PLANT NUTRITION

Author: BELASTEGUI XANA MELISSA.
Year: 2004.
University: PAÍS VASCO [www.ehu.es].
Place of defense: FACULTAD DE CIENCIA Y TECNOLOGIA.
Place of preparation: FACULTAD DE CIENCIA Y TECNOLOGIA.

Summary: In this study has been evaluated by a hand phototoxicity of the possible use of nitrification inhibitors DCD and DMPP, and on the other hand, the tolerance of clover and raigrás to nutrition ammonia. The results show that the DCD produces a phytotoxic per se in clover and lettuce, both broad-leaf species, while the DMPP not seen visual symptoms of phototoxicity. The phototoxicity of DCD is associated with the induction of an ion imbalance that probably has to do with his apparent ability chelator divalent cations. Likewise, its application induces an increase in the activity of the alternative route of mitochondrial respiration and an increase in the rate of respiration residual symptoms of a possible induction of oxidative stress. The study of the effect of ammoniacal nutrition in clover and raigrás revealed that both species tolerate this type of nutrition, but through different strategies. With nutrition ammonia accumulation ammonium root is higher in raigrás in clover. The ammonium assimilation takes place mainly in root through the cycle GS / GOGAT in both species, while also can be found in leaf. Thus, there is the existence of ammonium transport via xylem. With the implementation of increasing concentrations of ammonium externally, at the root of both species increases the content of proteins GDH and GS, also observed an increase in activity GDH, although to a lesser extent raigrás in clover. In both species probably activity GDH is providing 2-oxoglutarato to maintain the integrity of cycle acids tricarboxílicos necessary for the provision of carbon skeletons. This role of GDH would be important especially in the clover, while the raigrás the contribution of activities ICDH and PEPCasa would be more relevant and Clover.

Author: CLEMENTE GALLARDO MARÍA REBECA.
Year: 2005.
University: ZARAGOZA [www.unizar.es].
Place of defense: FACULTAD DE CIENCIAS (EDIFICIO DE MATEMÁTICAS).
Place of preparation: ESTACIÓN EXPERIMENTAL DE AULA DEI (CSIC).

Summary: The model legume Lotus japonicus produces majority (96%) homoglutatión in the leaves and roots, and glutathione (65%) in the nodule. These variations in the content of thiol of tissues are determined by differential expression of the enzyme glutathione synthetase and homoglutatión synthetase. The expression of glutathione synthetase gene exclusively in nodules indicates that glutathione can play a specific role in the symbiosis. There is a single copy of glutathione synthetase gene in the genome Lotus. However, the nodules can be identified two populations of transcripts encoding, respectively, glutathione synthetase without signal peptide (cytosolic isoform) or with a signal peptide at the N-terminal end (isoform plastidial). Cadmium induces rapid biosynthesis in plants thiol Lotus. Particularly notable are increased? -glutamilcisteína And activation of the synthesis of (homo) fitoquelatinas in the early hours of treatment. Since the mRNA gene y-glutamilcisteína synthase is not affected by treatment with cadmium, while the protein content increases twice and the y-glutamilcisteína hundred times, the enzyme is regulated at traduccional and mainly postraduccional. The Lotus genome contains three genes fitoquelatina synthase (pcs), which are clustered on chromosome 1, and probably came from two events of duplication. The analysis of DNA and protein sequences suggest that the first duplication resulted Ljpcs1 and a gene that led to Ljpcs2 and Ljpcs3. The latter probably took place during evolution, once pulses had divergido other higher plants. Moreover, the gene "phytochelatin synthase-Iike" (psl) encodes a genuine fitoquelatina synthase, unlike what postulated by the authors who initially scored the stream. In indeterminate nodules there is a differential expression of genes of CuZnSOD cytosolic and MnSOD mitochondrial. At the level of mRNA and protein, CuZnSOD is located predominantly in the meristemo and in the area of invasion, while the MnSOD is very abundant in the area-fixing, particularly in infected cells. This suggests an involvement of CuZnSOD in the early stages of development and nodular a protective role of MnSOD in the symbiotic interaction. Studies co-location of CuZnSOD and H2O2 in the nodules, along with those of enzyme inhibitors using electron microscopy, leading to propose that the production of H2O2, at least in the cords of infection is produced by the sequential action a generating NADPH oxidase and superoxide of CuZnSOD cytosolic. The results also support the participation of a peroxidase of the cell wall in the production of H202 in apoplasto.

Author: ANDALUZ GIL SOFÍA.
Year: 2005.
University: ZARAGOZA [www.unizar.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: ESTACIÓN EXPERIMENTAL DE AULA DEI. CSIC. ZARAGOZA..

Summary: Iron is an essential element for plants and participating in some of the most important functions of metabolism. In alkaline and calcareous soil, the concentration of iron available is not enough to sustain the needs of the plant. In this situation, dicotyledons and monocotyledons not plant grasses Strategy (1) develop a series of physiological responses aimed at maintaining iron homeostasis in the plant. In this work we have studied, both physiological and molecular some of the most important responses of plants Strategy 1 to iron deficiency, as well as the changes brought about by this deficiency in the proteome of different plant tissues. The expression of genes of the ATPase (Mtha1) reductase and Faith membrane plamática (MtFro1) of Medicago truncatula, as well as genes associated with the route biosynthesis flavinas, Mtriba in Medicago truncatula, and MtDMRLs and BvDMRLs in Medicago truncatula and Beta vulgaris, respectively, increases with Fe deficiency. Furthermore, the gene MtSULT1, corresponding to a sulfotransferasa is sobreexpresado roots of plants deficient in Faith of Medicago truncatula. The technique IEF-SDS PAGE has proven useful for the separation of polypeptides in the tissues studied protein obtained maps of root and tilacoides Beta vulgaris and phloem of Lupinus texensis. Fe deficiency induces significant changes in the proteome of root tips of Beta vulgaris, is the most important change the appearance of the polypeptide of DMRL synthase in the gels 2-D of the yellow tips (both plants as deficient in Faith of the plants that have received a contribution of Faith after the deficiency). In extracts of yellow root tips of Beta vulgaris deficient in Faith has found a large increase in activity PEPC with respect to the controls. This increase was approximately 30-50 (on a fresh weight basis) and 7-14 times (based on protein). But this increase in activity does not appear to be mediated by phosphorylation of the enzyme. The expression of genes of the PEPC increases with deficiency Faith in Medicago truncatula (MtPEPC) and Beta vulgaris (BvPEPC). The deficiency induces Faith also decreases the relative amount of the complex trasportadores electron increases in the relative amount of other proteins. It has also been encountered a group of proteins in tilacoides Beta vulgaris deficient in Faith, which includes several proteins normally found in the stroma of cloroplato. In drips of phloem of Lupinus texensis have identified two proteins that may be involved in the transport of Fe and three more proteins that may be involved in the transport of Zn.