Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake effi...Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake efficiency was the main contributor to P tolerance, and the relative P content in P-tolerant genotypes, 99180 and 99239 were higher than that in sensitive genotype, 99152. At earing stage, P-tolerant genotypes, compared to P-sensitive ones, had higher accumulation of P in upper leaves. When came to the silking stage, P uptake and redistribution efficiency of P-tolerant genotypes were higher than those in 99152. The results also suggested that there are different mechanisms of P nutrient uptake and distribution in different P-tolerant genotypes. Inbred line 99239, according to the investigation, was considered as an efficient stock in the P-uptake while 99180 fallen to the efficient stock of P redistribution.展开更多
The study was conducted to investigate the effects of applying different concentrations of the macronutrients K＋,Ca2＋,and Mg2＋ on the responses of contrasting rice（Oryza sativa L.） genotypes under salt stress.A s...The study was conducted to investigate the effects of applying different concentrations of the macronutrients K＋,Ca2＋,and Mg2＋ on the responses of contrasting rice（Oryza sativa L.） genotypes under salt stress.A solution culture experiment was conducted in a phytotron at the International Rice Research Institute（IRRI）,under controlled temperature and humidity and natural sunlight.When subjected to salt stress of 100 mmol L-1 using NaCl,the salt tolerant genotypes FL478 and IR651,accumulated less Na＋ and maintained lower ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ than the sensitive genotypes IR29 and Azucena.These tolerant genotypes also had higher concentrations of K＋ in their shoots and greater root and shoot biomass and green leaf area.Tolerant genotypes also maintained much lower concentration of Na＋ and lower and more favorable ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in their active and developing tissues.Salt tolerance and shoot and root growth of both tolerant and sensitive genotypes were enhanced considerably when higher concentrations of Ca2＋ and Mg2＋ were applied in culture solution.The concentration of Na＋ and the ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in shoots also declined significantly.The beneficial effects of higher calcium were greater than that of magnesium and application of higher concentration of K＋ seems to have minor effects.Responses to salinity in rice can therefore be considerably enhanced through proper nutrient management,by increasing the concentrations of nutrient elements that have favorable effects such as Ca2＋ and Mg2＋.Calcium is particularly more effective than both magnesium and potassium,and can be applied at relatively larger quantities in salt affected soils.展开更多
Nutrient and stress factor 1(Nsf1),a transcription factor containing the classical Cys2-His2(C_(2)H_(2))zinc finger motif,is expressed under non-fermentable carbon conditions and in response to salt stress in Saccharo...Nutrient and stress factor 1(Nsf1),a transcription factor containing the classical Cys2-His2(C_(2)H_(2))zinc finger motif,is expressed under non-fermentable carbon conditions and in response to salt stress in Saccharomyces cerevisiae.However,the role of Nsf1 in filamentous fungi is not well understood.In this study,the orthologue of Nsf1 was investigated in Fusarium graminearum(named FgNsf1),a causal agent of Fusarium head blight(FHB).The functions of FgNsf1 were evaluated by constructing a FgNSF1 deletion mutant,designated asΔFgNsf1,and its functional complementation mutantΔFgNsf1-C.Gene deletion experiments showed that the mycelial growth rate,asexual and sexual reproduction ofΔFgNsf1 were significantly reduced,but the pigment production ofΔFgNsf1 was remarkably increased compared with the PH-1 andΔFgNsf1-C.In addition,the tolerance ofΔFgNsf1 to osmotic pressures,cell wall-damaging agents and oxidative stress increased significantly.Sensitivity tests to different fungicides revealed thatΔFgNsf1 exhibited increased sensitivity to carbendazim(MBC)and tebuconazole,and enhanced tolerance to fludioxonil and iprodione than PH-1 andΔFgNsf1-C.The virulence ofΔFgNsf1 to wheat coleoptiles and flowering wheat heads were dramatically decreased,which was consistent with the decrease in the yield of deoxynivalenol(DON).All of these defects were restored by target gene complementation.These results indicated that FgNsf1 plays a crucial role in vegetative growth,asexual and sexual reproduction,stress responses,fungicide sensitivity,and full virulence in F.graminearum.展开更多
Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic(orthophosphate) or organic(β-gly...Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic(orthophosphate) or organic(β-glycerophosphate or polyphosphate) phosphorus and at different N:P ratios with 50:1, 30:1, 16:1, 4:1 and 1:4, serving as the phosphorus source. Fluorescence parameters were measured to determine the response of cellular responses to nutrient stress. Scanning electron microscopy(SEM) and estimates of antioxidant activity were employed to examine potential mechanisms of physical change. The results demonstrate that inorganic phosphorus was more bioavailable to M. aeruginosa relative to organic phosphorus in culture. The highest cell concentration(2.21×10~6 cells/mL), chlorophyll-a(0.39 pg/cell) and phycocyanin(1.57 pg/cell) quotas and high levels of chlorophyll fluorescence parameters( rETR, E_k, α, φ_(PSⅡ) and F_v/F_m) were obtained when phosphorus was supplied as K_2 HPO_4 at a N:P ratio of 16–30. Organic sources of phosphorus(β-glycerophosphate and polyphosphate) were bioavailable to M. aeruginosa. In addition, too concentrated orthophosphate(N:P=1:4) resulted in the oxidative stress and lipid peroxidation of cell membrane(identified by the antioxidant system activity), and the photosynthetic activity declined consequently. This study has demonstrated the effects of different phosphorus chemistries and N:P ratios on the cyanobacterial growth, photosynthetic activity and cell physiology, which could be an effective tool for predicting cyanobacterial dominance or N-deficiency in natural lakes(due to the superior ability of cyanobacteria for dissolved N and fix atmospheric N in some cases).展开更多
基金This work was supported by the National 863 Program of China(2001AA241051).
文摘Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake efficiency was the main contributor to P tolerance, and the relative P content in P-tolerant genotypes, 99180 and 99239 were higher than that in sensitive genotype, 99152. At earing stage, P-tolerant genotypes, compared to P-sensitive ones, had higher accumulation of P in upper leaves. When came to the silking stage, P uptake and redistribution efficiency of P-tolerant genotypes were higher than those in 99152. The results also suggested that there are different mechanisms of P nutrient uptake and distribution in different P-tolerant genotypes. Inbred line 99239, according to the investigation, was considered as an efficient stock in the P-uptake while 99180 fallen to the efficient stock of P redistribution.
基金the National Key Technology R&D Program of China(2007BAD87B11)the 948 Program,Minsitry of Agriculture,China (200803030)
文摘The study was conducted to investigate the effects of applying different concentrations of the macronutrients K＋,Ca2＋,and Mg2＋ on the responses of contrasting rice（Oryza sativa L.） genotypes under salt stress.A solution culture experiment was conducted in a phytotron at the International Rice Research Institute（IRRI）,under controlled temperature and humidity and natural sunlight.When subjected to salt stress of 100 mmol L-1 using NaCl,the salt tolerant genotypes FL478 and IR651,accumulated less Na＋ and maintained lower ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ than the sensitive genotypes IR29 and Azucena.These tolerant genotypes also had higher concentrations of K＋ in their shoots and greater root and shoot biomass and green leaf area.Tolerant genotypes also maintained much lower concentration of Na＋ and lower and more favorable ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in their active and developing tissues.Salt tolerance and shoot and root growth of both tolerant and sensitive genotypes were enhanced considerably when higher concentrations of Ca2＋ and Mg2＋ were applied in culture solution.The concentration of Na＋ and the ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in shoots also declined significantly.The beneficial effects of higher calcium were greater than that of magnesium and application of higher concentration of K＋ seems to have minor effects.Responses to salinity in rice can therefore be considerably enhanced through proper nutrient management,by increasing the concentrations of nutrient elements that have favorable effects such as Ca2＋ and Mg2＋.Calcium is particularly more effective than both magnesium and potassium,and can be applied at relatively larger quantities in salt affected soils.
