Binary Vector pCAMBIA Research Articles

Regulation of astaxanthin and its intermediates through cloning and genetic transformation of β-carotene ketolase in Haematococcus pluvialis

Astaxanthin, a high-value ketocarotenoid used in the pharmaceutical and nutraceutical industries is mainly produced from green alga, Haematococcus pluvialis. It is biosynthesized by the action of key enzyme, β-carotene ketolase (BKT) on β-carotene through intermediates echinenone and canthaxanthin. In this study, the β-carotene ketolase (bkt) gene was isolated from H. pluvialis and cloned in a vector pRT100 and further mobilized to a binary vector pCAMBIA 1304. The T-DNA of pCAMBIA 1304, which consists of cloned bkt, was successfully transformed to H. pluvialis through Agrobacterium mediation. The cloning and transformation of bkt in H. pluvialis was confirmed by Southern blotting and also by PCR analysis. Total carotenoids and astaxanthin content in the transformed cells were found to be 2–3-fold higher, while the intermediates like echinenone and canthaxanthin were found to be 8–10-fold higher than in the control cells. The expression level of carotenogenic genes like phytoene synthase (psy), phytoene desaturase (pds), lycopene cyclase (lcy), bkt, and β-carotene hydroxylase (bkh) were found to be higher in transformed cells compared to the non-transformed (NT) H. pluvialis.

In vitro plant regeneration from cotyledonary explants and Agrobacterium mediated transformation of pigeon pea (Cajanus cajan L. Millsp.) var. LRG 41

A reliable method of plant regeneration was developed from overnight soaked de embryonic seed cotyledons of red gram. Shoots appeared from explants when cultured on Murashige and Skoog medium supplemented with benzyl amino purine, naphthalene acetic acid and kinetin under various combinations. Elongated shoots were rooted with 70.6 % rooting frequency on MS medium supplemented with indole butyric acid at 1.0 mg l−1. The rooted plantlets were established in soilrite medium with 91 % success and time taken for acclimatization was 12.8 days. This protocol was used for Agrobacterium mediated transformation. The transformation was carried out using the Agrobacterium strain LBA 4404 containing the binary vector pCAMBIA2301 harboring npt II as selectable marker and GUS as reporter gene. The present study established the regeneration protocol with high shoot and rooting frequencies in redgram. Agrobacterium mediated transfer of GUS gene into LRG 41 cultivar genetic background has been proved to be simple and efficient, which can be further exploited for development of transgenic plants with desired traits.

High efficiency transformation of banana [Musa acuminata L. cv. Matti (AA)] for enhanced tolerance to salt and drought stress through overexpression of a peanut salinity-induced pathogenesis-related class 10 protein.

Bananas and plantains (Musa spp. L.) are important subsistence crops and premium export commodity in several countries, and susceptible to a wide range of environmental and biotic stress conditions. Here, we report efficient, rapid, and reproducible Agrobacterium-mediated transformation and regeneration of an Indian niche cultivar of banana [M. acuminata cv. Matti (AA)]. Apical meristem-derived highly proliferative multiple shoot clump (MSC) explants were transformed with the Agrobacterium strain EHA105 harboring a binary vector pCAMBIA-1301 carrying hptII and uidA. Sequential agro-infiltration (10 min, 400 mmHg), infection (additional 35 min, Agrobacterium density A 600 = 0.8) and co-cultivation (18 h) regimen in 100 µM acetosyringone containing liquid medium were critical factors yielding high transformation efficiency (~81 %) corroborated by transient GUS expression assay. Stable transgenic events were recovered following two cycles of meristem initiation and selection on hygromycin containing medium. Histochemical GUS assay in several tissues of transgenic plants and molecular analyses confirmed stable integration and expression of transgene. The protocol described here allowed recovery of well-established putative transgenic plantlets in as little as 5 months. The transgenic banana plants could be readily acclimatized under greenhouse conditions, and were phenotypically similar to the wild-type untransformed control plants (WT). Transgenic plants overexpressing Salinity-Induced Pathogenesis-Related class 10 protein gene from Arachis hypogaea (AhSIPR10) in banana cv. Matti (AA) showed better photosynthetic efficiency and less membrane damage (P < 0.05) in the presence of NaCl and mannitol in comparison to WT plants suggesting the role of AhSIPR10 in better tolerance of salt stress and drought conditions.

