Purpose of this work was to study changes in the ion balance under salt stress in roots and leaves of seedlings of T. aestivum L. and its wild congeners with different genomic composition. Laboratory assessment of sal...Purpose of this work was to study changes in the ion balance under salt stress in roots and leaves of seedlings of T. aestivum L. and its wild congeners with different genomic composition. Laboratory assessment of salt tolerance in seedlings was carried out and contents of ions K^＋, Na^＋ and Ca^2＋ in roots and leaves were defined. Considerable change of ionic balance in roots and leaves of studied forms of wheat against salt stress is shown. It is noticed that the parity K^＋/Na^＋ decreases in process of strengthening of salt stress. Authentic negative correlation between a relative gain of a biomass of leaves and roots in the stress conditions and accumulation of ions Na^＋ and between a relative gain of a biomass of leaves in the stress conditions and a parity in them of ions K^＋/Na^＋ is revealed. The research results also show that the stability characteristics of indicators of changes in ionic composition or balance in the leaves of young plants are more informative than in the roots and allow to reveal the form, characterized by relatively high of K^＋/Na^＋ ratio and the relatively low accumulation of Ca2^＋ as the most resistant to salt stress.展开更多
An ideal surrogate host for heterologous production of various natural products is expected to have efficient nutrient utilization,fast growth,abundant precursors and energy supply,and a pronounced gene expression.Str...An ideal surrogate host for heterologous production of various natural products is expected to have efficient nutrient utilization,fast growth,abundant precursors and energy supply,and a pronounced gene expression.Streptomyces albus BK3-25 is a high-yield industrial strain producing type-Ⅰ polyketide sahnomycin,with a unique ability of bean oil utilization.Its potential of being a surrogate host for heterologous production of PKS was engineered and evaluated herein.Firstly,introduction of a three-gene cassette for the biosynthesis of ethylmalonyl-CoA resulted in accumulation of ethylmalonyl-CoA precursor and sahnomycin,and subsequent deletion of the sahnomycin biosynthetic gene cluster resulted in a host with rich supplies of common polyketide precursors,including malonyl-CoA,methylmalonyl-CoA,and ethylmalonyl-CoA.Secondly,the energy and reducing force were measured,and the improved accumulation of ATP and NADPH was observed in the mutant.Furthermore,the strength of a series of selected endogenous promoters based on microarray data was assessed at different growth phases,and a strong constitutive promoter was identified,providing a useful tool for further engineered gene expression.Finally,the potential of the BK3-25 derived host ZXJ-6 was evaluated with the introduction of the actinorhodin biosynthetic gene cluster from Streptomyces coelicolor,and the heterologous production of actinorhodin was obtained.This work clearly indicated the potential of the high-yield sahnomycin producer as a surrogate host for heterologous production of polyketides,although more genetic manipulation should be conducted to streamline its performance.展开更多
文摘Purpose of this work was to study changes in the ion balance under salt stress in roots and leaves of seedlings of T. aestivum L. and its wild congeners with different genomic composition. Laboratory assessment of salt tolerance in seedlings was carried out and contents of ions K^＋, Na^＋ and Ca^2＋ in roots and leaves were defined. Considerable change of ionic balance in roots and leaves of studied forms of wheat against salt stress is shown. It is noticed that the parity K^＋/Na^＋ decreases in process of strengthening of salt stress. Authentic negative correlation between a relative gain of a biomass of leaves and roots in the stress conditions and accumulation of ions Na^＋ and between a relative gain of a biomass of leaves in the stress conditions and a parity in them of ions K^＋/Na^＋ is revealed. The research results also show that the stability characteristics of indicators of changes in ionic composition or balance in the leaves of young plants are more informative than in the roots and allow to reveal the form, characterized by relatively high of K^＋/Na^＋ ratio and the relatively low accumulation of Ca2^＋ as the most resistant to salt stress.
基金supported by grants from the National Natural Science Foundation of China(21661140002 and 31470157)the Ministry of Science and Technology of China(2012CB721005 and 2012AA022107)
文摘An ideal surrogate host for heterologous production of various natural products is expected to have efficient nutrient utilization,fast growth,abundant precursors and energy supply,and a pronounced gene expression.Streptomyces albus BK3-25 is a high-yield industrial strain producing type-Ⅰ polyketide sahnomycin,with a unique ability of bean oil utilization.Its potential of being a surrogate host for heterologous production of PKS was engineered and evaluated herein.Firstly,introduction of a three-gene cassette for the biosynthesis of ethylmalonyl-CoA resulted in accumulation of ethylmalonyl-CoA precursor and sahnomycin,and subsequent deletion of the sahnomycin biosynthetic gene cluster resulted in a host with rich supplies of common polyketide precursors,including malonyl-CoA,methylmalonyl-CoA,and ethylmalonyl-CoA.Secondly,the energy and reducing force were measured,and the improved accumulation of ATP and NADPH was observed in the mutant.Furthermore,the strength of a series of selected endogenous promoters based on microarray data was assessed at different growth phases,and a strong constitutive promoter was identified,providing a useful tool for further engineered gene expression.Finally,the potential of the BK3-25 derived host ZXJ-6 was evaluated with the introduction of the actinorhodin biosynthetic gene cluster from Streptomyces coelicolor,and the heterologous production of actinorhodin was obtained.This work clearly indicated the potential of the high-yield sahnomycin producer as a surrogate host for heterologous production of polyketides,although more genetic manipulation should be conducted to streamline its performance.
