Puga M.I.,CSIC - National Center for Biotechnology |
Mateos I.,CSIC - National Center for Biotechnology |
Mateos I.,Centro Hispano Luso Of Investigaciones Agrarias |
Charukesi R.,CSIC - National Center for Biotechnology |
And 14 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014
To cope with growth in low-phosphate (Pi) soils, plants have evolved adaptive responses that involve both developmental and metabolic changes. PHOSPHATE STARVATION RESPONSE 1 (PHR1) and related transcription factors play a central role in the control of Pi starvation responses (PSRs). How Pi levels control PHR1 activity, and thus PSRs, remains to be elucidated. Here, we identify a direct Pi-dependent inhibitor of PHR1 in Arabidopsis, SPX1, a nuclear protein that shares the SPX domain with yeast Pi sensors and with several Pi starvation signaling proteins from plants. Double mutation of SPX1 and of a related gene, SPX2, resulted in molecular and physiological changes indicative of increased PHR1 activity in plants grown in Pi-sufficient conditions or after Pi refeeding of Pi-starved plants but had only a limited effect on PHR1 activity in Pi-starved plants. These data indicate that SPX1 and SPX2 have a cellular Pi-dependent inhibitory effect on PHR1. Coimmunoprecipitation assays showed that the SPX1/PHR1 interaction in planta is highly Pi-dependent. DNA-binding and pull-down assays with bacterially expressed, affinity-purified tagged SPX1 and ΔPHR1 proteins showed that SPX1 is a competitive inhibitor of PHR1 binding to its recognition sequence, and that its efficiency is highly dependent on the presence of Pi or phosphite, a nonmetabolizable Pi analog that can repress PSRs. The relative strength of the SPX1/PHR1 interaction is thus directly influenced by Pi, providing a link between Pi perception and signaling. © 2014, National Academy of Sciences. All rights reserved.
Garcia-Fraile P.,University of Salamanca |
Garcia-Fraile P.,John Innes Center |
Carro L.,University of Salamanca |
Robledo M.,University of Salamanca |
And 16 more authors.
PLoS ONE | Year: 2012
The biofertilization of crops with plant-growth-promoting microorganisms is currently considered as a healthy alternative to chemical fertilization. However, only microorganisms safe for humans can be used as biofertilizers, particularly in vegetables that are raw consumed, in order to avoid sanitary problems derived from the presence of pathogenic bacteria in the final products. In the present work we showed that Rhizobium strains colonize the roots of tomato and pepper plants promoting their growth in different production stages increasing yield and quality of seedlings and fruits. Our results confirmed those obtained in cereals and alimentary oil producing plants extending the number of non-legumes susceptible to be biofertilized with rhizobia to those whose fruits are raw consumed. This is a relevant conclusion since safety of rhizobia for human health has been demonstrated after several decades of legume inoculation ensuring that they are optimal bacteria for biofertilization. © 2012 Garcia-Fraile et al.
Gutierrez J.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca |
Gonzalez-Perez S.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca |
Garcia-Garcia F.,National Institute for Bioinformatics |
Lorenzo O.,Centro Hispano Luso Of Investigaciones Agrarias |
Arellano J.B.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca
Plant Signaling and Behavior | Year: 2011
Can Arabidopsis cell suspension cultures (ACSC) provide a useful working model to investigate genetically-controlled defense responses with signaling cascades starting in chloroplasts? In order to provide a convincing answer, we analyzed the early transcriptional profile of Arabidopsis cells at high light (HL). The results showed that ACSC respond to HL in a manner that resembles the singlet oxygen ( 1O 2)-mediated defense responses described for the conditional fluorescent (flu) mutant of Arabidopsis thaliana. The flu mutant is characterized by the accumulation of free protochlorophyllide (Pchlide) in plastids when put into darkness and the subsequent production of 1O 2 when the light is on. In ACSC, 1O 2 is produced in chloroplasts at HL when excess excitation energy flows into photosystem II (PSII). Other reactive oxygen species are also produced in ACSC at HL, but to a lesser extent. When the HL stress ceases, ACSC recovers the initial rate of oxygen evolution and cell growth continues. We can conclude that chloroplasts of ACSC are both photosynthetically active and capable of initiating 1O 2-mediated signaling cascades that activate a broad range of genetically-controlled defense responses. The upregulation of transcripts associated with the biosynthesis and signaling pathways of OPDA (12-oxophytodienoic acid) and ethylene (ET) suggests that the activated defense responses at HL are governed by these two hormones. In contrast to the flu mutant, the 1O 2-mediated defense responses were independent of the upregulation of EDS1 (enhanced disease susceptibility) required for the accumulation of salicylic acid (SA) and genetically-controlled cell death. Interestingly, a high correlation in transcriptional expression was also observed between ACSC at HL, and the aba1 and max4 mutants of Arabidopsis, characterized by defects in the biosynthesis pathways of abscisic acid (ABA) and strigolactones, respectively. © 2011 Landes Bioscience.
Brocca L.,CNR Research Institute for Geo-hydrological Protection |
Massari C.,CNR Research Institute for Geo-hydrological Protection |
Ciabatta L.,CNR Research Institute for Geo-hydrological Protection |
Moramarco T.,CNR Research Institute for Geo-hydrological Protection |
And 6 more authors.
Journal of Hydrology and Hydromechanics | Year: 2015
Rain gauges, weather radars, satellite sensors and modelled data from weather centres are used operationally for estimating the spatial-temporal variability of rainfall. However, the associated uncertainties can be very high, especially inoorly equipped regions of the world. Very recently, an innovative method, named SM2RAIN, that uses soil moisture observations to infer rainfall, has beenroposed by Brocca et al. (2013) with veryromising results when applied with in situ and satellite-derived data. However, a thorough analysis of thehysical consistency of the SM2RAIN algorithm has not been carried out yet. In this study, synthetic soil moisture data generated from ahysically-based soil water balance model are employed to check the reliability of the assumptions made in the SM2RAIN algorithm. Next, high quality and multiyear in situ soil moisture observations, at different depths (5-30 cm), and rainfall for ten sites across Europe are used for testing theerformance of the algorithm, its limitations and applicability range. SM2RAIN shows very high accuracy in the synthetic experiments with a correlation coefficient, R, between synthetically generated and simulated data, at daily time step, higher than 0.940 and an average Bias lower than 4%. When real datasets are used, the agreement between observed and simulated daily rainfall is slightly lower with average R-values equal to 0.87 and 0.85 in the calibration and validationeriods, respectively. Overall, theerformance is found to be better in humid temperate climates and for sensors installed vertically. Interestingly, algorithms of different complexity in the reproduction of the underlying hydrologicalrocessesrovide similar results. The average contribution of surface runoff and evapotranspiration components amounts to less than 4% of the total rainfall, while the soil moisture variations (63%) and subsurface drainage (30%) termsrovide a much higher contribution. Overall, the SM2RAIN algorithm is found toerform well both in the synthetic and real data experiments, thus offering a new and independent source of data for improving rainfall estimation, and consequently enhancing hydrological, meteorological and climatic studies.