Construction of ATMT System for Clonostachys rosea and Its Conditional Optimization of Colonization into Glycyrrhiza uralensis Seeds / 中国实验方剂学杂志

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.

Effect of type of mature embryo explants and acetosyringone on agrobacterium-mediated transformation of moroccan durum wheat

Drought is one of the major constraints in durum wheat production in the Mediterranean Basin. In order to overcome this problem, the genetic transformation of durum wheat is one of the choices for improvement. However, the recalcitrance to Agrobacterium-mediated transformation in durum wheat (Triticum turgidum L.) is one of the factors limiting a successful genetic transformation. The aim of this study was to investigate the effect of explant type and acetosyringone concentration for the efficient Agrobacterium-mediated genetic transformation of three Moroccan durum wheat varieties (Amria, Chaoui, and Marouane). The mature embryos (intact, halved and pieces) were inoculated with Agrobacterium tumefaciens strain EHA101 harboring the binary vector pTF101.1 containing drought tolerance gene HVA1 from barley, and a selectable marker phosphinothricin (PPT) resistance (bar) gene. The explants were inoculated with A. tumefaciens (cell density OD650 at 0.7) at four different concentrations of acetosyringone (0, 100, 200, and 400 µM). The results showed that embryogenic calli from mature embryos showed higher regeneration and transformation than mature embryo halves and pieces. The integration of the transgene was confirmed by PCR amplification using primers specific to the bar gene, 2x35S promoter, and HVA1 gene. The transformation efficiency ranging from 0.33% to 2.33% was obtained in Amira variety using embryogenic calli and acetosyringone concentrations of 200 and 400 µM. The integration, as well as inheritance of the transgene, was confirmed by PCR amplification in T0 and T1 generations. This is the first report describing a genetic transformation of Moroccan durum wheat varieties via Agrobacterium tumefaciens.

Overexpression of ribonucleotide reductase small subunit, RNRM, increases cordycepin biosynthesis in transformed Cordyceps militaris / 中国天然药物

Cordycepin was the first adenosine analogue used as an anticancer and antiviral agent, which is extracted from Cordyceps militaris and hasn't been biosynthesized until now. This study was first conducted to verify the role of ribonucleotide reductases (RNRs, the two RNR subunits, RNRL and RNRM) in the biosynthesis of cordycepin by over expressing RNRs genes in transformed C. militaris. Quantitative real-time PCR (qRT-PCR) and western blotting results showed that the mRNA and protein levels of RNR subunit genes were significantly upregulated in transformant C. militaris strains compared to the control strain. The results of the HPLC assay indicated that the cordycepin was significantly higher in the C. militaris transformants carrying RNRM than in the wild-type strain, whereas the RNRML was preferentially downregulated. For the C. militaris transformant carrying RNRL, the content of cordycepin wasn't remarkably changed. Furthermore, we revealed that inhibiting RNRs with Triapine (3-AP) almost abrogated the upregulation of cordycepin. Therefore, our results suggested that RNRM can probably directly participate in cordycepin biosynthesis by hydrolyzing adenosine, which is useful for improving cordycepin synthesis and helps to satisfy the commercial demand of cordycepin in the field of medicine.

An Enzymolysis-Assisted Agrobacterium tumefaciens-Mediated Transformation Method for the Yeast-Like Cells of Tremella fuciformis

Agrobacterium tumefaciens-mediated transformation (ATMT), as a simple and versatile method, achieves successful transformation in the yeast-like cells (YLCs) of Tremella fuciformis with lower efficiency. Establishment of a more efficient transformation system of YLCs is important for functional genomics research and biotechnological application. In this study, an enzymolysis-assisted ATMT method was developed. The degradation degree of YLCs depends on the concentration and digestion time of Lywallzyme. Lower concentration (≤0.1%) of Lywallzyme was capable of formation of limited wounds on the surface of YLCs and has less influence on their growth. In addition, there is no significant difference of YLCs growth among groups treated with 0.1% Lywallzyme for different time. The binary vector pGEH under the control of T. fuciformis glyceraldehyde-3-phosphate dehydrogenase gene (gpd) promoter was utilized to transform the enzymolytic wounded YLCs with different concentrations and digestion time. The results of PCR, Southern blot, quantitative real-time PCR (qRT-PCR) and fluorescence microscopy revealed that the T-DNA was integrated into the YLCs genome, suggesting an efficient enzymolysis-assisted ATMT method of YLCs was established. The highest transformation frequency reached 1200 transformants per 106 YLCs by 0.05% (w/v) Lywallzyme digestion for 15 min, and the transformants were genetically stable. Compared with the mechanical wounding methods, enzymolytic wounding is thought to be a tender, safer and more effective method.

