Content uploaded by Cecilia Creus
Author content
All content in this area was uploaded by Cecilia Creus on May 25, 2014
Content may be subject to copyright.
A preview of the PDF is not available
Water relations and yield in Azospirillum- inoculated wheat exposed to drought in the field
Abstract
There are scarce data connecting water relations in Azospirillum-inoculated wheat suffering drought during anthesis with the yield and mineral content of grains. Azospirillum brasilense Sp245-inoculated seeds of Triticum aestivum 'Pro INTA Oasis' were sown in nonirrigated and control plots. Water potential, water content, and relative water content were determined on flag leaves. Plant water status was calculated from pressure-volume curves. At maturity, grain yield and its components were determined. P, Ca, Mg, K, Fe, Cu, and Zn were determined in dried grains. Even though the cultivar underwent osmotic adjustment, significantly higher water content, relative water content, water potential, apoplastic water fraction, and lower cell wall modulus of elasticity values were obtained in Azospirillum-inoculated plants suffering drought Grain yield loss to drought was 26.5% and 14.1% in noninoculated and Azospirillum-inoculated plants, respectively. Grain Mg and K diminished in nonirrigated, noninoculated plots. However, grains harvested from Azospirillum-inoculated plants had significantly higher Mg, K, and Ca than noninoculated plants. Neither drought nor inoculation changed grain P, Cu, Fe, and Zn contents. A better water status and an additional "elastic adjustment" in Azospirillum-inoculated wheat plants could be crucial in promoting higher grain yield and mineral quality at harvest, particularly when drought strikes during anthesis.
... Furthermore, certain strains of Rhizobium bacteria produce cytokinins that facilitate nodule formation and growth in leguminous plants [59]. From these findings, one can conclude Increased the length of potato tubers and sprouting capacity [39] Pseudomonas fluorescens increased the length of coleoptiles of avena [40] Pseudomonas fluorescens and Bacillus subtilis increase root length, shoot length, root and shoot fresh and dry weight, on bacterial inoculated onion seeds [41] Klebsiella strains significantly increased root and shoot length of inoculated wheat seedlings [42] Bacillus megaterium, Lactobacillus casei, Bacillus subtilis, Bacillus cereus, and Lactobacillus acidophilus, increased growth and yield of wheat and maize [43] Enterobacter spp. ...
... For instance, a study by Kumar et al. [42] demonstrated that B. pumilus treatment increased JA levels in rice plants, leading to enhanced disease resistance and overall plant growth. A study by Creus et al. [43] demonstrated that A. brasilense treatment increased JA synthesis in maize plants, leading to improved root growth, nutrient uptake, and overall plant growth. Jasmonic acid stimulates the production of secondary metabolites, such as phenols, flavonoids, and defense-related compounds. ...
Phytohormone-producing rhizobacteria are a group of beneficial bacteria residing in the rhizosphere that have the unique ability to produce, release, and also modulate phytohormones such as auxins, cytokinins, gibberellins, ethylene, and jasmonic acid (JA). This work explores a diverse group of rhizobacteria that possess the ability to synthesize and secrete phytohormones and their effects on the growth of different plants. Indole-3-acetic acid (IAA) is a commonly produced hormone by many rhizobacteria that include Azospirillum brasilense, Pseudomonas putida, and Pseudomonas fluorescens. IAA producers promote plant growth through multiple mechanisms. Gibberellic acid (GA3) produced by certain species of rhizobacteria, which include Serratia marcescens and Bacillus licheniformis, enhances plant height and biomass in different crops. Cytokinins are produced by rhizobacteria, including Bacillus, Pseudomonas, and Azospirillum. Few rhizobacteria strains also produce abscisic acid (ABA). For example, A. brasilense produces abscisic acid, which can regulate the plant water status and enhance drought tolerance in different crops. Several rhizobacteria, including P. fluorescens, P. putida, and Pseudomonas aeruginosa, have been reported to induce JA production in plants, promoting defense responses against pathogens. Overall, this work indicates that rhizobacteria produce key phytohormones, enabling them to promote plant growth through multifarious ways, and hence phytohormone-producing rhizobacteria are potential input in agricultural production.
