Blue-native PAGE in plants: a tool in analysis of protein-protein interactions

Plant Methods is a new journal for plant biologists, specialising in the rapid publication of peer-reviewed articles with a focus on technological innovation in the plant sciences. The aim of Plant Methods is to stimulate the development and adoption of new and improved techniques and research tools in plant biology. We hope to promote more consistent standards in the plant sciences, and make readily accessible laboratory and computer-based research tools available to the whole community. This will be achieved by publishing Research articles, Methodology papers and Reviews using the BioMed Central Open Access publishing model. The journal is supported by a prestigious editorial board, whose members all recognise the importance of technological innovation as a driver for basic science.     

The effect of combined Azospirillum inoculation and nitrogen fertilizer on plant growth promotion and yield response of the blanket flower Gaillardia pulchella

The investigation was carried out to examine the performance of Azospirillum isolates on growth and N uptake of Gaillardia pulchella with two nitrogen levels. Azospirillum strain OAD-2 inoculation significantly increased plant height, number of leaves per plant, branches per plant and total dry mass accumulation in G. pulchella than other inoculations and/or uninoculated control. The application of 150 kg N ha⁻¹ further enhanced the above plant growth parameters significantly over application of 112 kg N ha⁻¹. The N uptake of G. pulchella was enhanced due to Azospirillum strain OAD-2 inoculation, which was further augmented in the presence of nitrogen. The combination of Azospirillum strain OAD-2 and 150 kg N ha⁻¹ showed the highest N uptake at 120 DAT. Plant growth and yield parameters also increased when inoculated with the non-diazotrophic, but efficient IAA producing, Azospirillum strain OAD-57. From this investigation, it can be concluded that Azospirillum strains OAD-2 and OAD-11 can play an important role in the N nutrition of G. pulchella.     

Development of expression vectors based on pepino mosaic virus

Background  

Plant viruses are useful expression vectors because they can mount systemic infections allowing large amounts of recombinant protein to be produced rapidly in differentiated plant tissues. Pepino mosaic virus (PepMV) (genus Potexvirus, family Flexiviridae), a widespread plant virus, is a promising candidate expression vector for plants because of its high level of accumulation in its hosts and the absence of severe infection symptoms. We report here the construction of a stable and efficient expression vector for plants based on PepMV.     

Evaluation of four methods for estimating leaf area of isolated trees

The accurate modeling of the physiological and functional processes of urban forests requires information on the leaf area of urban tree species. Several non-destructive, indirect leaf area sampling methods have shown good performance for homogenous canopies. These methods have not been evaluated for use in urban settings where trees are typically isolated and measurement may be complicated by proximity to residential areas, buildings, signs, and other infrastructure elements. We evaluated the accuracy, precision, efficiency and other practical considerations associated with four methods of estimating the leaf area of open-grown deciduous trees in urban forests. The methods included color digital image processing (CD), the LAI-2000 Plant Canopy Analyzer, the CI-100 Digital Plant Canopy Imager, and a logarithmic regression equation. Regression coefficients, adjusted R², and confidence intervals were used to determine the best method when using true leaf area of 25 Platanus x acerifolia Willd. and 25 Platanus racemosa Nutt. as an independent variable. Practical considerations included ease of data collection and processing and costs associated with each method. The CD method and LAI-2000 estimates showed good correlation with true leaf area (R² 0.71); however, only the CD method produced estimates within 25 percent of mean true leaf area and met additional requirements for accuracy, precision, and efficient use in urban settings.     