Factores que afectan la expresión transitoria del gen GUS en yuca (Manihot esculenta Crantz) / Factors affecting the transient expression of gene GUS in cassava (Manihot esculenta Crantz)

RESUMEN La expresión transitoria es una métodología ampliamente utilizada para el estudio de genes. Sin embargo, hasta la fecha no existe un reporte en donde se utilice esta técnica en hojas de yuca de plantas adultas. Por esta razón este trabajo se centró en la determinación de algunos parámetros críticos para la expresión transitoria del gen GUS en yuca como son: la metodología para introducir [a bacteria, [a cepa de Agrobacterium, el tiempo post-inoculación, la introducción del gen VirG y la expresión del gen GUS en algunas variedades de yuca. Los resultados indicaron niveles más altos de expresión del gen GUS entre 5-7 días postinoculación (dpi), agroinfiltrando con la cepa GV3101 y un incremento en la virulencia de esta cepa mediante la introducción del gen VirG. Por último se observaron diferentes niveles de expresión del gen GUS entre [as variedades de yuca evaluadas, [o que indica que el factor genético es clave en la eficiencia de la agroinfiltración en este cultivo.

ABSTRACT Transient expression is a common technique used for the co-expression of proteins for a wide range of experiments in molecular biology. This technique has been frequently used for gene study in plant pathogen interaction and has proved to be versatile and effective. However, there are still few reports and sparse data for transient expression in cassava leaves from adult/mature plants. For this reason, in this study we evaluated some regards of transient expression for the gene GUS in cassava: bacteria introduction methods, type of Agrobacterium strains, time post-inoculation, introduction of gene VirG and GUS and their expression into different cassava varieties. The results show that GUS expression is more efficient between 5-7 days post-inoculation with the GV3101 strain, moreover the virulence of this strain increases with the VirG gene. Finally, we observed a range of GUS expression pattern between different cassava varieties, altogether showing that the genetic factor is important for an accurate and effective agroinfiltration in cassava.

Agrobacterium-mediated transformation of the wild orchid Cattieya maxima Lindi / Transformación mediada por Agrobacterium de la orquídea silvestre Cattleya maxima Lindl / Transformação da orquídea silvestre Cattleya maxima Lindl mediada por Agrobacterium

Abstract Protocorms are unique anatomical structures; they are akin to rhizoids and are formed by young orchid seedlings under physiological conditions. Explanted orchid tissues produce similar structures called protocorm-like bodies (PLBs) when exposed to appropriate in vitro growing conditions. Both the propagative nature of PLBs and the easiness by which they can be generated, make these structures an attractive alternative to seed-mediated production for growing large numbers of plants. To increase somatic embryogenesis and optimize the procedure, PLBs of Cattleya maxima were transformed using the Agrobacterium tumefaciens method. The T-DNA carried a Hygromycin-resistance gene, a visible marker (GFP5-GUSA) and a rice gene encoding the Somatic Embryogenesis Receptor Kinase, deemed to be important for somatic embryogenesis. Treated PLBs generated somatic embryos developing Hygromycin-resistant plantlets. The insertion of T-DNA was confirmed by PCR, and GFP expression was observed using a fluorescent stereomicroscope. Transformed Cattleya maxima PLBs were more efficient in forming somatic embryos (60 - 80%) than untransformed controls (45 - 57%), and this contrast was maximized in hormone-free, Murashige and Skoog (MS) medium (80% of the transformed plants compared to 57% of the untransformed ones). This finding supports the notion that SERK plays an important role in Orchid embryogenesis.

