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The effect of sodium bicarbonate on plant performance and iron acquisition system of FA-5 (Forner-Alcaide 5) citrus seedlings
Abstract
This work studies the effect of bicarbonate on plant performance and the iron acquisition system of Forner-Alcaide 5 (FA-5) seedlings, a citrus genotype known for its tolerance to calcareous soils. Plants were irrigated for 6 weeks with or without 10 mM NaHCO3. Treatment significantly decreased shoot growth, photosynthetic levels and iron concentration in shoots and roots. o,o-57FeEDDHA experiments indicated that 57Fe uptake by roots was inhibited in treated plants. Moreover, those seedlings accumulated more 57Fe in roots, and enhanced mRNA accumulation of ferric reductase genes FRO1 and FRO2 and FC-R activity in roots. H+-ATPase activity and HA1 gene expression were also increased, while HA2 was not affected. In addition, expression of the iron transporter gene IRT1 was increased, while IRT2 was not significantly affected. Finally, according to PEPC enzymatic activity, PEPC1 gene expression was higher in treated roots. In conclusion, it appears that bicarbonate prevents medium acidification by roots, thus reducing Fe2+ uptake. Accordingly, Fe deficiency enhanced the expression of some genes related with the Fe acquisition system (IRT1, FRO1, FRO2, HA1 and PEPC1) and the activity of the corresponding enzymes, which appear to constitute an adaptive mechanism of FA-5 in these soils.
... Saline-alkali stress is one of the most serious abiotic stresses affecting plant growth and development (Martínez-Cuenca et al. 2013). Saline-alkali problem seriously affects crop growth and development and has become one of the main environmental factors limiting crop yield (Zhu and Gong 2014). ...
Soil salinization, as one of the major abiotic stress, restricts the development of global agriculture. Transcription factors always act on the upstream of signal transduction to control a wide range of downstream genes, thus effectively participating in the regulation of various abiotic stress tolerance. In this research, based on transcriptome of Malus halliana, we screened out the transcription factor Anthocyanin synthase (ANS, LOC103437326) in flavonoid metabolic pathway which was significantly induced by saline-alkali stress. Quantitative real-time PCR confirmed that the expression of MhANS in the leaves was 17.15% of that of the control (0 h) under12 h of stress. However, the mechanism of its regulation of saline-alkali stress is unclear. Subsequently, the MhANS gene was isolated and its functional characteristics were further studied in Arabidopsis thaliana, tobacco and apple calli. MhANS contains a complete open reading frame with a length of 1074 bp and encodes 357 amino acids with an isoelectric point of 5.82. Phylogenetic tree analysis showed that MhANS had the highest homology and the closest genetic relationship with Pyrus × bretschneideri. In addition, overexpression of MhANS reduced the tolerance of Arabidopsis thaliana, tobacco and apple calli to saline-alkali stress, and caused a variety of biochemical changes: the contents of chla and chlb of transgenic Arabidopsis thaliana and tobacco were significantly lower than those of wild type, while the electrical conductivity was higher than that of wild type. The enzyme activities (SOD, POD, CAT) of transgenic Arabidopsis, tobacco and overexpressed apple calli decreased significantly, while the contents of malondialdehyde and proline increased. Additionally, the growth of overexpressed apple calli was retarded under saline-alkali stress. All results indicated that resistance to saline-alkali stress was weaked due to the overexpression of MhANS. In conclusion, the ANS gene of flavonoid metabolic pathway respond to saline-alkali stress and play a down-regulation role, providing gene for the regulatory network of saline-alkali stress response in apple, aiming to excavate the excellent resistance genes of apple and provide a theoretical basis for the breeding of apple varieties with strong saline-alkali resistance.
... Apple is the most important temperate deciduous fruit all over the world. The northwest loess plateau of China is the world's largest apple production base (Martínez-Cuenca et al. 2013). However, soil salinization in this region has become a major limiting factor for apple growth and production, and continues to worsen around the world (Radanielson et al. 2018). ...
Main conclusion
qRT-PCR analysis showed that MhPR1 was strongly induced by saline-alkali stress. Overexpression of MhPR1 enhanced tolerance to saline-alkali stress in transgenic tobacco (Nicotiana tabacum L.) and apple calli.
