ABSTRACT
ObjectiveAgrobacterium tumefaciens-mediated transformation （ATMT） of Clonostachys rosea， an endophytic fungus of Glycyrrhiza uralensis seeds， was established and optimized， and orthogonal test was designed to optimize the colonization conditions of C. rosea for G. uralensis seeds， so as to lay foundation for the development of biofertilizer and the breeding of high-quality G. uralensis. MethodThe conditions of ATMT were optimized from three aspects， including the concentration of acetosyringone， co-culture time and the concentration of conidia of recipient fungi. Then， high-quality transformants were selected. Orthogonal test was used to optimize the colonization conditions by taking co-culture temperature， co-culture time and spore concentration as factors and colonization rate as index. ResultWhen spore concentration was 1×107 cfu·mL-1， acetosyringone concentration was 150 μmol·L-1 and the co-culture time was 60 h， the transformation efficiency of C. rosea was the highest， which was 135 transformants per 1×107 recipient fungal spores. The accuracy and stability of the transformations were tested by cloning the marker gene green fluorescent protein （GFP） and β-glucuronidase （GUS） staining. When co-culture temperature was 25 ℃， co-culture time was 36 h and the spore concentration was 1×106 cfu·mL-1， the colonizing rate for C. rosea back dyeing into G. uralensis seeds by seed soaking method was the highest， which was 71.11%. ConclusionThis study successfully establishes stable and efficient technical systems not only of ATMT in C. rosea， but also of colonization of the transformants into G. uralensis seeds， which can lay a foundation for the development of biofertilizer of G. uralensis.
ABSTRACT
An efficient genetic transformation system and suitable promoters are essential prerequisites for gene expression studies and genetic engineering in streptomycetes. In this study, firstly, a genetic transformation system based on intergeneric conjugation was developed in Streptomyces rimosus M527, a bacterial strain which exhibits strong antagonistic activity against a broad range of plant-pathogenic fungi. Some experimental parameters involved in this procedure were optimized, including the conjugative media, ratio of donor to recipient, heat shock temperature, and incubation time of mixed culture. Under the optimal conditions, a maximal conjugation frequency of 3.05×10-5 per recipient was obtained. Subsequently, based on the above developed and optimized transformation system, the synthetic promoters SPL-21 and SPL-57, a native promoter potrB, and a constitutive promoter permE* commonly used for gene expression in streptomycetes were selected and their activity was analyzed using gusA as a reporter gene in S. rimosus M527. Among the four tested promoters, SPL-21 exhibited the strongest expression activity and gave rise to a 2.2-fold increase in β-glucuronidase (GUS) activity compared with the control promoter permE*. Promoter SPL-57 showed activity comparable to that of permE*. Promoter potrB, which showed the lowest activity, showed a 50% decrease in GUS activity compared with the control permE*. The transformation system developed in this study and the tested promotors provide a basis for the further modification of S. rimosus M527.
Subject(s)
Conjugation, Genetic , Glucuronidase/genetics , Promoter Regions, Genetic , Streptomyces rimosus/geneticsABSTRACT
An efficient genetic transformation system and suitable promoters are essential prerequisites for gene expression studies and genetic engineering in streptomycetes. In this study, firstly, a genetic transformation system based on intergeneric conjugation was developed in Streptomyces rimosus M527, a bacterial strain which exhibits strong antagonistic activity against a broad range of plant-pathogenic fungi. Some experimental parameters involved in this procedure were optimized, including the conjugative media, ratio of donor to recipient, heat shock temperature, and incubation time of mixed culture. Under the optimal conditions, a maximal conjugation frequency of 3.05×10-5 per recipient was obtained. Subsequently, based on the above developed and optimized transformation system, the synthetic promoters SPL-21 and SPL-57, a native promoter potrB, and a constitutive promoter permE" commonly used for gene expression in streptomycetes were selected and their activity was analyzed using gusA as a reporter gene in S. rimosus M527. Among the four tested promoters, SPL-21 exhibited the strongest expression activity and gave rise to a 2.2-fold increase in (3-glucuronidase (GUS) activity compared with the control promoter permE*. Promoter SPL-57 showed activity comparable to that of permE*. Promoter potrB, which showed the lowest activity, showed a 50% decrease in GUS activity compared with the control permE*. The transformation system developed in this study and the tested promotors provide a basis for the further modification of S. rimosus M527.
ABSTRACT
Objective: Trying to find the ways to enhance the expression of cyp71av1 gene encoding cytochrome P450 mono-oxygenase which is a key enzyme in artemisinin biosynthesis pathway accelerating the artemisinin synthesis, the promoter of cyp71av1 was isolated and characterized. Methods: 5′ untranslated regions of cyp71av1 were isolated from Artemisia annua with thermal asymmetric interlaced PCR. For functional characterization, the isolated fragments were fused with β-glucuronidase GUS reporter gene and introduced into Nicotiana tabacum by Agrobacterium-mediated transformation. The GUS expression regulated by 5′ untranslated regions of cyp71av1 in transgenic N. tabacum under the normal or stressed conditions were detected by histochemical staining and quantitative spectrophotometry assay. Results: Two DNA fragments upstream of cyp71av1 coding sequence, a long fragment and a truncated fragment, were isolated from A. annua and introduced into N. tabacum respectively. Histochemical staining showed that two isolated fragments confered stable GUS expression in transgenic plants, and no significant difference was found between the two fragments on the GUS activity. The quantitative results also showed that the GUS activity in transgenic tobacco plants treated by dehydration, low-temperature (4 °C), and ultraviolet irradiation were 1.4 to 2.7 folds higher than that in the controls. Conclusion: It suggests that the isolated fragments has promoter activity and may be responsive to adverse environmental stresses.