English

This is the first report of genetic transformation of indica rice cultivar Ratna (IET 1411). Agrobacterium tumefaciens strain LBA 4404 carrying a binary vector pCAMBIA1301 harboring the CaMV35S promoter driven modified GUS gene was used. Various parameters critical to rice transformation were optimized including callus induction medium, bacterial concentration, co-cultivation conditions, concentration of the plant &nbsp;growth regulator 2,4-D and the concentration of acetosyringone. The transformed lines were analyzed using PCR for marker sequence and gusA gene expression by GUS activity assays. The regeneration and transformation frequency were calculated to be 70 and 47% respectively. This is a reproducible high efficiency transformation technique for the Indica rice cultivar Ratna (IET 1411). &nbsp; Key words: Indica rice, Agrobacterium tumefaciens, callus induction, transformation, regeneration, GUS.

Agrobacterium tumefaciens-mediated genetic transformation of haptophytes (Isochrysis species).

Isochrysis galbana and Isochrysis sp. are economically important microalgae from the division of haptophytes. Here, we report Agrobacterium-mediated stable DNA transfer into their nuclear genomes. Initial studies were performed to standardize co-cultivation media and determine the sensitivity of the microalgae to selective agents. Up to 1 mg/ml of the antibiotic hygromycin did not inhibit growth, whereas both the haptophytes bleached in artificial seawater (ASW) medium containing micromolar concentrations of the herbicide norflurazon. Co-cultivation of Isochrysis sp. and I. galbana with Agrobacterium tumefaciens strain LBA 4404 harboring the binary vector pCAMBIA 1380-pds-L504R yielded norflurazon-resistant (NR) colonies visible on selective plates after 20-30 days. pCAMBIA 1380-pds-L540R was constructed by cloning a mutated genomic phytoene desaturase (pds) gene from Haematococcus pluvialis as a selectable marker gene into the binary vector system pCAMBIA 1380. Co-cultivation of Isochrysis sp. with A. tumefaciens in ASW medium containing 200 μM of acetosyringone for 72 h produced the highest number of NR cells. For I. galbana, 100 μM of acetosyringone, ASW medium, and 48 h co-cultivation period appeared to be optimum co-cultivation parameters. The NR colonies kept their resistance phenotype for at least 24 months, even in the absence of selective pressure. The transfer of the pds gene in NR cells was shown by PCR amplification of the T-DNA sequences from the genomic DNA of NR cells and Southern blot analysis using T-DNA sequences as probes. The genetic manipulation described here will allow metabolic engineering and a better understanding of several biochemical pathways in the future.

Agrobacterium mediated genetic transformation of commercial jute cultivar Corchorus capsularis cv. JRC 321 using shoot tip explants

We have developed a reproducible method of Agrobacterium tumefaciens mediated stable genetic transformation of white jute (Corchorus capsularis cv. JRC 321) utilizing the shoot organogenesis potential of the shoot tip apical meristem. A. tumefaciens strain LBA4404 harboring the binary vector pCAMBIA 1301 was used in the transformation experiments. The explants were subjected to varying durations of preculture and cocultivation with A. tumefaciens in the presence of acetosyringone in order to optimize the conditions conducive for the highest expression of transgene. A schedule of 1 day preculture of shoot tips followed by 3 days cocultivation was optimized for Agrobacterium mediated stable genetic transformation of C. capsularis cv. JRC 321. The optimized lethal doses of the antibiotic hygromycin B for shoot tips (12 mg/L) and for 5 days old seedlings (14 mg/L) were employed in efficient selection of the transformed tissues. This method of transformation resulted in a mean transformation efficiency of 4.09 %. Stable expression of the intron harbored gusA transgene was observed in mature organs of the transformed plants and their progenies. Genomic integration and inheritance of the hpt transgene was further confirmed by Southern blot analysis. The transformed plants exhibited normal morphology and most of them produced viable progenies, many of which segregated in a 3:1 ratio following Mendelian inheritance for a single dominant locus. However, strong P value support for 3:1 segregation ratio was obtained in case of two lines of independent transformants. Nevertheless, the method of transformation mentioned in this protocol could be effectively implemented in genetic transformation of many other cultivars of jute due to the genotype independent regeneration potential of the shoot tip explants.

