Acid Content In Roots Research Articles

Wind disturbance-based tomato seedlings growth control

Wind-disturbance is a potential eco-friendly technique for tackling leggy seedlings. This study uses orthogonal experimental design and seedlings vigour assessment by strong seedling index (SSI) to investigate wind-disturbance on regulating tomato seedlings growth. Changes in endogenous hormone levels and biomechanical properties of tomato seedlings were investigated using enzyme-linked immunosorbent assay and uniaxial tension tests. Results showed that factors influencing significantly SSI, in descending order, are wind disturbance time (T), seedling age at the onset of wind disturbance (SA), wind velocity (V), and interval time (I). The wind-disturbance effect was found to be optimal with SSI = 0.126 for a condition where V, T, I and SA values are 3 m s−1, 1 min, 30 min, and 15 days, respectively. V and T were positively correlated with the ethylene and abscisic acid content in seedling leaves, abscisic acid and auxin content in stems, cytokinin and ethylene content in roots, and the elastic moduli of stems and roots but negatively associated with the cytokinin content in stems and leaves, auxin and abscisic acid content in roots, and leaves’ elastic modulus. Wind disturbance mechanism for controlling seedlings growth involved eliciting the accumulation of abscisic acid in stems and leaves and reduction of the auxin content in roots to about the optimal threshold for roots growth thereby reducing seedling stems and leaves development and promoting a better roots growth and a high SSI. This work offers theoretical insights and technical guidance for utilising wind-disturbance as a sustainable seedling cultivation and personalised seedling management approach.

Physiological and transcriptomic analyses reveal that phytohormone pathways and glutathione metabolism are involved in the arsenite toxicity response in tomatoes

The main forms of inorganic arsenic (As) in soil are arsenate [As(V)] and arsenite [As(III)]. Both forms inhibit plant growth. Here, we investigate the effects of As(III) toxicity on the growth of tomatoes by integrating physiological and transcriptomic analyses. As(III) toxicity induces oxidative damage, inhibits photosynthetic efficiency, and reduces soluble sugar levels. As(III) toxicity leads to reductions in auxin, cytokinin and jasmonic acid contents by 29 %, 39 % and 55 %, respectively, but leads to increases in the ethylene precursor 1-amino-cyclopropane carboxylic acid, abscisic acid and salicylic acid contents in roots, by 116 %, 79 % and 39 %, respectively, thereby altering phytohormone signalling pathways. The total glutathione, reduced glutathione (GSH) and oxidized glutathione (GSSG) contents are reduced by 59 %, 49 % and 94 % in roots; moreover, a high GSH/GSSG ratio is maintained through increased glutathione reductase activity (increased by 214 %) and decreased glutathione peroxidase activity (decreased by 40 %) in the roots of As(III)-treated tomato seedlings. In addition, As(III) toxicity affects the expression of genes related to the endoplasmic reticulum stress response. The altered expression of aquaporins and ABCC transporters changes the level of As(III) accumulation in plants. A set of hub genes involved in modulating As(III) toxicity responses in tomatoes was identified via a weighted gene coexpression network analysis. Taken together, these results elucidate the physiological and molecular regulatory mechanism underlying As(III) toxicity and provide a theoretical basis for selecting and breeding tomato varieties with low As(III) accumulation. Therefore, these findings are expected to be helpful in improving food safety and to developing sustainable agricultural.

Genome-Wide Characterization of DGATs and Their Expression Diversity Analysis in Response to Abiotic Stresses in Brassica napus.