Abstract: Soil salinization seriously threaten apple growth in Northwest loess plateau of China. Malus halliana has developed special system to adapt to saline-alkali environmental stress. To obtain a more detailed understanding of the adaptation mechanisms involved in M. halliana, a transcriptomic approach was used to analyze the leaves’ pathways in the stress and its regulatory mechanisms. RNA-Seq showed that among the 16,246 investigated unigenes under saline-alkali stress, 7268 genes were up-regulated and 8978 genes were down-regulated. KEGG analysis indicated that most of the enriched saline-alkali-responsive genes were mainly involved in plant hormone, calcium signal transduction, amino acids, carotenoid and flavonoids biosynthesis, carbon and phenylalanine metabolism, and other secondary metabolites. Expression profile analysis by quantitative real-time PCR confirmed that the maximum up-regulation of MhPR1 under saline-alkali stress was 7.1 folds in leaves. Overexpression of MhPR1 enhanced tolerance to saline-alkali stress in transgenic tobacco (Nicotiana tabacum L.) and apple calli. Taken together, our results demonstrate that MhPR1 encodes a saline-alkali-responsive transcriptional activator and provide valuable information for further study of PR1 functions in apple.
... The presence of HCO 3 − and CO 3 2− and other alkaline salts impart to the buffer capacity of the soil and cause an increase in soil pH, resulting in the precipitation and adsorption of the major plant macro-and micronutrients such as calcium, magnesium, iron and zinc [12,13]. Plants irrigated with water having high alkaline salt concentrations always show chlorosis (due to iron deficiency) of young leaves [14,15], resulting in reduced root growth and uptake or utilization of nutrients. Additionally, higher exchangeable sodium (exchangeable sodium percentage > 15) in the presence of alkaline pH (pH > 8.3) will replace Ca 2+ and Mg 2+ on the soil exchange sites will lead to dispersion of the soil particles [16]. ...
The mechanisms by which plants respond to alkali salt stress are still obscure, and the relevance of alkaline pH under combined alkali salt stress. Early stress responses can indicate mechanisms leading to damage and plant resistance. The apoplast contains essential determinants for plant growth, specifically early apoplastic pH fluctuations are induced by many stressors and hypothesized to be involved in stress signalling. Hence, this study aims to identify fast responses specific to alkaline pH and alkali salt stress by exposing the root of hydroponically grown Vicia faba L. plants to 150 min of either 50 mM NaHCO3 (pH 9) treatment or alkaline pH 9 alone. Apoplastic pH was monitored in real-time by ratiometric fluorescence microscopy simultaneously with SWIR transmission-based measurements of leaf water content (LWC). Moreover, we examined the effect of these stresses on apoplastic, symplastic and xylem ion and metabolite composition together with transcriptions of certain stress-responsive genes. Physiological and transcriptional changes were observed in response to NaHCO3 but not to alkaline pH alone. NaHCO3 elicited a transient reduction in LWC, followed by a transient alkalinization of the apoplast and stomatal closure. Simultaneously, organic acids and sugars accumulated. Fast upregulation of stress-responsive genes showed the significance of gene regulation for early plant adaptation to alkali salt stress.
Data availability
The material used in this study is available for non-commercial research purposes upon reasonable request.
... Plants are exposed to many abiotic stresses, and the most limiting factors for plant growth and development are salinity and alkaline stress [6]. Soil and water salinity and alkalinity are major abiotic stress for agriculture worldwide, causing severe harm to crop development and declining crop productivity [7]. Salinity stress blocks electron transfer from reaction centers (RCs) to plastoquinone [8]. ...
Strawberry is one of the plants sensitive to salt and alkalinity stress. Light quality affects plant growth and metabolic activities. However, there is no clear answer in the literature on how light can improve the performance of the photosynthetic apparatus of this species under salt and alkalinity stress. The aim of this work was to investigate the effects of different spectra of supplemental light on strawberry (cv. Camarosa) under salt and alkalinity stress conditions. Light spectra of blue (with peak 460 nm), red (with peak 660 nm), blue/red (1:3), white/yellow (1:1) (400–700 nm) and ambient light were used as control. There were three stress treatments: control (no stress), alkalinity (40 mM NaHCO 3 ), and salinity (80 mM NaCl). Under stress conditions, red and red/blue light had a positive effect on CO 2 assimilation. In addition, blue/red light increased intrinsic water use efficiency ( WUE i) under both stress conditions. Salinity and alkalinity stress decreased OJIP curves compared to the control treatment. Blue light caused an increase in its in plants under salinity stress, and red and blue/red light caused an increase in its in plants under alkalinity. Both salt and alkalinity stress caused a significant reduction in photosystem II (PSII) performance indices and quantum yield parameters. Adjustment of light spectra, especially red light, increased these parameters. It can be concluded that the adverse effects of salt and alkalinity stress on photosynthesis can be partially alleviated by changing the light spectra.