Optimization of genetic transformation of Artemisia annua L. Using Agrobacterium for Artemisinin production.

Background:Artemisinin, a sesquiterpene lactone endoperoxide isolated from the medicinal plant Artemisia annua L., is a choice and effective drug for malaria treatment. Due to the low yield of artemisinin in plants, there is a need to enhance the production of artemisinin from A. annua and biotechnological technique may be one of the methods that can be used for the purpose.Aim:To study the transformation efficiency of Agrobacterium tumefaciens in A. annua that could be applied to enhance the production of artemisinin by means of transgenic plants.Setting and Designs:The factors influencing Agrobacterium-mediated transformation of A. annua were explored to optimize the transformation system, which included A. tumefaciens strain and effect of organosilicone surfactants. Three strains of A. tumefaciens, that is, LBA4404, GV1301, and AGL1 harboring the binary vector pCAMBIA 1303 have been used for transformation. The evaluation was based on transient β-glucuronidase (GUS).Materials and Methods:Plant cell cultures were inniatiated from the seeds of A. annua using the germination Murashige and Skoog medium. A. tumefaciens harboring pCAMBIA were tranformed into the leaves of A.annua cultures from 2-week-old-seedling and 2-month-old-seedling for 15 min by vacuum infiltration. Transformation efficiency was determinated by measuring of blue area (GUS expression) on the whole leaves explant using ImageJ 1.43 software. Two organosilicon surfactants, that is, Silwet L-77 and Silwet S-408 were used to improve the transformation efficiency.Results:The transformation frequency with AGL1 strain was higher than GV3101 and LBA4404 which were 70.91, 49.25, and 45.45%, respectively. Effect of organosilicone surfactants, that is, Silwet L-77 and Silwet S-408 were tested on A. tumefaciens AGL1 and GV3101 for their level of transient expression, and on A. rhizogenes R1000 for its hairy root induction frequency. For AGL1, Silwet S-408 produced higher level of expression than Silwet L-77, were 2.3- and 1.3-fold, respectively. For GV3101, Silwet L-77 was still higher than Silwet S-408, were 1.5- and 1.4-fold, respectively. However, GV3101 produced higher levels of expression than AGL1. The area of GUS expression spots of AGL1, LBA4404, and GV3101 strains was 53.43%, 41.06%, and 30.51%, respectively.Conclusion:A. tumefaciens AGl1 strain was the most effective to be transformed in to A. annua than GV3101 and LBA4404 strain. Surfactant Silwet S-408 produced the highest efficiency of transformation.

Transgenic banana cv. Rasthali (AAB, Silk gp) harboring Ace-AMP1 gene imparts enhanced resistance to Fusarium oxysporum f.sp. cubense race 1

Banana cultivar Rasthali (AAB, Silk gp) is one of the favored varieties known for its flavor and keeping quality in southern India. The cultivar is affected by Fusarium wilt which has reached serious proportions, almost wiping it out. Highly regenerative embryogenic cell suspensions of cultivar Rasthali were developed using male floral meristems. Agrobacterium strain LB4404 harboring binary vector pCAMBIA2301 with a gene encoding antimicrobial peptide (Ace-AMP1) cloned from onion seeds driven by CaMV35S promoter and nos terminator was used in transformation. Embryogenic cells were transformed with the gene and 148 putative transformants were developed. Molecular characterization of transformants demonstrated that 20 plants were PCR positive and the transgenes had been stably integrated into the banana genome in ten lines and expression of the gene was confirmed by ELISA and Western blot in them. Transformants were root challenged with Fusarium oxysporum f.sp. cubense race1 (Foc) in earthen pots and observed over a period of six months. External symptoms appeared after 4–5 months and by 6 months plants showed only 0–20% of PDI and 38–48% VDI as compared to untransformed control plants which showed severe disease symptoms (100%) within three months and died. Significantly higher AMP protein content in transgenic lines was negatively correlated and higher root colonization was positively correlated with disease symptoms. Six transgenic lines were selected for field evaluation.