Triacylglycerol (TAG) is the most important storage lipid for oil plant seeds. Diacylglycerol acyltransferases (DGATs) are a key group of rate-limiting enzymes in the pathway of TAG biosynthesis. In plants, there are three types of DGATs, namely, DGAT1, DGAT2 and DGAT3. Brassica napus, an allotetraploid plant, is one of the most important oil plants in the world. Previous studies of Brassica napus DGATs (BnaDGATs) have mainly focused on BnaDGAT1s. In this study, four DGAT1s, four DGAT2s and two DGAT3s were identified and cloned from B. napus ZS11. The analyses of sequence identity, chromosomal location and collinearity, phylogenetic tree, exon/intron gene structures, conserved domains and motifs, and transmembrane domain (TMD) revealed that BnaDGAT1, BnaDGAT2 and BnaDGAT3 were derived from three different ancestors and shared little similarity in gene and protein structures. Overexpressing BnaDGATs showed that only four BnaDGAT1s can restore TAG synthesis in yeast H1246 and promote the accumulation of fatty acids in yeast H1246 and INVSc1, suggesting that the three BnaDGAT subfamilies had greater differentiation in function. Transcriptional analysis showed that the expression levels of BnaDGAT1s, BnaDGAT2s and BnaDGAT3s were different during plant development and under different stresses. In addition, analysis of fatty acid contents in roots, stems and leaves under abiotic stresses revealed that P starvation can promote the accumulation of fatty acids, but no obvious relationship was shown between the accumulation of fatty acids with the expression of BnaDGATs under P starvation. This study provides an extensive evaluation of BnaDGATs and a useful foundation for dissecting the functions of BnaDGATs in biochemical and physiological processes.

Alterations of Endogenous Hormones, Antioxidant Metabolism, and Aquaporin Gene Expression in Relation to γ-Aminobutyric Acid-Regulated Thermotolerance in White Clover.

Persistent high temperature decreases the yield and quality of crops, including many important herbs. White clover (Trifolium repens) is a perennial herb with high feeding and medicinal value, but is sensitive to temperatures above 30 °C. The present study was conducted to elucidate the impact of changes in endogenous γ-aminobutyric acid (GABA) level by exogenous GABA pretreatment on heat tolerance of white clover, associated with alterations in endogenous hormones, antioxidant metabolism, and aquaporin-related gene expression in root and leaf of white clover plants under high-temperature stress. Our results reveal that improvement in endogenous GABA level in leaf and root by GABA pretreatment could significantly alleviate the damage to white clover during high-temperature stress, as demonstrated by enhancements in cell membrane stability, photosynthetic capacity, and osmotic adjustment ability, as well as lower oxidative damage and chlorophyll loss. The GABA significantly enhanced gene expression and enzyme activities involved in antioxidant defense, including superoxide dismutase, catalase, peroxidase, and key enzymes of the ascorbic acid–glutathione cycle, thus reducing the accumulation of reactive oxygen species and the oxidative injury to membrane lipids and proteins. The GABA also increased endogenous indole-3-acetic acid content in roots and leaves and cytokinin content in leaves, associated with growth maintenance and reduced leaf senescence under heat stress. The GABA significantly upregulated the expression of PIP1-1 and PIP2-7 in leaves and the TIP2-1 expression in leaves and roots under high temperature, and also alleviated the heat-induced inhibition of PIP1-1, PIP2-2, TIP2-2, and NIP1-2 expression in roots, which could help to improve the water transportation and homeostasis from roots to leaves. In addition, the GABA-induced aquaporins expression and decline in endogenous abscisic acid level could improve the heat dissipation capacity through maintaining higher stomatal opening and transpiration in white clovers under high-temperature stress.

Biochemical and Proteomic Changes in the Roots of M4 Grapevine Rootstock in Response to Nitrate Availability.

In agricultural soils, nitrate (NO3−) is the major nitrogen (N) nutrient for plants, but few studies have analyzed molecular and biochemical responses involved in its acquisition by grapevine roots. In viticulture, considering grafting, NO3− acquisition is strictly dependent on rootstock. To improve the knowledge about N nutrition in grapevine, this study analyzed biochemical and proteomic changes induced by, NO3− availability, in a hydroponic system, in the roots of M4, a recently selected grapevine rootstock. The evaluation of biochemical parameters, such as NO3−, sugar and amino acid contents in roots, and the abundance of nitrate reductase, allowed us to define the time course of the metabolic adaptations to NO3− supply. On the basis of these results, the proteomic analysis was conducted by comparing the root profiles in N-starved plants and after 30 h of NO3− resupply. The analysis quantified 461 proteins, 26% of which differed in abundance between conditions. Overall, this approach highlighted, together with an increased N assimilatory metabolism, a concomitant rise in the oxidative pentose phosphate pathway and glycolysis, needed to fulfill the redox power and carbon skeleton demands, respectively. Moreover, a wide modulation of protein and amino acid metabolisms and changes of proteins involved in root development were observed. Finally, some results open new questions about the importance of redox-related post-translational modifications and of NO3− availability in modulating the dialog between root and rhizosphere.

