Journal of Plant Physiology 2010 (doi:10.1016/j.jplph.2009.11.001)

Stress-induced co-expression of two alternative oxidase (VuAox1 and 2b) genes in Vigna unguiculata.

Costa JH, Mota EF, Cambursano MV, Lauxmann MA, de Oliveira LM, Silva Lima Mda G, Orellano EG, Fernandes de Melo D

Abstract

Cowpea (Vigna unguiculata) alternative oxidase is encoded by a small multigene family (Aox1, 2a and 2b) that is orthologous to the soybean Aox family. Like most of the identified Aox genes in plants, VuAox1 and VuAox2 consist of 4 exons interrupted by 3 introns. Alignment of the orthologous Aox genes revealed high identity of exons and intron variability, which is more prevalent in Aox1. In order to determine Aox gene expression in V. unguiculata, a steady-state analysis of transcripts involved in seed development (flowers, pods and dry seeds) and germination (soaked seeds) was performed and systemic co-expression of VuAox1 and VuAox2b was observed during germination. The analysis of Aox transcripts in leaves from seedlings under different stress conditions (cold, PEG, salicylate and H2O2 revealed stress-induced co-expression of both VuAox genes. Transcripts of VuAox2a and 2b were detected in all control seedlings, which was not the case for VuAox1 mRNA. Estimation of the primary transcript lengths of V. unguiculata and soybean Aox genes showed an intron length reduction for VuAox1 and 2b, suggesting that the two genes have converged in transcribed sequence length. Indeed, a bioinformatics analysis of VuAox1 and 2b promoters revealed a conserved region related to a cis-element that is responsive to oxidative stress. Taken together, the data provide evidence for co-expression of Aox1 and Aox2b in response to stress and also during the early phase of seed germination. The dual nature of VuAox2b expression (constitutive and induced) suggests that the constitutive Aox2b gene of V. unguiculata has acquired inducible regulatory elements.
Copyright 2009 Elsevier GmbH. All rights reserved.

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BMC Genomics 2010 (http://www.biomedcentral.com/1471-2164/11/462)

Transcriptome analysis of the oil-rich seed of the bioenergy crop Jatropha curcas L

Gustavo GL Costa, Kiara C Cardoso, Luiz EV Del Bem, Aline C Lima, Muciana AS Cunha Luciana de Campos-Leite, Renato Vicentini, Fábio Papes, Raquel C Moreira, José A Yunes, Francisco AP Campos and Márcio J Da Silva

Background
To date, oil-rich plants are the main source of biodiesel products. Because concerns have been voiced about the impact of oil-crop cultivation on the price of food commodities, the interest in oil plants not used for food production and amenable to cultivation on non-agricultural land has soared. As a non-food, drought-resistant and oil-rich crop, Jatropha curcas L. fulfils many of the requirements for biofuel production.
Results
We have generated 13,249 expressed sequence tags (ESTs) from developing and germinating Jatropha seeds. This strategy allowed us to detect most known genes related to lipid synthesis and degradation. We have also identified ESTs coding for proteins that may be involved in the toxicity of Jatropha seeds. Another unexpected finding is the high number of ESTs containing transposable element-related sequences in the developing seed library (800) when contrasted with those found in the germinating seed library (80).
Conclusions
The sequences generated in this work represent a considerable increase in the number of sequences deposited in public databases. These results can be used to produce genetically improved varieties of Jatropha with increased oil yields, different oil compositions and better agronomic characteristics.

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Journal of Ethnopharmacology 2010 (doi: 10.1016/j.jep.2010.03.038)

Proteins from latex of Calotropis procera prevent septic shock due to lethal infection by Salmonella enterica serovar Typhimurium

José V. Lima-Filho, Joyce M. Patriota, Ayrles F.B. Silva, Nicodemos T. Filho, Raquel S.B. Oliveira, Nylane M.N. Alencar, Márcio V. Ramos

Aim of the study: The latex of Calotropis procera has been used in traditional medicine to treat different inflammatory diseases. The anti-inflammatory activity of latex proteins (LP) has been well documented using different inflammatory models. In this work the anti-inflammatory protein fraction was evaluated in a true inflammatory process by inducing a lethal experimental infection in the murine model caused by Salmonella enterica Subsp. enterica serovar Typhimurium.

Materials and methods: Experimental Swiss mice were given 0.2 ml of LP (30 or 60 mg/kg) by the intraperitoneal route 24 h before or after lethal challenge (0.2 ml) containing 106 CFU/ml of Salmonella Typhimurium using the same route of administration.

Results: All the control animals succumbed to infection within 6 days. When given before bacterial inoculums LP prevented the death of mice, which remained in observation until day 28. Even, LP-treated animals exhibited only discrete signs of infection which disappeared latter. LP fraction was also protective when given orally or by subcutaneous route. Histopathological examination revealed that necrosisand inflammatory infiltrates were similar in both the experimental and control groups on days 1 and 5after infection. LP activity did not clear Salmonella Typhimurium, which was still present in the spleen at approximately 104 cells/g of organ 28 days after challenge. However, no bacteria were detected in the liver at this stage. LP did not inhibit bacterial growth in culture medium at all. In the early stages of infection bacteria population was similar in organs and in the peritoneal fluid but drastically reduced in blood. Titration of TNF-_ in serum revealed no differences between experimental and control groups on days 1and 5 days after infection while IL-12 was only discretely diminished in serum of experimental animals on day 5. Moreover, cultured macrophages treated with LP and stimulated by LPS released significantlyless IL-1_.

