Field studies were conducted at Bushland, Texas, USA, in 2004 to examine usefulness of canopy temperature depression （CTD）, the difference of air-canopy temperature, in screening wheat （Triticum aestivum L.） genot...Field studies were conducted at Bushland, Texas, USA, in 2004 to examine usefulness of canopy temperature depression （CTD）, the difference of air-canopy temperature, in screening wheat （Triticum aestivum L.） genotypes for yield under dryland and irrigated. Forty winter wheat genotypes were grown under irrigation and dryland. CTDs were recorded after heading between 1 330 and 1 530 h on 6 clear days for dryland and 9 days for irrigation. Drought susceptible index （DSI） for each genotype was calculated using mean yield under dryland and irrigated conditions. Genotypes exhibited great differences in CTD under each environment. The dryland CTDs averaged 1.33℃ ranging from -0.67 to 2.57℃, and the average irrigation CTD were 4.59℃ ranging from 3.21 to 5.62℃. A low yield reduction was observed under dryland conditions relative to irrigated conditions for high-CTD genotypes. CTD values were highly negatively correlated with DSI under dryland, and genotypes of CTDs = 1.3℃ in dryland condition were identified as drought resistant. For 21 genotypes classified as drought resistant by DSI, their CTDs were 1.68℃ for dryland and 4.35℃ for irrigation on average; for 19 genotypes classified as drought susceptible by DSI, average CTD was 0.94℃ in dryland and 4.85℃ in irrigation. The high-yield genotypes consistently had high CTD values, and the low-yield ones had low CTD values for all measurements in dryland. After heading, genotypes maintained consistent ranking for CTD. Regression results for CTD and yield suggested that the best time for taking CTD measurement was 3-4 weeks after heading in irrigation but any time before senescence in dryland. Crop water stress index （CWSI） calculated from CTD data was highly correlated with CWSI calculated from yield, which suggesting traditional costly CWSI measurement may be improved by using portable infrared thermometers. Most importantly, grain yield was highly correlated with CTD under dryland （R^2 = 0.79-0.86） and irrigation （R^2 = 0.46-0.58） c展开更多
Xanthomonas oryzae pv.oryzae(Xoo),the causal agent of bacterial blight of rice,employs the transcription activator-like effectors(TALEs)to induce the expression of the OsSWEET family of putative sugar transporter gene...Xanthomonas oryzae pv.oryzae(Xoo),the causal agent of bacterial blight of rice,employs the transcription activator-like effectors(TALEs)to induce the expression of the OsSWEET family of putative sugar transporter genes,which function in conferring disease susceptibility(S)in rice plants.To engineer broadspectrum bacterial blight resistance,we used CRISPR/Cas9-mediated gene editing to disrupt the TALEbinding elements(EBEs)of two S genes,OsSWEETH and OsSWEET14,in rice cv.Kitaake,which harbors the recessive resistance allele of Xa25/OsSWEET13.The engineered rice line MS14K exhibited broadspectrum resistance to most Xoo strains with a few exceptions,suggesting that the compatible strains may contain new TALEs.We identified two PthXo2-like TALEs,Tal5LN18 and Tal7PX061,as major virulence factors in the compatible Xoo strains LN18 and PX061,respectively,and found that Xoo encodes at least five types of PthXo2-like effectors.Given that PthXo2/PthXo2.1 target OsSlVEETf3 for transcriptional activation,the genomes of 3000 rice varieties were analyzed for EBE variationsin the OsSWEET13 promoter,and 10Xa25-like haplotypes were identified.We found that Tal5LN18 and Tal7PX〇6i bind slightly different EBE sequences in the OsSWEET13 promoter to activate its expression.CRISPR/Cas9 technology was then used to generate InDels in the EBE of the OsSWEET13 promoter in MS14K to creat a new germplasm with three edited OsSWEET EBEs and broad-spectrum resistance against all Xoo strains tested.Collectively,our findings illustrate how to disarm TALE-S co-evolved loci to generate broad-spectrum resistance through the loss of effector-triggered susceptibility in plants.展开更多