Resumen Los protocormos son estructuras anatómicas únicas: son similares a los rizoides y se forman por vástagos jóvenes de orquídeas bajo condiciones fisiológicas. Los tejidos explantados de orquídeas producen estructuras llamadas Cuerpos Similares a Protocormos (PLBs) cuando están expuestos a condiciones apropiadas de crecimiento in vitro. Tanto la naturaleza propagativa de los PLBs como la facilidad con que se generan, hacen de estas estructuras una alternativa atractiva, frente a la mediada por semillas, para la producción de gran número de plantas en crecimiento. Para aumentar la embriogénesis somática y optimizar el procedimiento, se transformaron PLBs de Cattleya maxima usando el método de Agrobacterium tumefaciens. El T-DNA portaba un gen de resistencia a la Higromicina, un marcador visible (GFP5-GUSA) y un gen de arroz que codificaba para el receptor tipo quinasa de embriogénesis somática (SERK), considerado importante en la embriogénesis somática. Los PLBs tratados generaron embriones somáticos y desarrollaron plántulas resistentes a la Higromicina. La inserción del T-DNA se confirmó por PCR, y la expresión de GFP se observó usando un estereomicroscopio fluorescente. Los PLBs transformados de Cattleya maxima fueron más eficientes en desarrollar embriones somáticos (60-80%) que los controles no transformados (45-57%) y este contraste se maximizó en medio Murashige y Skoog (MS) libre de hormonas (80% de las plantas transformadas en comparación con 57% de las no transformadas). Estos hallazgos apoyan la noción de que SERK juega un papel importante en la embriogénesis de orquídeas.

Resumo Os protocormos são estruturas anatômicas únicas: são similares aos rizoides e se formam por hastes jovens de orquídeas sob condições fisiológicas. Os tecidos explantados de orquídeas produzem estruturas chamadas Corpos Similares a Protocormos (PLBs) quando estão expostos a condições apropriadas de crescimento in vitro. Tanto a natureza propagativa dos PLBs como a facilidade com que se generam, fazem com que estas estruturas sejam uma alternativa atrativa, comparativamente a mediada por sementes, para a produção de grandes números de plantas em crescimento. Para aumentar a embriogênesis somática e otimizar o procedimento, se transformaram PLBs de Cattleya maxima utilizando o método de Agrobacterium tumefaciens. O T-DNA carregava um gen de resistencia a Higromicina, um marcador visível (GFP5-GUSA) e um gen de arroz que codificava para o receptor tipo quinasa de embriogênesis somática (SERK), considerado importante na embriogênesis somática. Os PLBs tratados geraram embriões somáticos e desenvolveram plântulas resistentes a Higromicina. A inserção do T-DNA se confirmou por PCR, e a expressão de GFP se observou utilizando um estereomicroscópio de fluorescência. Os PLBs transformados de Cattleya maxima foram mais eficientes em desenvolver embriões somáticos (60-80%) que os controles não transformados (45-57%) e este contraste se potencializou em meio Murashige y Skoog (MS) livre de hormônios (80% das plantas transformadas em comparação com 57% das não-transformadas). Estes resultados apoiam a noção de que SERK desempenha um papel importante na embriogênesis de orquídeas.

Cloning and heterologous expression of a hydrophobin gene Ltr. hyd from the tiger milk mushroom Lentinus tuber-regium in yeast-like cells of Tremella fuciformis

Background: Hydrophobins are small proteins secreted by filamentous fungi, which show a highly surface activity. Because of the signally self-assembling abilities and surface activities, hydrophobins were considered as candidates in many aspects, for example, stabilizing foams and emulsions in food products. Lentinus tuber-regium, known as tiger milk mushroom, is both an edible and medicinal sclerotium-producing mushroom. Up to now, the hydrophobins of L. tuber-regium have not been identified. Results: In this paper, a Class I hydrophobin gene, Ltr.hyd, was cloned from L. tuber-regium and expressed in the yeast-like cells of Tremella fuciformis mediated by Agrobacterium tumefaciens. The expression vector pGEH-GH was under the control of T. fuciformis glyceraldehyde-3-phosphate dehydrogenase gene (gpd) promoter. The integration of Ltr.hyd into the genome of T. fuciformis was confirmed by PCR, Southern blot, fluorescence observation and quantitative real-time PCR (qRT-PCR). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that recombinant hydrophobin rLtr.HYD with an expected molecular mass of 13 kDa was extracted. The yield of rLtr.HYD was 0.66 mg/g dry weight. The emulsifying activity of rLtr.HYD was better than the typical food emulsifiers sodium caseinate and Tween 20. Conclusions: We evaluated the emulsifying property of hydrophobin Ltr.HYD, which can be potentially used as a food emulsifier.