Yield formation in Brussels sprouts

Summary

The effects of three planting dates and three plant densities, covering most of the planting dates and densities used in the Netherlands, on yield determining factors of Brussels sprouts (Brassica olerácea var. gemmifera), were studied in field experiments during three seasons. Planting dates were between the end of April and early July. Plant density ranged between 2.7 and 4.4 plants per m². Planting late in the season initially resulted in more leaves being formed, a higher Leaf Area Index and a longer stem. During crop growth this trend was reversed to a lower number of leaves formed, and in two of the three years a lower LAI and stem length when planting was delayed. The effect of plant density on these characteristics was generally either less pronounced than that of planting date or was absent. There was no, or only limited, interaction between the effects of planting date and plant density on these characteristics. The initial rate of dry-matter accumulation after planting was higher after planting late in the season, but the final amount of standing dry matter was reduced by the late planting. Plant density did not influence the final amount of standing dry matter. There was no interaction between the effects of planting date and plant density on dry-matter accumulation. Planting date and plant density hardly influenced the radiation use efficiency. Overall radiation use efficiency was 2.2 g MJ^–1. The time of bud initiation expressed as numbers of days after planting was advanced by delayed planting, but was not influenced by plant density. Planting late in the season decreased the number of buds per plant and in one of the three years also reduced the weight per bud. A decrease in the number of buds per plant due to increased plant density was more than compensated for by the increase in number of plants per hectare. The final number of buds as a percentage of the final number of leaves, was either not, or not consistently, influenced by treatment. Bud dry-matter concentration at final harvest decreased when planting was delayed, but was not influenced by plant density. There was no interaction between the effects of planting date and plant density on bud dry-matter concentration. The dry-matter harvest index of 30–45% was not greatly affected by treatments. To aim for high yields, planting should be as early as field conditions allow.     

Influence of temperature on selenium and sulphur accumulation in Brassica oleracea L.

Summary

Selenium (Se) and sulphur (S) accumulation are affected by many factors in plants. To understand how growing temperature affected Se and S uptake and accumulation in Brassica oleracea, plants were grown at three different temperatures: 10°, 20° and 30°C. Plant growth, as reflected in fresh weight (FW) and dry weight (DW), increased with increasing temperature. Se and S accumulation were temperature-dependent and tissue-specific. Se levels increased linearly with increasing temperature in the leaves, and varied from 1.73 – 2.54 mg Se g^–1 DW. Conversely, Se accumulation decreased linearly with increasing temperature in the roots, and varied from 2.17 – 2.87 mg Se g^–1 DW. Growing temperature significantly affected S accumulation in leaves, but not in shoots or in roots. Sulphur levels ranged from 20.83 – 30.98 mg g^–1 DW in leaves, and increased with higher temperatures. Sulphate accumulation was similar to S, except that accumulation decreased at the highest growing temperature. Vegetables that accumulate S can be an efficient means and an effective alternative to deliver Se in human diets. To ensure that optimal levels of Se are attained in plants, without negative effects on plant productivity, factors that affect uptake and accumulation, such as growing temperature, need to be better understood.     

The effect of planting date and plant density on nitrogen uptake and nitrogen harvest by Brussels sprouts

Summary

Single and combined effects of three planting dates and three plant densities on nitrogen uptake and nitrogen harvest by Brussels sprouts (Brassica olerácea var. gemmifera) were studied in field experiments. The total amount of nitrogen taken up by the crop at harvest ranged between 220 and 325 kg ha^–1. Although final crop dry matter decreased, total nitrogen uptake was not lower when planting was delayed. This resulted in increased nitrogen concentrations both in the total crop and in the harvested product. Forty to fifty per cent of the nitrogen taken up by the harvest was removed from the field with the product. Within the range of 2.7 to 4.4 plants per m², plant density had no effect on final nitrogen uptake nor on the amount of nitrogen harvested with the product. The results indicate that nitrogen fertilizer recommendations should take planting date into account, because with delayed planting less dry matter will be accumulated with a corresponding lower nitrogen requirement. There was no interaction of effects of planting date and plant density on nitrogen uptake.     