基金This work was supported by the National Key Research&Development Program of China(2016YED0201007,2018YFD0201201 and 2018YFD0201000)the National Natural Science Foundation of China(31672065)+1 种基金the Agricultural Science and Technology Projects of Jiangsu Province,China(BE2018378,BA2018039,PZCZ201715,CX(19)3003,and CX(18)2005)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(KYCX18_0670).
文摘Nutrient and stress factor 1(Nsf1),a transcription factor containing the classical Cys2-His2(C_(2)H_(2))zinc finger motif,is expressed under non-fermentable carbon conditions and in response to salt stress in Saccharomyces cerevisiae.However,the role of Nsf1 in filamentous fungi is not well understood.In this study,the orthologue of Nsf1 was investigated in Fusarium graminearum(named FgNsf1),a causal agent of Fusarium head blight(FHB).The functions of FgNsf1 were evaluated by constructing a FgNSF1 deletion mutant,designated asΔFgNsf1,and its functional complementation mutantΔFgNsf1-C.Gene deletion experiments showed that the mycelial growth rate,asexual and sexual reproduction ofΔFgNsf1 were significantly reduced,but the pigment production ofΔFgNsf1 was remarkably increased compared with the PH-1 andΔFgNsf1-C.In addition,the tolerance ofΔFgNsf1 to osmotic pressures,cell wall-damaging agents and oxidative stress increased significantly.Sensitivity tests to different fungicides revealed thatΔFgNsf1 exhibited increased sensitivity to carbendazim(MBC)and tebuconazole,and enhanced tolerance to fludioxonil and iprodione than PH-1 andΔFgNsf1-C.The virulence ofΔFgNsf1 to wheat coleoptiles and flowering wheat heads were dramatically decreased,which was consistent with the decrease in the yield of deoxynivalenol(DON).All of these defects were restored by target gene complementation.These results indicated that FgNsf1 plays a crucial role in vegetative growth,asexual and sexual reproduction,stress responses,fungicide sensitivity,and full virulence in F.graminearum.
基金Supported by the National Key R&D Program of China(No.2016YFC0502700)the Major Program of National Social Science Foundation of China(No.14ZDB140)the National Science Foundation(USA)(Nos.IOS1451528,DEB1240870)
文摘Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic(orthophosphate) or organic(β-glycerophosphate or polyphosphate) phosphorus and at different N:P ratios with 50:1, 30:1, 16:1, 4:1 and 1:4, serving as the phosphorus source. Fluorescence parameters were measured to determine the response of cellular responses to nutrient stress. Scanning electron microscopy(SEM) and estimates of antioxidant activity were employed to examine potential mechanisms of physical change. The results demonstrate that inorganic phosphorus was more bioavailable to M. aeruginosa relative to organic phosphorus in culture. The highest cell concentration(2.21×10~6 cells/mL), chlorophyll-a(0.39 pg/cell) and phycocyanin(1.57 pg/cell) quotas and high levels of chlorophyll fluorescence parameters( rETR, E_k, α, φ_(PSⅡ) and F_v/F_m) were obtained when phosphorus was supplied as K_2 HPO_4 at a N:P ratio of 16–30. Organic sources of phosphorus(β-glycerophosphate and polyphosphate) were bioavailable to M. aeruginosa. In addition, too concentrated orthophosphate(N:P=1:4) resulted in the oxidative stress and lipid peroxidation of cell membrane(identified by the antioxidant system activity), and the photosynthetic activity declined consequently. This study has demonstrated the effects of different phosphorus chemistries and N:P ratios on the cyanobacterial growth, photosynthetic activity and cell physiology, which could be an effective tool for predicting cyanobacterial dominance or N-deficiency in natural lakes(due to the superior ability of cyanobacteria for dissolved N and fix atmospheric N in some cases).
