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
Erwinia carotovora subsp, carotovora （Ecc） infects and causes soft rot disease in hundreds of crop species including vegetables, flowers and fruits. Lignin biosynthesis has been implicated in defensive reactions to ...Erwinia carotovora subsp, carotovora （Ecc） infects and causes soft rot disease in hundreds of crop species including vegetables, flowers and fruits. Lignin biosynthesis has been implicated in defensive reactions to injury and pathogen infection in plants. In this work, variations of lignin content and gene expression in the molecular interaction between Chinese cabbage and Ecc were investigated. H2O2 accumulation and peroxidase activity were detected by 3, 3＇- Dimethoxybenzidine staining at mocked and Ecc-inoculated sites of Chinese cabbage leafstalks. Klason lignin content in inoculated plants increased by about 7.84%, 40.37%, and 43.13% more than that of the mocked site at 12, 24 and 72 h after inoculation, respectively. Gas chromatography detected more p-coumaryl （H） and less coniferyl （G） and sinapyl （S） monolignins in leafstalks of Chinese cabbage. All three monomers increased in Ecc-infected leafstalks, and the Ecc-induced ＂defense lignin＂ were composed of more G and H monolignins, and less S monolignin. After searching the expressed sequence tags （EST） data of Chinese cabbage, 12 genes putatively encoding enzymes involved in lignin biosynthesis were selected to study their expression. All of these genes could be induced by mock inoculation and Ecc infection, while the gene expression lasted for several more hours in the infected samples than in mocked and untreated plants. Our results indicated that ＂defense lignin＂ was different from the developmental lignin in composition; G and S monolignins were significantly induced in plants in response to the soft rot Ecc; thus, lignin biosynthesis was differentially regulated and played a role in plant response to the soft rot Ecc.展开更多
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 Beijing Natural Science Foundation （5051002） and the High-Tech Research and Development （863） Program of China （2006AA10Z123）.The authors thank Professor Cui-Chong Shi of the Horticultural College, Northeast Agricultural University for providing plant seeds and Dr Wei-Jian Hua of our center for help in determining lignin contents.
文摘Erwinia carotovora subsp, carotovora （Ecc） infects and causes soft rot disease in hundreds of crop species including vegetables, flowers and fruits. Lignin biosynthesis has been implicated in defensive reactions to injury and pathogen infection in plants. In this work, variations of lignin content and gene expression in the molecular interaction between Chinese cabbage and Ecc were investigated. H2O2 accumulation and peroxidase activity were detected by 3, 3＇- Dimethoxybenzidine staining at mocked and Ecc-inoculated sites of Chinese cabbage leafstalks. Klason lignin content in inoculated plants increased by about 7.84%, 40.37%, and 43.13% more than that of the mocked site at 12, 24 and 72 h after inoculation, respectively. Gas chromatography detected more p-coumaryl （H） and less coniferyl （G） and sinapyl （S） monolignins in leafstalks of Chinese cabbage. All three monomers increased in Ecc-infected leafstalks, and the Ecc-induced ＂defense lignin＂ were composed of more G and H monolignins, and less S monolignin. After searching the expressed sequence tags （EST） data of Chinese cabbage, 12 genes putatively encoding enzymes involved in lignin biosynthesis were selected to study their expression. All of these genes could be induced by mock inoculation and Ecc infection, while the gene expression lasted for several more hours in the infected samples than in mocked and untreated plants. Our results indicated that ＂defense lignin＂ was different from the developmental lignin in composition; G and S monolignins were significantly induced in plants in response to the soft rot Ecc; thus, lignin biosynthesis was differentially regulated and played a role in plant response to the soft rot Ecc.