Enzymes are biological catalysts that can convert substrates into products in biochemical reactions.In 1926,the first enzyme,urease,was determined to be a protein by James B.Sumner who won the Nobel Prize in 1946.Sinc...Enzymes are biological catalysts that can convert substrates into products in biochemical reactions.In 1926,the first enzyme,urease,was determined to be a protein by James B.Sumner who won the Nobel Prize in 1946.Since then,enzymes have been considered to be proteins,which allows them to achieve their high catalytic activity with high specific activity under mild conditions.However,in general,the enzyme activity of proteins is lost after exposure to extremes of p H and high temperature,and proteins are also susceptible to digestion by proteases in the environment,which dramatically hinders their practical applications in展开更多
Dear Editor,Since September 2012, the Middle East respiratory syndrome coronavirus (MERS-CoV) cases have been reported in more than 27 countries, and more than 2,000 cases have been confirmed in the laboratory (http:/...Dear Editor,Since September 2012, the Middle East respiratory syndrome coronavirus (MERS-CoV) cases have been reported in more than 27 countries, and more than 2,000 cases have been confirmed in the laboratory (http://www.who.int/emergencies/mers-cov/en/). MERS-CoV causes an acute and severe respiratory illness with a high mortality rate(~35%) in humans (Shi et al., 2017, Zaki et al., 2012).Neutralizing antibodies targeting the spike of MERS-CoV have been shown to be a therapeutic option for treatment of lethal disease (Agrawal et al., 2016, Ying et al., 2014).展开更多
Fusarium head blight（FHB）,caused primarily by Fusarium graminearum,is a destructive disease of wheat throughout the world.However,the mechanisms of host resistance to FHB are still largely unclear.Deoxynivalenol（DO...Fusarium head blight（FHB）,caused primarily by Fusarium graminearum,is a destructive disease of wheat throughout the world.However,the mechanisms of host resistance to FHB are still largely unclear.Deoxynivalenol（DON）produced by F graminearum which enhances the pathogen to spread could be converted into inactive form D3 G by UDP-glycosyltransferases（UGTs）.A DON responsive UGT gene,designated as TaUGT4,was first cloned from wheat in this study.The putative open reading frame（ORF） of TaUGT4 was 1386 bp,encoding 461 amino acids protein.TaUGT4 was placed on chromosome 2D using a set of nulli-tetrasomic lines of wheat cultivar Chinese Spring（CS）.When fused with eGFP at C terminal,TaUGT4 was shown to localize in cytoplasm of the transformed tobacco cells.The transcriptional analysis revealed that TaUGT4 was strongly induced by F graminearum or DON in both of FHB-resistant cultivar Sumai 3 and susceptible cultivar Kenong 199,especially in Sumai 3 under DON treatment.Similar increase of TaUGT4 expression was observed in Sumai 3 and Kenong 199 in response to salicylic acid（SA） treatment.But interestingly,the transcripts level of TaUGT4 in Sumai 3 showed significantly higher than that in Kenong 199 after treated with methyl jasmonate（MeJA）.According to the expression patterns,TaUGT4 might lead to different effects between FHB-resistant genotype and susceptible genotype in the process against F graminearum inoculation.It had also been discussed in this paper that JA signaling pathway might play a significant role in the resistance against F.graminearum compared to SA signaling pathway.展开更多
The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside th...The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa （aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica）. Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly （r=0.87, P≤0.05） with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11 （aus）, Shenliangyou 1 （hybrid aus） and Cliangyou 4418 （hybrid indica） were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.展开更多
