Gamma-aminobutyric acid( GABA) is a four-carbon non-protein amino acid conserved from bacteria to plants and vertebrates. Increasing evidence supports a regulatory role for GABA in plant development and the plant'...Gamma-aminobutyric acid( GABA) is a four-carbon non-protein amino acid conserved from bacteria to plants and vertebrates. Increasing evidence supports a regulatory role for GABA in plant development and the plant's response to environmental stress. The biosynthesis of nicotine,the main economically important metabolite in tobacco,is tightly regulated. GABA has not hitherto been reported to function in nicotine biosynthesis. Here we found that water flooding treatment( hypoxia) markedly induced the accumulation of GABA and stimulated nicotine biosynthesis. Suppressing GABA accumulation by treatment with glutamate decarboxylase inhibitor impaired flooding-induced nicotine biosynthesis,while exogenous GABA application directly induced nicotine biosynthesis. Based on these results,we propose that GABA triggers nicotine biosynthesis in tobacco seedlings subjected to flooding. Our results provide insight into the molecular mechanism of nicotine biosynthesis in tobacco plants exposed to environmental stress.展开更多
Jasmonate(JA),as an important signal,plays a key role in multiple processes of plant growth,development and stress response.Nicotine and related pyridine alkaloids in tobacco(Nicotiana tabacum L.) are essential second...Jasmonate(JA),as an important signal,plays a key role in multiple processes of plant growth,development and stress response.Nicotine and related pyridine alkaloids in tobacco(Nicotiana tabacum L.) are essential secondary metabolites.Whether environmental factors control nicotine biosynthesis and the underlying mechanism remains previously unreported.Here,we applied physiological and biochemical approaches to investigate how salt stress affects nicotine biosynthesis in tobacco.We found that salt stress induced the biosynthesis of JA,which subsequently triggered the activation of JA-responsive gene expression and,ultimately,nicotine synthesis.Bioinformatics analysis revealed the existence of many Nt MYC2a-recognized G-box motifs in the promoter regions of Nt LOX,Nt AOS,Nt AOC and Nt OPR genes.Applying exogenous JA increased nicotine content,while suppressing JA biosynthesis reduced nicotine biosynthesis.Salt treatment could not efficiently induce nicotine biosynthesis in transgenic anti-COI1 tobacco plants.These results demonstrate that JA acts as the essential signal which triggers nicotine biosynthesis in tobacco after salt stress.展开更多
基金supported by major Science and Technology Program ( 110201101003-TS-03,TS-02-20110014,2011YN02 and 2011YN03)
文摘Gamma-aminobutyric acid( GABA) is a four-carbon non-protein amino acid conserved from bacteria to plants and vertebrates. Increasing evidence supports a regulatory role for GABA in plant development and the plant's response to environmental stress. The biosynthesis of nicotine,the main economically important metabolite in tobacco,is tightly regulated. GABA has not hitherto been reported to function in nicotine biosynthesis. Here we found that water flooding treatment( hypoxia) markedly induced the accumulation of GABA and stimulated nicotine biosynthesis. Suppressing GABA accumulation by treatment with glutamate decarboxylase inhibitor impaired flooding-induced nicotine biosynthesis,while exogenous GABA application directly induced nicotine biosynthesis. Based on these results,we propose that GABA triggers nicotine biosynthesis in tobacco seedlings subjected to flooding. Our results provide insight into the molecular mechanism of nicotine biosynthesis in tobacco plants exposed to environmental stress.
基金supported by the Major Science and Technology Program NOs.110201101003-TS-03,2011YN02 and 2011YN03
文摘Jasmonate(JA),as an important signal,plays a key role in multiple processes of plant growth,development and stress response.Nicotine and related pyridine alkaloids in tobacco(Nicotiana tabacum L.) are essential secondary metabolites.Whether environmental factors control nicotine biosynthesis and the underlying mechanism remains previously unreported.Here,we applied physiological and biochemical approaches to investigate how salt stress affects nicotine biosynthesis in tobacco.We found that salt stress induced the biosynthesis of JA,which subsequently triggered the activation of JA-responsive gene expression and,ultimately,nicotine synthesis.Bioinformatics analysis revealed the existence of many Nt MYC2a-recognized G-box motifs in the promoter regions of Nt LOX,Nt AOS,Nt AOC and Nt OPR genes.Applying exogenous JA increased nicotine content,while suppressing JA biosynthesis reduced nicotine biosynthesis.Salt treatment could not efficiently induce nicotine biosynthesis in transgenic anti-COI1 tobacco plants.These results demonstrate that JA acts as the essential signal which triggers nicotine biosynthesis in tobacco after salt stress.