Expression of Hemagglutinin-Neuraminidase and fusion epitopes of Newcastle Disease Virus in transgenic tobacco

Background: Newcastle disease is an important avian infectious disease that brings about vast economic damage for poultry industry. Transgenic plants represent a cost-effective system for the production of therapeutic proteins and are widely used for the production of poultry vaccines. In an attempt to develop a recombinant vaccine, a plant expression binary vector pBI121, containing the genes encoding Hemagglutinin-Neuraminidase (HN) and Fusion (F) epitopes of Newcastle Disease Virus (NDV) under the control of CaMV35S promoter and NOS terminator was constructed and introduced into the tobacco ( Nicotiana tabacum) plant by Agrobacterium-mediated transformation. Results: Putative transgenic plants were screened in a selection medium containing 50 mg/L kanamycin and 30 mg/L meropenem. Integration of the foreign gene in plant genome was confirmed by PCR. Expression of foreign gene was analyzed at transcription level by RT-PCR and at translation level by means of dot blotting and ELISA. All analyses confirmed the expression of recombinant protein. Conclusion: Developments in genetic engineering have led to plant-based systems for recombinant vaccine production. In this research, tobacco plant was used to express F and HN epitopes of NDV. Our results indicate that for the production of recombinant vaccine, it is a novel strategy to use concatenated epitopes without their genetic fusion onto larger scaffold structure such as viral coat protein.

Antitumor and anti-angiogenic potentials of isolated crude saponins and various fractions of Rumexhastatus D. Don

BACKGROUND: Cancer, being the foremost challenge of the modern era and the focus of world-class investigators, gargantuan research is in progress worldwide to explore novel therapeutic for its management. The exploitation of natural sources has been proven to be an excellent approach to treat or minify the excessive angiogenesis and proliferation of cells. Similarly, based the ethnomedicinal uses and literature survey, the current study is designed to explore the anti-tumor and anti-angiogenic potentials of Rumex hastatus. Anti-tumor and anti-angiogenic activities were carried out using potato-disc model and chorioallantoic membrane (CAM) assay respectively. Moreover, R. hastatus was also assessed for antibacterial activity against Agrobacterium tumefaciens (tumor causing bacterial strain). The positive controls used in anti-tumor, anti-angiogenic and antibacterial activities were vincristine sulphate, dexamethasone and cefotaxime respectively. RESULTS: The crude saponins (Rh.Sp), methanolic extract (Rh.Cr) and other solvent extracts like n-hexane (Rh.Hex), chloroform (Rh.Chf), ethylacetate (Rh.EtAc) and aqueous fraction (Rh.Aq) exhibited notable anti-tumor and anti-angiogenic activities. In potato tumor assay, the chloroform and saponin fractions were observed to be the most effective showing 86.7 and 93.3 % tumor inhibition at 1000 µg/ml with IC50 values 31.6 and 18.1 µg/ml respectively. Similarly, these two samples i.e., chloroform and saponins also excelled among the entire test samples in anti-angiogenic evaluation exhibiting 81.6 % (IC50 = 17.9 µg/ml) and 78.9 % (IC50 = 64.9 µg/ml) at 1000 µg/ml respectively. In contrast, the antibacterial investigations revealed a negligible potential against A. tumefaciens. CONCLUSION: Based on our results we can claim that R. hastatus possesses both anti-tumor and anti-angiogenic potentials. In all of the solvent fractions, Rh.Chf and Rh.Sp were most effective against tumor and angiogenesis while having negligible activity against A. tumefaciens. It can be concluded that Rh.Chf and Rh.Sp might be potential targets in the isolation of natural product having anti-neoplastic action.

