Saponins can be potential candidates for the development of safe biopesticides,due to their widely acknowledged insecticidal,fungicidal and nematicidal activity,but information on their effects on soil biological prop...Saponins can be potential candidates for the development of safe biopesticides,due to their widely acknowledged insecticidal,fungicidal and nematicidal activity,but information on their effects on soil biological properties is still limited.This study aimed to investigate the short-term fate of saponins from Medicago sativa in soil and their dose-effect relationship with microbial biomass and selected enzyme activities in soils with different origin,physical and chemical properties.Microbial degradation of total saponins ranged from 46%to 91%,according to soil characteristics,within 28 days from their incorporation into the soil.Both saponin glycosidic chains and triterpenic aglycones were also microbially degraded,though by dynamics changing among the different soils.In all soils,M.sativa saponins significantly reduced microbial biomass at rates of 10 and 20 mg saponin mixture per g of soil.Microbial enzymatic activities were less affected as indicating an adaptive response of soil microbial communities to the presence of saponins.展开更多
In the Medicago genus, triterpenic saponins are bioactive secondary metabolites constitutively synthesized in the aerial and subterranean parts of plants via the isoprenoid pathway. Exploitation of saponins as pharmac...In the Medicago genus, triterpenic saponins are bioactive secondary metabolites constitutively synthesized in the aerial and subterranean parts of plants via the isoprenoid pathway. Exploitation of saponins as pharmaceutics, agrochemicals and in the food and cosmetic industries has raised interest in identifying the enzymes involved in their synthesis. We have identified a cytochrome P450 （CYP72A67） involved in hemolytic sapogenin biosynthesis by a reverse genetic TILLING approach in a Medicago truncatula ethyl- methanesulfonate （EMS） mutagenized collection. Genetic and biochemical analyses, mutant complementation, and expression of the gene in a microsome yeast system showed that CYP72A67 is responsible for hydroxylation at the C-2 position downstream of oleanolic acid synthesis. The affinity of CYP72A67 for substrates with different substitutions at multiple carbon positions was investigated in the same in vitro yeast system, and in relation to two other CYP450s （CYP72A68） responsible for the production of medicagenic acid, the main sapogenin in M. truncatula leaves and roots. Full sib mutant and wild-type plants were compared for their sapogenin profile, expression patterns of the genes involved in sapogenin synthesis, and response to inoculation with Sinorhizobium meliloti. The results obtained allowed us to revise the hemolytic sapogenin pathway in M. truncatula and contribute to highlighting the tissue specificities （leaves/roots） of sapogenin synthesis.展开更多
基金supported by the ROP ERDF 2014-2020 Lombardy-Innovation and Competitiveness.
文摘Saponins can be potential candidates for the development of safe biopesticides,due to their widely acknowledged insecticidal,fungicidal and nematicidal activity,but information on their effects on soil biological properties is still limited.This study aimed to investigate the short-term fate of saponins from Medicago sativa in soil and their dose-effect relationship with microbial biomass and selected enzyme activities in soils with different origin,physical and chemical properties.Microbial degradation of total saponins ranged from 46%to 91%,according to soil characteristics,within 28 days from their incorporation into the soil.Both saponin glycosidic chains and triterpenic aglycones were also microbially degraded,though by dynamics changing among the different soils.In all soils,M.sativa saponins significantly reduced microbial biomass at rates of 10 and 20 mg saponin mixture per g of soil.Microbial enzymatic activities were less affected as indicating an adaptive response of soil microbial communities to the presence of saponins.
文摘In the Medicago genus, triterpenic saponins are bioactive secondary metabolites constitutively synthesized in the aerial and subterranean parts of plants via the isoprenoid pathway. Exploitation of saponins as pharmaceutics, agrochemicals and in the food and cosmetic industries has raised interest in identifying the enzymes involved in their synthesis. We have identified a cytochrome P450 （CYP72A67） involved in hemolytic sapogenin biosynthesis by a reverse genetic TILLING approach in a Medicago truncatula ethyl- methanesulfonate （EMS） mutagenized collection. Genetic and biochemical analyses, mutant complementation, and expression of the gene in a microsome yeast system showed that CYP72A67 is responsible for hydroxylation at the C-2 position downstream of oleanolic acid synthesis. The affinity of CYP72A67 for substrates with different substitutions at multiple carbon positions was investigated in the same in vitro yeast system, and in relation to two other CYP450s （CYP72A68） responsible for the production of medicagenic acid, the main sapogenin in M. truncatula leaves and roots. Full sib mutant and wild-type plants were compared for their sapogenin profile, expression patterns of the genes involved in sapogenin synthesis, and response to inoculation with Sinorhizobium meliloti. The results obtained allowed us to revise the hemolytic sapogenin pathway in M. truncatula and contribute to highlighting the tissue specificities （leaves/roots） of sapogenin synthesis.
