Cyperus difformis L.is a troublesome weed in paddy fields and has attracted attention due to its resistance to acetohydroxyacid synthase(AHAS)inhibitors.It was found that the amino acid mutation in AHAS was the primar...Cyperus difformis L.is a troublesome weed in paddy fields and has attracted attention due to its resistance to acetohydroxyacid synthase(AHAS)inhibitors.It was found that the amino acid mutation in AHAS was the primary cause for the resistance of Cyperus difformis.However,the effect of different mutations on AHAS function is not clear in Cyperus difformis.To confirm the effect of mutations on AHAS function,six biotypes were collected,including Pro197Arg,Pro197Ser,Pro197Leu,Asp376Glu,Trp574Leu and wild type,from Hunan,Anhui,Jiangxi and Jiangsu provinces,China and the function of AHAS was characterized.The AHAS in vitro inhibition assay results indicated that the mutations decreased the sensitivity of AHAS to pyrazosulfuron-ethyl,in which the I_(50)(the half maximal inhibitory concentration)of wild type AHAS was 0.04μmol L^(-1)and Asp376Glu,Pro197Leu,Pro197Arg,Pro197Ser and Trp574Leu mutations were 3.98,11.50,40.38,38.19 and 311.43μmol L^(-1),respectively.In the determination of enzyme kinetics parameters,the Km and the maximum reaction velocity(Vmax)of the wild type were 5.18 mmol L^(-1)and 0.12 nmol mg^(-1)min^(-1),respectively,and the Km values of AHAS with Asp376Glu,Trp574Leu,Pro197Leu and Pro197Ser mutations were 0.38-0.93 times of the wild type.The Km value of the Pro197Arg mutation was 1.14times of the wild type,and the Vmax values of the five mutations were 1.17-3.33-fold compared to the wild type.It was found that the mutations increased the affinity of AHAS to the substrate,except for the Pro197Arg mutation.At a concentration of 0.0032-100 mmol L^(-1)branched-chain amino acids(BCAAs),the sensitivity of the other four mutant AHAS biotypes to feedback inhibition decreased,except for the Pro197Arg mutation.This study elucidated the effect of different mutations on AHAS function in Cyperus difformis and provided ideas for further study of resistance development.展开更多
稗草是中国南方双季稻稻田的恶性杂草，对水稻生产造成严重威胁。为明确稗草对双季稻生长的影响及其经济危害允许水平，采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻生长与产量性状的变化规律。结果表明，在稗草的竞争干...稗草是中国南方双季稻稻田的恶性杂草，对水稻生产造成严重威胁。为明确稗草对双季稻生长的影响及其经济危害允许水平，采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻生长与产量性状的变化规律。结果表明，在稗草的竞争干扰下，双季早、晚稻的株高、分蘖数、有效穗数、每穗实粒数、千粒重及产量均随稗草密度的增加而逐渐降低。指数模型 y ＝beax 可以较好地拟合稗草对早稻分蘖数、有效穗数和产量的影响，而二次曲线模型 y ＝ax 2＋bx＋c 拟合稗草与株高、每穗实粒数、千粒重和产量损失间的关系最佳；二次曲线模型 y ＝ax 2＋bx＋c 均可较好地拟合稗草与晚稻株高、分蘖数、有效穗数、每穗实粒数、千粒重、产量和产量损失间的关系。稻田使用化学除草剂（丁草胺、二氯喹啉酸、五氟磺草胺）防除时，双季早、晚稻稻田稗草的经济危害水平分别为1．64％～2．91％和1．28％～2．28％，经济阈值分别为0．63～1．23株／m^2和1．30～1．85株／m^2。稗草对水稻生长有抑制作用，并导致水稻产量损失；通过对经济阈值分析，化学除草剂防治稗草具有明显的经济优势。展开更多
基金funded by the National Natural Science Foundation of China(31972281)。
文摘Cyperus difformis L.is a troublesome weed in paddy fields and has attracted attention due to its resistance to acetohydroxyacid synthase(AHAS)inhibitors.It was found that the amino acid mutation in AHAS was the primary cause for the resistance of Cyperus difformis.However,the effect of different mutations on AHAS function is not clear in Cyperus difformis.To confirm the effect of mutations on AHAS function,six biotypes were collected,including Pro197Arg,Pro197Ser,Pro197Leu,Asp376Glu,Trp574Leu and wild type,from Hunan,Anhui,Jiangxi and Jiangsu provinces,China and the function of AHAS was characterized.The AHAS in vitro inhibition assay results indicated that the mutations decreased the sensitivity of AHAS to pyrazosulfuron-ethyl,in which the I_(50)(the half maximal inhibitory concentration)of wild type AHAS was 0.04μmol L^(-1)and Asp376Glu,Pro197Leu,Pro197Arg,Pro197Ser and Trp574Leu mutations were 3.98,11.50,40.38,38.19 and 311.43μmol L^(-1),respectively.In the determination of enzyme kinetics parameters,the Km and the maximum reaction velocity(Vmax)of the wild type were 5.18 mmol L^(-1)and 0.12 nmol mg^(-1)min^(-1),respectively,and the Km values of AHAS with Asp376Glu,Trp574Leu,Pro197Leu and Pro197Ser mutations were 0.38-0.93 times of the wild type.The Km value of the Pro197Arg mutation was 1.14times of the wild type,and the Vmax values of the five mutations were 1.17-3.33-fold compared to the wild type.It was found that the mutations increased the affinity of AHAS to the substrate,except for the Pro197Arg mutation.At a concentration of 0.0032-100 mmol L^(-1)branched-chain amino acids(BCAAs),the sensitivity of the other four mutant AHAS biotypes to feedback inhibition decreased,except for the Pro197Arg mutation.This study elucidated the effect of different mutations on AHAS function in Cyperus difformis and provided ideas for further study of resistance development.
文摘稗草是中国南方双季稻稻田的恶性杂草，对水稻生产造成严重威胁。为明确稗草对双季稻生长的影响及其经济危害允许水平，采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻生长与产量性状的变化规律。结果表明，在稗草的竞争干扰下，双季早、晚稻的株高、分蘖数、有效穗数、每穗实粒数、千粒重及产量均随稗草密度的增加而逐渐降低。指数模型 y ＝beax 可以较好地拟合稗草对早稻分蘖数、有效穗数和产量的影响，而二次曲线模型 y ＝ax 2＋bx＋c 拟合稗草与株高、每穗实粒数、千粒重和产量损失间的关系最佳；二次曲线模型 y ＝ax 2＋bx＋c 均可较好地拟合稗草与晚稻株高、分蘖数、有效穗数、每穗实粒数、千粒重、产量和产量损失间的关系。稻田使用化学除草剂（丁草胺、二氯喹啉酸、五氟磺草胺）防除时，双季早、晚稻稻田稗草的经济危害水平分别为1．64％～2．91％和1．28％～2．28％，经济阈值分别为0．63～1．23株／m^2和1．30～1．85株／m^2。稗草对水稻生长有抑制作用，并导致水稻产量损失；通过对经济阈值分析，化学除草剂防治稗草具有明显的经济优势。