Identification of the Genes Involved in the Fruiting Body Production and Cordycepin Formation of Cordyceps militaris Fungus

A mutant library of Cordyceps militaris was constructed by improved Agrobacterium tumefaciens-mediated transformation and screened for degradation features. Six mutants with altered characters in in vitro and in vivo fruiting body production, and cordycepin formation were found to contain a single copy T-DNA. T-DNA flanking sequences of these mutants were identified by thermal asymmetric interlaced-PCR approach. ATP-dependent helicase, cytochrome oxidase subunit I and ubiquitin-like activating enzyme were involved in in vitro fruiting body production, serine/threonine phosphatase involved in in vivo fruiting body production, while glucose-methanol-choline oxidoreductase and telomerase reverse transcriptase involved in cordycepin formation. These genes were analyzed by bioinformatics methods, and their molecular function and biology process were speculated by Gene Ontology (GO) analysis. The results provided useful information for the control of culture degeneration in commercial production of C. militaris.

Transient GUS gene expression in cassava (Manihot esculenta Crantz) using Agrobacterium tumefaciens leaf infiltration / Expresión transitoria del gen GUS en yuca (Manihot esculenta Crantz) utilizando infiltración con Agrobacterium tumefaciens

Objective. Assess transient gene expression of GUS in cassava (Manihot esculenta Crantz) leaves using Agrobacterium tumefaciens infiltration. Materials and methods. A. tumefaciens strains GV3101 and AGL1 containing pCAMBIA1305.2 were used to evaluate transient gene expression of β-glucuronidase (GUS). A. tumefaciens infiltration (agroinfiltration) was made using both leaves from in vitro and 1 month old greenhouse plants. Leaves were incubated in X-GLUC buffer, stained and photographed to detect GUS activity. Results. Agroinfiltration assays showed GUS transient expression in leaves of cassava varieties widely cultivated in the north coast and eastern savannah, MCOL2215 (Venezuelan) and CM6438-14 (Vergara), respectively. A. tumefaciens agressive strain AGL1 showed high efficiency inducing GUS expression in cassava leaves. Conclusions. We recommend using A. tumefaciens agressive strain AGL1 for agroinfiltration to assess transient expression in cassava leaves.

Objetivo. Evaluar la expresión transitoria del gen GUS en hojas de yuca (Manihot esculenta Crantz) por medio de infiltración con Agrobacterium tumefaciens. Materiales y métodos. Se utilizaron las cepas GV3101 y AGL1 de A. tumefaciens conteniendo el plásmido pCAMBIA1305.2, para evaluar la expresión transitoria del gen GUS. La infiltración de A. tumefaciens (agroinfiltración) se realizó tanto en hojas de plantas "in Vitro" como de plantas adultas de 1 mes. Las hojas se incubaron en tampón X-GLUC, se destiñeron y se fotografiaron para detectar la actividad de la enzima β-glucuronidasa (GUS). Resultados. Los ensayos de agroinfiltración en hoja muestraron la expresión transitoria del gen GUS en variedades cultivadas en la costa norte y en los llanos orientales, MCOL2215 (Venezolana) y CM6438-14 (Vergara) respectivamente, tanto en plantas "in Vitro" como en plantas adultas. La cepa hipervirulenta de A. tumefaciens AGL1 mostró una mayor eficiencia para la expresión transitoria en hojas de yuca. Conclusiones. Se recomienda utilizar la cepa AGL1 para evaluar la expresión transitoria de genes de interés por agroinfiltración en hojas de yuca.

Studies on genetic transformation of Rehmannia glutinosa mediated by Agrobacterium tumefaciens / 中草药

Objective: To determine the optimal concentration of hormone and hygromycin for seedling regeneration of Rehmannia glutinosa. Methods: Using the young leaf of sterile plantlet from R. glutinosa as explants, we conducted the transformation mediated by Agrobacterium tumefaciens, analyzed the efficiency of hygromycin and acetosyringone (AS) on resistant callus induction and plant regeneration. Results: The concentration of hygromycin had greatly affected the production of resistant callus and seedlings. The critical concentration of hygromycin on the resistant callus induction and shoot regeneration were 9 and 6 mg/L, respectively. The optimal concentration of hygromycin for the genetic transformation of Wen 85-5 was 12 mg/L. Adding 100 μmol/L AS could greatly improve the transformation efficiency of R. glutinosa. It was confirmed by PCR detection of hpt gene and GUS staining that the foreign gene was integrated into the genome of R. glutinosa. Conclusion: The stable genetic transformation system of R. glutinosa is established, which lays the foundations for the research on molecular pharmacognosy and genetic improvement.