... The effect of PGPB is significant in the presence of water (Casanovas et al., 2002). According to (Creus et al., 2011) , the inoculation of Azospirillum under water scarceness reduced the yield of wheat and increased the ion contents, such as magnesium (Mg2+), potassium (K+), and calcium (Ca2+), in grains. ...
This is an Open Access Journal / article distributed under the terms of the Creative Commons Attribution License (CC BY-NC-ND 3.0) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. All rights reserved. In the climate changes scenario the drought has been diagnosed as major stress affecting crop productivity. Drought is the most hazardous abiotic stress causing huge losses to crop yield worldwide. Osmotic stress decreases relative water and chlorophyll content and increases the accumulation of osmolytes, epicuticular wax content, antioxidant enzymatic activities, reactive oxygen species, secondary metabolites, membrane lipid peroxidation, and abscisic acid. Plant growth-promoting rhizobacteria (PGPR) eliminate the effect of drought stress by altering root morphology, regulating the stress-responsive genes, producing phytohormones, osmolytes, siderophores, volatile organic compounds, and exopolysaccharides. This review deals with recent progress on the use of PGPR to eliminate the harmful effects of drought stress in traditional agriculture crops.
... Our results suggest that environmental influence have a substantial impact on liquid formulations, which may explain why it fluctuates from year to year. The effects of inoculating cereals with growth promoter bacteria have been extensively studied throughout the world ( Okon and Labandera-Gonzalez 1994;Garcia De Salamone et al. 1996;Creus et al. 2004;Díaz-Zorita and Fernández-Canigia 2009). However, the probability of a positive response to an inoculant is a function of the frequency of the response at multiple field locations, as well as the magnitudes of those responses. ...
by inoculation also varied depending on the environment. The weight of thousand grains explained the increase in yield at high yielding potential environment, whereas the number of grains explained the increase at lower yielding environment. The evidence collected here demonstrates that chitosan/starch beads are suitable for delivery of bacteria consortia as inoculants and more efficient than liquid inoculation, broadening the range of inoculant applications to diverse geographic areas and crop management
... Marulanda et al. (2009), reported the survival of plants under drought stress inoculated with IAA producing Pseudomonas putida. Maize (Cohen et al., 2009) and wheat (Creus et al., 2004) plants had better survival under drought stress when inoculated with the GA producing, Azospirillum lipoferum. Inoculation of cytokinin producing Bacillus subtilis improved shoot cytokinins in lettuce under water stress conditions (Arkhipova et al., 2007). ...
... The higher level of ethylene production in the cell is sensed by different receptors, which triggers some cellular responses as well [73]. Not only ACC deaminase producing PGPR are involved in the alteration the root morphology, but nitric oxide producing bacteria such as Azospirillum sp. may also affect the root morphology [74][75]. ...
The food and nutritional security of the increasing human population is one of the biggest challenges of the present century. Various kinds of plant stresses (due to different biotic and abiotic causes) are one of the major limiting factors for the increase in crop productivity. Out of the various methods tried to overcome the adverse effects of the different plant stresses, the use of plant growth-promoting bacteria has been established as a potential method to reduce the adverse effects of plant stress in an ecologically sustainable manner. The treatment of a PGPR may be combined with another PGPR species (one or more) to get a more desirable outcome. Further, the combination of PGPR with the other soil-inhabiting micro- and macro-organisms has also been found effective. These combinations include the use of mycorrhizal fungi and microalgae as microorganisms and earthworms as the macro-organisms; along with one or more PGPR species. The present chapter, therefore, is an attempt to explore the potential of these combinations of PGPR with other compatible soil micro- and macro-organisms as a better stress ameliorating treatment than the treatment with a PGPR species alone in overcoming the adverse effects of different plant stresses. Moreover, the combination approach can also be
helpful in improving the soil properties, reducing the use of agrochemicals in an ecologically sustainable manner besides improving crop productivity under stressful environments.
... Such bacteria are also capable to promote growth by suppressing fungus through antagonistic effect (Puri et al., 2018) siderophore production and antibiotics (Dunne et al., 1997). Mechanism of increment in growth bolstered by diazotrophs could be through phytohormone production, stress resistance power build-up, nutrient uptake, improved water status (Creus et al., 2004) and ammonium secretion (Aguilar et al., 1998). Various studies under pot and field conditions suggested endophytes from cereals possess biofertilization property. ...