Molecular screening of major rice blast resistance genes was determined with molecular markers, which showed close-set linkage to 11 major rice blast resistance genes（Pi-d2, Pi-z, Piz-t, Pi-9, Pi-36, Pi-37, Pi5, Pi-b...Molecular screening of major rice blast resistance genes was determined with molecular markers, which showed close-set linkage to 11 major rice blast resistance genes（Pi-d2, Pi-z, Piz-t, Pi-9, Pi-36, Pi-37, Pi5, Pi-b, Pik-p, Pik-h and Pi-ta2）, in a collection of 32 accessions resistant to Magnaporthe oryzae. Out of the 32 accessions, the Pi-d2 and Pi-z appeared to be omnipresent and gave positive express. As the second dominant, Pi-b and Piz-t gene frequencies were 96.9% and 87.5%. And Pik-h and Pik-p gene frequencies were 43.8% and 28.1%, respectively. The molecular marker linkage to Pi-ta2 produced positive bands in eleven accessions, while the molecular marker linkage to Pi-36 and Pi-37 in only three and four accessions, respectively. The natural field evaluation analysis showed that 30 of the 32 accessions were resistant, one was moderately resistant and one was susceptible. Infection types were negatively correlated with the genotype scores of Pi-9, Pi5, Pi-b, Pi-ta2 and Pik-p, although the correlation coefficients were very little. These results are useful in identification and incorporation of functional resistance genes from these germplasms into elite cultivars through marker-assisted selection for improved blast resistance in China and worldwide.展开更多
网络舆情话题的传播机理与传染病的扩散机理类似,研究舆情话题的传播机理有助于相关部门的决策部署。分析了舆情话题传播过程中用户情绪的变化趋势,在传统的SEIR(susceptible,exposed,infected and removed)模型的基础上,考虑舆情话题...网络舆情话题的传播机理与传染病的扩散机理类似,研究舆情话题的传播机理有助于相关部门的决策部署。分析了舆情话题传播过程中用户情绪的变化趋势,在传统的SEIR(susceptible,exposed,infected and removed)模型的基础上,考虑舆情话题在传播过程中受到用户情绪的影响,使用信息熵来刻画影响传播率的用户情绪,提出了一个具有动态传播率的传播模型;从模型的角度分析了网络舆情传播的关键节点,为相关部门提供了决策的理论依据。根据真实的网络话题进行了实证分析,结果表明,提出的模型能够较好地模拟出真实传播趋势,验证了模型的合理性。展开更多
Goosegrass is a worst grass weed in orchards and turf.The increased use of glyphosate for goosegrass control has led to the occurrence of many resistant populations.Although glyphosate has been used to control weeds f...Goosegrass is a worst grass weed in orchards and turf.The increased use of glyphosate for goosegrass control has led to the occurrence of many resistant populations.Although glyphosate has been used to control weeds for the past 30 years in China,few reports are available on glyphosate-resistant（GR） googegrass.In this study,we determined the GR level of 14 goosegrass populations from Chengdu and Guangzhou,China.Glyphosate only controlled 3.1 and 25.0%of the populations SL5 and SL1,respectively,at the dose of 1 680 g acid equivalent（ae） ha^（-1） at 14 days after treatment（DAT）.In contrast,the susceptible population（XD1） was completely（100%） controlled.The resistant index（Rl） of SL5 and SL1 were 5.1 and 4.5,and the Rl for SL2,SL3 and ZC1 were 4.2,3.2 and 2.6,respectively.The Rl for other populations was range from 1.8 to 2.5.Under the dose of glyphosate at 1 640 g ae ha^-1 at 10 DAT,shikimate accumulation in susceptible population XD1 was 17.6 and 16.4 times higher than SL5 and SL1,respectively.And the chlorophyll content in the plant leaf of populations SL1,SL2 and SL5 were decreased slightly ranging from 22.6 to 28.0.These results confirmed that the SL1,SL2,SL3,ZC1 and SL5 populations had evolved moderate resistance to glyphosate.This is the first report for the GR goosegrass populations confirmed in Chengdu,China.展开更多
In this paper, an impulsive epidemic model with time delay is proposed, which susceptible population is divided into two groups: high risk susceptibles and non-high risk susceptibles. We introduce two thresholds R1, R...In this paper, an impulsive epidemic model with time delay is proposed, which susceptible population is divided into two groups: high risk susceptibles and non-high risk susceptibles. We introduce two thresholds R1, R2 and demonstrate that the disease will be extinct if R11 . Our results show that larger pulse vaccination rates or a shorter the period of pulsing will lead to the eradication of the disease. The conclusions are confirmed by numerical simulations.展开更多
基金This study was financially supported by the China National 863 Program(2002AA2Z4011)the China National R&D Program(2004BA508B09)Texas wheat breed and physiology program.These assistances are gratefully acknowledged.We also thank Gail Petersion and Melanie Allred for their assistance when the study was going on.
