N6-benzyladenosine derivatives as novel N-donor ligands of platinum(II) dichlorido complexes

The platinum(II) complexes trans-[PtCl₂(Ln)₂]∙xSolv 1-13 (Solv = H₂O or CH3OH), involving N6-benzyladenosine-based N-donor ligands, were synthesized; L(n) stands for N6-(2-methoxybenzyl)adenosine (L₁, involved in complex 1), N6-(4-methoxy-benzyl)adenosine (L₂, 2), N6-(2-chlorobenzyl)adenosine (L₃, 3), N6-(4-chlorobenzyl)-adenosine (L₄, 4), N6-(2-hydroxybenzyl)adenosine (L₅, 5), N6-(3-hydroxybenzyl)-adenosine (L₆, 6), N6-(2-hydroxy-3-methoxybenzyl)adenosine (L₇, 7), N6-(4-fluoro-benzyl)adenosine (L₈, 8), N6-(4-methylbenzyl)adenosine (L₉, 9), 2-chloro-N6-(3-hydroxy-benzyl)adenosine (L₁₀, 10), 2-chloro-N6-(4-hydroxybenzyl)adenosine (L₁₁, 11), 2-chloro-N6-(2-hydroxy-3-methoxybenzyl)adenosine (L₁₂, 12) and 2-chloro-N6-(2-hydroxy-5-methylbenzyl)adenosine (L₁₃, 13). The compounds were characterized by elemental analysis, mass spectrometry, IR and multinuclear (¹H-, ¹³C-, ¹⁹⁵Pt- and ¹⁵N-) and two-dimensional NMR spectroscopy, which proved the N7-coordination mode of the appropriate N6-benzyladenosine derivative and trans-geometry of the title complexes. The complexes 1-13 were found to be non-toxic in vitro against two selected human cancer cell lines (HOS and MCF7; with IC₅₀ > 50.0 µM). However, they were found (by ESI-MS study) to be able to interact with the physiological levels of the sulfur-containing biogenic biomolecule L-methionine by a relatively simple 1:1 exchange mechanism (one L(n) molecule was replaced by one L-methionine molecule), thus forming a mixed-nitrogen/sulfur-ligand dichlorido-platinum(II) coordination species.

Endogenous cytokinin and auxin profiles during in vitro organogenesis from vegetative buds of Pinus radiata adult trees

In Pinus radiata D. Don, the transition from the juvenile to the mature phase is characterized by a reduction in the tree's organogenic potential, which is usually reverted in breeding programs by reinvigoration procedures to enable vegetative propagation. In this work, we have determined the best culture conditions for in vitro reinvigoration of radiata pine buds, tested different cytokinin (CK) types [N⁶-benzyladenine (BA), meta-topolin (mT) and trans-zeatin] and concentrations (25 and 50 µM), and studied the effect of culture conditions on endogenous CK and indole-3-acetic acid (IAA) levels at different stages of the organogenic process. To this end, the levels of 43 CKs and IAA were determined in P. radiata buds before and during the reinvigoration process. When BA or mT was applied to the induction medium, we did not observe any significant increase or decrease in endogenous isoprenoid CK content. We also report for the first time the presence of O-glucosides in non-treated P. radiata explants from the field and remark the importance of O-glucosides as storage forms.

6-Benzylaminopurine alleviates chilling injury of postharvest cucumber fruit through modulating antioxidant system and energy status

BACKGROUND

6-Benzylaminopurine (6-BA) has a close relationship with the stress resistance of plants. Little research has been carried out on the effects of 6-BA on the cold resistance of postharvest fruits and vegetables. Therefore the aim of the present study was to evaluate the effects of 6-BA on chilling injury (CI), antioxidant system and energy status in cucumber during storage.

RESULTS

The results showed that 6-BA at 50 mmol L(-1) was most effective to restrain CI in cucumber fruit. Fruits treated with 50 mmol L(-1) 6-BA maintained higher levels of chlorophyll, ascorbic acid, total phenolics and total antioxidant capacity. Furthermore, this treatment reduced the increases in membrane permeability and lipid peroxidation, delayed the increases in both rate of O2•- production and H2O2 content and increased the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) under chilling stress. The treatment also increased the content of adenosine triphosphate (ATP) and resulted in a higher level of energy charge.

