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ABSTRACT: We have performed the isolation, functional characterization and expression analysis of aquaporins in roots and leaves of Helianthemum almeriense, in order to evaluate their roles in tolerance to water deficit. Five cDNAs, named HaPIP1;1, HaPIP1;2, HaPIP2;1, HaPIP2;2 and HaTIP1;1, were isolated from H. almeriense. A phylogenetic analysis of deduced proteins confirmed that they belong to the water channel proteins family. The HaPIP1;1, HaPIP2;1 and HaTIP1;1 genes encode functional water channel proteins, as indicated by expression assays in Saccharomyces cerevisiae, showing divergent roles in the transport of water, CO2 and NH3. The expression patterns of the genes isolated from H. almeriense, and of a previously described gene from Terfezia claveryi (TcAQP1), were analyzed in mycorrhizal and non-mycorrhizal plants cultivated under well-watered or drought stress conditions. Some of the studied aquaporins were subjected to fine-tuned expression only under drought stress conditions. A beneficial effect on plant physiological parameters was observed in mycorrhizal plants with respect to non-mycorrhizal ones. Moreover, stress induced a change in the mycorrhizal type formed, which was more intracellular under drought stress. The combination of a high intracellular colonization, together with the fine-tuned expression of AQPs, could result in a morpho-physiological adaptation of this symbiosis to drought conditions.
Molecular Plant-Microbe Interactions 05/2013; · 4.43 Impact Factor
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ABSTRACT: Physiological parameters of mycorrhizal symbiosis by Helianthemum almeriense and Terfezia claveryi in orchards were characterized under water deficit conditions. Our orchard included 40 mycorrhizal and 40 nonmycorrhizal
plants. Only mycorrhizal plants survived at the beginning of the experimental period, indicating dependency on fungal symbionts
in roots for survival. Drought stress significantly affected the mycorrhizal colonization percentage which was 70% in nonirrigated
mycorrhizal and 48% in irrigated mycorrhizal plants. No significant differences in plant growth were observed between nonirrigated
and irrigated mycorrhizal plants before and after drought stress. Stomatal conductance was more sensitive to water stress
than shoot water potential. It decreased more than two-fold under drought-stress compared to control mycorrhizal plants under
irrigation/light saturating conditions, indicating important stomatal closure with water deficit. Plants’ water use efficiency
improved with drought with stomatal conductance values below 0.3mol m−2 s−1. The ability to maintain open stomata and photosynthesis under drought increased carbon supply for growth, and ascocarp fruiting
which requires current photosynthates. Basically, H. almeriense shows a conservative water use strategy based mainly on avoiding drought stress by reducing stomatal conductance as soil
water potential decreases and atmospheric conditions dry. The results show that mycorrhizal H. almeriense plants maintain good physiological parameters with low soil matric potentials, thus making them an alternative agricultural
crop in arid/semi-arid areas.
KeywordsDesert truffle cultivation-Drought stress avoidance-Ectendomycorrhiza
Symbiosis 04/2012; 52(2):133-139. · 1.21 Impact Factor
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ABSTRACT: In Morocco, yields of date palms are highly decreased by the pathogen fungi Fusarium oxysporum. To solve this issue, mycorrhizal fungi and biocontrol agents could enhance plant resistance to pathogens. Here, we studied
peroxidases in roots and leaves of Phoenix dactylifera in response to inoculation with the fungi Glomus mosseae and Trichoderma harzianum. Date palm plants were harvested 57 weeks after inoculation with mycorrhizal fungi and biocontrol fungi. We measured the
dry biomass, arbuscular colonization, cytochemistry of peroxidase, and peroxidase forms and activities in roots and leaves.
Our results show that mycorrhization increased the plant dry biomass by about 57%. The rate of mycorrhizal colonization ranged
from 25% to 30%. Peroxidase activity in roots colonized by T. harzianum alone was 1.6 times higher than in control plants. Peroxidase activity in roots colonized by G. mosseae and T. harzianum was about 2 times higher than in control plants. Peroxidase activity in leaves increased by + 419% when plants were inoculated
by both fungi. The cytochemical results show an accumulation of structural substances in root cell walls after inoculation
with T. harzianum. These structural substances may increase the mechanical strength of the host cell walls in order to inhibit pathogen invasion.
