, five isolates were chosen, three isolates (EcPo1, EcPo2, and Eco3) were highly pathogenic, while two isolates (Eco4 and Eco5) were weakly pathogenic. The antagonistic bacteria, Streptomyces diastatochromogenes strain sk-6, and Streptomyces graminearuss strain sk-2, have a highly significant effect on soft rot bacteria isolates (Ecc), more than the other tested antagonistic organisms in vitro screening biotests. The Streptomyces diastatochromogenes sk-6 was selected for the control assay of storage potatoes against the most common soft rot bacterial strain in Kyrgyzstan, Erwinia carotovora sp. carotovora EcPo2. The pretreatment of potato tubers with antagonistic bacteria successfully prevented the initial infection multiplication of soft rot bacteria and reduced soft rot disease of potatoes in storage. These results justify selection of the dose 10<sup>6</sup> cells/ml of bacteria Streptomyces diastatochromogenes sk-6 for use in powdering the infected or non-infected potato tubers to suppress the development soft rot during storage. Streptomyces diastatochromogenes sk-6 as a biological disinfectant could destroy surface and internal infections, protect the tubers from the growth of phytopathogenic bacteria in the early period of their reproduction, and improve the overwintering of winter crops.展开更多
Potato(Solanum tuberosum L.)is an important crop throughout the world.An uncharacterized disease has been observed on potato plants during the growing season and tubers during the storage period from Nileke County,Qit...Potato(Solanum tuberosum L.)is an important crop throughout the world.An uncharacterized disease has been observed on potato plants during the growing season and tubers during the storage period from Nileke County,Qitai County and other locations in Xinjiang,China.A particular fungus was consistently isolated from the infected potato plants and tubers.Based on its morphology,molecular characteristics,pathogenicity test and internal transcribed spacer(ITS)sequence,the pathogens was identified as Galactomyces candidum F12.Further study also showed that the hyphae and conidia of the pathogenic fungus grew faster as the temperature was 30℃,pH was 7,soluble starch was used as optimal carbon source and yeast powder as optimal nitrogen source.In addition,12-h continuous ilumination light was beneficial to the hyphal growth,while 24-h continuous ilumination was beneficial to the sporulation of the strain at 30℃.To our knowledge,this is the first report of Galactomyces candidum causing leaf wilt and postharvest tuber rot on potato in China.展开更多
文摘The susceptibility of different regions in Dioscorea rotundata (white yam) tuber to rot infecting fungi was investigated. Isolation was made from the periphery of the rotted tuber tissues, followed by a pathogenicity test and identification of isolates. Three fungi associated with D. rotundata (white yam) were isolated;they include Penicillium oxalicum, Aspergillus niger and Rhizopus stolonifer. Each of the isolates from pure cultures were inoculated on the head, middle and tail regions of healthy yam tubers. The three fungi were found to be pathogenic at different rates at the head, middle and tail ends of the yam tuber respectively. The head region was less susceptible to the three fungi with the following rot depths (P. oxalicum 25 mma, A. niger 18.2 mma and R. stolenifer 12.7 mmb). Rot depth in the middle region was (P. oxalicum 15 mma, A. niger 10.6 mma and R. stolenifer 8.8 mmb). While the tail region of the yam tuber recorded rot depth of (P. oxalicum 32.0 mma, A. niger 26.4 mma and R. stolenifer 20.8 mmb) respectively. Generally, the tail region of D. rotundata was more susceptible to fungal attack and the rot recorded in the tail region was significantly different from rot at the middle and the head. It was recommended that yam tubers should be stacked with their head on the ground to reduce incidence of rotting in stock-piled yam tubers.
文摘Ten isolates of Erwinia carotovora ssp. carotovora (Ecc) were isolated from infected potato tubers of Picasso, Sante, and Nevskiy varieties collected from different regions in Kyrgyzstan. Isolates were identified as Erwinia carotovora ssp. carotovora (Ecc) by standard bacteriological techniques and pathogenicity tests on tubers and also by PCR analyses. Tests on the pathogenicity of E. carotovora ssp. carotovora (Ecc) strains to host plants by artificial inoculation have shown a high sensibility of the Picasso variety. As a result, five isolates were chosen, three isolates (EcPo1, EcPo2, and Eco3) were highly pathogenic, while two isolates (Eco4 and Eco5) were weakly pathogenic. The antagonistic bacteria, Streptomyces diastatochromogenes strain sk-6, and Streptomyces graminearuss strain sk-2, have a highly significant effect on soft rot bacteria isolates (Ecc), more than the other tested antagonistic organisms in vitro screening biotests. The Streptomyces diastatochromogenes sk-6 was selected for the control assay of storage potatoes against the most common soft rot bacterial strain in Kyrgyzstan, Erwinia carotovora sp. carotovora EcPo2. The pretreatment of potato tubers with antagonistic bacteria successfully prevented the initial infection multiplication of soft rot bacteria and reduced soft rot disease of potatoes in storage. These results justify selection of the dose 10<sup>6</sup> cells/ml of bacteria Streptomyces diastatochromogenes sk-6 for use in powdering the infected or non-infected potato tubers to suppress the development soft rot during storage. Streptomyces diastatochromogenes sk-6 as a biological disinfectant could destroy surface and internal infections, protect the tubers from the growth of phytopathogenic bacteria in the early period of their reproduction, and improve the overwintering of winter crops.
基金Supported by the Basic Scientific Research Fund Project of the Public Welfare Scientific Research Institute of Xinjiang Autonomous Region,China(KY2018012,KY2019020)the Open Fund of Key Laboratory of Integrated Pest Management on Crop in Northwestern Oasis,Ministry of Agriculture and Rural Affairs,China(KFJJ202006).
文摘Potato(Solanum tuberosum L.)is an important crop throughout the world.An uncharacterized disease has been observed on potato plants during the growing season and tubers during the storage period from Nileke County,Qitai County and other locations in Xinjiang,China.A particular fungus was consistently isolated from the infected potato plants and tubers.Based on its morphology,molecular characteristics,pathogenicity test and internal transcribed spacer(ITS)sequence,the pathogens was identified as Galactomyces candidum F12.Further study also showed that the hyphae and conidia of the pathogenic fungus grew faster as the temperature was 30℃,pH was 7,soluble starch was used as optimal carbon source and yeast powder as optimal nitrogen source.In addition,12-h continuous ilumination light was beneficial to the hyphal growth,while 24-h continuous ilumination was beneficial to the sporulation of the strain at 30℃.To our knowledge,this is the first report of Galactomyces candidum causing leaf wilt and postharvest tuber rot on potato in China.