CONCLUSION

These results indicated that 6-BA alleviated CI in cucumber fruit through improving antioxidant enzyme activities and total antioxidant capacity and maintaining higher levels of ATP content and energy charge.

Maintaining quality and bioactive compounds of broccoli by combined treatment with 1-methylcyclopropene and 6-benzylaminopurine

BACKGROUND

Broccoli deteriorates very quickly after harvest at ambient temperature due to the loss of green colour and the consequent yellowing of florets. To search for an effective method to control quality deterioration, the effect of 1-methylcyclopropene (1-MCP) combined with 6-benzylaminopurine (6-BA) treatment on visual quality, antioxidant enzymes and bioactive compounds in broccoli florets were investigated.

RESULTS

A combined treatment of 2.5 µL L⁻¹ 1-MCP and 200 mg L⁻¹ 6-BA significantly reduced the increase of lightness (L*) value, and retained a high level for the hue value (H) and chlorophyll content. Superoxide dismutase, ascobate peroxidase and catalase activities increased while the activity of peroxidase decreased during storage in treated samples in comparison with the controls. The combined treatment enhanced the biosynthesis of glucosinolate and the formation of the anticarcinogen sulforaphane, which improved the health benefit of broccoli.

CONCLUSION

These results indicate that a combined treatment of 1-MCP and 6-BA could be a good candidate for maintaining the visual quality and enhancing the nutritional value in broccoli during storage at 15 °C.

Proteome analysis in Arabidopsis reveals shoot- and root-specific targets of cytokinin action and differential regulation of hormonal homeostasis

The plant hormones cytokinins (CKs) regulate multiple developmental and physiological processes in Arabidopsis (Arabidopsis thaliana). Responses to CKs vary in different organs and tissues (e.g. the response to CKs has been shown to be opposite in shoot and root samples). However, the tissue-specific targets of CKs and the mechanisms underlying such specificity remain largely unclear. Here, we show that the Arabidopsis proteome responds with strong tissue and time specificity to the aromatic CK 6-benzylaminopurine (BAP) and that fast posttranscriptional and/or posttranslational regulation of protein abundance is involved in the contrasting shoot and root proteome responses to BAP. We demonstrate that BAP predominantly regulates proteins involved in carbohydrate and energy metabolism in the shoot as well as protein synthesis and destination in the root. Furthermore, we found that BAP treatment affects endogenous hormonal homeostasis, again with strong tissue specificity. In the shoot, BAP up-regulates the abundance of proteins involved in abscisic acid (ABA) biosynthesis and the ABA response, whereas in the root, BAP rapidly and strongly up-regulates the majority of proteins in the ethylene biosynthetic pathway. This was further corroborated by direct measurements of hormone metabolites, showing that BAP increases ABA levels in the shoot and 1-aminocyclopropane-1-carboxylic acid, the rate-limiting precursor of ethylene biosynthesis, in the root. In support of the physiological importance of these findings, we identified the role of proteins mediating BAP-induced ethylene production, METHIONINE SYNTHASE1 and ACC OXIDASE2, in the early root growth response to BAP.

The effect of roots and media constituents on trichomes and artemisinin production in Artemisia annua L

KEY MESSAGE : Rooting of Artemisia annua increases trichome size on leaves and helps drive the final steps of the biosynthesis of the sesquiterpene antimalarial drug, artemisinin. Artemisia annua produces the antimalarial drug, artemisinin (AN), which is synthesized and stored in glandular trichomes (GLTs). In vitro-grown A. annua shoots produce more AN when they form roots. This may be a function not of the roots, but rather media components such as the phytohormones, α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP), or salts and sucrose used to maintain either rooted or unrooted shoot cultures. We investigated how three main media components altered artemisinic metabolite production, pathway gene transcripts, and GLT formation in both mature and developing leaves in rooted and unrooted cultures. Although transcript levels of AN biosynthetic genes were not altered, AN levels were significantly different, and there were major differences in both artemisinic metabolite levels and trichomes in mature versus developing leaves. For example, NAA induced higher AN production in rooted shoots, but only in mature leaves. In developing leaves, BAP increased GLT density on the leaf surface. When both phytohormones were present, GLTs were larger on young developing leaves, but smaller on mature leaves. Furthermore, although other media components increased GLT density, their size decreased on young leaves, but there was no effect on mature leaves. Roots also appeared to drive conversion of artemisinic precursors towards end products. These results suggest that, while the presence of roots affects AN and trichome production, phytohormones and other media constituents used for in vitro culture of A. annua also exert an influence.