Agrotransformación y evaluación de la resistencia a Phytophthora infestans en Solanum tuberosum L. variedad Désirée

El Oomiceto Phytophthora infestans (Mont.) de Bary, agente causal de la enfermedad denominada tizón tardío, es el principal responsable del déficit en rendimiento y producción en el cultivo de papa a nivel mundial; una de las alternativas a considerar en la lucha contra este patógeno es la integración de secuencias completas de genes R en el genoma de la papa a través de Agrotransformación. El gen Rpi-blb2 (gen R) de la especie silvestre Solanum bulbocastanum Dunal, presenta una amplia resistencia a los aislamientos de P. infestans, haciéndolo un importante candidato en los estudios de mejoramiento genético en plantas. En el presente trabajo se describe la introducción del gen Rpi-blb2 por Agrobacterium tumefaciens en el genoma de la papa variedad Désirée, la caracterización molecular de 29 eventos transformados e infección de plantas completas con el aislamiento POX067 de P. infestans obtenido en el Perú. Los eventos Désirée [Rpi-blb2] 4 y Désirée [ Rpi-blb2] 30, presentaron una resistencia considerable frente a la infección de P. infestans, comprobando de esta manera la transferencia del gen Rpi-blb2 de una especie silvestre a una cultivada mediante transformación genética.

The Oomycete Phytophthora infestans (Mont.) de Bary, the causal agent of the disease known as late blight, is primarily responsible for the decreased in production performance and potato crops worldwide. The integration of the complete R genes sequences in the potato genome using Agro-transformation appears an alternative to be considered in the fight against this pathogen. The Rpi-blb2 gene (R gene) from the wild species Solanum bulbocastanum Dunal shows a broad resistance to isolates of P. infestans, making it an important candidate for plant breeding studies. This paper reports the integration of the Rpi-blb2 gene into potato var. Désirée genome by Agrobacterium tumefaciens - mediated transformation system, the molecular characterization of 29 events transformed and whole plant infection with isolate POX67 of P. infestans from Peru. Désirée events [Rpi-blb2] 4 and Désirée [Rpi-blb2] 30, showed a substantial resistance to P. infestans infection confirming complete transfer of the Rpi-blb2 gene from a wild species to a cultivated species by genetic transformation.

Plant regeneration and Agrobacterium-mediated transformation of Achyranthes bidentata using cotton EREBP gene

The aim of this work was to study the plant regeneration and Agrobacterium-mediated transformation of Achyranthes bidentata using cotton EREBP gene. Results showed that the callus induction rate of stems from A. bidentata was the highest (100%) and bud was in approximately 70% of calli from stems. However bud differentiation rate of the callus from leaves and petioles was very low. Compared with ceftriaxone, 200mg/L cefotaxime could completely control Agrobacterium tumefaciens and had relatively less toxic action on the stems of A. bidentata. In addition, the induction rate of callus resistant to hygromycin was the highest when infected for 3 min and co-cultivated for 3 d. Six positive transgenic plants transformed with pCAMBIA1304-GhEREB2 expression vector were obtained and confirmed by PCR. The expression of target gene GhEREB2 was detected in five transgenic plants by RT-PCR. In brief, an efficient system of genetic transformation and plant regeneration was established for A. bidentata.

Expression of verocytotoxic Escherichia coli antigens in tobacco seeds and evaluation of gut immunity after oral administration in mouse model

Verocytotoxic Escherichia (E.) coli strains are responsible for swine oedema disease, which is an enterotoxaemia that causes economic losses in the pig industry. The production of a vaccine for oral administration in transgenic seeds could be an efficient system to stimulate local immunity. This study was conducted to transform tobacco plants for the seed-specific expression of antigenic proteins from a porcine verocytotoxic E. coli strain. Parameters related to an immunological response and possible adverse effects on the oral administration of obtained tobacco seeds were evaluated in a mouse model. Tobacco was transformed via Agrobacteium tumefaciens with chimeric constructs containing structural parts of the major subunit FedA of the F18 adhesive fimbriae and VT2e B-subunit genes under control of a seed specific GLOB promoter. We showed that the foreign Vt2e-B and F18 genes were stably accumulated in storage tissue by the immunostaining method. In addition, Balb-C mice receiving transgenic tobacco seeds via the oral route showed a significant increase in IgA-positive plasma cell presence in tunica propria when compared to the control group with no observed adverse effects. Our findings encourage future studies focusing on swine for evaluation of the protective effects of transformed tobacco seeds against E. coli infection.