Contribution of Host Intracellular Transport Machineries to Intercellular Movement of Turnip Mosaic Virus

The contribution of different host cell transport systems in the intercellular movement of turnip mosaic virus (TuMV) was investigated. To discriminate between primary infections and secondary infections associated with the virus intercellular movement, a gene cassette expressing GFP-HDEL was inserted adjacent to a TuMV infectious cassette expressing 6K2:mCherry, both within the T-DNA borders of the binary vector pCambia. In this system, both gene cassettes were delivered to the same cell by a single binary vector and primary infection foci emitted green and red fluorescence while secondarily infected cells emitted only red fluorescence. Intercellular movement was measured at 72 hours post infiltration and was estimated to proceed at an average rate of one cell being infected every three hours over an observation period of 17 hours. To determine if the secretory pathway were important for TuMV intercellular movement, chemical and protein inhibitors that blocked both early and late secretory pathways were used. Treatment with Brefeldin A or Concanamycin A or expression of ARF1 or RAB-E1d dominant negative mutants, all of which inhibit pre- or post-Golgi transport, reduced intercellular movement by the virus. These treatments, however, did not inhibit virus replication in primary infected cells. Pharmacological interference assays using Tyrphostin A23 or Wortmannin showed that endocytosis was not important for TuMV intercellular movement. Lack of co-localization by endocytosed FM4-64 and Ara7 (AtRabF2b) with TuMV-induced 6K2-tagged vesicles further supported this conclusion. Microfilament depolymerizing drugs and silencing expression of myosin XI-2 gene, but not myosin VIII genes, also inhibited TuMV intercellular movement. Expression of dominant negative myosin mutants confirmed the role played by myosin XI-2 as well as by myosin XI-K in TuMV intercellular movement. Using this dual gene cassette expression system and transport inhibitors, components of the secretory and actomyosin machinery were shown to be important for TuMV intercellular spread.

Expression of the Vigna aconitifolia P5CSF129A gene in transgenic pigeonpea enhances proline accumulation and salt tolerance

Abiotic stress is the major limiting factor of plant growth and crop yield which can be improved by osmoprotectants. Proline acts as an osmoprotectant and plays an important role in osmotic balancing, protection of sub-cellular structures, enzymes and in increasing cellular osmolarity that provide the turgor necessary for cell expansion under stress conditions. ∆1-pyrroline-5-carboxylate synthetase (P5CS), a rate-limiting enzyme in proline biosynthesis which is known for conferring enhanced salt and drought stress is subjected to feedback inhibition by proline. Therefore, in the present study, we used a mutagenized version P5CSF129A of wild P5CS which is not subjected to feedback control. Efficient in vitro transformation of embryonic structures of pigeonpea (Cajanus cajan (L.) Millsp.) was obtained using Agrobacterium tumefaciens strain LBA4404 harbouring a modified binary vector pCAMBIA 1301 carrying the hptII gene for resistance to hygromycin sulphate, GUS reporter gene, encoding β-glucuronidase, and the Vigna aconitifolia P5CSF129A genes under a constitutive 35S promoter. Embryonic structures showed blue color when tested for GUS after first cycle of antibiotic selection. Integration of T-DNA into nuclear genome of transformed plants and its sexual transmission to the progeny of the transgenic plants are confirmed by PCR amplification of 340 bp hptII, 800 bp P5CSF129A fragments and Southern blot hybridization analysis. The resultant primary transgenic plants showed more proline accumulation than their non-transformed plants. Levels of proline were also elevated in T1 transgenic plants when grown in the presence of 200 mM NaCl. In addition to their enhanced growth performance, more chlorophyll and relative water content under high salinity, these plants also had lower levels of lipid peroxidation. This suggests that overproduction of proline might play an important role against salt shock and cellular integrity.

Development of an efficient regeneration and Agrobacterium-mediated transformation system in crab apple (Malus micromalus) using cotyledons as explants

