A strain of Bacillus subtilis strain YB 1, isolated and preserved in our lab., showed a high nicosulfuron-degrading activity. Optimization of culture conditions on production of nicosulfuron-degrading enzyme from Baci...A strain of Bacillus subtilis strain YB 1, isolated and preserved in our lab., showed a high nicosulfuron-degrading activity. Optimization of culture conditions on production of nicosulfuron-degrading enzyme from Bacillus subtilis strain YB 1 was carried out through mono-factor experiments. The characterization of degrading enzyme（s） was studied in this paper. The results showed that B. subtilis YB1 can use nicosulfuron as sole carbon source under aerobic condition. The key enzyme（s） involved in the initial biodegradation of nicosulfuron was localized to extracellular proteins and showed to be induced expressed. Enzyme-specific activity was up to 89.34 U mg-1 at pH 8.0 and 30℃, incubation for 96 h, inoculum 4.5x108 CFU mL-1 in Luria-Bertani liquid medium with nicosulfuron of 40 mg L-1. The maximum degradation rate of extracellular crude enzymes on nicosulfuron was 66% at pH 9.0, 35℃ in the enzymatic reaction system with nicosulfuron of 5 mg L-1. This degrading enzyme（s） was sensitive to high temperature, but kept high activity under alkaline conditions.展开更多
A bacterial strain ZWS11 was isolated from sulfonylurea herbicide-contaminated farmland soil and identified as a potential nicosulfuron-degrading bacterium. Based on morphological and physicochemical characterization ...A bacterial strain ZWS11 was isolated from sulfonylurea herbicide-contaminated farmland soil and identified as a potential nicosulfuron-degrading bacterium. Based on morphological and physicochemical characterization of the bacterium and phylogenetic analysis of the 16 S r RNA sequence, strain ZWS11 was identified as Alcaligenes faecalis. The effects of the initial concentration of nicosulfuron, inoculation volume, and medium p H on degradation of nicosulfuron were investigated. Strain ZWS11 could degrade 80.56% of the initial nicosulfuron supplemented at 500.0 mg/L under the conditions of p H 7.0, 180 r/min and30°C after incubation for 6 days. Strain ZWS11 was also capable of degrading rimsulfuron,tribenuron-methyl and thifensulfuron-methyl. Four metabolites from biodegradation of nicosulfuron were identified, which were 2-aminosulfonyl-N, N-dimethylnicotinamide（M1）, 4, 6-dihydroxypyrimidine（M2）, 2-amino-4, 6-dimethoxypyrimidine（M3） and2-（1-（4,6-dimethoxy-pyrimidin-2-yl）-ureido）-N,N-dimethyl-nicotinamide（M4）. Among the metabolites detected, M2 was reported for the first time. Possible biodegradation pathways of nicosulfuron by strain ZWS11 were proposed. The degradation proceeded mainly via cleavage of the sulfonylurea bridge, O-dealkylation, and contraction of the sulfonylurea bridge by elimination of a sulfur dioxide group. The results provide valuable information for degradation of nicosulfuron in contaminated environments.展开更多
Postemergence application of nicosulfuron for weed control in maize fields can cause great damage to certain maize inbred lines and hybrids. Two maize genotypes, tolerant inbred(HBR) and sensitive inbred(HBS), were fo...Postemergence application of nicosulfuron for weed control in maize fields can cause great damage to certain maize inbred lines and hybrids. Two maize genotypes, tolerant inbred(HBR) and sensitive inbred(HBS), were found to significantly differ in their phenotypic responses to nicosulfuron, with the EC50(50% effective concentration) values differed statistically(763.6 and 5.9 g a.i. ha–1, respectively). Pre-treatment with malathion, a known cytochrome P450 inhibitor, increased nicosulfuron injury