Tobacco(Nicotiana tabacum)and tomato(Solanum lycopersicum)are two major economic crops in China.Tobacco mosaic virus(TMV;genus Tobamovirus)is the most prevalent virus infecting both crops.Currently,some widely cultiva...Tobacco(Nicotiana tabacum)and tomato(Solanum lycopersicum)are two major economic crops in China.Tobacco mosaic virus(TMV;genus Tobamovirus)is the most prevalent virus infecting both crops.Currently,some widely cultivated tobacco and tomato cultivars are susceptible to TMV and there is no effective strategy to control this virus.Cross-protection can be a safe and environmentally friendly strategy to prevent viral diseases.However,stable attenuated TMV mutants are scarce.In this study,we found that the substitutions in the replicase p126,arginine at position 196(R^(196))with aspartic acid(D),glutamic acid at position 614(E^(614))with glycine(G),serine at position 643(S^(643))with phenylalanine(F),or D at position 730(D^(730))with S,significantly reduced the virulence and replication of TMV.However,only the mutation of S^(643) to F reduced the RNA silencing suppression activity of TMV p126.A double-mutant TMV-E614G-S643F induced no visible symptom and was genetically stable through six successive passages in tobacco plants.Furthermore,our results showed that TMV-E614G-S643F double-mutant could provide effective protection against the wild-type TMV infection in tobacco and tomato plants.This study reports a promising mild mutant for cross-protection to control TMV in tobacco and tomato plants.展开更多
The phytohormone abscisic acid （ABA） plays crucial roles in plant development and plant responses to environmental stresses. Although ABA receptors and a minimal set of core molecular components have recently been d...The phytohormone abscisic acid （ABA） plays crucial roles in plant development and plant responses to environmental stresses. Although ABA receptors and a minimal set of core molecular components have recently been discovered, understanding of the ABA signaling pathway is still far from complete. In this work, we characterized the function of ROP11, a member of the plant-specific ROP small GTPases family, in the ABA signaling process. ROP11 is preferentially expressed in guard cells in all plant organs with stomata. Expression of a constitutively active ROP11 （CA-ROP11） suppresses ABA-mediated responses, whereas reduced expression of ROP11 or expression of its dominant-negative form （DN-ROP11） causes the opposite phenotypes. The affected ABA-mediated responses by ROP11 include seed germination, seedling growth, stomatal closure, induction of ABA-responsive genes, as well as plant response to drought stress. Furthermore, we showed that ROP11 and its closest-related family member, ROP10, act in parallel in mediating these responses. ABA treatment does not affect ROP11 transcription and protein abundance; however, it causes the accumulation of CA-ROP11 in the nucleus. These results demonstrated that ROP11 is a negative regulator of multiple ABA responses in Arabidopsis.展开更多
细菌的σ54(R poN)是一类可选择性识别启动子序列的σ因子,主要参与环境适应、细胞生理过程等,如氮代谢、鞭毛和菌毛的生物合成。在一些病原菌中,σ54也与致病性密切有关。为了明确σ54在野油菜黄单胞菌野油菜致病变种(X cc)中是否参与...细菌的σ54(R poN)是一类可选择性识别启动子序列的σ因子,主要参与环境适应、细胞生理过程等,如氮代谢、鞭毛和菌毛的生物合成。在一些病原菌中,σ54也与致病性密切有关。为了明确σ54在野油菜黄单胞菌野油菜致病变种(X cc)中是否参与致病过程,用同源单交换定点突变方法,将X cc 8004中的两个σ54编码基因rp oN 1(XC 1256)和rp oN 2(XC 2168)做单突变及双突变。突变体表型分析结果表明,单个和同时突变rp oN 1和rp oN 2基因均不影响野油菜黄单胞菌的正常生长,对胞外多糖(EPS)产生、胞外酶的合成也无明显影响。植株致病性检测结果表明,rp oN 1和rp oN 2基因的单突变或双突变体的致病力与野生型菌株没有显著差异,表明野油菜黄单胞菌野油菜致病变种的致病过程不需要σ54因子参与。展开更多
Two mutants in nitrogenase of Klebsiella pneu-moniae are constructed by site-directed mutagenesis and gene replacement procedure, which express the nitrogenases with Lysine and Glutamine substituting for a-Glutamine 1...Two mutants in nitrogenase of Klebsiella pneu-moniae are constructed by site-directed mutagenesis and gene replacement procedure, which express the nitrogenases with Lysine and Glutamine substituting for a-Glutamine 190 and a-Histidine 194 respectively (Kp-Q a190 K and Kp-H a194 Q). The above two substitutions are respectively intro-duced into a nifV mutant (expressing a citrate-containing nitrogenase) and sequentially two double mutants are ob-tained (Kp-Q a190 K-nifV- and Kp-H a194 Q-nifV-). All four mutants exhibit strict Nif- phenotype under the N2-fixation condition and fail to grow diazotrophically. Altered ni-trogneases are effectively depressed and the C2H2 reduction analysis shows that the double substitutions in Kp-Q a190 K-nifV abolish cell C2H2 reduction activity, but Kp-H a194 Q-nifV- cells maintain a C2H2 reduction activity at 10% of that of wild type. Whole cell C2D2 reduction by all four mu-tants in comparison to the wild type and nifV mutant is also detected. The results show that only single a-Gln194 substitu-tion does not perturb the stereospecificity of protonation of C2D2. These results indicate that the a- Glutamine 190 and its combination with homocitrate are essential to the catalytic activity of nitrogenase and it is proposed that a-Glutamine 190 and its combination with homocitrate are involved in the proton and/or electron transfer to FeMoco. The nitrogenases from these double mutants will be useful in further analysis of the entry of the proton and/or electron to FeMoco and the substrate binding sites.展开更多