Comparative salt responses at cell and whole-plant levels of cultivated and wild tomato species and their hybrid

SUMMARY

Response to increased salinity was compared in whole plants and calli from leaf, stem and root of Lycopersicon esculentum Mill. cv. P-73, Lycopersicon pennellii (Correll) D'Arcy ac PE-47 and their interspecific hybrid. Three NaCl treatments were applied (0, 70 and 140 raM) for 28 d. In both calli and whole plants, L. pennellii was more salt-tolerant than the cultivated species and the hybrid according to the growth responses, although different degrees of salt tolerance were generally found between plants and calli. The Na⁺ and CI" accumulations with salinity were higher in L. pennellii than in L. esculentum at both levels oforganization. The interspecific hybrid showed an accumulation ability for Na⁺ and CI^" intermediate to its parents in the shoot of the whole plants and similar to L. pennellii in the callus tissues. Either no decrease or a small decrease of K⁺ concentrations with salinity were found in both whole plants and callus tissues of L. esculentum. However, K⁺ concentrations decreased in the organs and calli of L. pennellii and the hybrid with increasing salinity. Only at the whole plant level did L. pennellii have a Na7K⁺ ratio higher than L. esculentum, showing the hybrid to have values between those of its parents in the shoot.     

Protocol: Precision engineering of plant gene loci by homologous recombination cloning in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Plant genome sequence data now provide opportunities to conduct molecular genetic studies at the level of the whole gene locus and above. Such studies will be greatly facilitated by adopting and developing further the new generation of genetic engineering tools, based on homologous recombination cloning in Escherichia coli, which are free from the constraints imposed by the availability of suitably positioned restriction sites. Here we describe the basis for homologous recombination cloning in E. coli, the available tools and resources, together with a protocol for long range cloning and manipulation of an Arabidopsis thaliana gene locus, to create constructs co-ordinately driven by locus-specific regulatory elements.     

Effects of culture conditions on in vitro bulblet induction in the medicinal plant Amana edulis (Miq.) Honda

Amana edulis (Miq.) Honda is an important medicinal plant with a variety of anti-cancer properties, and it is of great importance to improve its reproductive rate through micropropagation technology to meet increasing demand. In the present study, in order to establish a rapid in vitro bulblet propagation protocol for A. edulis, an L₁₆ (4⁵) orthogonal design was used to investigate the effects of sucrose, 6-benzyladenine (6-BA), α-naphthaleneacetic acid (NAA), and macro-elements on bulblet induction. The results show that the sucrose concentration was the crucial factor for A. edulis bulblet initiation, followed by 6-BA and macro-elements, while NAA had the weakest effect. The optimal medium for in vitro bulblet induction was Murashige and Skoog medium supplemented with 0.1 mg·L^?1 6-BA, 0.01 mg·L^?1 NAA, and 100 g·L^?1 or 80 g·L^?1 sucrose (pH 5.8), in which A. edulis shoot clusters (without roots) were cultured at 5(±2)°C for 35 d or 60 d and then incubated at 23(±2)°C for 90 d. The entire cultivation process occurred in the dark. The present study demonstrates that this protocol can be used for the propagation of A. edulis.     

Improved seed development and germination of stenospermic grapes by plant growth regulators

Plant growth regulators were applied to the foliage and immature fruit clusters of the stenospermic grape selection ‘C35-33’ at various periods before bloom to stimulate viable seed development. In the 1987 season five different plant growth regulators were used, but in 1988 the growth retardants Cycocel and XE-1019 were used exclusively. Chemical treatments applied 35 days after bud break increased significantly germination percentage. Experimental results indicate that the use of certain plant growth regulators may aid in increasing the efficiency of seedless grape breeding by providing an alternative to in-ovulo embryo culture.     

