Production of transgenic adult plants from clementine mandarin by enhancing cell competence for transformation and regeneration

Genetic transformation of mature trees is difficult because adult tissues are recalcitrant to Agrobacterium tumefaciens infection and transformation and because transgenic mature events are less competent for regeneration. We have shown that reinvigoration allows manipulation of the vegetative phase to increase the potential for transformation and regeneration without loss of competence for flowering and fruiting. To produce transgenic plants from clementine mandarin (Citrus clementina hort. ex Tanaka), we optimized the conditions of the source material both ex vitro and in vitro. Grafting of mature buds on juvenile rootstocks in the spring and preventing multiple bud sprouting by removing all but one bud permitted selection of vigorous first flushes for in vitro culture. Use of additional virulence genes from A. tumefaciens to increase transformation frequency and optimization of culture media and conditions to enhance explant cell competence for T-DNA integration and organogenesis resulted in efficient and reliable transgenic plant production. Transformed regenerants from explants, cultured in media without antibiotics, were identified by a screenable marker (either beta-glucuronidase or green fluorescent protein (GFP)), creating the possibility of generating transgenic clementine plants without antibiotic resistance marker genes. Stable integration of foreign genes was demonstrated by Southern blot analysis, and expression of these foreign genes was confirmed by detection of GFP fluorescence in leaves, floral organs and fruits of the transgenic plants.     

植物提取物生产过程中废水的治理

概述植物提取物生产过程中废水的来源、特点、分类以及废水治理的方法,并对各种治理方法的优缺点进行论述,对植物提取物加工过程中废水治理的一般流程进行阐述。针对目前植物提取物废水治理的现状,提出由于植物提取行业废水的多样化,应根据其水质的特异性,采用不同的治理方法或是不同治理方法组合的观点。     

Growth response of Pinus pinaster Ait. to climatic variables in central Spanish forests

? The effect of climatic variables (temperature and precipitation) on radial growth of the Mediterranean Maritime pine (Pinus pinaster Ait.) was studied using dendrochronological techniques in the Iberian Peninsula.

? Ten tree-ring width chronologies, along the central distribution area of the species, were built. Chronology variability was analysed using Principal Component Analysis (PCA) for the period 1952–2005.

? The first principal component (PC1) explained 56% of tree-growth variability. Tree-growth association with climate was analysed at regional and local scales using correlation coefficient and bootstrapped response functions.

? Radial growth at both scales was positively correlated with rainfall during and prior to the growing season at all sites, and with summer rainfall before the growing season at five sites. Mean temperature effect changed according to the sampling site, from non-significant at the highest sites to significant (positive relationship in winter) at the lowest sites. Growth season temperature also had a negative effect.

? The Kalman filter was applied to estimate changing association between growth and climate over-time. Results suggested a change in association, initiated in the 80s, from non-significant to significant (*p < 0.05) at six of the sampling sites.

? Pinus pinaster is an accurate species for analysing tree-growth association with climate and for studying plant behaviour under global change conditions.

     

Response of Scots pine (Pinus sylvestris L.) and pubescent oak (Quercus pubescens Willd.) to soil and atmospheric water deficits under Mediterranean mountain climate

The physiological responses to water deficits of Scots pine (Pinus sylvestris L.) and pubescent oak (Quercus pubescens Willd.) were studied under Mediterranean mountain climate. Minimum leaf water potentials were ?3.2 MPa for oak and ?2.1 MPa for pine, with higher predawn values for pubescent oak. Relative sap flow declined in both species when vapour pressure deficit (D) went above ca. 1.2 kPa, but stomatal control was stronger for pine during the 2003 summer drought. P. sylvestris plant hydraulic conductance on a half-total leaf area basis (k _L,s?1) was 1.2–2.6 times higher than the values shown by Q. pubescens, and it showed a considerably steeper decrease during summer. Leaf-level gas exchange was positively related to k _L,s?1 in both species. Scots pine was more vulnerable to xylem embolism and closed stomata to prevent substantial conductivity losses. The results of this study confirm that pubescent oak is more resistant to extreme drought events.     

Thinning intensity and growth response in SW-European Scots pine stands

The effect of different thinning intensities on growth and yield was studied in Pinus sylvestris L. stands at the south-western limit of its distribution area (Central Spain), using five long-term thinning trials. Data were analysed collectively considering several factors (trial, block, plot and period) as random effects. Total volume and volume increment decreased with thinning intensity, this loss being more significant in the case of moderate and heavy thinning. No difference was found among treatments for total basal area or the increment in basal area. The results revealed an optimum basal area (Assmann’s definition) between 85 and 100% of the basal area in unthinned plots. Volume growth loss associated with heavy thinnings (reduction of 18% in volume increment) was smaller than that reported in Central and Northern European regions (greater than 25%). Height increment was not influenced by thinning, whereas dominant and quadratic mean diameter increments increased with the thinning intensity. The response of diameter growth to thinning was greater at younger ages (less than 50 y) and in medium-sized trees.     