Peroxidase activities were found in plant cell walls; the tonoplast and host plasmalemma in the chloroplast; mitochondrial
membranes; and intercellular spaces of plants inoculated with G. mosseae and T. harzianum. SDS-PAGE analyses of leaf extracts gave a main band at 54 kDa for all the treatments. The stimulatory effect of Trichoderma on the peroxidase activity is a resistance mechanism of date plants to pathogens. The use of Trichoderma could thus be an alternative to chemicals in crop protection.
Peroxidase–
Trichoderma
–date palm–arbuscular mycorrhizal
Agronomy for Sustainable Development 04/2012; 28(3):411-418. · 3.33 Impact Factor
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ABSTRACT: The influence of inorganic and organic phosphorus (P) and the absence of P in the culture medium on the type of mycorrhizal colonization formed (ecto-, ectendo-, or endomycorrhiza) during Helianthemum almeriense x Terfezia claveryi symbiosis in in vitro conditions was analyzed. This is the first time that the relative proportions of the different mycorrhizal types in mycorrhizal roots of H. almeriense have been quantified and statistically analyzed. The relative proportions of the mycorrhizal types depended on the P source in the medium, suggesting that it is the organic P form that induces the formation of intracellular colonization. The above association should be considered as a continuum between intra- and intercellular colonizations, the most appropriate term for defining it being ectendomycorrhiza. The influence of the endogenous concentration of P on plant growth was also analyzed. P translocation was observed from shoot to roots, especially in mycorrhizal plants because mycorrhizal roots showed higher growth than non-mycorrhizal roots and/or because of an extra P demand from mycelium inside the roots. Soluble and cell wall acid phosphatases activities from H. almeriense roots were kinetically characterized at optimum pH (5.0), using p-nitrophenyl phosphate as substrate, with K (m) values of 3.4 and 1.8 mM, respectively. Moreover, the plant acid phosphatase and fungal alkaline phosphatases activities were histochemically localised in mycorrhizal H. almeriense roots by fluorescence with enzyme-labelled fluorescence substrate.
Mycorrhiza 03/2012; 22(7):565-75. · 2.63 Impact Factor
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ABSTRACT: Terfezia claveryi is a hypogeous mycorrhizal fungus belonging to the so-called "desert truffles," with a good record as an edible fungus and of considerable economic importance. T. claveryi improves the tolerance to water stress of the host plant Helianthemum almeriense, for which, in field conditions, symbiosis with T. claveryi is valuable for its survival. We have characterized cDNAs from T. claveryi and identified a sequence related to the aquaporin gene family. The full-length sequence was obtained by rapid amplification of cDNA ends and was named TcAQP1. This aquaporin gene encoded a functional water-channel protein, as demonstrated by heterologous expression assays in Saccharomyces cerevisiae. The mycorrhizal fungal aquaporin increased both water and CO(2) conductivity in the heterologous expression system. The expression patterns of the TcAQP1 gene in mycelium, under different water potentials, and in mycorrhizal plants are discussed. The high levels of water conductivity of TcAQP1 could be related to the adaptation of this mycorrhizal fungus to semiarid areas. The CO(2) permeability of TcAQP1 could be involved in the regulation of T. claveryi growth during presymbiotic phases, making it a good candidate to be considered a novel molecular signaling channel in mycorrhizal fungi.
Molecular Plant-Microbe Interactions 11/2011; 25(2):259-66. · 4.43 Impact Factor
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ABSTRACT: The ability of two species of desert truffle, Terfezia claveryi strain TcS2 and Picoa lefebvrei strain OL2, to tolerate water stress in pure culture has been investigated. Both T. claveryi and P. lefebvrei strains exhibited a mycelium growth pattern characteristic of drought tolerant species. However, they were only tolerant to moderate water stress, below -1.07 MPa, with the P. lefebvrei isolate being slightly more drought tolerant than the T. claveryi isolate. The increased alkaline phosphatase (ALP) activity observed in both fungi at moderate water stress with respect to the control indicated the functional adaptation of these mycelia to these drought conditions. ALP activity can be used as an indicator of the metabolic activity of these fungi. Slight water stress (-0.45 MPa) could improve mycelial inoculum production of these desert truffles. Moreover, P. lefebvrei could be a good candidate for further desert truffle mycorrhizal plant cultivation programmes in semiarid Mediterranean areas.