in both HBR and HBS. Our results support the hypothesis that nicosulfuron selectivity in maize is associated with cytochrome P450 metabolism. Further analysis of the maize genome resulted in the identification of 314 full length cytochrome P450 monooxygenase(CYP) genes. These genes were classified into 2 types, 10 clans and 44 families. The CYP71 clan was represented by all A-type genes(168) belonging to 17 families. Nine clans possessed 27 families containing 146 non-A-type genes. The consensus sequences of the heme-binding regions of A-type and non-A-type CYP proteins are ‘PFGXGRRXCPG’ and ‘FXXGPRXCXG’, respectively. Illumina transcriptome sequence results showed that there were 53 differentially expressed CYP genes on the basis of high variation in expression between HBS and HBR, nicosulfuron-treated and untreated samples. These genes may contribute to nicosulfuron tolerance in maize. A hierarchical clustering analysis obtained four main clusters named C1 to C4 in which 4, 15, 21, and 13 CYP genes were found in each respective cluster. The expression patterns of some CYP genes were confirmed by RT-q PCR analysis. The research will improve our understanding of the function of maize cytochrome P450 in herbicide metabolism.展开更多
[Objective]The paper was to study efficacy and phytotoxicity of different dosages of 4% nicosulfuron on weeds in corn fields.[Method]With summer corn variety Zhengdan 958commonly used in field production in Hengshui a...[Objective]The paper was to study efficacy and phytotoxicity of different dosages of 4% nicosulfuron on weeds in corn fields.[Method]With summer corn variety Zhengdan 958commonly used in field production in Hengshui area of Hebei Province of China as the test material,different dosages（1 050,1 500 and 1 950mL/hm2）of corn postemergence herbicide 4% nicosulfuron SC were sprayed during five-leaf stage of corn,and the treatments with water spraying and manual weeding were set as controls.The effects of different dosages of 4% nicosulfuron SC on weed control efficacy and safety and yield of corn were analyzed in order to determine the optimal dosage.[Result]Spraying 4% nicosulfuron SC with dosage of 1 500mL/hm2 during five-leaf stage of corn not only had better control effect against various weeds,but also did not produce phytotoxicity on corn,and the yield of corn was higher.[Conclusion]The study provided scientific information for using 4% nicosulfuron to eradicate weeds in corn fields.展开更多
基金the National Natural Science Foundation of China (31171877)the Youth Foundation Program for Science and Technology of Hebei Province, China (2010141)
文摘A strain of Bacillus subtilis strain YB 1, isolated and preserved in our lab., showed a high nicosulfuron-degrading activity. Optimization of culture conditions on production of nicosulfuron-degrading enzyme from Bacillus subtilis strain YB 1 was carried out through mono-factor experiments. The characterization of degrading enzyme（s） was studied in this paper. The results showed that B. subtilis YB1 can use nicosulfuron as sole carbon source under aerobic condition. The key enzyme（s） involved in the initial biodegradation of nicosulfuron was localized to extracellular proteins and showed to be induced expressed. Enzyme-specific activity was up to 89.34 U mg-1 at pH 8.0 and 30℃, incubation for 96 h, inoculum 4.5x108 CFU mL-1 in Luria-Bertani liquid medium with nicosulfuron of 40 mg L-1. The maximum degradation rate of extracellular crude enzymes on nicosulfuron was 66% at pH 9.0, 35℃ in the enzymatic reaction system with nicosulfuron of 5 mg L-1. This degrading enzyme（s） was sensitive to high temperature, but kept high activity under alkaline conditions.