Apple has become a model species for Rosaceae genetic and genomic research, but it is difficult to obtain transgenic apple plants by Agrobacterium-mediated transformation using in vitro leaves as explants. In this study, we developed an efficient regeneration and Agrobacterium-mediated transformation system for crab apple (Malus micromalus) using cotyledons as explants. The proximal cotyledons of M. micromalus, excised from seedlings that emerged from mature embryos cultured for 10–14 d in vitro, were suitable as explants for regeneration and Agrobacterium-mediated transformation. Cotyledon explants were cocultivated for 3 d with Agrobacterium tumefaciens strain EHA105 harboring the binary vector pCAMBIA2301 on regeneration medium. Kanamycin-resistant buds were produced on cotyledon explants cultured on selective regeneration medium containing 20 mg/L kanamycin. Acetosyringone supplemented in the Agrobacterium suspension or in the cocultivation medium slightly enhanced the regeneration of kanamycin-resistant buds. The maximum percentage of explants with kanamycin-resistant buds was 11.7%. The putative transformed plants were confirmed by histochemical analysis of β-glucuronidase activity and the polymerase chain reaction amplification of the neomycin phosphotransferase II gene. This transformation system also enables recovery of nontransformed isogenic controls developed from embryo buds and is therefore suitable for functional genomics studies in apple.

Construction of an infectious cDNA clone of radish mosaic virus, a crucifer-infecting comovirus

Radish mosaic virus (RaMV) is a crucifer-infecting comovirus that has been detected worldwide. Here, we report the successful construction of a full-length infectious cDNA clone of RaMV. The full-length cDNA clones corresponding to RNA1 and RNA2 of a Japanese isolate of RaMV were cloned into the pBlueScript plasmid or the binary vector pCAMBIA1301 downstream of the cauliflower mosaic virus 35S promoter. Mechanical inoculation or agroinoculation of Nicotiana benthamiana with these vectors resulted in systemic RaMV infections causing symptoms similar to those caused by the wild-type parental virus. The presence of progeny virus was verified by western blot analysis and electron microscopy.

Hairy Root Cultures and Plant Regeneration in &amp;lt;i&amp;gt;Solidago nemoralis&amp;lt;/i&amp;gt; Transformed with &amp;lt;i&amp;gt;Agrobacterium rhizogenes&amp;lt;/i&amp;gt;

By screening a native plant extract library we identified Solidago nemoralis as a novel source of agonists for alpha7 nicotinic receptors for acetylcholine with therapeutic potential. The next phase of our drug discovery strategy is to increase the yields of active compounds in the plant species by gain of function mutations in hairy root cultures [1]. Here we report a protocol for Agrobacterium rhizogenes-mediated genetic transformation of hairy root cultures of Solidago nemoralis which will enable this. Leaf explants of this species were successfully transformed with a frequency of 30%-35% using A. rhizogenes strain R1000 harboring the binary vector pCambia 1301. Transformation was confirmed using the β-glucuronidase (GUS) histochemical assay. Transformed hairy roots showed spontaneous regeneration of adventitious shoots in media without the addition of cytokines, albeit at very low frequency. However, media supplementation with auxin (α-naphthaleneacetic acid, NAA) increased shoot regeneration frequency to 35% and resulted in viable adventitious shoots. Transformation was confirmed at all phases of plant regeneration by GUS staining. Hairy root transformation of Solidago altissima has been previously reported, but this is the first report of genetic transformation of S. nemoralis. The protocol will allow for a large population of activation tagged mutants of S. nemoralis to be generated which will be then screened for the presence of stable mutants which are over-producing metabolites with activity at alpha7 nicotinic receptors. These over-producing mutant cultures will then be regenerated into intact mutant plants.

Optimization of Agrobacterium mediated genetic transformation of cotyledonary node explants of Vigna radiata.

A reproducible and highly efficient protocol for genetic transformation mediated by Agrobacterium has been established for greengram (Vigna radiata L. Wilczek). Double cotyledonary node (DCN) explants were inoculated with Agrobacterium tumefaciens strain LBA 4404 harboring a binary vector pCAMBIA 2301 containing neomycin phosphotransferase (npt II) gene as selectable marker, β-glucuronidase (GUS) as a reporter (uidA) gene and annexin 1 bj gene. Important parameters like optical density of Agrobacterium culture, culture quantity, infection medium, infection and co-cultivation time and acetosyringone concentration were standardized to optimize the transformation frequency. Kanamycin at a concentration of 100 mg/l was used to select transformed cells. Transient and stable GUS expressions were studied in transformed explants and regenerated putative plants, respectively. Transformed shoot were produced on regeneration medium containing 100 mg/l kanamycin and 250 mg/l cefotaxime and rooted on ½ MS medium. Transient and constitutive GUS expression was observed in DCN explants and different tissues of T0 and T1 plants. Rooted T0 and T1 shoots confirming Polymerase Chain Reaction (PCR) positive for npt II and annexin 1bj genes were taken to maturity to collect the seeds. Integration of annexin gene into the greengram genome was confirmed by Southern blotting.