In vitro plant propagation of Catharanthus roseus and assessment of genetic fidelity of micropropagated plants by RAPD marker assay

An investigation was carried out to develop an efficient micropropagation protocol for Catharanthus roseus. Experiments were conducted to optimize suitable media for in vitro shoot multiplication and root induction. Out of the different media compared for in vitro shoot multiplication, Murashige and Skoog (MS) medium supplemented with 1 mg/l of 6-benzylaminopurine and 0.2 mg/l α-naphthaleneacetic acid showed better response in terms of the emergence of shoots from axillary buds as well as proliferation and multiplication of shoots. The shoots when placed on half strength of MS medium having 1 mg/l indole 3-butyric acid and 0.25 % charcoal showed cent percent root induction with maximum number of roots per shoot (4.2) as well as maximum root length (1.72 cm). Further, clonal fidelity of the in vitro-raised plants was carried out using randomly amplified polymorphic DNA marker and results indicated that all the tissue culture-derived plants are true-to-type and there were no somaclonal variations among these plants.

High-frequency regeneration via multiple shoot induction of an elite recalcitrant cotton (Gossypium hirsutum L. cv Narashima) by using embryo apex

Cotton (Gossypium hirsutum L.) is one of the most commercially important fiber crops in the world. Compared with other crops, cotton represents a recalcitrant species for regeneration protocols. The development of efficient and rapid regeneration protocol for elite Indian cotton variety could help improve the quality characteristics and biotic or abiotic stress tolerance. Here we report a novel regeneration protocol in Indian cotton cultivar Narashima. The maximum number of multiple shoots obtained was 16 per explants, performance which has never been achieved in any prior reports. The embryo apex explants were isolated from 2 d old in vitro growing seedlings. Explants were cultured on MS medium containing different plant growth regulator combinations in order to induce multiple shoots. Among the tested combinations, the 2 mg/l of 6-benzylaminopurine (BAP) and 2 mg/l kinetin (KIN) proved to be most suited for achieving the maximum number of multiple shoots. The elongation of multiple shoots was obtained in media supplemented with gibberellic acid (GA3). The regenerated plants were successfully hardened in earthen pots after adequate acclimatization. This method avoids callus tissue, the stage of regeneration which may lead to somaclonal variation. The important feature of the presented method is shortening of regeneration time, as well as the induction of a high number of multiple shoots per explants. The present protocol may provide an efficient and rapid regeneration tool for obtaining more stable transformants from embryo apex explants of Indian cotton cultivar Narashima.

[Study on optimization of induction system of test-tube tuberous roots from leaves of Rehmannia glutinosa]

OBJECTIVE

To study the effect of sucrose and plant growth substances of different concentrations on the induction of test-tube tuberous roots of Rehmannia glutinosa, in order to establish an efficient system for the induction of test-tube tuberous roots from leaves of R. glutinosa.

METHOD

Leaves from test-tube seedlings of 85-5 R. glutinosa were used as explants. After rooting induction, they were transferred to medium with orthogonal design for inducing test-tube tuberous roots of R. glutinosa.

RESULT AND CONCLUSION

NAA played a significant role in induction of test-tube tuberous roots of R. glutinosa, followed by sucrose and 6-BA. With leaves from test-tube seedlings as the explants, the optimal medium for inducing test-tube tuberous roots of R. glutinosa was MS + BA 3.0 mg x L(-1) + NAA 0.1 mg x L(-1) + sucrose 7%. The study provides an efficient induction system for studies on artificial seeds and secondary metabolism with test-tube tuberous roots of R. glutinosa.