文摘Field studies were conducted at Bushland, Texas, USA, in 2004 to examine usefulness of canopy temperature depression （CTD）, the difference of air-canopy temperature, in screening wheat （Triticum aestivum L.） genotypes for yield under dryland and irrigated. Forty winter wheat genotypes were grown under irrigation and dryland. CTDs were recorded after heading between 1 330 and 1 530 h on 6 clear days for dryland and 9 days for irrigation. Drought susceptible index （DSI） for each genotype was calculated using mean yield under dryland and irrigated conditions. Genotypes exhibited great differences in CTD under each environment. The dryland CTDs averaged 1.33℃ ranging from -0.67 to 2.57℃, and the average irrigation CTD were 4.59℃ ranging from 3.21 to 5.62℃. A low yield reduction was observed under dryland conditions relative to irrigated conditions for high-CTD genotypes. CTD values were highly negatively correlated with DSI under dryland, and genotypes of CTDs = 1.3℃ in dryland condition were identified as drought resistant. For 21 genotypes classified as drought resistant by DSI, their CTDs were 1.68℃ for dryland and 4.35℃ for irrigation on average; for 19 genotypes classified as drought susceptible by DSI, average CTD was 0.94℃ in dryland and 4.85℃ in irrigation. The high-yield genotypes consistently had high CTD values, and the low-yield ones had low CTD values for all measurements in dryland. After heading, genotypes maintained consistent ranking for CTD. Regression results for CTD and yield suggested that the best time for taking CTD measurement was 3-4 weeks after heading in irrigation but any time before senescence in dryland. Crop water stress index （CWSI） calculated from CTD data was highly correlated with CWSI calculated from yield, which suggesting traditional costly CWSI measurement may be improved by using portable infrared thermometers. Most importantly, grain yield was highly correlated with CTD under dryland （R^2 = 0.79-0.86） and irrigation （R^2 = 0.46-0.58） c
基金This research was supported by the National Key Research and Development Program of China(2016YFD0100601)the National Natural Science Foundation of China(31830072)the National Transgenic Major Program(2016ZX08001-002).
文摘Xanthomonas oryzae pv.oryzae(Xoo),the causal agent of bacterial blight of rice,employs the transcription activator-like effectors(TALEs)to induce the expression of the OsSWEET family of putative sugar transporter genes,which function in conferring disease susceptibility(S)in rice plants.To engineer broadspectrum bacterial blight resistance,we used CRISPR/Cas9-mediated gene editing to disrupt the TALEbinding elements(EBEs)of two S genes,OsSWEETH and OsSWEET14,in rice cv.Kitaake,which harbors the recessive resistance allele of Xa25/OsSWEET13.The engineered rice line MS14K exhibited broadspectrum resistance to most Xoo strains with a few exceptions,suggesting that the compatible strains may contain new TALEs.We identified two PthXo2-like TALEs,Tal5LN18 and Tal7PX061,as major virulence factors in the compatible Xoo strains LN18 and PX061,respectively,and found that Xoo encodes at least five types of PthXo2-like effectors.Given that PthXo2/PthXo2.1 target OsSlVEETf3 for transcriptional activation,the genomes of 3000 rice varieties were analyzed for EBE variationsin the OsSWEET13 promoter,and 10Xa25-like haplotypes were identified.We found that Tal5LN18 and Tal7PX〇6i bind slightly different EBE sequences in the OsSWEET13 promoter to activate its expression.CRISPR/Cas9 technology was then used to generate InDels in the EBE of the OsSWEET13 promoter in MS14K to creat a new germplasm with three edited OsSWEET EBEs and broad-spectrum resistance against all Xoo strains tested.Collectively,our findings illustrate how to disarm TALE-S co-evolved loci to generate broad-spectrum resistance through the loss of effector-triggered susceptibility in plants.