Genetic transformation and full recovery of alfalfa plants via secondary somatic embryogenesis

A genetic transformation method via secondary somatic embryogenesis was developed for alfalfa (Medicago sativa L.). Mature somatic embryos of alfalfa were infected by Agrobacterium strain GV3101 containing the binary vector pCAMBIA2301. pCAMBIA2301 harbors the uidA Gus reporter gene and npt II acts as the selectable marker gene. Infected primary embryos were placed on SH2K medium containing plant growth regulators to induce cell dedifferentiation and embryogenesis under 75 mg/L kanamycin selection. The induced calli were transferred to plant medium free of plant growth regulators for embryo formation while maintaining selection. Somatic embryos germinated normally upon transfer to a germination medium. Plants were recovered and grown in a tissue culture room before transfer to a greenhouse. Histochemical analysis showed high levels of GUS activity in secondary somatic embryos and in different organs of plants recovered from secondary somatic embryos. The presence and stable integration of transgenes in recovered plants were confirmed by polymerase chain reaction using transgene-specific primers and Southern blot hybridization using the npt II gene probe. The average transformation efficiency achieved via secondary somatic embryogenesis was 15.2%. The selection for transformation throughout the cell dedifferentiation and embryogenic callus induction phases was very effective, and no regenerated plants escaped the selection procedure. Alfalfa transformation is usually achieved through somatic embryogenesis using different organs of developed plants. Use of somatic embryos as explants for transformation can avoid the plant development phase, providing a faster procedure for introduction of new traits and facilitates further engineering of previously transformed lines.

IN VITRO CALLOGENESIS AND AGROBACTERIUM-MEDIATED TRANSFORMATION OF GLOBE ARTICHOKE

Micropropagation techniques have been widely applied in globe artichoke (C. cardunculus L. var. scolymus), however, efficient protocols for the establishment of in vitro callogenesis and organogenesis, a pre-requisite for Agrobacterium-mediated genetic transformation, have not been set up so far. We developed an efficient protocol for callus induction from leaf explants of three globe artichoke genotypes of the varietal type ‘Romanesco’; after just one week culture callus formed with an efficiency close to 100%. Leaf explants were transformed with Agrobacterium tumefaciens Agl0 01-124 strain, harboring the binary vector pCAMBIA 2301 with the gene marker GUS, under the control of CaMV 35S promoter. After two weeks, about 30% of the calli obtained from infected leaf explants were positive to GUS assay.

Vacuum infiltration enhances the Agrobacterium-mediated genetic transformation in Indian soybean cultivars

For the first time we have developed a reliable and efficient vacuum infiltration-assisted Agrobacterium-mediated genetic transformation (VIAAT) protocol for Indian soybean cultivars and recovered fertile transgenic soybean plants through somatic embryogenesis. Immature cotyledons were used as an explant and three Agrobacterium tumefaciens strains (EHA 101, EHA 105, and KYRT 1) harbouring the binary vector pCAMBIA1301 were experimented in the co-cultivation. The immature cotyledons were pre-cultured in liquid somatic embryo induction medium prior to vacuum infiltration with the Agrobacterium suspension and co-cultivated for 3 days on co-cultivation medium containing 50 mg l−1 citric acid, 100 µM acetosyringone, and 100 mg l−1 l-cysteine. The transformed somatic embryos were selected in liquid somatic embryo induction medium containing 10 mg l−1 hygromycin and the embryos were germinated in basal medium containing 20 mg l−1 hygromycin. The presence and integration of the hpt II and gus genes into the soybean genome were confirmed by GUS histochemical assay, polymerase chain reaction, and Southern hybridization. Among the different combinations tested, high transformation efficiency (9.45 %) was achieved when immature cotyledons of cv. Pusa 16 were pre-cultured for 18 h and vacuum infiltrated with Agrobacterium tumefaciens KYRT 1 for 2 min at 750 mm of Hg. Among six Indian soybean cultivars tested, Pusa 16 showed highest transformation efficiency of 9.45 %. The transformation efficiency of this method (VIAAT) was higher than previously reported sonication-assisted Agrobacterium-mediated transformation. These results suggest that an efficient Agrobacterium-mediated transformation protocol for stable integration of foreign genes into soybean has been developed.

