In Arabidopsis, systemic acquired resistance （SAR） is established beyond the initial infection by a pathogen or is directly induced by treatment with salicylic acid （SA） or its functional analogs, 2,6-dichloroison...In Arabidopsis, systemic acquired resistance （SAR） is established beyond the initial infection by a pathogen or is directly induced by treatment with salicylic acid （SA） or its functional analogs, 2,6-dichloroisonicotinic acid （INA） and benzothiadiazole （BTH）. NPR1 protein is considered the master regulator of SAR in both SA signal sensing and transduction. In wheat （Triticum aesfivum） and barley （Hordeum vulgare）, both pathogen infection and BTH treatment can induce broad-spectrum resistance to various diseases, including powdery mildew, leaf rust, Fusarium head blight, etc. However, three different types of SAR-like responses including acquired resistance （AR）, systemic immunity （SI）, and BTH-induced resistance （BIR） seem to be achieved by activating different gene pathways. Recent research on wheat and barley NPR1 homologs in AR and SI has provided the initial clue for understanding the mechanism of SAR in these two plant species. In this review, the specific features ofAR, Si, and BIR in wheat and barley were summarized and compared with that of SAR in model plants of Arabidopsis and rice. Research updates on downstream genes of SAR, including pathogenesis-related （PR） and BTH-induced genes, were highlighted.展开更多
Systemic acquired resistance (SAR), known as the broad-spectrum, inducible plant immunity, is a defense response triggered by pathogen infection. The response starts from the recognition of plant resistance (R) with t...Systemic acquired resistance (SAR), known as the broad-spectrum, inducible plant immunity, is a defense response triggered by pathogen infection. The response starts from the recognition of plant resistance (R) with the corresponding avirulence (avr) gene from the pathogen. There are some genes for convergence of signals downstream of different R/avr interacting partners into a single signaling pathway. Salicylic acid (SA) is required for the induction of SAR and involved in transducing the signal in target tissues. The SA signal is transduced through NPR1, a nuclear-localized protein that interacts with transcription factors that are involved in regulating SA-mediated gene expression. Some chemicals that mimic natural signaling compounds can also activate SAR. The application of biochemical activators to agriculture for plant protection is a novel idea for developing green chemical pesticide.展开更多
Induced systemic resistance(ISR)is a mechanism by which certain plant beneficial rhizobacteria and fungi produce immunity,which can stimulate crop growth and resilience against various phytopathogens,insects,and paras...Induced systemic resistance(ISR)is a mechanism by which certain plant beneficial rhizobacteria and fungi produce immunity,which can stimulate crop growth and resilience against various phytopathogens,insects,and parasites.These beneficial rhizobacteria and fungi improve plant performance by regulating hormone signaling,including salicylic acid(SA),jasmonic acid(JA),prosystemin,pathogenesis-related gene 1,and ethylene(ET)pathways,which activate the gene expression of ISR,the synthesis of secondary metabolites,various enzymes,and volatile compounds that ultimately induce defense mechanisms in plant.To protect themselves from disease,plants have various advanced defense mechanisms in which local acquired resistance,systemic gene silencing,systemic wound response,systemic acquired resistance(SAR),and ISR are involved.Several rhizobacteria activate the SA-dependent SAR pathway by producing SA at the root’s surface.In contrast,other rhizobacteria can activate different signaling pathways independent of SA(SA-independent ISR pathways)such as those dependent on JA and ET signaling.The main objective of this review is to provide insight into the types of induced resistance utilized for plant defense.Further to this,the genetic approaches used to suppress disease-causing genes,i.e.,RNA interference and antisense RNA,which are still underutilized in sustainable agriculture,along with the current vision for virus-induced gene silencing are also discussed.展开更多