Development of pollen mediated activation tagging system for Phalaenopsis and Doritaenopsis

In the present study, a novel plant transformation system for Doritaenopsis and Phalaenopsis has been developed. The pollen-mediated activation tagging system was established by artificial pollination. The pollens, co-cultured with Agrobacterium tumefaciens strain EHA105 harbouring an activation tagging vector (pTAG-8), were used for pollination. In order to optimize the transformation efficiency, several factors (concentration of A. tumefaciens, concentration of acetosyringone during co-cultivation and the duration of co-cultivation) known to influence Agrobacterium-mediated DNA transfer were examined. A concentration of 0.5-1 x 10(8) CFU/ml for A. tumefaciens, 0.1 mM acetosyringone, and 6 hrs of co-culture period were found to be the optimal condition for high transformation efficiency. Integration of T-DNA into the genome of putative transgenic plants was confirmed by PCR and DNA blot analyses. Single copy of the transgene was observed in all transgenic plants analyzed. Most of the transgenic plants had a morphologically normal phenotype and the overall capsule formation efficiency was similar to control plant. Our results showed a new approach of genetic transformation in orchids and this method can be employed for genetic improvement of the orchids.

Selective agent and A. tumefaciens overgrowth-control antibiotics in Eucalyptus camaldulensis Cotiledonary culture

The objectives of the present work were to establish the minimal lethal dose of the selective agent to determine the type and concentration of appropriate antibiotics for the elimination of Agrobacterium tumefaciens inoculated explants, without interfering with the regenerative potential of the E. camaldulensis cotyledonary explants. Non-transformed explants were cultivated in medium supplemented with kanamycin. The results showed that the antibiotic was suitable for the selection of transformed cells in the concentration of 9 mg L-1 as it inhibited the growth of non-transformed cells. Cotyledons infected with A. tumefaciens were cultivated in MS N/2 medium supplemented with BAP, ANA, Km and cefotaxime or AugmentinÒ . The highest average of regenerated shoots by explant (5,4) was observed in the presence of 300 mg L-1 of AugmentinÒ /15 days, followed by 150 mg L-1/15 days and 100 mg L-1/30 days.

O presente trabalho teve como objetivos determinar o tipo e a concentração de antibióticos adequados para a eliminação de Agrobacterium tumefaciens de explantes inoculados e estabelecer a dose letal mínima do agente seletivo canamicina (Km), sem interferir com o potencial regenerativo do explante cotiledonar de E. camaldulensis. Para a avaliação da eficiência dos antibióticos, cotilédones infectados com A. tumefaciens foram cultivados em meio MS N/2 com BAP, ANA, canamicina e cefotaxima ou AugmentinaÒ . Foi observada a maior média de brotos regenerados por explante (5,4) na presença de 300 mg.L-1 de AugmentinaÒ /15 dias, seguido por 150 mg.L-1/30 dias, e 100 mg.L-1/30 dias. Explantes cotiledonares não transformados foram cultivados em meio de cultura suplementado com antibiótico canamicina onde a concentração adequada para a seleção de células transformadas foi de 9 mg.L-1.

REGENERACION Y SENSIBILIDAD A MANOSA EN ENTRENUDOS DE PAPA (Solanum tuberosum spp. andígena Var Diacol Capiro). / REGENERATION AND MANNOSE SENSIBILITY IN POTATO INTERNODAL EXPLANTS (Solanum tuberosum spp. andígena Var Diacol Capiro)