文摘Enzymes are biological catalysts that can convert substrates into products in biochemical reactions.In 1926,the first enzyme,urease,was determined to be a protein by James B.Sumner who won the Nobel Prize in 1946.Since then,enzymes have been considered to be proteins,which allows them to achieve their high catalytic activity with high specific activity under mild conditions.However,in general,the enzyme activity of proteins is lost after exposure to extremes of p H and high temperature,and proteins are also susceptible to digestion by proteases in the environment,which dramatically hinders their practical applications in
基金supported by the National Key Research and Development Program of China (2016YFD0500300 to Wenjie Tan)
文摘Dear Editor,Since September 2012, the Middle East respiratory syndrome coronavirus (MERS-CoV) cases have been reported in more than 27 countries, and more than 2,000 cases have been confirmed in the laboratory (http://www.who.int/emergencies/mers-cov/en/). MERS-CoV causes an acute and severe respiratory illness with a high mortality rate(~35%) in humans (Shi et al., 2017, Zaki et al., 2012).Neutralizing antibodies targeting the spike of MERS-CoV have been shown to be a therapeutic option for treatment of lethal disease (Agrawal et al., 2016, Ying et al., 2014).
基金supported by the National Natural Science Foundation of China(31071405 and 31171553)the National High-Tech R&D Program of China(863 Program,2011AA100102 and 2012AA101105)+3 种基金the Transgenic Special Item,China(2011ZX08002-004 and 2011ZX08009-003)the International Collaboration Program(948 Project,2013-S19)the Doctoral Fund of Ministry of Education of China(20133702120002)the Promotive Research Fund for Young and Middle-Aged Scientisits of Shandong Province,China(BS2013NY006)
文摘Fusarium head blight（FHB）,caused primarily by Fusarium graminearum,is a destructive disease of wheat throughout the world.However,the mechanisms of host resistance to FHB are still largely unclear.Deoxynivalenol（DON）produced by F graminearum which enhances the pathogen to spread could be converted into inactive form D3 G by UDP-glycosyltransferases（UGTs）.A DON responsive UGT gene,designated as TaUGT4,was first cloned from wheat in this study.The putative open reading frame（ORF） of TaUGT4 was 1386 bp,encoding 461 amino acids protein.TaUGT4 was placed on chromosome 2D using a set of nulli-tetrasomic lines of wheat cultivar Chinese Spring（CS）.When fused with eGFP at C terminal,TaUGT4 was shown to localize in cytoplasm of the transformed tobacco cells.The transcriptional analysis revealed that TaUGT4 was strongly induced by F graminearum or DON in both of FHB-resistant cultivar Sumai 3 and susceptible cultivar Kenong 199,especially in Sumai 3 under DON treatment.Similar increase of TaUGT4 expression was observed in Sumai 3 and Kenong 199 in response to salicylic acid（SA） treatment.But interestingly,the transcripts level of TaUGT4 in Sumai 3 showed significantly higher than that in Kenong 199 after treated with methyl jasmonate（MeJA）.According to the expression patterns,TaUGT4 might lead to different effects between FHB-resistant genotype and susceptible genotype in the process against F graminearum inoculation.It had also been discussed in this paper that JA signaling pathway might play a significant role in the resistance against F.graminearum compared to SA signaling pathway.
基金supported by the grants from the National Natural Science Foundation of China (31571986)the National Basic Research Programme of China (2013CB127502)
文摘The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa （aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica）. Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly （r=0.87, P≤0.05） with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11 （aus）, Shenliangyou 1 （hybrid aus） and Cliangyou 4418 （hybrid indica） were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.
