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December 2010 - present
January 2014 - present
August 2008 - September 2010
Publications
Publications (32)
Bacteria belonging to the Burkholderia genus have been extensively studied for their potential as biocontrol agents, particularly their ability to produce bioactive compounds. In this study, we investigated the antagonistic capabilities of an indigenous strain of Burkholderia gladioli BNM349 against a wide spectrum of bacterial and fungal phytopath...
The Burkholderia species are prolific producers of bioactive secondary metabolites (antibacterial, antifungal, antitumoral, antinematodal, herbicidal and insecticidal compounds) with many potential biotechnological applications. Burkholderia gladioli was initially identified as a pathogen of flowering plants of genus Gladiolus and later isolated fr...
Burkholderia ambifaria T16 is a bacterium isolated from the rhizosphere of barley plants that showed a remarkable antifungal activity. This strain was also able to degrade fusaric acid (5-Butylpyridine-2-carboxylic acid) and detoxify this mycotoxin in inoculated barley seedlings. Genes and enzymes responsible for fusaric acid degradation have an im...
Burkholderia ambifaria T16 is a bacterial strain isolated from the rhizosphere of barley plants, which showed a potent antifungal activity against several Fusarium species. In this work, the construction of a mini-Tn5 insertional library in this strain allowed us the identification of several genes involved in the antifungal activity. In particular...
Background and aims:
Proteases are responsible for protein degradation during leaf senescence, allowing nutrients to be redirected to sink tissues. In a previous work, we reported that sulphur deficiency produced a delay in the leaf senescence of barley (Hordeum vulgare L.) plants, both at vegetative and reproductive stages. In this work we analys...
The capacity of arbuscular mycorrhizal fungi (AMF) to alleviate the negative effects incited by root pathogens in a range of plant hosts has been established. On the other hand, accumulated evidence also shows that fertilization practices can negatively impact AMF. Nevertheless, the interaction between AMF, pathogens and fertilizers, especially nit...
Proteases play a main role in the mobilization of storage proteins during seed germination. Until today, there is little information about the involvement of serine proteases, particularly subtilases, in the germination of barley grains. The aims of the present work were to study the contribution of serine proteases to the total proteolytic activit...
Plant proteolytic enzymes belonging to the S8 family of serine proteases are known as subtilases or subtilisin-like proteases. Subtilases compose the largest family of plant serine peptidases and have been associated to a wide range of physiological responses and developmental stages. We here describe a simple and fast method to reveal subtilase ac...
Fusaric acid (FA) is a fungal metabolite produced by several Fusarium species responsible for wilts and root rot diseases of a great variety of plants. Bacillus spp. and Pseudomonas spp. have been considered as promising biocontrol agents against phytopathogenic Fusarium spp., however it has been demonstrated that FA negatively affects growth and p...
Understanding the way in which N and P availability affects the transport of sugar and amino acids is crucial to improve grain quality and yield. Thus, in the present study, two greenhouse and field experiments were conducted with barley plants grown with different N and P availabilities to assess the dynamics of the phloem transport of assimilates...
The phloem transport of amino acids is a key step in the efficient use of nitrogen (N). Despite the importance of this issue, little information is known about the regulation of phloem transport of amino acids in plants with low phosphorus (P) supply and even less in relation to N availability. To this end, we studied not only the assimilate partit...
Sulphur (S) is incorporated into diverse primary and secondary metabolites that play important roles in proper growth and development of plants. In cereals, a fraction of the nitrogen (N) accumulated in developing grains is guaranteed by amino acid remobilization from vegetative tissues, a contribution that becomes critical when soil nutrients are...
Results:
showed that subtilase specific activity as well as two inmunoreactive bands representing putative subtilases increased in barley leaves submitted to natural and dark-induced senescence. Gene expression analysis showed that two of the eleven subtilase genes analyzed, HvSBT3 and HvSBT6, were up-regulated in all the senescence conditions tes...
An essential goal for modern agriculture is the simultaneous improvement of productivity efficiency and nutrient use efficiency. One way to achieve this goal in crops is to enhance nitrogen (N) and phosphorus (P) acquisition through the mycorrhizal association. This study examined the effect of mycorrhization on post-anthesis N and P dynamics and i...
The commercial quality of malting barley is dependent on the content and composition of grain proteins which are subjected to nitrogen (N) and sulfur (S) control. In nutrient deficient soils, grain protein content is mainly a consequence of the remobilization efficiency. In order to evaluate the effect of N and S soil availability on phloem amino a...
DegP/HtrA proteases are ATP-independent serine endopeptidases widely distributed in nearly all organisms. As yet, their physiological role in oxygenic photosynthetic organisms is unclear, although it has been widely speculated that they participate in the photosystem II repair cycle. Here, we investigated the ability of Deg proteases to degrade Psb...