The present study was conducted to study the nifH gene containing endophytic bacterial frequency in wheat seed and roots obtained from the soil of Chitwan and Kaski. One hundred and four isolates were studied for the presence of the nifH gene. There was a diversity in isolate characters obtained from root sample Root (R), direct seed sample (ds), and plant sample (P). None of the isolates from any sources showed indole-producing ability. About 18 isolates (15% of the total) contained the nifH gene through amplification of the gene by universal primers PolF and PolR. About 6 isolates from seed sample ds and 12 isolates from root sample R contained nifH gene. None of the isolates from root sample P manifested the presence of the nifH gene. Among 18 nifH-containing isolates, only 6 isolates manifested presence of cel3 gene of 400 bp, whereas, 11 isolates showed cel3 gene of 200 bp. All nifH gene containing isolates were confirmed to be bacteria by PCR amplification of 16s rRNA gene by universal primer 27F and 1492R and visualization of agarose gel matrix with bp range of approximately 530 under UV ray. Further research scope exists to use these microbes as a bio fertilizer in plant growth promotion studies by inoculation.
This volume is a compilation of reviews on the industrial usage of soil microorganisms. The contents include 16 brief reviews on different soil microbe assisted industrial processes. Readers will be updated about recent applications of soil bacteria, fungi and algae in sectors such as agriculture, biotechnology, environmental management.
The reviews also cover special topics like sustainable agriculture, biodiversity, ecology, and intellectual property rights of patented strains, giving a broad perspective on industrial applications of soil microbes.
Volume 3 emphasizes various soil microorganisms including cyanobacteria and mycorrhiza. The 16 chapters cover the ecological significance of mycorrhiza to and their role in sustainable agriculture, microbial interactions with nematodes, microbes as biocontrol agents, and the use of endophytes in agriculture, Chapters also shed light on industrial aspects and microbial biotransformation, providing a comprehensive view of sustainable agricultural practices. Special topics such as the microbial carotenoids are also included.
In order to capture the drought impacts on seed quality acquisition in Brassica napus and its potential interaction with early biotic stress, seeds of the ‘Express’ genotype of oilseed rape were characterized from late embryogenesis to full maturity from plants submitted to reduced watering (WS) with or without pre‐occurring inoculation by the telluric pathogen Plasmodiophora brassicae (Pb + WS or Pb, respectively), and compared to control conditions (C). Drought as a single constraint led to significantly lower accumulation of lipids, higher protein content and reduced longevity of the WS‐treated seeds. In contrast, when water shortage was preceded by clubroot infection, these phenotypic differences were completely abolished despite the upregulation of the drought sensor RD20 . A weighted gene co‐expression network of seed development in oilseed rape was generated using 72 transcriptomes from developing seeds from the four treatments and identified 33 modules. Module 29 was highly enriched in heat shock proteins and chaperones that showed a stronger upregulation in Pb + WS compared to the WS condition, pointing to a possible priming effect by the early P. brassicae infection on seed quality acquisition. Module 13 was enriched with genes encoding 12S and 2S seed storage proteins, with the latter being strongly upregulated under WS conditions. Cis‐element promotor enrichment identified PEI1/TZF6, FUS3 and bZIP68 as putative regulators significantly upregulated upon WS compared to Pb + WS. Our results provide a temporal co‐expression atlas of seed development in oilseed rape and will serve as a resource to characterize the plant response towards combinations of biotic and abiotic stresses.
The present study was conducted to determine the effect of osmotic stress on the plant growth hormone production by six osmotolerant plant growth promoting bacterial strains. These strains originated from the phytomicrobiome of chilli cultivated in the drought prone areas of Andhra Pradesh. They possessed multiple plant growth promotion traits including the ability to produce a variety of plant growth hormones. The effect of osmotic stress on the plant growth hormone production was determined by High Performance Liquid Chromatography (HPLC) under normal and in vitro osmotic stress conditions using 25% Poly Ethylene Glycol (PEG) 8000. In general, it was observed that osmotic stress impacted the plant growth hormone production of the isolates, but nevertheless plant hormones were detected in all the bacterial strains. An exception to this was the cytokinin molecule zeatin riboside, which was produced at higher levels by five of the six bacterial isolates under osmotic stressed conditions.