Direct and indirect method of plant regeneration from root explants of Caesalpinia bonduc (L.) Roxb.--a threatened medicinal plant of Western Ghats

An in vitro regeneration protocol has been standardized via direct and indirect methods from excised root explants of C. bonduc, a threatened woody legume used for the treatment of contagious diseases, inflammation, leprosy, antiperiodic, febrifuge, anthelmenthic, urinary disorders, leucorrhoea, piles and to heal wounds. MS medium supplemented with 17.75 micromol BAP and 2.46 micromol IBA, induced a mean of 3.40 +/- 1.07 shoots directly from the surface of excised root explant. Subsequently, the shoots rooted readily on MS half strength medium with out growth regulators. In indirect organogenesis, callogenic frequency was optimized (96.66%) at the concentration of 9.04 micromol 2, 4-D and 0.88 micromol BAP. An average, 15.30 +/- 5.25 shoots were differentiated from the root callus at the concentration of 17.57 micromol BAP and 2.85 micromol IAA. Shoots regenerated through callus were rooted well on MS half strength medium with growth regulators at 2.95 micromol IBA. Rooted plantlets were transferred to the pots containing sterilized soil and were successfully hardened at greenhouse condition for three weeks then exposed to the natural environment. Survival rate was more (95%) in plantlets derived through direct organogenesis than (60%) the plantlets regenerated through root calli.

Induction of somatic embryogenesis in endangered butterfly ginger Hedychium coronarium J. Koenig

An efficient protocol has been developed for regeneration of complete plants through somatic embryogenesis in H. coronarium. Creamish white, pale yellow and brown calli were obtained on MS medium supplemented with different concentrations of auxins [2, 4-Dichlorophenoxy acetic acid (2, 4-D), Indole-3 acetic acid (IAA) and 1-Naphthylacetic acid (NAA)] after 4 weeks. Creamy white calli developed on 0.5 mg L(-1) 2, 4-D turned embryogenic when subcultured on basal medium and produced small globular somatic embryos after 6 weeks. Further growth of somatic embryos required their transfer to medium containing 6-benzylaminopurine (BAP) or kinetin (KN). BAP was more effective than KN in promoting shoot proliferation. Maximum shoot length was obtained with 0.5 mg L(-1) BAP whereas maximum shoot number was obtained with 1.0 mg L(-1) BAP. The plantlets thus formed were successfully hardened, and transferred to sand-soil and farm yard manure (1:1:1) with 95% survival.

Physiological responses and endogenous cytokinin profiles of tissue-cultured 'Williams' bananas in relation to roscovitine and an inhibitor of cytokinin oxidase/dehydrogenase (INCYDE) treatments

The effect of supplementing either meta-topolin (mT) or N(6)-benzyladenine (BA) requiring cultures with roscovitine (6-benzylamino-2-[1(R)-(hydroxymethyl)propyl]amino-9-isopropylpurine), a cyclin-dependent kinase (CDK) and N-glucosylation inhibitor, and INCYDE (2-chloro-6-(3-methoxyphenyl)aminopurine), an inhibitor of cytokinin (CK) degradation, on the endogenous CK profiles and physiology of banana in vitro was investigated. Growth parameters including multiplication rate and biomass were recorded after 42 days. Endogenous CK levels were quantified using UPLC-MS/MS while the photosynthetic pigment and phenolic contents were evaluated spectrophotometrically. The highest regeneration rate (93 %) was observed in BA + roscovitine while mT + INCYDE plantlets produced most shoots. Treatment with BA + roscovitine had the highest shoot length and biomass. Although not significant, there was a higher proanthocyanidin level in BA + roscovitine treatments compared to the control (BA). The levels of total phenolics and flavonoids were significantly higher in mT + roscovitine treatment than in the mT-treated regenerants. The presence of roscovitine and/or INCYDE had no significant effect on the photosynthetic pigments of the banana plantlets. Forty-seven aromatic and isoprenoid CKs categorized into nine CK-types were detected at varying concentrations. The presence of mT + roscovitine and/or INCYDE increased the levels of O-glucosides while 9-glucosides were higher in the presence of BA. Generally, the underground parts had higher CK levels than the aerial parts; however, the presence of INCYDE increased the level of CK quantified in the aerial parts. From a practical perspective, the use of roscovitine and INCYDE in micropropagation could be crucial in the alleviation of commonly observed in vitro-induced physiological abnormalities.