Assessing of growth, antioxidant enzymes, and phytohormone regulation in Cucurbita pepo under cadmium stress.

One of the major problems worldwide is soil pollution by trace metal elements, which limits plant productivity and threatens human health. In this work, we have studied the effect of different concentrations of cadmium on Cucurbita pepo plants, evaluating different physiological and biochemical parameters: hormone signaling, metabolite concentration (malondialdehyde and hydrogen peroxide) and, in addition, the antioxidant enzyme activities of catalase and superoxide dismutase were evaluated. The production of biomass decreased under the Cd‐stress. The results showed that C. pepo accumulates higher amounts of Cd2+ in roots than in shoots and fruits. Cd2+ differently affected the content of endogenous phytohormones. Furthermore, data suggest an essential involvement of roots in the regulation of tolerance to trace elements. As a result, indole acetic acid content increased in roots of treated plants, indicating that this phytohormone can stimulate root promotion and growth under Cd‐stress. Similarly, salicylic acid content in roots and shoots increased in response to Cd2+, as well as abscisic acid levels in roots and fruits. In roots, the rambling accumulation pattern observed for jasmonic acid and salicylic acid suggests the lack of a specific regulation role against trace element toxicity. The activity of catalase and superoxide dismutase decreased, disrupted by the metal stress. However, the proline, malondialdehyde and hydrogen peroxide content significantly increased in Cd2+in all the analyzed tissues of the stressed plants. All these data suggest that C. pepo plants are equipped with an effective antioxidant mechanism against oxidative stress induced by cadmium up to a concentration of 500 μM.

Crosstalk of phenylpropanoid biosynthesis with hormone signaling in Chinese cabbage is key to counteracting salt stress

Salt stress limits the regional distribution of Chinese cabbage, yet the molecular factors that confer tolerance to salt stress in Chinese cabbage remain poorly understood. To further investigate this issue, salt-tolerant and salt-sensitive Chinese cabbage cultivars were selected, and their responses to salt stress were tested. Then, comparative transcriptome profiling was performed on the roots of salt-tolerant and salt-sensitive Chinese cabbage cultivars under salt stress. The results showed that Qinghua and Biyu are considered to be salt-tolerant and salt-sensitive Chinese cabbage cultivars, respectively. Qinghua had higher water content and lower Na+/K+ in roots and leaves, better root development, higher lignin content and higher abscisic acid content in roots than Biyu. Comparative transcriptome profiling showed that the abscisic acid and ethylene signaling pathways of Qinghua roots were more actively expressed than those of Biyu. During root adaptation to salt stress, abscisic acid crosstalk with suberin biosynthesis and ethylene signaling crosstalk with lignin biosynthesis were observed. Suberin development and lignin accumulation in the Qinghua roots were found to be important strategies for resisting salt stress in this study. These strategies are not independent, but rather coordinate to promote salt tolerance in Chinese cabbage. The increased lignin content in the roots of Qinghua under salt stress may prevent embolism. Embolism prevention can maintain the flow of water transport, and thus compensate for the reduction in water permeability of these suberized cells in a process that occurs concurrently with greater sodium ion limitation. These results provide novel insight into the crosstalk of phenylpropanoid biosynthesis with hormone signaling under salt stress, and facilitate further dissection of molecular mechanism of adaptive response to salt stress in Chinese cabbage.