Monitoring paneer for Listeria monocytogenes- A high risk food pathogen by multiplex PCR

An Agrobacterium -mediated genetic transformation system for chrysanthemum ‘Orlando’ using petal explants was developed. After decontamination, petals were divided into two parts; terminal (position 1) and middle (position 2) parts, and were pre-cultured for two days on Murashige and Skoog (MS) medium containing 1.0 mg·L -1 indole acetic acid (IAA), 1.0 mg·L -1 6-benzylaminopurine (BA), and 0.1 mg·L -1 kinetin (SIM, shoot induction medium). Then, the explants were transformed by co-cultivation with Agrobacterium tumefaciens strain LBA-4404 harboring a binary vector pCAMBIA 2301 carrying the reporter gene β-glucuronidase (GUS), and the marker gene neomycin phosphotransferase (NPT II). The highest frequency of transgenic shoot induction was obtained when the explants were co-cultivated with A. tumefaciens for two days. The formation of transgenic shoots varied with the position of explant. The highest regeneration frequency (13.3) was obtained when position 2 explants were cultured on the shoot induction medium supplemented with 7.5 mg·L -1 kanamycin and 250 mg·L -1 cefotaxime. Putative transgenic plants were obtained after rooting on the MS medium supplemented with 20 mg·L -1 kanamycin and 250 mg·L -1 cefotaxime. Histochemical GUS assay and polymerase chain reaction analysis of transgenic plants confirmed the presence of the GUS gene. Thus, successful transformation of chrysanthemum 'Orlando' petal explants mediated by A. tumefaciens was confirmed. Keywords: Chrysanthemum, co-cultivation, GUS, kanamycin, NPTII, petal explants

Expression of the synthetic phytochelatin gene in tobacco

In the process of obtaining transgenic plants suitable for phytoremediation of heavy metal-contaminated soils, a synthetic pseudophytochelatin gene coding for a phytochelatin analog Met(GluCys)6Gly was de novo designed and cloned. Contrary to natural enzymatically synthesized phytochelatins, this peptide can be made by a template synthesis. A construct carrying the gene in question under the control of the viral constitutive 35S promoter was made on the basis of a binary vector pCAMBIA 1305.1. This construct was used to express the pseudophytochelatin gene in the model transgenic tobacco plants (Nicotiana tabacum L.), and the above plants acquired additional resistance to various cadmium concentrations.

The Agrobacterium-mediated transformation of common wheat (Triticum aestivum L.) and triticale (x Triticosecale Wittmack): role of the binary vector system and selection cassettes

The influence of two binary vector systems, pGreen and pCAMBIA, on the Agrobacterium-mediated transformation ability of wheat and triticale was studied. Both vectors carried selection cassettes with bar or nptII driven by different promoters. Two cultivars of wheat, Kontesa and Torka, and one cultivar of triticale, Wanad, were tested. The transformation rates for the wheat cultivars ranged from 0.00 to 3.58% and from 0.00 to 6.79% for triticale. The best values for wheat were 3.58% for Kontesa and 3.14% for Torka, and these were obtained after transformation with the pGreen vector carrying the nptII selection gene under the control of 35S promoter. In the case of the bar selection system, the best transformation rates were, respectively, 1.46 and 1.79%. Such rates were obtained when the 35S::bar cassette was carried by the pCAMBIA vector; they were significantly lower with the pGreen vector. The triticale cultivar Wanad had its highest transformation rate after transformation with nptII driven by 35S in pCAMBIA. The bar selection system for the same triticale cultivar was better when the gene was driven by nos and the selection cassette was carried by pGreen. The integration of the transgenes was confirmed with at least three pairs of specific starters amplifying the fragments of nptII, bar, or gus. The expression of selection genes, measured by reverse transcriptase polymerase chain reaction (RT-PCR) in relation to the actin gene, was low, ranging from 0.00 to 0.63 for nptII and from 0.00 to 0.33 for bar. The highest relative transcript accumulation was observed for nptII driven by 35S and expressed in Kontesa that had been transformed with pGreen.