[Effect on different concentrations of exogenous hormones on baicalin in Scutellaria baicalensis callus]

OBJECTIVE

To determine the content of baicalin in Scutellaria baicalensis callus induced by different doncentrations of exogenous hormones.

METHOD

HPLC system was adopted to determine baicalin in S. baicalensis callus. Chromatographic conditions: ODS column was adopted, with methanol-water-phosphate (47: 53: 0.2) as the mobile phase. The flow velocity was 1 mL x min(-1), the detective wavelength was 280 nm, and the temperature of column was room temperature.

RESULT

S. baicalensis callus induced by 6-BA 1.0 mg x L(-1) + NAA 0.5 mg x L(-1) showed the highest baicalin content, up to 49.78 mg x g(-1).

CONCLUSION

The experiment is such a simple, rapid and stable method for determining the baicalin content that it can be used for determining the baicalin content in S. baicalensis callus.

[Somatic embryogenesis in in vitro culture of three larch species]

Embryogenic callus formation in different larch species from Siberia (Larix sibirica, L. gmelinii, and L. sukaczewii) was carried out on MSGm medium supplemented with growth regulators (2.4-D and BAP) and followed one and the same scheme: elongation of somatic cells and their asymmetric division with formation of initial and tube cells. The cells of embryo initial underwent sequential divisions and formed embryonic globules which caused the formation of somatic embryos. Somatic embryos became mature and germinated by addition of ABA and PEG into the medium. Long-term proliferating cell lines and regenerant plants were obtained in Sukachev larch and its hybrid with Siberian larch. The success of somatic embryogenesis depended on the genotype of the donor tree.

Role of plant growth regulators and a saprobic fungus in enhancement of metal phytoextraction potential and stress alleviation in pearl millet

"Assisted phytoextraction" involving application of chemical additives such as plant growth regulators (PGRs) has become a trend in phytoremediation technology. This study identifies a cost-effective, naturally available crude PGR (PGR1) that produces the same effects as the commercial PGR (PGR2), increasing metal uptake by plants and the reduction of metal stress. Assisted phytoextraction by pearl millet (Pennisetum glaucum) from a multi-metal (Cd, Cr, Cu, Fe, Na and Zn) contaminated soil medium with tannery solid waste (TSW) soil amendments of 5 and 10%, was evaluated in a full-factorial pot trial with PGR1, PGR2 and Trichoderma pseudokoningii as factors. The effects of these phytoextraction assistants were measured through dry biomass production, heavy metal uptake, stress tolerance enzymes catalase (CAT) and superoxide dismutase (SOD), soluble protein content of plant, and phytoextraction efficiency. Dry biomass and multi-metal accumulation were the highest in the soil treatments with a combined application of PGR1, PGR2 and T. pseudokoningii and the lowest in the control. The soluble protein contents and the SOD and CAT values were the highest in the 10% TSW treatment provided with PGR2+T. pseudokoningii, while the lowest were in the control. Thus, application of crude PGR in combination with other phytoextraction assistants can increase biomass production as well as multi-metal accumulation in plants. However, the biochemical properties of the plant depend on the level of TSW stress in the soil treatment as well as the type of phytoextraction assistants.

Role of TDZ in the quick regeneration of multiple shoots from nodal explant of Vitex trifolia L.--an important medicinal plant