Effect of Azospirillum Lectins on the Ascorbate Peroxidase Activity and Ascorbic Acid Content in Wheat Seedling Roots Exposed to Abiotic Stresses

We examined the effect of lectins from two Azospirillum strains (the epiphyte A.brasilense Sp7 and the endophyte A. brasilense Sp245) on the ascorbate peroxidase activity and ascorbic acid content in roots of etiolated wheat (Triticum aestivum L.) seedlings under simulated abiotic stresses: hypothermic (5°С) and hyperthermic (42°С) stress, salinity (1% NaCl), drought (5% sucrose), and heavy metal toxicity (CoSO4, ZnSO4, Pb(CH3COO)2, and CuSO4). Both lectins increased ascorbate peroxidase activity and ascorbate content in stressed seedling roots. Based on the obtained data, we propose that the antioxidant action of the Azospirillum lectins underlies the protective effect of these proteins toward wheat seedling roots subjected to abiotic stresses.

ABA Alleviates Uptake and Accumulation of Zinc in Grapevine (Vitis vinifera L.) by Inducing Expression of ZIP and Detoxification-Related Genes.

Abscisic acid (ABA) is a plant hormone that can mitigate heavy metal toxicity. Exogenous ABA and ABA mimic 1 (AM1) were applied to study the influence on Zn uptake and accumulation in Vitis vinifera L. cv. Merlot seedlings exposed to excess Zn. The seedlings were treated with either normal or excess levels of Zn in combination with applications of ABA and AM1. Excess Zn exposure resulted in decreased lateral root length, decreased photosynthesis, elevated uptake, and accumulation of Zn in roots, trunks, and stems, decreased jasmonic acid content in roots and leaves, and induced the expression of Zn transportation- and detoxification-related genes. Remarkably, in the presence of toxic amounts of Zn, the exogenous application of ABA, but not of AM1, reduced the uptake and accumulation of Zn in roots and induced higher expression of both ZIP genes and detoxification-related genes in root and leaf. These results indicate that exogenous ABA enhances the tolerance of grape seedlings to excess Zn and that AM1 is not a suitable ABA mimic compound for Zn stress alleviation in grapes.

Total Phenolic and Caffeic Acid Contents in Roots of Solanum indicum L. from Different Agroclimatic Regions of Madhya Pradesh State of India

Abstract: Introduction: Solanum indicum L. is one of the species of Dashmularishta, a wellestablished ayurvedic medicine used in the treatment of fatigue, oral sores and gynecological disorders. The present investigation dealt with the estimation of total phenolic and caffeic acid contents in roots of S. indicum from different agroclimatic regions of Madhya Pradesh. Materials and Methods: The roots were collected from 8 places of 7 agroclimatic regions of Madhya Pradesh following purposive sampling. Phenolic content was determined with spectrophotometric method and caffeic acid content was estimated using HPTLC device. Results: The roots from Indore (Malwa plateau) and Balaghat (Chhattisgarh plains) contained maximum (0.859%) and minimum (0.595%) phenolic content respectively. Similarly, the highest content of caffeic acid was detected in the roots (0.0198%) collected from Chhindwara and Betul (Satpura plateau) and lowest content (0.0084%) in roots of Amarkantak (Northern Hill’s Zone of Chhattisgarh). Conclusion: The present investigation revealed the highest phenolic content in root samples of Indore belonging to Malwa plateau and maximum content of caffeic acid in root samples of Chhindwara and Betul belonging to Satpura plateau agroclimatic regions. The populations of Chhindwara and Betul can be considered as superior chemotypes in terms of caffeic acid content and can be in-situ as well as ex-situ conserved for future. Key words: Solanum indicum, Roots, Phenols, Caffeic acid, Agroclimatic regions, Superior chemotypes.

Influence of Nitrogen on Physiological Responses to Bicarbonate in a Grapevine Rootstock