Mycorrhiza 05/2011; 21(4):247-53. · 2.63 Impact Factor
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ABSTRACT: The influence of a water deficit treatment and mycorrhizal inoculation with Pisolithus tinctorius (Pers.) Coker and Couch on the water relations, gas exchange, and plant growth in Arbutus unedo L. plants was studied in order to evaluate the hardening process during the nursery period. The ability to withstand the adverse conditions after transplantation was also studied. Mycorrhizal and non-mycorrhizal seedlings of A. unedo were pot-grown for 4 months in a greenhouse (nursery period), during which time two irrigation treatments, well watered (100% water holding capacity, leaching 20% of the applied water) and deficit irrigation (50% of the well watered), were applied. Subsequently, the plants were transplanted to the field and well irrigated (transplanting period), after which and until the end of the experiment they received no water (establishment period). At the end of the nursery period, both water deficit and mycorrhizae were seen to have altered the plant morphology. Mycorrhizal plants had lower leaf area and improved leaf color parameters, while the water deficit increased root dry weight and the root/shoot ratio. Mycorrhizal plants had higher leaf water potential values than non-inoculated plants. Mycorrhizae increased stomatal conductance and photosynthesis values, especially in stressed plants. Drought led to an osmotic adjustment and a decrease in the leaf water potential values at turgor loss point in the mycorrhizal plants. Cell wall rigidity, measured as increased bulk modulus of elasticity, was decreased by the mycorrhizae effect. After transplanting, no differences were found in the water relations or gas exchange values between treatments. During the establishment period, the plants that had been exposed to both drought and mycorrhizae showed a better water status (higher leaf water and turgor potential values) and higher gas exchange values. In conclusion, water deficit and mycorrhizal inoculation of A. unedo plants in nursery produced changes in tissue water relations, gas exchange, and growth, related with the acclimation process in the seedlings, which could provide better resistance to drought and stress conditions following planting.
Mycorrhiza 01/2011; 21(1):53-64. · 2.63 Impact Factor
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ABSTRACT: Publicado on-line: 7 junio 2011 Pleurotus eryngii (Fr.) Quél, conocida como seta de cardo, es un excelente comestible que pertenece al grupo de hongos de la pu-drición blanca. Gracias a su versátil complejo enzimático lignocelu-lósico, se conocen diversas aplicaciones biotecnológicas y medici-nales de esta especie de basidiomiceto. El objetivo de este trabajo se ha centrado en mejorar la producción de la misma. Se han ca-racterizado los óptimos de crecimiento miceliares de dos cepas sil-vestres de seta de cardo en medio sólido y líquido. Se evaluó la productividad de tres cepas de seta de cardo sobre diversos resi-duos agroalimentarios (cascarilla de arroz, paja de trigo, aserrines y bagazo) con el fin de conocer la viabilidad de los mismos para producción de basidiomas. El bagazo, subproducto de la fabrica-ción de la cerveza, se ha usado por primera vez en el cultivo de P. eryngii, resultando ser el sustrato más efectivo donde fructificaron las tres cepas. Abstract Characterization and culture of three Pleurotus eryngii (Fries) Quélet strains on food and agriculture wastes.
Anales de Biología. 01/2011; 33:53-66.
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ABSTRACT: A morphological and anatomical study of the root systems of the palm species Brahea armata S. Watson, Chamaerops humilis L., Phoenix canariensis Chabaud and Phoenix dactylifera L. has been carried out to determine possible mycorrhizal colonization sites. Furthermore, the arbuscular mycorrhizal (AM) anatomical types formed by the four palm species in association with Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe have been examined. The presence of a continuous sclerenchymatic ring in the outer cortex and aerenchyma in the inner cortex that are anatomical indicators of mycorrhizal nonsusceptibility in all four palm species is observed. The root systems of B. armata and C. humilis present only one group of third-order roots, while the third-order roots of P. canariensis and P. dactylifera may be divided into five different groups: short thick roots, mycorrhizal thickened roots, fine short roots, fine long roots, and pneumatorhizas. Third-order and some second-order roots of B. armata and C. humilis are susceptible to colonization by AM fungi, while only the mycorrhizal thickened roots form mycorrhizas with arbuscules in the Phoenix species. The root system of the Phoenix species also presents AM colonization in fine roots with only intraradical hyphae and spores, but without arbuscules, and pseudomantles of spores anchored in the pneumatorings of the second-order roots, which are described for the first time. The mycorrhizas formed by the four palm species are of an intermediate type, between the Arum and the Paris types, and are characterized by intercalary arbusculate coils and not only by intracellular but also by intercellular fungal growth. Our study suggests that a different degree of adaptation may exist among palm mycorrhizas toward the slow growth of palms and low spore numbers in the soil where they grow.