基金supported by the National Natural Science Foundation of China(Grant No.31221004)the Central Academy(Institute)Research Project on Public Welfare(Grant No.2014RG001-3)+2 种基金the Special Fund for Agroscientific Research in the Public Interest(Grant No.20120301400903039-5)the Sichuan Program for Major Crop,Poultry and Livestock Breeding,China(Grant No.2012YZGG-25-3)a fund from the Chinese Academy of Agricultural Sciences to the Scientific and Technical Innovation Team
文摘Molecular screening of major rice blast resistance genes was determined with molecular markers, which showed close-set linkage to 11 major rice blast resistance genes（Pi-d2, Pi-z, Piz-t, Pi-9, Pi-36, Pi-37, Pi5, Pi-b, Pik-p, Pik-h and Pi-ta2）, in a collection of 32 accessions resistant to Magnaporthe oryzae. Out of the 32 accessions, the Pi-d2 and Pi-z appeared to be omnipresent and gave positive express. As the second dominant, Pi-b and Piz-t gene frequencies were 96.9% and 87.5%. And Pik-h and Pik-p gene frequencies were 43.8% and 28.1%, respectively. The molecular marker linkage to Pi-ta2 produced positive bands in eleven accessions, while the molecular marker linkage to Pi-36 and Pi-37 in only three and four accessions, respectively. The natural field evaluation analysis showed that 30 of the 32 accessions were resistant, one was moderately resistant and one was susceptible. Infection types were negatively correlated with the genotype scores of Pi-9, Pi5, Pi-b, Pi-ta2 and Pik-p, although the correlation coefficients were very little. These results are useful in identification and incorporation of functional resistance genes from these germplasms into elite cultivars through marker-assisted selection for improved blast resistance in China and worldwide.
文摘网络舆情话题的传播机理与传染病的扩散机理类似,研究舆情话题的传播机理有助于相关部门的决策部署。分析了舆情话题传播过程中用户情绪的变化趋势,在传统的SEIR(susceptible,exposed,infected and removed)模型的基础上,考虑舆情话题在传播过程中受到用户情绪的影响,使用信息熵来刻画影响传播率的用户情绪,提出了一个具有动态传播率的传播模型;从模型的角度分析了网络舆情传播的关键节点,为相关部门提供了决策的理论依据。根据真实的网络话题进行了实证分析,结果表明,提出的模型能够较好地模拟出真实传播趋势,验证了模型的合理性。
基金funded by the Special Fund for Agro-Scientific Research in the Public Interest,China(201303022)
文摘Goosegrass is a worst grass weed in orchards and turf.The increased use of glyphosate for goosegrass control has led to the occurrence of many resistant populations.Although glyphosate has been used to control weeds for the past 30 years in China,few reports are available on glyphosate-resistant（GR） googegrass.In this study,we determined the GR level of 14 goosegrass populations from Chengdu and Guangzhou,China.Glyphosate only controlled 3.1 and 25.0%of the populations SL5 and SL1,respectively,at the dose of 1 680 g acid equivalent（ae） ha^（-1） at 14 days after treatment（DAT）.In contrast,the susceptible population（XD1） was completely（100%） controlled.The resistant index（Rl） of SL5 and SL1 were 5.1 and 4.5,and the Rl for SL2,SL3 and ZC1 were 4.2,3.2 and 2.6,respectively.The Rl for other populations was range from 1.8 to 2.5.Under the dose of glyphosate at 1 640 g ae ha^-1 at 10 DAT,shikimate accumulation in susceptible population XD1 was 17.6 and 16.4 times higher than SL5 and SL1,respectively.And the chlorophyll content in the plant leaf of populations SL1,SL2 and SL5 were decreased slightly ranging from 22.6 to 28.0.These results confirmed that the SL1,SL2,SL3,ZC1 and SL5 populations had evolved moderate resistance to glyphosate.This is the first report for the GR goosegrass populations confirmed in Chengdu,China.
文摘In this paper, an impulsive epidemic model with time delay is proposed, which susceptible population is divided into two groups: high risk susceptibles and non-high risk susceptibles. We introduce two thresholds R1, R2 and demonstrate that the disease will be extinct if R11 . Our results show that larger pulse vaccination rates or a shorter the period of pulsing will lead to the eradication of the disease. The conclusions are confirmed by numerical simulations.