The modifiable areal unit problem of spatial heterogeneity of plant community in the transitional zone between oasis and desert using semivariance analysis

The modifiable areal unit problem has significant implications for ecological research that involve investigating and analyzing the spatial heterogeneity of plant community. In this paper, semivariance analysis was used to evaluate the spatial characteristics of plant community in the␣transitional zone between oasis and desert. The spatial structures of the plant community were characterized using exponent model variogram parameters, including nugget (C ₀) range (A ₀) and sill (C ₀+C). Two methods were employed to determine the scale effect of spatial heterogeneity. (1) A constant grain size (10×10 m²) and variational plot areas have been used to analyze spatial heterogeneity of the plant community. (2) The grain size was only changed to analyze spatial heterogeneity. In addition, the plot of 500×500 m² was clustered into nested units of different shapes and different directions to analyze zoning effect. Finally, using semivariance analysis, we obtained a suitable plot area and zoning approach to weaken the scale and zoning effects. The results showed that the effects of scale on different variogram parameters had significant difference. For example, C ₀ and C ₀+C were very sensitive at small scales, A ₀ was influenced significantly by plot area at larger scales, and C ₀ and A ₀ were relatively sensitive to different zoning approaches. In order to get more representative characteristic of spatial heterogeneity of the plant community, the sampling area should be more than 200×200 m² for Nitraria sphaerocarpa populations, 100×100 m² for Reaumuria soongorica populations, and a grain size from 20×20 m² to 30×30 m² for both populations.     

Establishment of in vitro tissue cultures from Echinacea angustifolia D.C. adult plants for the production of phytochemical compounds

The establishment of in vitro cultures of Echinacea angustifolia D.C. was obtained directly from sections of flower stalks of adult plants. The shoot formation was obtained from this plant material placed on a modified MS basal medium named CH supplemented with 0.5 mg L⁻¹ 6-benzylaminopurine (BA). The in vitro propagation procedure of E. angustifolia consisted of three distinct phases: an initial regeneration phase from stalk sections (IP shoots on basal medium with 0.25 mg L⁻¹ BA), an elongation phase on active charcoal and an axillary proliferation of the shoots (AP shoots on basal medium with 0.5 mg L⁻¹ BA).Regenerating calli were established from leaves of in vitro shoots cultured on CH medium supplemented with 3 mg L⁻¹ BA and 0.5 mg L⁻¹ indole-3-butyric acid (IBA). Developed shoots from the callus cultures were subcultured on the CH medium with 0.5 mg L⁻¹ BA (leaf regenerated shoots: LR shoots). The secondary metabolite content of the in vitro plant material was compared with that of the greenhouse growing plants. The quali-quantitative LC-DAD-ESI-MS analysis on the extracts from axillary proliferation shoots (AP shoots) showed significant production of caffeic acid derivatives while leaf callus and LR shoots, accumulated mainly alkamides. These results showed that the proper choice of the procedures for in vitro multiplication allowed us to obtain plant biomass able to produce the active compounds typical of E. angustifolia plants.     

Green roofs sown with an annual plant mix attain high cover and functional diversity regardless of irrigation frequency

Annual plant species have great potential on green roofs as many are highly attractive, fast and cheap to establish via sowing and can provide rapid cover and growth, which is important for ecosystem service provision. While irrigation is essential for survival and growth of annual plants in seasonally hot or dry climates, it is also important to minimize water use as availability is often limited. Therefore, we evaluated how irrigation frequency affects plant cover, species abundance, richness and diversity, plant traits and functional diversity of a 16 species mixture of Australian annual species (4 g m⁻² ~ 2100 seeds m⁻²) sown onto thirty 0.25 m² green roof modules. The experiment was carried out in Melbourne, Australia, from January (summer) to July (winter) 2020. After a 2-month irrigated establishment phase (to ensure germination and seedling establishment), three irrigation treatments (2, 4 and 6 days between irrigation) were applied to the modules for three months. Plant cover was reduced at lower irrigation frequency (6 days), but ≥ 80% plant cover was achieved in all irrigation treatments. There was no effect of irrigation frequency on species abundance and richness; however, abundance, richness and diversity reduced over time, likely due to competition effects. Plant height and leaf area were also reduced by lower irrigation frequency. At the community level, functional diversity was unaffected by irrigation frequency. Our results indicate that green roofs sown with a mixture of annual plants can achieve good plant coverage, as recommended by green roof guidelines, and maintain high diversity when minimally irrigated in their first growing season.     