The presence of bicarbonate in soils is an important inducer of nutritional deficiencies in some grapevine genotypes. The aim of this experiment was to assess the effects of different nitrogen sources on physiological variables in the grapevine rootstock 110 Richter grown in a sub-alkaline media. Plants of the grapevine rootstock 110 Richter were treated with different nitrogen sources (NO3−, NH4+, or NH4NO3) in a nutrient solution enriched with bicarbonate. Root enzyme (PEPC, MDH, CS, NADP+-IDH) activities, organic acid concentrations in roots, plant growth and leaf greenness, leaf gas exchange, and mineral concentrations in leaves were determined. The presence of NH4+ promoted an enhancement in leaf greenness, and the treated plants did not trigger physiological response mechanisms to nutritional deficiencies in the roots. However, NH4+ decreased the leaf K concentration. On the other hand, the presence of NO3− in the nutrient solution decreased the leaf greenness, and increased the organic acid concentration in the roots, indicating that these plants were affected by nutritional deficiencies. Instead, intermediate results were obtained in plants treated with NH4NO3. Under the experimental conditions used in this experiment, treatments did not significantly influence the plant biomass, the activity of some enzymes related to organic acids biosynthesis, and the leaf gas exchange. These results suggest that the presence of NH4+ can be an effective strategy to alleviate the negative effects on plant nutrition induced by bicarbonate in plants, an alternative to the soil acidification through inorganic acid applications to the soil.

Omics approaches revealed how arbuscular mycorrhizal symbiosis enhances yield and resistance to leaf pathogen in wheat

Besides improved mineral nutrition, plants colonised by arbuscular mycorrhizal (AM) fungi often display increased biomass and higher tolerance to biotic and abiotic stresses. Notwithstanding the global importance of wheat as an agricultural crop, its response to AM symbiosis has been poorly investigated. We focused on the role of an AM fungus on mineral nutrition of wheat, and on its potential protective effect against Xanthomonas translucens. To address these issues, phenotypical, molecular and metabolomic approaches were combined. Morphological observations highlighted that AM wheat plants displayed an increased biomass and grain yield, as well as a reduction in lesion area following pathogen infection. To elucidate the molecular mechanisms underlying the mycorrhizal phenotype, we investigated changes of transcripts and proteins in roots and leaves during the double (wheat-AM fungus) and tripartite (wheat-AM fungus-pathogen) interaction. Transcriptomic and proteomic profiling identified the main pathways involved in enhancing plant biomass, mineral nutrition and in promoting the bio-protective effect against the leaf pathogen. Mineral and amino acid contents in roots, leaves and seeds, and protein oxidation profiles in leaves, supported the omics data, providing new insight into the mechanisms exerted by AM symbiosis to confer stronger productivity and enhanced resistance to X. translucens in wheat.

Strategies of organic acid production and exudation in response to low-phosphorus stress in Chinese fir genotypes differing in phosphorus-use efficiencies

Plants with high P-use efficiency adapted more effectively via increased organic acid content in roots and root exudates than those with low P-use efficiency. Plants with high P-use efficiency also redistributed P in their tissues as an adaptive response, when organic acid exudation did not improve P-use efficiency. Increased organic acid exudation enables plants to cope with low-phosphorus (P) stress conditions. We aimed to clarify the variation in organic acid exudation strategies among different breeding genotypes presenting high-phosphorous (P) use efficiency. In this study, Chinese fir [Cunninghamia lanceolata (Lamb.) Hook.] seedlings differing in P-use efficiency were compared regarding low-molecular weight organic acid content in roots and root exudates under low-P stress conditions, and dry weight and P-use efficiency also were examined. Compared to the genotype characterized by low P-use efficiency (M24), passive low-P tolerance (M1) or active capture of soil P (M4) genotypes effectively increased organic acid content in roots and root exudates. Although M1 was more sensitive to low P than M4, the former exhibited a specific tolerance to low P. Accordingly, the production of organic acids was slower, and the resultant stress response was less effective in M1 than in M4. Organic acid exudation did not improve P-use efficiency, given the absence of insoluble P in the rhizosphere, but M1 and M4 redistributed P in the tissues as an adaptive response. M4 also increased the root/shoot ratio and allocated more assimilation to root system to enhance P acquisition under low-P condition. In conclusion, the studied genotypes revealed different organic acid exudation strategies. Plants with high P-use efficiency adapted more effectively than those with low P-use efficiency. Metabolic and energy-use adjustments by plant organs, which facilitate plants’ passive adaptation under P-stress, are important survival strategies that allow adaptation to low-P environments.