On the independence between clupeid stocks and their recruitment

The statistical independence between the reproductive stock and its corresponding recruitment to a fishery was tested for 43 stocks of clupeids in the Ransom Myers database by using the chi-squared test of a contingency table. The method was validated by simulating stock and recruitment (SR) contingency tables for data close to hypothetical SR curves that represent several known phenomena. The clupeid SR data were grouped by the criteria of percentile points to build the contingency tables. The independence test of the clupeid stocks was rejected in only 15 cases, thus the independence hypothesis was sustained in the remaining 28 cases. This demonstrates that fitting an SR model in these clupeid stocks is not justified because their abundance could be affected by several causes other than reproductive stock fluctuations.

     

Simultaneous detection of six RNA plant viruses affecting tomato crops using a single digoxigenin-labelled polyprobe

A polyprobe for the simultaneous detection by non-isotopic molecular hybridisation has been developed to detect any of the following six viruses causing important economic losses in tomato crops: Tomato spotted wilt virus, Tomato mosaic virus, Pepino mosaic virus, Cucumber mosaic virus, Potato Y virus and Parietaria mottle virus. The polyprobe detected all six viruses with similar sensitivity to that obtained using individual riboprobes. In addition, we evaluated the possible use of the tissue-printing as a sample preparation technique applied to routine diagnosis of tomato plants with the polyprobe. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Differential effects of phytotoxic metabolites from <Emphasis Type="Italic">Alternaria tagetica</Emphasis> on <Emphasis Type="Italic">Tagetes erecta</Emphasis> cell cultures

Alternaria tagetica, a fungus that causes early blight in marigold (Tagetes erecta), produces two groups of phytotoxic metabolites: one hydrophilic and the other lipophilic that show phytotoxic activity when tested by the leaf-spot assay in T. erecta. We evaluated the cellular effects of the phytotoxic culture filtrate of A. tagetica and the hydrophilic and lipophilic fractions, then determined whether the filtrate or the fractions differentially induced pathogenesis-related mechanisms in the plant. The culture filtrate and the phytotoxic fractions had adverse effects on cell viability, fresh mass, and the number of cells, and induced ROS accumulation, lipid peroxidation and DNA damage on T. erecta cell suspension cultures, and these effects are related to pathogenic mechanisms attributed to phytotoxins. However, although exposure of marigold cells to the phytotoxic culture filtrate of A. tagetica triggered programmed cell death, the hydrophilic and the lipophilic phytotoxic fractions induced death that was more related to a toxic effect leading to necrosis. This study presents a complementary perspective in the search for the roles of metabolites, including phytotoxins, produced by phytopathogenic fungi during plant infection.     

Multivariate analysis of toxicological and environmental properties of soil nematicides

BACKGROUND: In intensive agriculture, the use of pesticides and soil fumigants is necessary to produce economically viable crops worldwide. However, this practice may involve undesirable effects on human health and the environment. In 1995, methyl bromide was restricted by the Montreal Protocol because of possible ozone depletion. The objective of this study was to compare intrinsic environmental and toxicological properties of 11 active substances with nematicidal properties, some of them recognized as methyl bromide alternatives. RESULTS: Four groups of active substances were discriminated by a series of principal component analyses (PCAs): (a) high toxicity to non-target fauna, humans and animals and medium persistence in the environment (cadusafos, ethoprophos and fenamiphos); (b) high toxicity to humans, animals and non-target fauna and high persistence (carbofuran and fosthiazate); (c) low toxicity to non-target fauna, humans and animals and low persistence (carbosulfan, benfuracarb and oxamyl); (d) low toxicity to humans, animals and non-target fauna and medium persistence in the environment (1,3-dichloropropene, chloropicrin and methyl bromide). CONCLUSION: Evaluating the multiple aspects of toxicological and environmental properties of active substances through PCA is proposed as a helpful tool for initially comparing the complex toxicological behaviour of active substances as plant protection products.     

Formulation affecting alachlor efficacy and persistence in sandy soils

BACKGROUND: The development of controlled‐release formulations of alachlor to extend the period of weed control was studied. This extended duration reduces the need for high herbicide application rates that could lead to environmental contamination. For this purpose, the influence of formulation, as well as the influence of soil characteristics, on alachlor efficacy and persistence in soil of a commercial formulation (CF) and different ethylcellulose microencapsulated formulations (MEFs) was evaluated. RESULTS: Higher alachlor rates yielded an enhanced initial herbicidal activity. The prolonged release of alachlor provided by the MEFs resulted in a higher herbicidal efficacy and a longer period of weed control compared with the effects of CF in the two soils tested (at 40 days after treatment, oat growth inhibition for CF and MEFs was 1.96% and 93.5% respectively). Soil characteristics strongly influenced alachlor efficacy and weed control by MEFs. The highest alachlor efficacy and persistence were observed in the soil with lowest microbial activity and clay and organic matter content. CONCLUSIONS: The use of MEFs can be advantageous because they permit the maintenance of the desired concentration of the herbicide in the soil for longer periods of weed control. Copyright © 2009 Society of Chemical Industry