Tryptophan-derived, indolic metabolites possess diverse functions in Arabidopsis innate immunity to microbial pathogen infection. Hers, we investigate the functional role and regulatory characteristics of indolic meta...Tryptophan-derived, indolic metabolites possess diverse functions in Arabidopsis innate immunity to microbial pathogen infection. Hers, we investigate the functional role and regulatory characteristics of indolic metabolism in Arabidopsis systemic acquired resistance （SAR） triggered by the bacterial pathogen Pseudomonas syringae. Indolic metabolism is broadly activated in both P. syringae-inoculated and distant, non-inoculated leaves. At inoculation sites, camalexin, indol-3-ylmethylamine （13A）, and indole-3-carboxylic acid （ICA） are the major accumulating compounds. Camalexin accumulation is positively affected by MYB122, and the cytochrome P450 genes CYP81F1 and CYP81F2. Local 13A production, by contrast, occurs via indole glucosinolate breakdown by PEN2- dependent and independent pathways. Moreover, exogenous application of the defense hormone salicylic acid stimulates 13A generation at the expense of its precursor indol-3-ylmethylglucosinolate （13M）, and the SAR regulator pipecolic acid primes plants for enhanced P. syringae-induced activation of distinct branches of indolic metabolism. In uninfected systemic tissue, the metabolic response is more specific and associated with enhanced levels of the indolics 13A, ICA, and indole-3-carbaldehyde （ICC）. Systemic indole accumulation fully depends on functional CYP79B2/3, PEN2, and MYB34/51/122, and requires functional SAR signaling. Genetic analyses suggest that systemi- cally elevated indoles are dispensable for SAR and associated systemic increases of salicylic acid. However, soil-grown but not hydroponically -cultivated cyp79b2/3 and pen2 plants, both defective in indolic secondary metabolism, exhibit pre-induced immunity, which abrogates their intrinsic ability to induce SAR.展开更多
Diclofop-methyl（DM）,a widely used herbicide in food crops,may partly contaminate the soil surface of natural ecosystems in agricultural area and exert toxic effects at low dose to nontarget plants.Even though rhizos...Diclofop-methyl（DM）,a widely used herbicide in food crops,may partly contaminate the soil surface of natural ecosystems in agricultural area and exert toxic effects at low dose to nontarget plants.Even though rhizosphere microorganisms strongly interact with root cells,little is known regarding their potential modulating effect on herbicide toxicity in plants.Here we exposed rice seedlings（Xiushui 63） to 100 μg/L DM for 2 to 8 days and studied the effects of DM on rice rhizosphere microorganisms,rice systemic acquired resistance（SAR） and rice-microorganisms interactions.The results of metagenomic 16 S rDNA Illumina tags show that DM increases bacterial biomass and affects their community structure in the rice rhizosphere.After DM treatment,the relative abundance of the bacterium genera Massilia and Anderseniella increased the most relative to the control.In parallel,malate and oxalate exudation by rice roots increased,potentially acting as a carbon source for several rhizosphere bacteria.Transcriptomic analyses suggest that DM induced SAR in rice seedlings through the salicylic acid（but not the jasmonic acid） signal pathway.This response to DM stress conferred resistance to infection by a pathogenic bacterium,but was not influenced by the presence of bacteria in the rhizosphere since SAR transcripts did not change significantly in xenic and axenic plant roots exposed to DM.The present study provides new insights on the response of rice and its associated microorganisms to DM stress.展开更多
N-hydroxy-pipecolic acid(NHP)activates plant systemic acquired resistance(SAR).Enhanced defense responses are typically accompanied by deficiency in plant development and reproduction.Despite of extensive studies on S...N-hydroxy-pipecolic acid(NHP)activates plant systemic acquired resistance(SAR).Enhanced defense responses are typically accompanied by deficiency in plant development and reproduction.Despite of extensive studies on SAR induction,the effects of NHPmetabolismon plant growth remain largely unclear.In this study,we discovered that NHP glycosylation is a critical factor that fine-tunes the tradeoff between SAR defense and plant growth.We demonstrated that a UDP-glycosyltransferase(UGT76B1)forming NHP glycoside(NHPG)controls the NHP to NHPG ratio.Consistently,the ugt76b1 mutant exhibits enhanced SAR response and an inhibitory effect on plant growth,while UGT76B1 overexpression attenuates SAR response,promotes growth,and delays senescence,indicating that NHP levels are dependent on UGT76B1 function in the course of SAR.Furthermore,our results suggested that,upon pathogen attack,UGT76B1-mediated NHP glycosylation forms a‘‘hand brake’’on NHP accumulation by attenuating the positive regulation of NHP biosynthetic pathway genes,highlighting the complexity of SAR-associated networks.In addition,we showed that UGT76B1-mediated NHP glycosylation in the local site is important for fine-tuning SAR response.Our results implicate that engineering plant immunity through manipulating the NHP/NHPG ratio is a promising method to balance growth and defense response in crops.展开更多