Overexpression of miR169o, an Overlapping MicroRNA in Response to Both Nitrogen Limitation and Bacterial Infection, Promotes Nitrogen Use Efficiency and Susceptibility to Bacterial Blight in Rice.

Limiting nitrogen (N) supply contributes to improved resistance to bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) in susceptible rice (Oryza sativa). To understand the regulatory roles of microRNAs (miRNAs) in this phenomenon, 63 differentially expressed overlapping miRNAs in response to Xoo infection and N limitation stress in rice were identified through deep RNA sequencing and stem-loop quantitative real-time PCR. Among these, miR169o was further assessed as a typical overlapping miRNA through the overexpression of the miR169o primary gene. Osa-miR169o-OX plants were taller, and had more biomass accumulation with significantly increased nitrate and total amino acid contents in roots than the wild type (WT). Transcript level assays showed that under different N supply conditions, miR169o oppositely regulated NRT2, and this is reduced under normal N supply conditions but remarkably induced under N-limiting stress. On the other hand, osa-miR169o-OX plants also displayed increased disease lesion lengths and reduced transcriptional levels of defense gene (PR1b, PR10a, PR10b and PAL) compared with the WT after inoculation with Xoo. In addition, miR169o impeded Xoo-mediated NRT transcription. Therefore, the overlapping miR169o contributes to increase N use efficiency and negatively regulates the resistance to BB in rice. Consistently, transient expression of NF-YA genes in rice protoplasts promoted the transcripts of PR genes and NRT2 genes, while it reduced the transcripts of NRT1 genes. Our results provide novel and additional insights into the co ordinated regulatory mechanisms of cross-talk between Xoo infection and N deficiency responses in rice.

MECHANISM OF ALUMINUM TOXICITY AVOIDANCE IN TROPICAL RICE (Oryza sativa), MAIZE (Zea mays), AND SOYBEAN (Glycine max)

Planting Al tolerant crops is an economically justifiable approach in crop production on acid soils. Experiments were conducted to study the mechanisms of Al tolerance among species and varieties of tropical rice, maize, and soybean with previously known levels of Al tolerance. These varieties were hydroponically cultured in 0, 5, 10, and 30 mg l-1 Al with complete nutrient solution at pH 4. The results show that root/shoot ratio of dry weight at 10 mg l-1 Al treatment was an important parameter to indicate differential Al tolerance in maize. Oxalic acid exudation from roots cannot always explain the Al tolerance. Total organic acid concentration in roots at 10 mg l-1 Al treatment indicated a difference of Al tolerance in soybean and lowland rice. Aluminum translocation from roots to shoots was lower in tolerant varieties than in sensitive varieties of soybean. Increased Al concentration in shoots with increased Al level in the solution was larger in soybean and maize than in lowland or upland rice. Among varieties of soybean, the Al concentration in shoots increased drastically in Wilis (Al-sensitive variety) with increase Al level, while in Kitamusume (Al-tolerant variety) it did not.

MECHANISM OF ALUMINUM TOXICITY AVOIDANCE IN TROPICAL RICE (Oryza sativa), MAIZE (Zea mays), AND SOYBEAN (Glycine max)

Planting Al tolerant crops is an economically justifiable approach in crop production on acid soils. Experiments were conducted to study the mechanisms of Al tolerance among species and varieties of tropical rice, maize, and soybean with previously known levels of Al tolerance. These varieties were hydroponically cultured in 0, 5, 10, and 30 mg l-1 Al with complete nutrient solution at pH 4. The results show that root/shoot ratio of dry weight at 10 mg l-1 Al treatment was an important parameter to indicate differential Al tolerance in maize. Oxalic acid exudation from roots cannot always explain the Al tolerance. Total organic acid concentration in roots at 10 mg l-1 Al treatment indicated a difference of Al tolerance in soybean and lowland rice. Aluminum translocation from roots to shoots was lower in tolerant varieties than in sensitive varieties of soybean. Increased Al concentration in shoots with increased Al level in the solution was larger in soybean and maize than in lowland or upland rice. Among varieties of soybean, the Al concentration in shoots increased drastically in Wilis (Al-sensitive variety) with increase Al level, while in Kitamusume (Al-tolerant variety) it did not.