... For this reason, it is very important to obtain new plant material that is able to face unfavorable situations, such as cold stress. In citrus, the grafting technique is widespread and used to face abiotic stresses [2][3][4][5]. Thus, the selection of a good rootstock is important and depends on the cultivation area [6]. ...
Climate change and global warming are leading to a change in weather patterns toward hot and cold waves. Citrus fruits are a tropical or subtropical crop whose growth is altered by changes in weather patterns. Thus, in the present work, two experiments are evaluated to obtain a screening method to select citrus rootstocks that help us to select new low-temperature-tolerant plant materials. One cold experiment was carried out with the Poncirus trifoliata and Citrus macrophylla rootstocks at 4 °C for 4, 8, 24 and 56 h. A second experiment was performed at 4 °C for 5 days with subsequent acclimatization lasting 0, 5, 10 and 24 h. The expression of the cold response genes CAMTA1, CAMTA3, CAMTA5, CBF1, ICE1 and COR413 IM1 was quantified. The results showed that the best rootstock selection strategy was the second experiment, as a higher expression of the genes CAMTA3, CAMTA5, CBF1 and COR413 IM1 was seen in the tolerant genotype P. trifoliata. We quantified the gene expression of proline biosynthesis P5CS1, dOAT and the proline transporters PROT1 and PROT2; the concentration of the amino acid proline in leaves was also quantified. These results once again showed that the best experiment to differentiate between tolerant and sensitive rootstocks was the second experiment with acclimation time.
... En este ensayo se confirmó que la capacidad de asimilación del hierro en los cítricos es altamente dependiente del pH del suelo. De este modo, se ha observado que la deficiencia de hierro debido a alto pH del medio, provocado por la adición de bicarbonato, induce la deficiencia del elemento en la planta al reducir la capacidad de acidificación de las plantas (Martínez-Cuenca et al., 2013b). Ello activa algunos genes relacionados con la respuesta para aumentar la absorción y transporte del elemento. ...
La deficiencia de hierro es una fisiopatía común en los cítricos de la zona mediterránea
debido al predominio de suelos calizos que tiene importantes repercusiones agronómicas.
El estudio de la absorción con el isótopo no radiactivo 57Fe reveló que la tasa de
absorción aumentó linealmente con la concentración creciente de éste en el sustrato.
Entre patrones, el Cleopatra el patrón con mayor capacidad de absorción, lo que explicaría
su mayor eficiencia y tolerancia a la clorosis. Adicionalmente, el cultivo de plántulas de
cítricos in vitro indicó que la capacidad de asimilación del hierro es altamente dependiente
del pH del suelo, encontrándose un máximo de absorción a pHs ácidos. La extrusión
de protones al medio para solubilizar el ión férrico, así como la liberación o exudación de
ácidos orgánicos se configuraron como estrategias altamente desarrolladas en genotipos
sensibles a la clorosis férrica y más en deficiencia de hierro. Los análisis enzimáticos y
moleculares sugieren que la capacidad de reducción de las formas férricas a ferrosas se
indujo significativamente en condiciones de déficit de hierro, en ambos patrones, y que el
transportador de este elemento al interior de la planta se mostró más activo en el patrón
más sensible, induciéndose su expresión de un modo muy significativo en condiciones
deficitarias.
In crop plants, the physiological basis of dry matter production is dependent on the source-sink concept, where the source is the potential capacity for photosynthesis and the sink is the potential capacity to utilize the photosynthetic products. This review focuses on the current understanding of source-sink relationship in plants, physiological processes involved in transferring photosynthates, the mechanics involved in alternative scenarios and how this relationship influences crop yield and quality of the produce. We represent the constraints associated in coordination between photosynthesis and yield under varying environmental conditions. We also highlight the possibility for manipulating source- sink dynamics to boost yields, as well as the importance of yield and nutritional quality resilience, which has implications for plant breeding techniques. A clear-cut understanding of source-sink relationship and developing well-modularized and highly mechanistic source-sink interaction models that can predict yield for various crops under various conditions, possess greater scope in improving overall agricultural productivity.