The effect of thidiazuron (TDZ) has been investigated in shoot multiplication for a simple, efficient, rapid, and commercially applicable regeneration protocol of an important medicinal plant, Vitex trifolia. Multiple shoots were induced in nodal explants obtained from a mature tree on Murashige and Skoog (MS) medium supplemented with TDZ in various concentrations (0.5, 1.0, 2.5, 5.0, 7.5, or 10.0 μM). Prolonged exposure of the culture to TDZ had an adverse affect. To avoid this, the cultures were transferred to TDZ-free MS medium or MS medium fortified with various concentrations of 6-benzyladenine (BA) alone or in combination with α-naphthalene acetic acid (NAA) to enhance multiplication, proliferation, and elongation of induced shoots. Optimum shoot multiplication and elongation was achieved when TDZ-exposed explants were repeatedly subcultured on MS media containing a combination of 1.0 μM BA and 0.5 μM NAA. The highest shoot regeneration frequency (90 %) and maximum number (22.3 ± 0.2) of shoots per explant with shoot length of (5.2 ± 0.2 cm) was recorded on MS medium fortified with 5.0 μM TDZ. In vitro rooting of isolated shoots was achieved best in half-strength MS medium containing 0.5 μM NAA. Properly rooted plantlets were successfully hardened off and acclimatized in thermocol cups containing sterile Soilrite. These plantlets were then transferred to pots containing different potting substrate; percentage survival of the plantlets was highest in vermiculite/garden soil mixture (1:1) and successfully transfer to greenhouse under sunlight.

In vitro mutagenesis and identification of mutants via ISSR in lily (Lilium longiflorum)

An efficient in vitro mutagenesis protocol for Lilium longiflorum Thunb. cv. White fox has been established. The effect of 6-BA and NAA on adventitious bud formation from the bulblet-scale thin cell layers was tested. Results showed that the optimal medium for adventitious bud induction is MS basal medium supplemented with 2.0 mg/l 6-BA and 0.1 mg/l NAA. The differentiation frequency and the average number of adventitious buds reached 95.55% and 3.00, respectively. Various doses (0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 Gy) of gamma rays were applied to investigate the effect of radiation on adventitious bud formation from bulblet-scale thin cell layers. The forming capacity of the adventitious buds significantly decreased with the increase of radiation dose. The results suggested that the optimal irradiation dose is 1.0 Gy. Dose of 1.0 Gy treatment resulted in 55.33% survival of irradiated bulblet-scale thin cell layers and 39.27% mutagenesis rate. The genetic variations among the morphological mutants were evaluated by DNA fingerprinting using ISSR molecular marker. The genetic variation frequency reached 36.06% using seven ISSR primers. Out of the 50 mutant lines transferred to the greenhouse, 9 were observed to have significantly different morphological characters than those of the controls.

Enhancement of folate content and its stability using food grade elicitors in coriander (Coriandrum sativum L.)

Folate (vitamin B₉) content was evaluated in 10 varieties of coriander with the aim of enhancing its concentration and stability, because of three reasons: 1) coriander is among a few widely used greens in the world and suits many cuisines, 2) folate deficiency is prevalent in developing countries causing anaemia, infant mortality and neural tube closure defects, and 3) natural folate is preferred due to doubts about health risks associated with the synthetic form. In C. sativum, the highest folate content of 1,577 μg/100 g DW was found in var. GS4 Multicut foliage of mature plants (marketable stage) with an insignificantly higher content (1,599.74 μg/100 g DW) at flowering, which is a stage not preferred in markets. In callus cultures treated with plant growth regulators (GRs) (6-benzylaminopurine, kinetin and abscisic acid) substantial increase in folate occurred after 6 h, whereas elicitors (methyl jasmonate and salicylic acid) caused rapid 2-fold increase of folate, particularly in response to salicylic acid. Based on these observations, foliar applications were done for in vivo plants, where salicylic acid (250 μM, 24 h) also enhanced folate level by 2-folds (3,112.33 μg/100 g DW), although the content varied with diurnal rhythms. Stability of folates in treated coriander foliage was 10 % higher than in untreated foliage when stored at 25 °C and 4 °C. This study has established for the first time that coriander foliage is rich in folates, which can be doubled by elicitation and impart 10 % more stability than control during processing and storage.