Mycorrhiza 08/2009; 20(2):103-15. · 2.63 Impact Factor
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ABSTRACT: This chapter focusses on showing some taxonomic and ecological characters of the main desert truffle species in Spain as well
as the main biotechnological procedures followed to produce mycorrhizal plants with some of these fungal species. The full
micropropagation protocol of the host plant Helianthemum violaceum is described for the first time. Five different ways of producing mycorrhizal synthesis between desert truffles and the Helianthemum species are reported, according to the type of fungal inoculum, plant source and culture conditions used. Finally, a management
protocol for the established desert truffle plantations is discussed. Irrigation, one of the most important factors considered
for successful cultivation, should be applied at the end of the summer during dry years when rainfall is less than 150 mm
and for a second time at the beginning of the fruiting season in very dry years.
06/2009: pages 221-233;
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ABSTRACT: Acid phosphatase (ACP) activity has been detected in roots of mycorrhizal and non-mycorrhizal Phoenix canariensis. This enzyme was ultrastructurally localized in arbusculate coils for the first time. This localization was carried out using a cerium-based method, which minimizes non-specific precipitation. The ACP was localized in inter- and intracellular hyphae, in the fungal cytoplasm as well as at the interface and the fungal cell wall and the periarbuscular membrane limiting it. The novel localization of an ACP in the arbuscular mycorrhizal (AM) interface of arbusculate coils suggests that this enzyme may be involved in the phosphorus efflux from the mycorrhizal fungus to the host. The results presented in this article indicate that the role played by ACP in AM symbiosis may be more important than was previously thought and that arbusculate coils are highly relevant when considering nutrient transfer through AM symbiosis.
Physiologia Plantarum 05/2008; 132(4):503-13. · 3.11 Impact Factor
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ABSTRACT: The aim of this study was to reassess the use of autofluorescence for evaluating AM colonization in mycorrhizal roots in the light of criticisms of this method that affirmed that only metabolically inactive arbuscules autofluoresce. It was also investigated whether other mycorrhizal structures, such as hyphae, vesicles and spores, could be detected by autofluorescence, and whether the autofluorescence pattern of AM fungal structures could be exploited methodologically, for example, in the detection and sorting of spores by flow cytometry. Mycorrhizal roots of the palm species Brahea armata, Chamaerops humilis, Phoenix canariensis and Phoenix dactylifera were sectioned and observed by means of fluorescence microscopy. In addition, fungal structures isolated from mycorrhizal roots of P. dactylifera were examined. The same root sections and isolated fungal structures were subjected to vital staining with nitro blue tetrazolium to determine their metabolic state (active or inactive). Moreover, spores of Glomus intraradices, and Glomus clarum were studied by epifluorescence and flow cytometry. Mycorrhizal whole roots of Medicago sativa were also assessed by autofluorescence detection. In contrast to previous reports, the results presented in this paper clearly demonstrate that all fungal structures, both intra- and extraradical, autofluoresced under blue light excitation, regardless of their state (dead or alive). Some arbuscules isolated from roots and mature spores showed further autofluorescence under green light excitation. The source of the autofluorescence was localized in the fungal cell wall. It was shown that AM spores can be detected by flow cytometry. The results support the use of autofluorescence for the evaluation of AM colonization, at least in palm species, and refute previous criticisms of the method.
Mycological Research 09/2006; 110(Pt 8):887-97. · 2.81 Impact Factor
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ABSTRACT: An esterase activity from Terfezia claveryi Chatin ascocarps, a mycorrhizal hypogeous fungus, is described for the first time. The enzyme was partially purified using phase partitioning in Triton X-114 (TX-114), achieving a reduction of 87% in the triglyceride content and the removal of 63% of phenols. The enzyme showed maximum activity toward short-chain p-nitrophenyl esters, and no interfacial activation was observed, indicating that the enzyme responsible for this activity is an esterase and not a lipase. This esterase presented its maximum activity at pH 7.4 and 60 degrees C. The values obtained for Km at pH 7.4 were 0.3 mM for p-nitrophenyl butyrate and 0.6 mM for p-nitrophenyl acetate with catalytic efficiencies (Vmax/Km) of 0.23 and 0.32, respectively. T. claveryi esterase was inhibited by phenylboric acid, indicating that serine residues were involved in the enzyme activity. This activity was localized only in the hypothecium and was absent from the peridium and gleba.
