Nuestros investigadores

Maite Olaetxea Indaburu

Publicaciones científicas más recientes (desde 2010)

Autores: Olaetxea, Maite; Garcia, C. A.; et al.
Revista: APPLIED SOIL ECOLOGY
ISSN 0929-1393  Vol. 123  2018  págs. 521 - 537
The ability of rhizospheric humic substances to improve plant growth has been well established by many studies carried out using diverse plant species cultivated under many different conditions. These beneficial effects of humic substances on plant development are expressed in both root and shoot. However, the mechanisms responsible for this action of humic substances are only partially known and poorly integrated. In fact, although the studies focused on plant root development are numerous, those dealing with plant shoot development are scarce. Likewise, studies integrating humic effects on root and shoot are also few. In this context, the main goal of this work is to summarize some of the results regarding the effects of humic substances on plant development within a hypothetical holistic framework that will allow us to interconnect these findings and disclose some features of the functional crosstalk between the effects on soil, root and shoot. Furthermore, the significance of all these mechanisms in plants growing in the field is also discussed.
Autores: Olaetxea, Maite; V.; García, A. C.; et al.
Revista: PLANT SIGNALLING & BEHAVIOR
ISSN 1559-2316  Vol. 11  Nº 4  2016  págs. e1161878
Numerous studies have shown the ability of humic substances to improve plant development. This action is normally reflected in an enhancement of crop yields and quality. However, the mechanisms responsible for this action of humic substances remain rather unknown. Our studies have shown that the shoot promoting action of sedimentary humic acids is dependent of its ability to increase root hydraulic conductivity through signaling pathways related to ABA, which in turn is affected in roots by humic acids in an IAA-NO dependent way. Furthermore, these studies also indicate that the primary action of humic acids in roots might also be physical, resulting from a transient mild stress caused by humic acids associated with a fouling-cleaning cycle of wall cell pores. Finally the role of alternative signal molecules, such as ROS, and corresponding signaling pathways are also discussed and modeled in the context of the above-mentioned framework.
Autores: Garcia, A. C.; Olaetxea, Maite; Santos, L. A.; et al.
Revista: BIOMED RESEARCH INTERNATIONAL
ISSN 2314-6133  Vol. 2016  2016  págs. 3747501
The importance of soil humus in soil fertility has been well established many years ago. However, the knowledge about the whole mechanisms by which humic molecules in the rhizosphere improve plant growth remains partial and rather fragmentary. In this review we discuss the relationships between two main signaling pathway families that are affected by humic substances within the plant: one directly related to hormonal action and the other related to reactive oxygen species (ROS). In this sense, our aims are to try the integration of all these events in a more comprehensive model and underline some points in the model that remain unclear and deserve further research.
Autores: Olaetxea, Maite; Mora, V.; Bacaicoa, E.; et al.
Revista: PLANT PHYSIOLOGY
ISSN 0032-0889  Vol. 169  Nº 4  2015  págs. 2587 - 2596
The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancement are discussed in detail. Experiments using cucumber (Cucumis sativus) plants show that the shoot growth enhancement caused by a structurally well-characterized humic acid with sedimentary origin is functionally associated with significant increases in abscisic acid (ABA) root concentration and root hydraulic conductivity. Complementary experiments involving a blocking agent of cell wall pores and water root transport (polyethylenglycol) show that increases in root hydraulic conductivity are essential in the shoot growth-promoting action of the model humic acid. Further experiments involving an inhibitor of ABA biosynthesis in root and shoot (fluridone) show that the humic acid-mediated enhancement of both root hydraulic conductivity and shoot growth depended on ABA signaling pathways. These experiments also show that a significant increase in the gene expression of the main root plasma membrane aquaporins is associated with the increase of root hydraulic conductivity caused by the model humic acid. Finally, experimental data suggest that all of these actions of model humic acid on root functionality, which are linked to its beneficial action on plant shoot growth, are likely related to the conformational structure of humic acid in solution and its interaction with the cell wall at the root surface.
Autores: Fuentes, Marta; Olaetxea, Maite; et al.
Revista: JOURNAL OF GEOCHEMICAL EXPLORATION
ISSN 0375-6742  Vol. 129  2013  págs. 14 - 17
The main objective of this study is to investigate the more relevant binding sites (functional groups) involved in the complexation of Fe(III) and Cu(II) by humic-based structures. To this aim we have generated a set of seven humic-based samples (MHA) by the application of a hemi-synthetic process consisting in the oxidative polymerization of different combinations of three sources of natural organic molecules: two humic acids obtained from peat and leonardite, and natural tannin extracted from the quebracho tree (Schinopsis sp.) bark. These MHA were extensively characterized by using complementary analytical techniques (13C NMR, size-exclusion chromatography, electron paramagnetic resonance, and total phenol-reductant content), and their ability to complex Fe(III) and Cu(II) was also calculated by fluorescence quenching method. The data were studied by using general correlation matrix and principal component analysis. The results obtained, taken together, indicated that in a set of humic-based structures presenting carboxylic, phenol and O-alkyl groups, and diverse aliphatic/aromatic character, the complexation of Fe(III) mainly involved specific structural arrangements including carboxylic groups distributed in aliphatic domains. However, Cu(II) complexation involved singular structural arrangements including phenols (and probably substituted phenols) and O-alkyl groups in side chains of aromatic domains.
Autores: V.; Olaetxea, Maite; E.; et al.
Libro:  Nitric oxide in plants: metabolism and role in stress physiology
2014  págs. 243 - 264
A number of studies have demonstrated the key role of nitric oxide in the regulation of many fundamental physiological processes that includes plant responses to abiotic and biotic stresses. On the other hand, beneficial action of humic substances on plant growth has been well corroborated, particularly when plants are subjected to abiotic stresses. Furthermore, several recent works have reported the functional links between the plant growth promoting action of humic substances and nitric oxide production and function in plants. In this article, we try to briefly review and discuss the main results showing the relationships between nitric oxide function and humic substances action on plants, also stressing the nitric oxide-dependent involvement of other plant growth regulators, such as auxin, ethylene, abscisic acid, and cytokinins.