This work compares the tolerance to long-term anoxia conditions (35 days) of five new citrus ‘King’ mandarin (Citrus nobilis L. Lour) × Poncirus trifoliata ((L.) Raf.) hybrids (named 0501XX) and Carrizo citrange (CC, Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), the widely used citrus rootstock in Spain. Growth parameters, chlorophyll concentration, gas exchange and fluorescence parameters, water relations in leaves, abscisic acid (ABA) concentration, and PIP1 and PIP2 gene expressions were assessed. With a waterlogging treatment, the root system biomass of most hybrids went down, and the chlorophyll a and b concentrations substantially dropped. The net CO2 assimilation rates (An) and stomatal conductance (gs) lowered significantly due to flooding, and the transpiration rate (E) closely paralleled the changes in gs. The leaf water and osmotic potentials significantly increased in most 0501 hybrids. As a trend, flooding stress lowered the ABA concentration in roots from most hybrids, but increased in the leaves of CC, 05019 and 050110. Under the control treatment (Ct) conditions, most 0501 hybrids showed higher PIP1 and PIP2 expressions than the control rootstock CC, but were impaired due to the flooding conditions in 05019 and 050110. From this study, we conclude that 0501 genotypes develop some adaptive responses in plants against flooding stress such as (1) stomata closure to prevent water loss likely mediated by ABA levels, and (2) enhanced water and osmotic potentials and the downregulation of those genes regulating aquaporin channels to maintain water relations in plants. Although these traits seemed especially relevant in hybrids 050110 and 050125, further experiments must be done to determine their behavior under field conditions, particularly their influence on commercial varieties and their suitability as flooding-tolerant hybrids for replacing CC, one of the main genotypes that is widely used as a citrus rootstock in Spain, under these conditions.
Due to climate change, we are forced to face new abiotic stress challenges like cold and heat waves that currently result from global warming. Losses due to frost and low temperatures force us to better understand the physiological, hormonal, and molecular mechanisms of response to such stress to face losses, especially in tropical and subtropical crops like citrus fruit, which are well adapted to certain weather conditions. Many of the responses to cold stress that are found are also conserved in citrus. Hence, this review also intends to show the latest work on citrus. In addition to basic research, there is a great need to employ and cultivate new citrus rootstocks to better adapt to environmental conditions.
Main Conclusion
51 MdbZIP genes were identified from the apple genome by bioinformatics methods. MhABF-OE improved tolerance to saline–alkali stress in Arabidopsis, indicating it is involved in positive regulation of saline–alkali stress response.
Abstract
Saline–alkali stress is a major abiotic stress limiting plant growth all over the world. Members of the bZIP family play an important role in regulating gene expression in response to many kinds of biotic and abiotic stress, including salt stress. According to the transcriptome data, 51 MdbZIP genes responding to saline–alkali stress were identified in apple genome, and their gene structures, conserved protein motifs, phylogenetic analysis, chromosome localization, and promoter cis-acting elements were analyzed. Based on transcriptome data analysis, a MdbZIP family gene (MD15G1081800), which was highly expressed under stress, was selected to isolate and named as MhABF. Expression profile analysis by quantitative real-time PCR confirmed that the expression of MhABF in the leaves of Malushalliana was 10.6-fold higher than that of the control (0 days) after 2 days of stress. Then an MhABF gene was isolated from apple rootstock M.halliana. CaMV35S promoter drived MhABF gene expression vector was constructed to infect Arabidopsis with Agrobacterium-mediated infection. And overexpression MhABF gene plants were obtained. Compared with wild type, transgenic plants grew better under saline–alkali stress and the MhABF-OE lines showed higher chlorophyll content, POD, SOD and CAT activity, which indicated that they had strong resistance to stress. These results indicate that MhABF plays an important role in plant resistance to saline–alkali stress, which lays a foundation for further study on the functions in apple.