NPR(Nonexpressor of pathogenesis-related genes)家族蛋白为植物水杨酸(SA)受体,在细胞核内作为共转录因子参与植物多种生理过程。NPR蛋白功能多样性的发挥依赖于SA诱导下空间结构的变化,NPR空间结构变化为其功能发挥奠定结构基础。...NPR(Nonexpressor of pathogenesis-related genes)家族蛋白为植物水杨酸(SA)受体,在细胞核内作为共转录因子参与植物多种生理过程。NPR蛋白功能多样性的发挥依赖于SA诱导下空间结构的变化,NPR空间结构变化为其功能发挥奠定结构基础。通过综述NPR家族蛋白在植物系统获得性抗性(SAR)、形态发育、冷胁迫、昼夜节律中发挥生物学功能以及NPR1、NPR1-TGA3(TGACG sequence-specific binding protein)复合物、NPR4空间结构的最新研究进展,为解决植物在胁迫条件下的培养问题提供新思路。展开更多
基金the National Natural Science Foundation of China (31701776, 31301649)the Young Talents Project of Hebei Education Department, China (BJ2016028)
文摘In Arabidopsis, systemic acquired resistance （SAR） is established beyond the initial infection by a pathogen or is directly induced by treatment with salicylic acid （SA） or its functional analogs, 2,6-dichloroisonicotinic acid （INA） and benzothiadiazole （BTH）. NPR1 protein is considered the master regulator of SAR in both SA signal sensing and transduction. In wheat （Triticum aesfivum） and barley （Hordeum vulgare）, both pathogen infection and BTH treatment can induce broad-spectrum resistance to various diseases, including powdery mildew, leaf rust, Fusarium head blight, etc. However, three different types of SAR-like responses including acquired resistance （AR）, systemic immunity （SI）, and BTH-induced resistance （BIR） seem to be achieved by activating different gene pathways. Recent research on wheat and barley NPR1 homologs in AR and SI has provided the initial clue for understanding the mechanism of SAR in these two plant species. In this review, the specific features ofAR, Si, and BIR in wheat and barley were summarized and compared with that of SAR in model plants of Arabidopsis and rice. Research updates on downstream genes of SAR, including pathogenesis-related （PR） and BTH-induced genes, were highlighted.
基金supported by National Natural Science Foundation of China(30000112)Shanxi Province Natural Science Foundation(20001037).
文摘Systemic acquired resistance (SAR), known as the broad-spectrum, inducible plant immunity, is a defense response triggered by pathogen infection. The response starts from the recognition of plant resistance (R) with the corresponding avirulence (avr) gene from the pathogen. There are some genes for convergence of signals downstream of different R/avr interacting partners into a single signaling pathway. Salicylic acid (SA) is required for the induction of SAR and involved in transducing the signal in target tissues. The SA signal is transduced through NPR1, a nuclear-localized protein that interacts with transcription factors that are involved in regulating SA-mediated gene expression. Some chemicals that mimic natural signaling compounds can also activate SAR. The application of biochemical activators to agriculture for plant protection is a novel idea for developing green chemical pesticide.
基金Gujarat Arts and Science College,India and Raiganj University,India for their support
文摘Induced systemic resistance(ISR)is a mechanism by which certain plant beneficial rhizobacteria and fungi produce immunity,which can stimulate crop growth and resilience against various phytopathogens,insects,and parasites.These beneficial rhizobacteria and fungi improve plant performance by regulating hormone signaling,including salicylic acid(SA),jasmonic acid(JA),prosystemin,pathogenesis-related gene 1,and ethylene(ET)pathways,which activate the gene expression of ISR,the synthesis of secondary metabolites,various enzymes,and volatile compounds that ultimately induce defense mechanisms in plant.To protect themselves from disease,plants have various advanced defense mechanisms in which local acquired resistance,systemic gene silencing,systemic wound response,systemic acquired resistance(SAR),and ISR are involved.Several rhizobacteria activate the SA-dependent SAR pathway by producing SA at the root’s surface.In contrast,other rhizobacteria can activate different signaling pathways independent of SA(SA-independent ISR pathways)such as those dependent on JA and ET signaling.The main objective of this review is to provide insight into the types of induced resistance utilized for plant defense.Further to this,the genetic approaches used to suppress disease-causing genes,i.e.,RNA interference and antisense RNA,which are still underutilized in sustainable agriculture,along with the current vision for virus-induced gene silencing are also discussed.
基金This work was supported by the German Research Foundation （DFG Cluster of Excellence on Plant Sciences and DFG Graduate program IRTG 1525）, and the Swiss National Science Foundation （SNF Grant No, 3100A-125374）.