Conclusions: LP-treated mice did not succumb to septic shock when submitted to a lethal infection. LP did not exhibit in vitro bactericidal activity. It is thought that protection of LP-treated mice against Salmonella Typhimurium possibly involves down-regulation of pro-inflammatory cytokines (other than TNF-_). LP inhibited IL-1_ release in cultured macrophages and discretely reduced IL-12 in serum of animals given LP. Results reported here support the folk use of latex to treat skin infections by topic application.

© 2010 Elsevier Ireland Ltd. All rights reserved.

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Protein fractions, amino acid composition and antinutritional constituents of high-yielding cowpea cultivars

Abstract

High-yielding cowpea (Vigna unguiculata) cultivars were analysed for major changes in seed protein types, amino acid profiles and antinutritional factors content. As usual, the globulins constitute the major seed proteins (493.2–573.3 g kg−1 total seed protein), followed by albumins (201.0–248.0 g kg−1), basic glutelins (119.1–154.3 g kg−1), acid glutelins (82.4–92.3 g kg−1) and prolamins (13.2–20.2 g kg−1). The electrophoretic patterns of seeds and protein fractions for all cowpea cultivars resembled to each other both qualitatively and quantitatively. However, they showed slight differences in the amino acid composition with common prevalence of glutamine/glutamic acid, asparagine/aspartic acid and phenylalanine + tyrosine. The methionine + cysteine contents were low for all cultivars and their protein fractions. Trypsin inhibitory activity varied among the cultivars and was much higher in the albumins (198.67–393.43 g kg−1 protein). Haemagglutinating activity was also higher in the albumin fraction and varied from 30,900 to 444,400 HU kg−1 flour. In conclusion, all cultivars showed the usual compositional characteristics of V. unguiculata, but the content of antinutritional factors differed among the cultivars although they remained concentrated in albumin and globulin fractions.
Copyright © 2009 Elsevier Inc. All rights reserved

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The role of organic and inorganic solutes in the osmotic adjustment of drought-stressed Jatropha curcas plants

Evandro Nascimento Silva, Sérgio Luiz Ferreira-Silva, Ricardo Almeida Viégas and Joaquim Albenísio Gomes Silveira

Abstract

This study aimed to assess the accumulation of organic and inorganic solutes and their relative contribution to osmotic adjustment in roots and leaves of Jatropha curcas subjected to different water deficit intensity. Plants were grown in vermiculite 50% (control), 40%, 30%, 20% and 10% expressed in gravimetric water content. The water potential, osmotic potential and turgor potential of leaves decreased progressively in parallel to CO2 photosynthetic assimilation, transpiration and stomatal conductance, as the water deficit increased. However, the relative water content, succulence and water content in the leaves did not show differences between the control and stressed plants, indicating osmotic adjustment associated with an efficient mechanisms to prevent water loss by transpiration through stomatal closure. The K+ ions had greater quantitative participation in the osmotic adjustment in both leaves and roots followed by Na+ and Cl−, while the NO3− ion only showed minor involvement. Of the organic solutes studied, the total soluble sugars showed the highest relative contribution to the osmotic adjustment in both organs and its concentration positively increased with more severe water deficit. The free amino acids and glycinebetaine also effectively contributed to the osmotic potential reduction of both the root and leaves. The role of proline was quantitatively insignificant in terms of osmotic adjustment, in both the control and stressed roots and leaves. Our data reveal that roots and leaves of J. curcas young plants display osmotic adjustment in response to drought stress linked with mechanisms to prevent water loss by transpiration by means of the participation of inorganic and organic solutes and stomatal closure. Of all the solutes studied, soluble sugars uniquely display a prominent drought-induced synthesis and/or accumulation in both roots and leaves.
Copyright © 2010 Elsevier B.V. All rights reserved.

Salt Tolerance is Associated with Differences in Ion Accumulation, Biomass Allocation and Photosynthesis in Cowpea Cultivars

S. C. Praxedes, C. F. De Lacerda, F. M. DaMatta, J. T. Prisco, E. Gomes-Filho

Abstract

Cowpea is widely cultivated in arid and semi-arid regions of the world where salinity is a major environmental stress that limits crop productivity. The effects of moderate salinity on growth and photosynthesis were examined during the vegetative phase of two cowpea cultivars previously classified as salt-tolerant (Pitiúba) and salt-sensitive (TVu). Two salt treatments (0 and 75 mm NaCl) were applied to 10-day-old plants grown in nutrient solution for 24 days. Salt stress caused decreases (59 % in Pitiúba and 72 % in TVu) in biomass accumulation at the end of the experiment. Photosynthetic rates per unit leaf mass, but not per unit leaf area, were remarkably impaired, particularly in TVu. This response was unlikely to have resulted from stomatal or photochemical constraints. Differences in salt tolerance between cultivars were unrelated to (i) variant patterns of Cl− and K+ tissue concentration, (ii) contrasting leaf water relations, or (iii) changes in relative growth rate and net assimilation rate. The relative advantage of Pitiúba over TVu under salt stress was primarily associated with (i) restricted Na+ accumulation in leaves paralleling an absolute increase in Na+ concentration in roots at early stages of salt treatment and (ii) improved leaf area (resulting from a larger leaf area ratio coupled with a larger leaf mass fraction and larger specific leaf area) and photosynthetic rates per unit leaf mass. Overall, these responses would allow greater whole-plant carbon gain, thus contributing to a better agronomic performance of salt-tolerant cowpea cultivars in salinity-prone regions
© 2009 Blackwell Verlag GmbH

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