基金supported by the National Basic Research Programme of China (No. 2010CB126104)
文摘A bacterial strain ZWS11 was isolated from sulfonylurea herbicide-contaminated farmland soil and identified as a potential nicosulfuron-degrading bacterium. Based on morphological and physicochemical characterization of the bacterium and phylogenetic analysis of the 16 S r RNA sequence, strain ZWS11 was identified as Alcaligenes faecalis. The effects of the initial concentration of nicosulfuron, inoculation volume, and medium p H on degradation of nicosulfuron were investigated. Strain ZWS11 could degrade 80.56% of the initial nicosulfuron supplemented at 500.0 mg/L under the conditions of p H 7.0, 180 r/min and30°C after incubation for 6 days. Strain ZWS11 was also capable of degrading rimsulfuron,tribenuron-methyl and thifensulfuron-methyl. Four metabolites from biodegradation of nicosulfuron were identified, which were 2-aminosulfonyl-N, N-dimethylnicotinamide（M1）, 4, 6-dihydroxypyrimidine（M2）, 2-amino-4, 6-dimethoxypyrimidine（M3） and2-（1-（4,6-dimethoxy-pyrimidin-2-yl）-ureido）-N,N-dimethyl-nicotinamide（M4）. Among the metabolites detected, M2 was reported for the first time. Possible biodegradation pathways of nicosulfuron by strain ZWS11 were proposed. The degradation proceeded mainly via cleavage of the sulfonylurea bridge, O-dealkylation, and contraction of the sulfonylurea bridge by elimination of a sulfur dioxide group. The results provide valuable information for degradation of nicosulfuron in contaminated environments.
基金funded by the National Natural Science Foundation of China (31501660)the Technology Research and Development Program of Hebei, China (17226507D)the Foundation of Institute of Cereal and Oil Crops of Hebei Academy of Agriculture and Forestry, China (LYS2015001)
文摘Postemergence application of nicosulfuron for weed control in maize fields can cause great damage to certain maize inbred lines and hybrids. Two maize genotypes, tolerant inbred(HBR) and sensitive inbred(HBS), were found to significantly differ in their phenotypic responses to nicosulfuron, with the EC50(50% effective concentration) values differed statistically(763.6 and 5.9 g a.i. ha–1, respectively). Pre-treatment with malathion, a known cytochrome P450 inhibitor, increased nicosulfuron injury in both HBR and HBS. Our results support the hypothesis that nicosulfuron selectivity in maize is associated with cytochrome P450 metabolism. Further analysis of the maize genome resulted in the identification of 314 full length cytochrome P450 monooxygenase(CYP) genes. These genes were classified into 2 types, 10 clans and 44 families. The CYP71 clan was represented by all A-type genes(168) belonging to 17 families. Nine clans possessed 27 families containing 146 non-A-type genes. The consensus sequences of the heme-binding regions of A-type and non-A-type CYP proteins are ‘PFGXGRRXCPG’ and ‘FXXGPRXCXG’, respectively. Illumina transcriptome sequence results showed that there were 53 differentially expressed CYP genes on the basis of high variation in expression between HBS and HBR, nicosulfuron-treated and untreated samples. These genes may contribute to nicosulfuron tolerance in maize. A hierarchical clustering analysis obtained four main clusters named C1 to C4 in which 4, 15, 21, and 13 CYP genes were found in each respective cluster. The expression patterns of some CYP genes were confirmed by RT-q PCR analysis. The research will improve our understanding of the function of maize cytochrome P450 in herbicide metabolism.
文摘[Objective]The paper was to study efficacy and phytotoxicity of different dosages of 4% nicosulfuron on weeds in corn fields.[Method]With summer corn variety Zhengdan 958commonly used in field production in Hengshui area of Hebei Province of China as the test material,different dosages（1 050,1 500 and 1 950mL/hm2）of corn postemergence herbicide 4% nicosulfuron SC were sprayed during five-leaf stage of corn,and the treatments with water spraying and manual weeding were set as controls.The effects of different dosages of 4% nicosulfuron SC on weed control efficacy and safety and yield of corn were analyzed in order to determine the optimal dosage.[Result]Spraying 4% nicosulfuron SC with dosage of 1 500mL/hm2 during five-leaf stage of corn not only had better control effect against various weeds,but also did not produce phytotoxicity on corn,and the yield of corn was higher.[Conclusion]The study provided scientific information for using 4% nicosulfuron to eradicate weeds in corn fields.
