Pseudomonas aeruginosa causes severe and persistent infections in immune compromised individuals and cystic fibrosis sufferers. The infection is hard to eradi- cate as P. aeruginosa has developed strong resistance to ...Pseudomonas aeruginosa causes severe and persistent infections in immune compromised individuals and cystic fibrosis sufferers. The infection is hard to eradi- cate as P. aeruginosa has developed strong resistance to most conventional antibiotics. The problem is further compounded by the ability of the pathogen to form biofilm matrix, which provides bacterial cells a protected environment withstanding various stresses including antibiotics. Quorum sensing （QS）, a cell density-based intercellular communication system, which plays a key role in regulation of the bacterial virulence and biofilm formation, could be a promising target for developing new strategies against P. aeruginosa infection. The QS network of P. aeruginosa is organized in a multi-layered hierarchy consisting of at least four interconnected signaling mechanisms. Evidence is accumulating that the QS regulatory network not only responds to bacte- rial population changes but also could react to envi- ronmental stress cues. This plasticity should be taken into consideration during exploration and development of anti-QS therapeutics.展开更多
Jasmonates （JAs） are plant hormones with essential roles in plant defense and development. The basic- helix-loop-helix （bHLH） transcription factor （TF） MYC2 has recently emerged as a master regulator of most asp...Jasmonates （JAs） are plant hormones with essential roles in plant defense and development. The basic- helix-loop-helix （bHLH） transcription factor （TF） MYC2 has recently emerged as a master regulator of most aspects of the jasmonate （JA） signaling pathway in Arabidopsis. MYC2 coordinates JA-mediated defense responses by antagonistically regulating two different branches of the JA signaling pathway that determine resistance to pests and pathogens, respectively. MYC2 is required for induced systemic resistance （ISR） triggered by beneficial soil microbes while MYC2 function is targeted by pathogens during effector-mediated suppression of innate immunity in roots. Another notable function of MYC2 is the regulation of crosstalk between the signaling pathways of JA and those of other phytohormones such as abscisic acid （ABA）, salicylic acid （SA）, gibberellins （GAs）, and auxin （IAA）. MYC2 also regulates interactions between JA signaling and light, phytochrome signaling, and the circadian clock, MYC2 is involved in JA-regulated plant development, lateral and adventitious root formation, flowering time, and shade avoidance syndrome. Related bHLH TFs MYC3 and MYC4 also regulate both overlapping and distinct MYC2-regulated functions in Arabidopsis while MYC2 orthologs act as ＇master switches＇ that regulate JA-mediated biosynthesis of secondary metabolites. Here, we briefly review recent studies that revealed mechanistic new insights into the mode of action of this versatile TF.展开更多
Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacte...Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacteria （IPSB） and organic P-mineralizing bacteria （OPMB） in soils taken from subtropical flooded and temperate non-flooded soils, and to compare inorganic P-solubilizing and organic P-solubilizing abilities between IPSB and OPMB. Ten OPMB strains were isolated and identified as Bacillus cereus and Bacillus megaterium, and five IPSB strains as B. megaterium, Burkholderia caryophyUi, Pseudomonas cichorii, and Pseudomonas syringae. P-solubilizing and -mineralizing abilities of the strains were measured using the methods taking cellular P into account. The IPSB strains exhibited inorganic P-solubilizing abilities ranging between 25.4-41.7 μg P mL^-1 and organic P-mineralizing abilities between 8.2-17.8μg P mL^-1. Each of the OPMB strains also exhibited both solubilizing and mineralizing abilities varying from 4.4 to 26.5 μg P mL^-1 and from 13.8 to 62.8 μg P mL^-1, respectively. For both IPSB and OPMB strains, most of the P mineralized from the organic P source was incorporated into the bacterial cells as cellular P. A significantly negative linear correlation （P 〈 0.05） was found between culture pH and P solubilized from inorganic P by OPMB strains. The results suggested that P solubilization and mineralization could coexist in the same bacterial strain.展开更多
基金This work was funded by the Biomedical Research Council, Agency for Science, Technology and Research （A＇STAR）, Singapore, and by the National Natural Science Foundation of China （Grant No. 31330002）. We apologize to the scientists who made contributionsto the field, but their works have not been cited due to space limitations.