Roles for a soybean RAV-like orthologue in shoot regeneration and photoperiodicity inferred from transgenic plants

The soybean gene Glyma10g34760 appears to encode a RAV2-like transcription factor orthologue (DQ147914; hereafter GmRAV) based on sequence similarity. The gene is a member of the ERF/AP2 transcription factor family that has been shown to be increased in transcript abundance by cytokinins (CKs). Transgenic GmRAV-overexpressing (-ox) tobacco plants exhibited increased CK signalling-related phenotypes including dwarfism, reduced apical dominance, extreme longevity, vigorous outgrowth of lateral buds, small and dark green leaves, reduced root growth, repressed flowering under both long- and short-day conditions, and altered sensitivity to daylength. In contrast, inhibition (-i) of GmRAV in soybean displayed the opposite phenotypic alterations which were consistent with defects in CK signalling. Phenotypes included earlier time of emergence; reduced numbers of branches, leaves, and flower buds; increased plant height; increased apical dominance; and earlier flowering and maturity. GmRAV-i soybean was less sensitive to cytokinin in hypocotyls and root growth inhibition assays. GmRAV-i soybean showed decreased frequency of adventious shoot formation in tissue culture in the presence of CKs, which might be attributed to the significantly decreased activities of CUC2, STM, and WUS involved in shoot meristem specification. GmRAV protein was localized in the nucleus in leaves. The GmRAV promoter-β-glucuronidase (GUS) fusion was largely expressed in a meristematic region of the shoot apex, which was consistent with expressed sequence tag and microarray data. GmRAV was inferred to play a key role in CK and photoperiod signalling that subsequently regulated plant development.

[Rapid detection of 6-benzylaminopurine residues in sprout beans by surface-enhanced raman spectroscopy]

New method for rapid and quantitative analysis of 6-benzylaminopurine (6-BA) residues in sprout beans was studied by using FAST-SPE and portable surface-enhanced Raman spectroscopy (SERS). With homemade sprout bean samples as blank control, 6-BA solutions extracted from inserted-treatment samples showed typical characteristic Raman peaks at 1002 cm(-1) tested by SERS, and normalized 1002 cm(-1) intensities had a good linear relationship with gradient concentrations of 6-BA insert-standard solutions. The high concentration linear range was 0.5-14 microg x mL(-1), and the low one was 0. 1-2 microg x mL(-1). The quantitative detection limit was down to 0.02 mg x kg(-1) that was below the maximum allowable residues (MAL) of 0. 2 mg kg(-1) in related National Standard. The recoveries were 82.3%-95.1% and the RSD was below 5%. This method with portable equipment and simple pre-treatment showed good reproducibility, short test time-consuming and easy operating, and thus it would provide efficient and sensitive solutions for large-scale on-site and rapid detections.

Effects of different combinations of benzyl adenine and indole acetic acid concentrations on in vitro plant regeneration in hexaploid wheat

Development of a reliable in vitro plant regeneration procedure for hexaploid bread wheat (Triticum aestivum L.) is a prerequisite for its improvement by genetic transformation. Here, we report the effects of two growth regulators, benzyl adenine (BA) and indole acetic acid (IAA) on callus induction and plant regeneration from scutellum cultures of two commercial bread wheat cultivars: Giza 164 and Sakha 69. Callus induction was obtained from isolated embryos cultured on modified Murashige and Skoog (MS) basal medium. After four weeks of callus induction, all calli were plated on MS basal medium for regeneration. Wheat genotype and callus induction medium played a dominant role in plantlet regeneration. 2.0 mg/L BA and 0.2 mg/L IAA were the best combinations for inducing callus and let to highest regeneration frequency (81.67%) across the cultivars. Overall, based on our medium conditions, Giza 164 displayed higher regeneration frequency (81.11%) than Sakha 69. These results will facilitate genetic transformation for the economic varieties Giza 164 and Sakha 69.

6-Benzylaminopurine delays senescence and enhances health-promoting compounds of harvested broccoli

The effect of 6-benzylaminopurine (6-BA) on the color, antioxidant activity, and contents of total phenols, glucosinolate, and sulforaphane in broccoli florets was investigated. The results showed that 6-BA treatment markedly inhibited the increase of the L* value and malondialdehyde (MDA) content and retarded the decrease of the H value. 6-BA treatment reduced the rate of chlorophyll degradation by regulating the activities of chlorophyllase and Mg-dechelatase. When compared to control florets, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) were enhanced in florets treated with 6-BA, whereas the activity of peroxidase (POD) was significantly reduced. The contents of total phenols, glucosinolate, and sulforaphane in broccoli florets were also profoundly increased after treatment with 6-BA. These results indicated that 6-BA could maintain the quality, delay senescence, and improve the nutritional value of broccoli.