Some of the measures suggested for amelioration of drought effects include application of N fertilizer and plant growth regulators (PGRs). Since N2-fixing bacteria produce plant growth substances (PGRs), the effect of foliar application of an active strain of Klebsiella sp. (KUPOS) on IR-50 rice was examined using three foliar sprays applied at 10-day intervals. Irrigation once every 3 days was essential for plant growth. Application of KUPOS and 40 kg N ha-1 improved grain yield of acutely water stressed plants from 330 kg ha-1 to more than 1300 kg ha-1 along with an improvement in several growth variables and yield determinants. Indole acetic acid, kinetin and GA3, in a mixture of 10-4M of each, were less effective than KUPOS in alleviating stress effects. The adverse effects of water stress on respiration and photosynthesis as indicated by CO2 exchange were also alleviated by these treatments. While uptake of K, Mg, Ca, Fe and Mo was increased, Na content decreased, accompanied by an increase in proline content. The order of effectiveness of the treatments was 40 kg N ha-1 >KUPOS>PGRs.
Water‐stressed pigeonpea leaves have high levels of osmotic adjustment at low leaf water potentials. The possible contribution of this adjustment of dehydration tolerance of leaves was examined in plants grown in a controlled environment. Osmotic adjustment was varied by withholding water from plants growing in differing amounts of soil, which resulted in different rates of decline of leaf water potential. The level of osmotic adjustment was inversely related to leaf water potential in all treatments. In addition, at any particular water potential, plants that had experienced a rapid development of stress exhibited less osmotic adjustment than plants that experienced a slower development of stress. Leaves with different levels of osmotic adjustment died at water potentials between –3.4 and –6.3 MPa, but all leaves died at a similar relative water content (32%). Consequently, leaves died when relative water content reached a lethal value, rather than when a lethal leaf water potential was reached. Osmotic adjustment delayed the time and lowered the leaf water potential when the lethal relative water content occurred, because it helped maintain higher relative water contents at low leaf water potentials. The consequences of osmotic adjustment for leaf survival in water‐stressed pigeonpea are discussed.
Four field experiments were carried out with wheat or sorghum in different regions of Brazil. The aim was to study the establishment of inoculated Azospirillum strains, marked with resistance to various antibiotics, in the rhizosphere and in roots. The levels of the various antibiotics were chosen according to the resistance of the indigenous Azospirillum population. Azospirillum brasilense strains Sp 107 and Sp 245 could be established in all three wheat experiments and predominated within the Azospirillum population in washed, and especially in surface sterilized, roots. Strains Sp 7 and Cd established poorly in wheat roots. Azospirillum lipoferum Sp S82 represented 72% of the root isolates from sorghum inoculated with this strain. This strain and natural Azospirillum infection became concentrated in the upper parts of the root system. Improved methods for root surface sterilization in which the absence of Azospirillum on the root surface was established by pre-incubating roots with paraffin-capped ends in NFb medium confirmed the establishment of inoculated Azospirillum strains within sorghum roots in the field.
As already explained in the previous chapter, generally the water potential, Ψ, of a plant cell is expressed as the sum of three components, as follows (Dainty 1976): $$psi = P + \pi + \tau$$ (2.1) where P, π and τ are the pressure, osmotic and matric potentials, respectively. In a tissue or organ, Eq. (2.1) applies to each cell individually but if different cells have different solute concentrations, moduli of elasticity or volumes of apoplasmic water, then even at equilibrium the cellular values of P, π and τ may differ from cell to cell. Although measurements of π have frequently been made on individual cells using plasmolytic methods and measurements of P have recently been made on individual cells of higher plants using the pressure probe (Steudle et al. 1975; Hüsken et al. 1978, 1980), it is in general not practical to make a large number of such measurements in the tissues and organs of higher plants. In spite of this problem Tyree and Hammel (1972) have argued that it is meaningful to define bulk values of the water relations parameters to characterize the water relations properties of tissues and organs.