Journal of Agricultural and Food Chemistry 08/2005; 53(14):5754-9. · 2.82 Impact Factor
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ABSTRACT: There is very little information available on the kinetic characteristics of fungal lipoxygenases (LOXs) because most data on the mechanism of this enzyme concern soybean LOX. In this paper, the kinetic properties of LOX from Terfezia claveryi Chatin ascocarps were studied for the first time. The enzyme did not show the "substrate aggregation-dependent activity" described for other LOXs and presented a K(m) for linoleic acid of 41 microM at pH 7.0. The effect of different inhibitors was also studied. The enzyme presented the characteristic lag phase of other LOXs, and the influence of different factors on its duration was analyzed. The lag period was reduced not only by the product of the reaction (13-HPOD) but also by 9-HPOD. Calculation of the activation constant is proposed for the first time as a useful tool for the characterization of LOX because this method makes it possible to quantify the effectiveness of different hydroperoxides as LOX activators. The activation constants obtained were 0.3 and 6.4 microM for 13- and 9-HPOD, respectively; thus, the product of the reaction was approximately 21-fold more effective than 9-HPOD as a T. claveryi LOX activator.
Journal of Agricultural and Food Chemistry 08/2005; 53(15):6140-5. · 2.82 Impact Factor
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ABSTRACT: The influence of the arbuscular mycorrhizal fungus Glomus deserticola on the water relations, gas exchange parameters, and vegetative growth of Rosmarinus officinalis plants under water stress was studied. Plants were grown with and without the mycorrhizal fungus under glasshouse conditions and subjected to water stress by withholding irrigation water for 14 days. Along the experimental period, a significant effect of the fungus on the plant growth was observed, and under water stress, mycorrhizal plants showed an increase in aerial and root biomass compared to non-mycorrhizal plants. The decrease in the soil water potential generated a decrease in leaf water potential (psi(l)) and stem water potential (psi(x)) of mycorrhizal and non-mycorrhizal plants, with this decrease being lower in mycorrhizal water-stressed plants. Mycorrhization also had positive effects on the root hydraulic conductivity (Lp) of water stressed plants. Furthermore, mycorrhizal-stressed plants showed a more important decrease in osmotic potential at full turgor (psi(os)) than did non-mycorrhizal-stressed plants, indicating the capacity of osmotic adjustment. Mycorrhizal infection also improved photosynthetic activity (Pn) and stomatal conductance (g(s)) in plants under water stress compared to the non-mycorrhizal-stressed plants. A similar behaviour was observed in the photochemical efficiency of PSII (Fv/Fm) with this parameter being lower in non-mycorrhizal plants than in mycorrhizal plants under water stress conditions. In the same way, under water restriction, mycorrhizal plants showed higher values of chlorophyll content than did non-mycorrhizal plants. Thus, the results obtained indicated that the mycorrhizal symbiosis had a beneficial effect on the water status and growth of Rosmarinus officinalis plants under water-stress conditions.
Journal of Plant Physiology 07/2004; 161(6):675-82. · 2.79 Impact Factor
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ABSTRACT: The monophenolase activity of Terfezia claveryi tyrosinase (EC 1.14.18.1) is described for the first time. This enzyme is fully latent and can only be detected if SDS is present in the reaction medium. Monophenolase activity was localized within the ascocarp using histochemical techniques. A detailed kinetic study of the parameters affecting this activity has been carried out. Both the characteristic lag period and the steady-state rate are affected by pH and the enzyme and substrate concentrations. The presence of catalytic concentrations of o-diphenols affected the lag period but not the steady-state rate. By increasing the concentration of o-diphenols, it was possible to evaluate the enzyme activation constant, Kact, which showed a value of 7.2 &mgr;M. The experimental results are compatible with the mechanism previously described for tyrosinases from other sources.
Physiologia Plantarum 11/2001; 113(2):203-209. · 3.11 Impact Factor
