Amelioration of saline stress on chia (Salvia hispanica L.) seedlings inoculated with halotolerant plant growth-promoting bacteria isolated from hypersaline

The rhizosphere and microbiome of halotolerant plants could be crucial for alleviating salinity stress during plant growth. The aims of this work were (1) to isolate bacteria from rhizosphere and bulk soil samples from the Salar del Hombre Muerto (Catamarca, Argentina), (2) to characterize different plant growth-promoting (PGP) activities produced by these bacterial isolates, and (3) to evaluate their effect on the initial growth of chia (Salvia hispanica L.) under saline stress. A total of 667 microorganisms were isolated, using different culture media with NaCl, and their abilities for nitrogen fixation, phosphate solubilization, siderophores production, and indole-3-acetic acid production were evaluated. Thirteen strains were selected for showing all the tested PGP activities; they belonged to the genera Kushneria, Halomonass, Pseudomonas, Planomicrobium, and Pseudarthrobacter. The strains Kushneria sp. and Halomonas sp. showed the highest salinity tolerance (from 50 to 2,000 mM NaCl) and biomass and biofilm production. Chia seeds were treated with six of the first 13 selected strains to evaluate their plant growth-promoting effect under saline stress (without and with 50 and 100 mM NaCl). Halomonas sp. 3R.12 and Kushneria sp. T3.7 produced heavier seedlings with a balanced shoot/root length ratio, while Pseudomonas sp. AN23 showed the best effect upon chia seedlings, with a morphological response similar to non-stressed seedlings. On the other hand, seedlings displayed no responses when inoculated with Planomicrobium sp. 3S.31 and Pseudarthrobacter sp. ER25. This study contributes to the knowledge on microorganisms from hypersaline environments as plant growth promoters for their use in the production of salt-sensitive crops, among other potential uses.Fil: Yañez Yazlle, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Romano Armada, Neli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Rajal, Verónica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Irazusta, Verónica Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentin

Potential of bioremediation and PGP traits in streptomyces as strategies for bio-reclamation of salt-affected soils for agriculture

Environmental limitations influence food production and distribution, adding up to global problems like world hunger. Conditions caused by climate change require global efforts to be improved, but others like soil degradation demand local management. For many years, saline soils were not a problem; indeed, natural salinity shaped different biomes around the world. However, overall saline soils present adverse conditions for plant growth, which then translate into limitations for agriculture. Shortage on the surface of productive land, either due to depletion of arable land or to soil degradation, represents a threat to the growing worldwide population. Hence, the need to use degraded land leads scientists to think of recovery alternatives. In the case of salt-affected soils (naturally occurring or human-made), which are traditionally washed or amended with calcium salts, bio-reclamation via microbiome presents itself as an innovative and environmentally friendly option. Due to their low pathogenicity, endurance to adverse environmental conditions, and production of a wide variety of secondary metabolic compounds, members of the genus Streptomyces are good candidates for bio-reclamation of salt-affected soils. Thus, plant growth promotion and soil bioremediation strategies combine to overcome biotic and abiotic stressors, providing green management options for agriculture in the near future.Fil: Romano Armada, Neli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingeniería; ArgentinaFil: Yañez Yazlle, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Irazusta, Verónica Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto Geonorte; ArgentinaFil: Rajal, Verónica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingeniería; Argentina. Nanyang Technological University; SingapurFil: Moraga, Norma Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingeniería; Argentin

Halotolerant bacteria isolated from extreme environments induce seed germination and growth of chia (Salvia hispanica L.) and quinoa (Chenopodium quinoa Willd.) under saline stress

The aim of the study was to characterize halotolerant bacteria and to evaluate their plant growth promotion potential on chia and quinoa seedlings under saline stress. Isolated microorganisms were evaluated for nitrogen fixation, phosphate solubilization, and production of siderophores and indole acetic acid. Three strains and two consortia were selected: Halomonas sp. (SFS), Micrococcus luteus (SA211), Bacillus sp. (HX11), C1 (SA211 + SFS), and C2 (SA211 + HX11). In vitro assays using water agar and half-strength Murashige-Skoog plates showed that an increase in salinity led to an increased seedlings mortality and a decrease in germination (lower than 40%), in total length (varying between 16% and 87% decreases), root length (from 60% to 92% lesser length) and dry weight (from 7% to 86% lower weight). Also, the relative growth index (RGI) decreased for both crops in most treatments, except those with HX11 and C2. These treatments had the highest growth parameters and RGI values in presence of high salinity in chia (50 and 100 mmol/L NaCl) and quinoa (200 and 400 mmol/L NaCl). SA211, the highest producer of indole acetic acid, showed a detrimental effect and anomalous phenotype on plants. Our results suggest that Bacillus sp. HX11, with multiple plant growth promotion traits and tolerance to saline stress, has a great potential as a bioinoculant in saline conditions and could be used as a biofertilizer for crop production.Fil: Yañez Yazlle, Maria Florencia. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Romano Armada, Neli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Acreche, Martin Moises. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Salta-Jujuy. Estación Experimental Agropecuaria Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Rajal, Verónica Beatriz. Nanyang Technological University; Singapur. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Irazusta, Verónica Patricia. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentin

Following the steps towards glyphosate bioremediation. How close are we to field success?