This chapter reviews iron nutrition of plants in calcareous soils. Many agricultural crops worldwide, especially in semiarid climates, suffer from iron deficiencies. Deficiencies are usually recognized by chlorotic, or yellowed, intervein areas in new leaves and are typically found among sensitive crops grown in calcareous soils. Iron deficiency in extreme cases may lead to complete crop failure. Two principal methods of treating iron deficiencies are accepted. Spraying foliage with inorganic salts has been shown to be of benefit, but often gives spotty results because of, limited penetration of iron into leaves. Also, repeated treatments are required during the course of canopy development. Soil treatment with synthetic chelates, principally FeEDDHA (ethylenediaminedi–o–hydroxyphenylacetic acid), has been found to be an unqualified success, but for the drawback of their high costs. Iron deficiency in plants causes chlorosis of leaf tissue because of inadequate chlorophyll synthesis. In a healthy plant, 60% of all leaf iron is concentrated in chloroplasts. The exact role of iron in chlorophyll synthesis is not certain but there is evidence of the involvement of ferrous iron in the condensation of succinic acid and glycine to form γ-aminolevulinic acid. Magnesium is incorporated into the molecule to form chlorophyll, possibly with the catalytic action of iron.
An understanding of the mineral nutrition of plants is of fundamental importance in both basic and applied plant sciences. The Second Edition of this book retains the aim of the first in presenting the principles of mineral nutrition in the light of current advances. This volume retains the structure of the first edition, being divided into two parts: Nutritional Physiology and Soil-Plant Relationships. In Part I, more emphasis has been placed on root-shoot interactions, stress physiology, water relations, and functions of micronutrients. In view of the worldwide increasing interest in plant-soil interactions, Part II has been considerably altered and extended, particularly on the effects of external and interal factors on root growth and chapter 15 on the root-soil interface. The second edition will be invaluable to both advanced students and researchers.
A protein determination method which involves the binding of Coomassie Brilliant Blue G-250 to protein is described. The binding of the dye to protein causes a shift in the absorption maximum of the dye from 465 to 595 nm, and it is the increase in absorption at 595 nm which is monitored. This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr. There is little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose. A small amount of color is developed in the presence of strongly alkaline buffering agents, but the assay may be run accurately by the use of proper buffer controls. The only components found to give excessive interfering color in the assay are relatively large amounts of detergents such as sodium dodecyl sulfate, Triton X-100, and commercial glassware detergents. Interference by small amounts of detergent may be eliminated by the use of proper controls.
The effect of bicarbonate and selected metal ions on the development of enhanced root Fe(III) reducing capacity (a response to Fe deficiency of dicotyledons) was studied in young plants of cucumber (Cucumis sativus L. cv. Ashley) grown in nutrient solution. Pretreatment of 11-day-old Fe-deficient cucumber plants with 20 mM NaHCO3, for at least 23 h prior to determination of root Fe(III) reducing capacity, markedly inhibited this response. The inhibitory effect of bicarbonate could be partly reversed by a 4- to 8-h treatment with either 10 mu M MnSO4, 10 mu M FeEDDHA, 2 mu M ZnSO4, 0.5 mu M NiCl2, or 0.25 mu M CoSO4 (final concentrations), added to the nutrient solution. By contrast, the addition of other salts of metal ions, like CuSO4 and Cd(NO3)(2), at 0.25, 0.5 or 1 mu M, or MgSO4, at 0.5, 1 or 2 mM (final concentrations), had no beneficial effect. The results suggest that bicarbonate may inhibit the development of root Fe(III) reducing capacity by diminishing the availability of certain metal ions required for this response.
Different root parts with or without increased iron-reducing activities have been studied in iron-deficient and iron-sufficient control sugar beet (Beta vulgaris L. Monohil hybrid). The distal root parts of iron-deficient plants, 0 to 5 mm from the root apex, were capable to reduce Fe(III)-chelates and contained concentrations of flavins near 700 μm, two characteristics absent in the 5 to 10 mm sections of iron-deficient plants and the whole root of iron-sufficient plants. Flavin-containing root tips had large pools of carboxylic acids and high activities of enzymes involved in organic acid metabolism. In iron-deficient yellow root tips there was a large increase in carbon fixation associated to an increase in phosphoenolpyruvate carboxylase activity. Part of this carbon was used, through an increase in mitochondrial activity, to increase the capacity to produce reducing power, whereas another part was exported via xylem. Root respiration was increased by iron deficiency. In sugar beet iron-deficient roots flavins would provide a suitable link between the increased capacity to produce reduced nucleotides and the plasma membrane associated ferric chelate reductase enzyme(s). Iron-deficient roots had a large oxygen consumption rate in the presence of cyanide and hydroxisalycilic acid, suggesting that the ferric chelate reductase enzyme is able to reduce oxygen in the absence of Fe(III)-chelates.