文摘Tryptophan-derived, indolic metabolites possess diverse functions in Arabidopsis innate immunity to microbial pathogen infection. Hers, we investigate the functional role and regulatory characteristics of indolic metabolism in Arabidopsis systemic acquired resistance （SAR） triggered by the bacterial pathogen Pseudomonas syringae. Indolic metabolism is broadly activated in both P. syringae-inoculated and distant, non-inoculated leaves. At inoculation sites, camalexin, indol-3-ylmethylamine （13A）, and indole-3-carboxylic acid （ICA） are the major accumulating compounds. Camalexin accumulation is positively affected by MYB122, and the cytochrome P450 genes CYP81F1 and CYP81F2. Local 13A production, by contrast, occurs via indole glucosinolate breakdown by PEN2- dependent and independent pathways. Moreover, exogenous application of the defense hormone salicylic acid stimulates 13A generation at the expense of its precursor indol-3-ylmethylglucosinolate （13M）, and the SAR regulator pipecolic acid primes plants for enhanced P. syringae-induced activation of distinct branches of indolic metabolism. In uninfected systemic tissue, the metabolic response is more specific and associated with enhanced levels of the indolics 13A, ICA, and indole-3-carbaldehyde （ICC）. Systemic indole accumulation fully depends on functional CYP79B2/3, PEN2, and MYB34/51/122, and requires functional SAR signaling. Genetic analyses suggest that systemi- cally elevated indoles are dispensable for SAR and associated systemic increases of salicylic acid. However, soil-grown but not hydroponically -cultivated cyp79b2/3 and pen2 plants, both defective in indolic secondary metabolism, exhibit pre-induced immunity, which abrogates their intrinsic ability to induce SAR.
基金supported by the National Natural Science Foundation of China(Nos.21277125,21577128)Xinmiao Talent Scheme(No.2016R403069)Changjiang Scholars and Innovative Research Team in University(No.IRT13096)
文摘Diclofop-methyl（DM）,a widely used herbicide in food crops,may partly contaminate the soil surface of natural ecosystems in agricultural area and exert toxic effects at low dose to nontarget plants.Even though rhizosphere microorganisms strongly interact with root cells,little is known regarding their potential modulating effect on herbicide toxicity in plants.Here we exposed rice seedlings（Xiushui 63） to 100 μg/L DM for 2 to 8 days and studied the effects of DM on rice rhizosphere microorganisms,rice systemic acquired resistance（SAR） and rice-microorganisms interactions.The results of metagenomic 16 S rDNA Illumina tags show that DM increases bacterial biomass and affects their community structure in the rice rhizosphere.After DM treatment,the relative abundance of the bacterium genera Massilia and Anderseniella increased the most relative to the control.In parallel,malate and oxalate exudation by rice roots increased,potentially acting as a carbon source for several rhizosphere bacteria.Transcriptomic analyses suggest that DM induced SAR in rice seedlings through the salicylic acid（but not the jasmonic acid） signal pathway.This response to DM stress conferred resistance to infection by a pathogenic bacterium,but was not influenced by the presence of bacteria in the rhizosphere since SAR transcripts did not change significantly in xenic and axenic plant roots exposed to DM.The present study provides new insights on the response of rice and its associated microorganisms to DM stress.
基金We are grateful to the Adelis Foundation,the Leona M.and Harry B.Helmsley Charitable Trust,the Jeanne and Joseph Nissim Foundation for Life Sciences,and especially the Tom and Sondra Rykoff Family Foundation Research for supporting the A.A.laboratory activityJ.C.was supported by the PBC(Public and Budgeting Committee)of the State of Israel Council for Higher Education fellowship program.A.A.is the incumbent of the Peter J.Cohn Professorial Chair
文摘N-hydroxy-pipecolic acid(NHP)activates plant systemic acquired resistance(SAR).Enhanced defense responses are typically accompanied by deficiency in plant development and reproduction.Despite of extensive studies on SAR induction,the effects of NHPmetabolismon plant growth remain largely unclear.In this study,we discovered that NHP glycosylation is a critical factor that fine-tunes the tradeoff between SAR defense and plant growth.We demonstrated that a UDP-glycosyltransferase(UGT76B1)forming NHP glycoside(NHPG)controls the NHP to NHPG ratio.Consistently,the ugt76b1 mutant exhibits enhanced SAR response and an inhibitory effect on plant growth,while UGT76B1 overexpression attenuates SAR response,promotes growth,and delays senescence,indicating that NHP levels are dependent on UGT76B1 function in the course of SAR.Furthermore,our results suggested that,upon pathogen attack,UGT76B1-mediated NHP glycosylation forms a‘‘hand brake’’on NHP accumulation by attenuating the positive regulation of NHP biosynthetic pathway genes,highlighting the complexity of SAR-associated networks.In addition,we showed that UGT76B1-mediated NHP glycosylation in the local site is important for fine-tuning SAR response.Our results implicate that engineering plant immunity through manipulating the NHP/NHPG ratio is a promising method to balance growth and defense response in crops.