The widely distributed members of the Deg/HtrA protease family play an important role in the proteolysis of misfolded and damaged proteins. Here we show that the Deg protease rHhoA is able to degrade PsbO, the extrinsic protein of the Photosystem II (PSII) oxygen-evolving complex in Synechocystis sp. PCC 6803 and in spinach. PsbO is known to be sta...
Recombinant PsbO is reduced even in the absence of reducing agents. Recombinant PsbO of Synechocystis 6803 was isolated from the strains 7S or 2RG and incubated with monobromobiname (mBBr) to label the sulfhydryl groups. To reduce or oxidize PsbO, samples were pre-treated with 2.5 mM DTT or 35 mM CuSO4, respectively, previous to mBBr labeling. Ten...
Alignment of PsbO sequences. Multiple sequence alignment of PsbO1 (ARAB 1, accession number AED98230.1) and PsbO2 (ARAB 2, accession number AEE78714.1) from A. thaliana, and PsbO from spinach (accession number P12359.1) and Synechocystis 6803 (SYNECHO, accession number NP441796.1). The alignment was generated using ClustalW2 software. Asterisk indi...
Redox-dependent degradation of PsbO in the presence of combinations of recombinant Deg proteases from Synechocystis sp. PCC 6803. PsbO was isolated from spinach leaves and incubated in the absence or the presence (PsbOred) of the complete thioredoxin system together with rHhoA and rHhoB, rHhoA and rHtrA or rHtrA and rHhoB for 5 h. Arrowheads indica...
Time course degradation of PsbO in the presence of recombinant Deg proteases from Synechocystis sp. PCC 6803. PsbO was isolated from spinach leaves and incubated in the absence (PsbO) or the presence (PsbOred) of the complete thioredoxin system for 10 h without addition of recombinant proteases (A) or after addition of rHhoA (B), rHhoB (C) or rHtrA...
Senescence is the final developmental stage of every plant organ, which leads to cell death. It is a highly regulated process, involving differential gene expression and outstanding increment in the rate of protein degradation. Senescence-associated proteolysis enables the remobilization of nutrients, such as nitrogen (N), from senescent tissues to...
The induction of two subtilisin-like proteases (P1 and P2) associated with stress-induced senescence in young plants was investigated
in adult wheat plants during the grain-filling period. Western blot analysis of flag leaf extracts showed that P1 was induced
very late in the life cycle of the plants (9 days post-anthesis) and that 7 days later it...
In a previous work we demonstrated that the suppression of blue light in shaded leaves of wheat increases their senescence rate and the development of oxidative stress symptoms. In order to better understand the interaction between the oxidative metabolism and light spectral quality in the regulation of leaf senescence, we studied the evolution of...
Nitrogen (N) remobilization in wheat (Triticum aestivum) plants is crucial because it determines the grain protein concentration and the baking quality of flour. In order to evaluate the influence of cytokinins on N remobilization during N starvation, we analyzed various N remobilization parameters in wheat plants that were watered with 6-benzylami...
The possible regulation of amino acid remobilization via the phloem in wheat (Triticum aestivum L.) by the primary enzyme in nitrogen (N) assimilation and re-assimilation, glutamine synthetase (GS, E.C. 6.3.1.2) was studied using two conditions known to alter N phloem transport, N deficiency and cytokinins. The plants were grown for 15 days in cont...
The sequence of events and the signals that regulate the remobilization of nitrogen (N) reserves during senescence induced
by N starvation were studied in leaf 3, the last fully expanded leaf, in 17-day-old wheat (Triticum aestivum L.) plants. The first event observed was a rapid decrease in the isopentenyl adenosine (iPA) concentration during the...
We have previously reported the occurrence of two serine endoproteases (referred to as P1 and P2) in dark-induced senescent wheat (Triticum aestivum L.) leaves. P1 enzyme was already purified and identified as a subtilisin-like serine endoprotease (Roberts et al. in Physiol Plant 118:483-490, 2003). In this paper, we demonstrate by Western blot ana...
A senescence-specific protease accounting for almost 70% of the total peptide hydrolytic activity of protein extracts, was isolated from detached wheat leaves induced to senescence by incubation in the dark for 72 h. Purification to apparent homogeneity was performed by ammonium sulphate precipitation, ion exchange chromatography and gel filtration...
In the present paper, we studied the participation of the 20S proteasome, the proteolytic component of the ubiquitin–proteasome pathway, in the remobilization of bulk proteins in senescing wheat leaves. The detached leaves of 15-d-old plants were incubated in darkness for several days, and various proteolytic activities were analysed in soluble ext...