文摘Pseudomonas aeruginosa causes severe and persistent infections in immune compromised individuals and cystic fibrosis sufferers. The infection is hard to eradi- cate as P. aeruginosa has developed strong resistance to most conventional antibiotics. The problem is further compounded by the ability of the pathogen to form biofilm matrix, which provides bacterial cells a protected environment withstanding various stresses including antibiotics. Quorum sensing （QS）, a cell density-based intercellular communication system, which plays a key role in regulation of the bacterial virulence and biofilm formation, could be a promising target for developing new strategies against P. aeruginosa infection. The QS network of P. aeruginosa is organized in a multi-layered hierarchy consisting of at least four interconnected signaling mechanisms. Evidence is accumulating that the QS regulatory network not only responds to bacte- rial population changes but also could react to envi- ronmental stress cues. This plasticity should be taken into consideration during exploration and development of anti-QS therapeutics.
文摘Jasmonates （JAs） are plant hormones with essential roles in plant defense and development. The basic- helix-loop-helix （bHLH） transcription factor （TF） MYC2 has recently emerged as a master regulator of most aspects of the jasmonate （JA） signaling pathway in Arabidopsis. MYC2 coordinates JA-mediated defense responses by antagonistically regulating two different branches of the JA signaling pathway that determine resistance to pests and pathogens, respectively. MYC2 is required for induced systemic resistance （ISR） triggered by beneficial soil microbes while MYC2 function is targeted by pathogens during effector-mediated suppression of innate immunity in roots. Another notable function of MYC2 is the regulation of crosstalk between the signaling pathways of JA and those of other phytohormones such as abscisic acid （ABA）, salicylic acid （SA）, gibberellins （GAs）, and auxin （IAA）. MYC2 also regulates interactions between JA signaling and light, phytochrome signaling, and the circadian clock, MYC2 is involved in JA-regulated plant development, lateral and adventitious root formation, flowering time, and shade avoidance syndrome. Related bHLH TFs MYC3 and MYC4 also regulate both overlapping and distinct MYC2-regulated functions in Arabidopsis while MYC2 orthologs act as ＇master switches＇ that regulate JA-mediated biosynthesis of secondary metabolites. Here, we briefly review recent studies that revealed mechanistic new insights into the mode of action of this versatile TF.
基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars, the Ministry of Education of the P.R. China.
文摘Microorganisms capable of solubilizing and mineralizing phosphorus （P） pools in soils are considered vital in promoting P bioavallability. The study was conducted to screen and isolate inorganic P-solubilizing bacteria （IPSB） and organic P-mineralizing bacteria （OPMB） in soils taken from subtropical flooded and temperate non-flooded soils, and to compare inorganic P-solubilizing and organic P-solubilizing abilities between IPSB and OPMB. Ten OPMB strains were isolated and identified as Bacillus cereus and Bacillus megaterium, and five IPSB strains as B. megaterium, Burkholderia caryophyUi, Pseudomonas cichorii, and Pseudomonas syringae. P-solubilizing and -mineralizing abilities of the strains were measured using the methods taking cellular P into account. The IPSB strains exhibited inorganic P-solubilizing abilities ranging between 25.4-41.7 μg P mL^-1 and organic P-mineralizing abilities between 8.2-17.8μg P mL^-1. Each of the OPMB strains also exhibited both solubilizing and mineralizing abilities varying from 4.4 to 26.5 μg P mL^-1 and from 13.8 to 62.8 μg P mL^-1, respectively. For both IPSB and OPMB strains, most of the P mineralized from the organic P source was incorporated into the bacterial cells as cellular P. A significantly negative linear correlation （P 〈 0.05） was found between culture pH and P solubilized from inorganic P by OPMB strains. The results suggested that P solubilization and mineralization could coexist in the same bacterial strain.