High-throughput <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated barley transformation

Background  

Plant transformation is an invaluable tool for basic plant research, as well as a useful technique for the direct improvement of commercial crops. Barley (Hordeum vulgare) is the fourth most abundant cereal crop in the world. It also provides a useful model for the study of wheat, which has a larger and more complex genome. Most existing barley transformation methodologies are either complex or have low (<10%) transformation efficiencies.     

Plant density studies with direct seeded tomatoes in Ontario, Canada

In direct seeded tomato density experiments with constant rectangularity of 1.0 carried out at Preston and Simcoe Research Stations, Ontario, Canada in 1971, the effect of increasing plant density from 4.2 to 62.1 plants/m² was to increase total plant weight, total fruit weight and ripe fruit weight per unit area. The proportion of ripe fruit to total fruit increased with increased density, and ripe fruit yields from a single harvest of up to 14 kg/m² were obtained.Using the reciprocal yield-density equation (when W is the mean weight per plant (or plant part) at density , A and B are constants, and density is the only variable) to analyse the experiments, showed that both the A and B constants were influenced by cultivar while the A constant was influenced more by fertilizer application than was the B constant. In general the effect of increased fertilizer was to increase the yield potential ( ) for total plant weight and total fruit weight, but this effect was not so marked for ripe fruit weight.     

Patterns of 14C-sucrose translocation in egg plant (Solanum melongena L.)

Summary

Patterns of distribution of ¹⁴C-sucrose were determined in egg plant (Solanum melongena L.) cv. Arka Shirish at the vegetative, flowering and fruit development stages. 5 μCi of ¹⁴C-sucrose was fed to the fifth leaf from the top at each growth stage and the plants were harvested, 48 h after feeding or at later stages, and the distribution of ^l4C-sucrose determined. Results indicated bidirectional transport of assimilates to both apical and basal portions of the stem. Within 48 h ¹⁴C moved to all the plant parts; roots, stem and leaves appeared to be strong sinks until the fruit began to develop. In plants fed at the fruit development stage, the fruit below the fed leaf were a major sink, although considerable activity was traced in other plant parts also. Only at later stages of crop growth did the fruit become a strong sink. Even at the fruit development stage, about 5-8% of the activity was still found in the roots and no retranslocation to fruit was observed.     

Morphology,yield and quality of ashwagandha (Withania somnifera L. Dunal) roots and its cultivation economics as influenced by tillage depth and plant population density

Summary

Ashwagandha (Withania somnifera L. Dunal; Solanaceae) is being cultivated around the world mainly for its root which has rejuvenative properties. Field experiments during 1999–2001 under semi-arid tropical conditions of Hyderabad, India studied the effect of tillage depths (15 and 30 cm) and plant population densities (20, 40, 60 and 80 plants m^–2) on root morphology, yield and quality and cultivation economics of ashwagandha. Preparatory tillage to 30 cm depth in combination with a density of 60 plants m^–2 gave the highest root yield of 1.2 t ha^–1 which was 50% higher than that following 15 cm tillage depth and the same density. This is attributed to the favourable effect of the former treatment leading to 33, 37 and 21% increases in plant height, number of branches per plant and shoot biomass yield, respectively. Further, this treatment produced most (68%) best quality root pieces. Main root length, length of lateral roots and diameter of lateral roots were significantly increased, while the diameter of main root and the number of laterals decreased. Furthermore, increase in plant density from 20–80 plants m^–2 increased production of best quality roots from 42% to 59% under shallow tillage and from 53% to 71% of root yield under deep tillage. The implications of change in root morphology are discussed in the light of production of different grades of roots, their market preferences and economics. Deep tillage was equally advantageous for seed production, but plant population density for maximum seed yield (211 kg ha^–1) was lower at 40 than at 60 plants m^–2 for maximum root yield. Maximum gross and net returns and benefit-cost ratio occurred following the highest root yield.