基金supported by funds from‘Taishan Scholar’Construction Project,China(TS2022-028 and 202101KN275)。
文摘Tobacco(Nicotiana tabacum)and tomato(Solanum lycopersicum)are two major economic crops in China.Tobacco mosaic virus(TMV;genus Tobamovirus)is the most prevalent virus infecting both crops.Currently,some widely cultivated tobacco and tomato cultivars are susceptible to TMV and there is no effective strategy to control this virus.Cross-protection can be a safe and environmentally friendly strategy to prevent viral diseases.However,stable attenuated TMV mutants are scarce.In this study,we found that the substitutions in the replicase p126,arginine at position 196(R^(196))with aspartic acid(D),glutamic acid at position 614(E^(614))with glycine(G),serine at position 643(S^(643))with phenylalanine(F),or D at position 730(D^(730))with S,significantly reduced the virulence and replication of TMV.However,only the mutation of S^(643) to F reduced the RNA silencing suppression activity of TMV p126.A double-mutant TMV-E614G-S643F induced no visible symptom and was genetically stable through six successive passages in tobacco plants.Furthermore,our results showed that TMV-E614G-S643F double-mutant could provide effective protection against the wild-type TMV infection in tobacco and tomato plants.This study reports a promising mild mutant for cross-protection to control TMV in tobacco and tomato plants.
基金supported by the National Basic Research Program of China(973Program)(2009CB119100)the National Natural Science Foundation of China(90717121)
文摘The phytohormone abscisic acid （ABA） plays crucial roles in plant development and plant responses to environmental stresses. Although ABA receptors and a minimal set of core molecular components have recently been discovered, understanding of the ABA signaling pathway is still far from complete. In this work, we characterized the function of ROP11, a member of the plant-specific ROP small GTPases family, in the ABA signaling process. ROP11 is preferentially expressed in guard cells in all plant organs with stomata. Expression of a constitutively active ROP11 （CA-ROP11） suppresses ABA-mediated responses, whereas reduced expression of ROP11 or expression of its dominant-negative form （DN-ROP11） causes the opposite phenotypes. The affected ABA-mediated responses by ROP11 include seed germination, seedling growth, stomatal closure, induction of ABA-responsive genes, as well as plant response to drought stress. Furthermore, we showed that ROP11 and its closest-related family member, ROP10, act in parallel in mediating these responses. ABA treatment does not affect ROP11 transcription and protein abundance; however, it causes the accumulation of CA-ROP11 in the nucleus. These results demonstrated that ROP11 is a negative regulator of multiple ABA responses in Arabidopsis.
文摘细菌的σ54(R poN)是一类可选择性识别启动子序列的σ因子,主要参与环境适应、细胞生理过程等,如氮代谢、鞭毛和菌毛的生物合成。在一些病原菌中,σ54也与致病性密切有关。为了明确σ54在野油菜黄单胞菌野油菜致病变种(X cc)中是否参与致病过程,用同源单交换定点突变方法,将X cc 8004中的两个σ54编码基因rp oN 1(XC 1256)和rp oN 2(XC 2168)做单突变及双突变。突变体表型分析结果表明,单个和同时突变rp oN 1和rp oN 2基因均不影响野油菜黄单胞菌的正常生长,对胞外多糖(EPS)产生、胞外酶的合成也无明显影响。植株致病性检测结果表明,rp oN 1和rp oN 2基因的单突变或双突变体的致病力与野生型菌株没有显著差异,表明野油菜黄单胞菌野油菜致病变种的致病过程不需要σ54因子参与。
文摘Two mutants in nitrogenase of Klebsiella pneu-moniae are constructed by site-directed mutagenesis and gene replacement procedure, which express the nitrogenases with Lysine and Glutamine substituting for a-Glutamine 190 and a-Histidine 194 respectively (Kp-Q a190 K and Kp-H a194 Q). The above two substitutions are respectively intro-duced into a nifV mutant (expressing a citrate-containing nitrogenase) and sequentially two double mutants are ob-tained (Kp-Q a190 K-nifV- and Kp-H a194 Q-nifV-). All four mutants exhibit strict Nif- phenotype under the N2-fixation condition and fail to grow diazotrophically. Altered ni-trogneases are effectively depressed and the C2H2 reduction analysis shows that the double substitutions in Kp-Q a190 K-nifV abolish cell C2H2 reduction activity, but Kp-H a194 Q-nifV- cells maintain a C2H2 reduction activity at 10% of that of wild type. Whole cell C2D2 reduction by all four mu-tants in comparison to the wild type and nifV mutant is also detected. The results show that only single a-Gln194 substitu-tion does not perturb the stereospecificity of protonation of C2D2. These results indicate that the a- Glutamine 190 and its combination with homocitrate are essential to the catalytic activity of nitrogenase and it is proposed that a-Glutamine 190 and its combination with homocitrate are involved in the proton and/or electron transfer to FeMoco. The nitrogenases from these double mutants will be useful in further analysis of the entry of the proton and/or electron to FeMoco and the substrate binding sites.