Glyphosate-based herbicides (GBH) are used in agriculture either for cropping glyphosate-resistant species or to control weeds in various crops, from herbaceous plants like tomatoes to trees such as vines and even forest plantations. Their extensive use exposes the land surface and water bodies to the herbicide, posing a risk to non-target organisms worldwide. GBH’s are broken down in the environment by the whole soil or water microbiome. There is incomplete understanding of different bacterial groups´ roles in this process Although not every single species can be isolated, its functional profile or metabolism counts. A species can be removed from the ensemble without a major negative impact on the overall process, as long as other microorganisms perform that same function. We currently have some insight into what single bacteria do when degrading glyphosate. In fact, the classic approach for bioremediation consists of isolating and studying the removal potential of single type of microorganism. Using this approach, investigators have identified the aminomethylphosphonic acid (AMPA) and sarcosine pathway as a primary route of glyphosate breakdown. However, there remains a need for a glyphosate removal strategy that mimics natural microbiomes’ action to avoid glyphosate pseudo persistence by accumulation in the environment.Fil: Romano Armada, Neli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Rajal, Verónica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentin

Construction of a combined soil quality indicator to assess the effect of glyphosate application

Although the use of agrochemicals allowed increasing the crops productivity, in many cases led to soil deterioration. In this study, eight composite samples from different soils of two locations (San Martín and Anta) in Salta, Argentina, were collected and analyzed. All the samples were from loamy Entisols (0–20 cm depth) under reduced tillage without and with direct spray application of glyphosate. Twenty six variables were determined (physical, chemical, and biological soil quality indicators). From them, those of higher specificity and sensitivity to changes following glyphosate application were identified by a stepwise reduction of variables aided by statistical analysis. Samples were grouped regarding location and application of glyphosate, to identify differential effects upon variables, and glyphosate sensitive variables were selected by discarding those influenced by other factors. Thence, they were used to compose a first approximation to a combined soil quality indicator (CSQI) to assess the effect of glyphosate use in agriculture upon the soil. Overall, the set of physical variables showed the same discriminating structure as the biological set. Finally, two biological, two chemical, and two physical indicators resulted as the most specific to quality variations by the application of the herbicide, being the most sensitive the microbial biomass carbon and the (Aminomethyl)phosphonic acid concentration in soil. When these two were considered into a CSQI, it was possible to discriminate samples with the application of glyphosate (lower quality) from those without application (higher quality). To the best of our knowledge, this is the first attempt to propose a CSQI that could play an important role to prevent degradation in soils subjected to glyphosate application, as it could aid in the early detection of soil quality loss. This would provide to land managers a decision tool to let the land rest from glyphosate application, to ensure sustainable practices in agriculture.Fil: Romano Armada, Neli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingeniería; ArgentinaFil: Amoroso, Maria Julia del R.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Rajal, Verónica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingeniería; Argentina. Nanyang Technological University.; Singapu

Effect of glyphosate application on soil quality and health under natural and zero tillage field conditions

Agriculture is a primary source of income in several countries, including Argentina. Among the many agrochemicals used, glyphosate-based herbicides raised controversy, encouraging research to clarify if the benefits of their use outweigh their alleged harmfulness. In this spirit, this study assessed soil quality indicators on glyphosate-sprayed fields under natural (NC) and zero tillage conditions (ZT) in Northwest Argentina, to analyze the effect of the herbicide application on soil degradation. The ZT soils underwent five years of continuous spraying (2-4 times a year) after land clearing, while the NC soil, without any laboring practices, was subjected to two consecutive applications. Among the measured indicators (physical, chemical, and biological), water-stable aggregates (WSA), particulate organic matter (POM) and dehydrogenase activity (DHA) showed quality differences between ZT and NC samples. The highest values were found in NC (WSA 72%; POM 4.9%; DHA 1460 mg TPF/gsoil/d) and the lowest in ZT (WSA 13%; POM 1.69%; DHA 180 mg TPF/gsoil/d); showing a lower quality in ZT regarding structure stability, nutrient availability and microbial activity. A Discriminant Analysis revealed that as glyphosate application increased, the overall soil quality decreased within the NC samples, resembling that of ZT. Thus, soil health deterioration was attributed solely to glyphosate spraying in NC. Furthermore, multivariate analysis allowed identification of chemical indicators as of higher sensitivity to the short-term response after application, and biological indicators as more sensitive to long-term changes. The quality decline in time in the NC soil, caused by the use of glyphosate-based herbicides, could endanger the soils sustainability.Fil: Romano Armada, Neli. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingenieria; ArgentinaFil: Amoroso, Maria Julia del R.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Rajal, Verónica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentina. Universidad Nacional de Salta. Facultad de Ingenieria; Argentin

In vivo light sheet fluorescence microscopy of calcium oscillations in arabidopsis thaliana

Calcium imaging in plants requires a high-resolution microscope, able to perform volumetric acquisition in a few seconds, inducing as low photobleaching and phototoxicity as possible to the sample. Light sheet fluorescence microscopy offers these capabilities, with the further chance to mount the sample in vertical position, mimicking the plant’s growth and physiological conditions. A protocol for plant preparation and mounting in a light sheet microscope is presented. First, the growth of Arabidopsis thaliana in a sample holder compatible with light sheet microscopy is described. Then, the requirements for sample alignment and image acquisition are detailed. Finally, the image processing steps to analyze calcium oscillations are discussed, with particular emphasis on ratiometric calcium imaging in Arabidopsis root hairs