Se estableció un sistema de organogénesis indirecta para la obtención de brotes múltiples a partir de segmentos internodales de la variedad Diacol Capiro. La ubicación de explantes en medio Murashige y Skoog (MS) suplementado con 2 mg/l de zeatina ribosido (ZR), 0,02 mg/l de ácido naftalenácetico (ANA) y 0,02 mg/l de ácido giberélico (AG3), permite la obtención de plántulas entre la séptima y novena semana con una efectividad del 80-100%. Mediante ubicación de explantes previamente cocultivados con la cepa LBA4404 de Agrobacterium tumefaciens que contiene el plásmido recombinante pNOV022, se verificó la utilidad del medio para procesos de transformación, obteniéndose tasas hasta del 100% de regeneración. Finalmente, con el objetivo de determinar el uso potencial de la manosa como agente selectivo en procesos de transformación, se evaluó el efecto de diferentes concentraciones de manosa sobre la viabilidad y capacidad regenerativa de explantes.

A system of indirect organogenesis for the multiple buds production from internode stem sections in Diacol Capiro variety was established. Explants on Murashige & Skoog (MS) medium with zeatine riboside (ZR) 2 mg/l, naftalenacetic acid (NAA) 0.02 mg/l and giberelic acid (GA3) 0.02 mg/l, produced plants ranging between 7 to 9 weeks with 80-100% effectiveness. In the same medium, explants infected with Agrobacterium LBA4404 strain which carries recombinant plasmid pNOV022, produced regeneration rates reached 100%, thus, the medium utility for trnsformation processes was verified. Finally, to determine the potential use of the mannose as selective agent in transformation processes, the effect of different mannose concentrations on explant viability and regenerative capacity was evaluated.

Development and Optimization of Method for Generating Unmarked A. tumefaciens Mutants / 生物化学与生物物理进展

Agrobacterium tumefaciens possesses many advantages as a model bacterium for the study of a wide variety of biological processes. Gene disruption or inactivation is a powerful and direct tool for investigation of in vivo gene functions. The intensive study ofA. tumefaciens has increased the need for simple and highly efficient procedures to manipulate its genome. The sacB gene was used as a counterselectable marker to develop a gene replacement procedure that allows precise insertion, deletion, and allele substitution of any gene sequence in A. tumefaciens without altering the genome in any other way. A kanamycin resistance (KmR) cassette was constructed to the suicide vector as the positive selection marker. The suicide plasmid containing DNA fragments homologous to the flanking sequences of the target gene was integrated into the recipient cell genome at the target gene locus by intermolecular homologous recombination, generating the KmR-single cross-over colonies. The effect of homologous sequence length on the intermolecular homologous recombination was analyzed. The second cross-over colonies generated by intramolecular homologous recombination occurring between two tandem repeats were simply screened out by counter-selection of sacB. Data showed that the intervening sequence length between two repeats significantly affected the intramolecular homologous recombination frequency in A. tumefaciens, indicating that A. tumefaciens adopted the homologous recombination mechanism similar to that in E. coli. All these results demonstrated that investigators could minimize the numbers of colonies to be analyzed and reduce the overall workload by optimizing the relative length of two homologous fragments and using the specific type of single cross-over transformants for screening the second cross-over event. This mutagenesis strategy had successfully been used to generate the double unmarked △vbp2△vbp3 mutant in two A. tumefaciens strains.

Progress in The Formation and Transfer of Agrobacterium T-complex / 生物化学与生物物理进展

Agrobacterium tumefaciens can transfer a DNA fragment (T-DNA) from its Ti plasmid to host plant and integrate the T-DNA fragment into host cell nuclear genome. Agrobacterium-mediated T-DNA transfer is the most widely used genetic transformation method for plant. The T-DNA is delivered in the form of single-stranded T-DNA-protein complex (T-complex) by the polar-located Agrobacterium type Ⅳ secretion system (T4SS) to the host cell. T4SS is ancestrally related to bacterial conjugation machines and still used by many plasmids as conjugation channel. Moreover, T4SS is also the secretion channel that used by many human bacterial pathogens to inject the effector proteins to host cells, thus contributing directly to the bacterial pathogenicity. Therefore, in addition to the technical application as a gene vector to create transgenic plants, Agrobacterium-mediated T-DNA transfer also provides a fascinating model system to study the intercellular transfer of macromolecules. The study on the molecular mechanism of T-DNA transfer arouses extensive interest and progresses rapidly in recent years. Here the recent advances in research on T-complex formation and T-complex transfer in Agrobacterium cell are reviewed.