Vitrification-based cryopreservation of shoot-tips of Pinus kesiya Royle ex. Gord

The present investigation was aimed at developing a protocol for long-term preservation of germplasm of Pinus kesiya Royle ex. Gord. through vitrification. Some of the critical components affecting explant tolerance to cryopreservation, such as effects of preculture, vitrification solutions, exposure time to vitrification solutions, volume of vitrification solution and its toxicity, washing of vitrified tissues after thawing, were analysed. The results showed that shoot regrowth of P. kesiya shoot-tips was considerably affected when exposed to cryoprotectants for longer periods of time (longer than 10 min). Among different vitrification solutions studied, maximum survival (76 percent) of shoot-tips was achieved with mVSL (using 0.6 ml of the solution) in MS basal medium containing 4.0 mg l-1 N6-benzyladenine (BA).

The pea TCP transcription factor PsBRC1 acts downstream of Strigolactones to control shoot branching

The function of PsBRC1, the pea (Pisum sativum) homolog of the maize (Zea mays) TEOSINTE BRANCHED1 and the Arabidopsis (Arabidopsis thaliana) BRANCHED1 (AtBRC1) genes, was investigated. The pea Psbrc1 mutant displays an increased shoot-branching phenotype, is able to synthesize strigolactone (SL), and does not respond to SL application. The level of pleiotropy of the SL-deficient ramosus1 (rms1) mutant is higher than in the Psbrc1 mutant, rms1 exhibiting a relatively dwarf phenotype and more extensive branching at upper nodes. The PsBRC1 gene is mostly expressed in the axillary bud and is transcriptionally up-regulated by direct application of the synthetic SL GR24 and down-regulated by the cytokinin (CK) 6-benzylaminopurine. The results suggest that PsBRC1 may have a role in integrating SL and CK signals and that SLs act directly within the bud to regulate its outgrowth. However, the Psbrc1 mutant responds to 6-benzylaminopurine application and decapitation by increasing axillary bud length, implicating a PsBRC1-independent component of the CK response in sustained bud growth. In contrast to other SL-related mutants, the Psbrc1 mutation does not cause a decrease in the CK zeatin riboside in the xylem sap or a strong increase in RMS1 transcript levels, suggesting that the RMS2-dependent feedback is not activated in this mutant. Surprisingly, the double rms1 Psbrc1 mutant displays a strong increase in numbers of branches at cotyledonary nodes, whereas branching at upper nodes is not significantly higher than the branching in rms1. This phenotype indicates a localized regulation of branching at these nodes specific to pea.

Correlation of leaf senescence and gene expression/activities of chlorophyll degradation enzymes in harvested Chinese flowering cabbage (Brassica rapa var. parachinensis)

Chinese flowering cabbage is one of the main leafy vegetables produced in China. They have a rapid leaf yellowing due to chlorophyll degradation after harvest that limits their marketing. In the present study, leaf senescence of the cabbages was manipulated by ethylene and 6-benzyl aminopurine (6-BA) treatment to investigate the correlation of leaf senescence and chlorophyll degradation related to gene expression/activities in the darkness. The patterns of several senescence associated markers, including a typical marker, the expression of senescence-associated gene SAG(12), demonstrated that ethylene accelerated leaf senescence of the cabbages, while 6-BA retarded this progress. Similar to the trends of BrSAG(12) gene expression, strong activation in the expression of three chlorophyll degradation related genes, pheophytinase (BrPPH), pheophorbide a oxygenase (BrPAO) and red chlorophyll catabolite reductase (BrRCCR), was detected in ethylene treated and control leaves during the incubation, while no evident increase was recorded in 6-BA treated leaves. The overall dynamics of Mg-dechelatase activities in all treatments displayed increasing trends during the senescence process, and a delayed increase in the activities was observed for 6-BA treated leaves. However, chlorophyllase activity as well as the expression of BrChlase1 and BrChlase2 decreased with the incubation in all treatments. Taken together, the expression of BrPPH, BrPAO and BrRCCR, and the activity of Mg-dechelatase was closely associated with the chlorophyll degradation during the leaf senescence process in harvested Chinese flowering cabbages under dark conditions.