Methyl jasmonate vapors affect the composition and peroxidation of major fatty acids in common buckwheat seedlings

The effect of methyl jasmonate (MJ) vapors on the composition and peroxidation of major fatty acids in the organs of common buckwheat seedlings was investigated. The composition of fatty acids in the hypocotyl and cotyledons of seedlings changed significantly under exposure to MJ vapors in closed jars. Four-day exposure to MJ led to a significant reduction in the concentrations of stearic, linoleic, and linolenic acids in the hypocotyl, whereas oleic acid levels increased approximately 3.5-fold. A decrease in stearic acid levels and an increase in the content of linolenic acid were noted in cotyledons, whereas oleic acid levels decreased in roots. Seven-day exposure to MJ vapor caused a further reduction in stearic acid content and an increase in oleic acid and linoleic acid levels in the hypocotyl. At the same time, the linoleic acid content of roots and linolenic acid levels in cotyledons were doubled, but a 5-fold reduction in linolenic acid concentrations was observed in roots. Methyl jasmonate intensified fatty acid peroxidation in cotyledons after 4 and 7 days and in roots after 4 days of exposure. Peroxidation was inhibited in the hypocotyl and roots after 7 days. The noted changes in the composition and peroxidation of fatty acids are probably indicative of senescence in buckwheat seedlings under the influence of MJ. Senescence seems to proceed faster in cotyledons than in other organs of buckwheat seedlings.

Metabolomics Suggests That Soil Inoculation with Arbuscular Mycorrhizal Fungi Decreased Free Amino Acid Content in Roots of Durum Wheat Grown under N-Limited, P-Rich Field Conditions

Arbuscular mycorrhizal fungi (AMF) have a major impact on plant nutrition, defence against pathogens, a plant’s reaction to stressful environments, soil fertility, and a plant’s relationship with other microorganisms. Such effects imply a broad reprogramming of the plant’s metabolic activity. However, little information is available regarding the role of AMF and their relation to other soil plant growth—promoting microorganisms in the plant metabolome, especially under realistic field conditions. In the present experiment, we evaluated the effects of inoculation with AMF, either alone or in combination with plant growth–promoting rhizobacteria (PGPR), on the metabolome and changes in metabolic pathways in the roots of durum wheat (Triticum durum Desf.) grown under N-limited agronomic conditions in a P-rich environment. These two treatments were compared to infection by the natural AMF population (NAT). Soil inoculation with AMF almost doubled wheat root colonization by AMF and decreased the root concentrations of most compounds in all metabolic pathways, especially amino acids (AA) and saturated fatty acids, whereas inoculation with AMF+PGPR increased the concentrations of such compounds compared to inoculation with AMF alone. Enrichment metabolomics analyses showed that AA metabolic pathways were mostly changed by the treatments, with reduced amination activity in roots most likely due to a shift from the biosynthesis of common AA to γ-amino butyric acid. The root metabolome differed between AMF and NAT but not AMF+PGPR and AMF or NAT. Because the PGPR used were potent mineralisers, and AMF can retain most nitrogen (N) taken as organic compounds for their own growth, it is likely that this result was due to an increased concentration of mineral N in soil inoculated with AMF+PGPR compared to AMF alone.

Waterlogging tolerance in barley is associated with faster aerenchyma formation in adventitious roots

Plant adaptation to waterlogged conditions requires a set of morphological and physiological/biochemical changes. The formation of aerenchyma is one of the most crucial adaptive traits for waterlogging tolerance. Enzymatic scavenging may also potentially contribute to waterlogging tolerance by providing detoxification of reactive oxygen species (ROS). Changes of root porosity (as an indicator of aerenchyma formation) and activities in leaves of four major antioxidant enzymes, γ-amino butyric acid (GABA) and lactic acid contents in roots were evaluated in six barley genotypes contrasting in waterlogging tolerance. Soil waterlogging caused significant increases in adventitious root porosity in all genotypes. Waterlogging-tolerant genotypes showed not only significantly higher adventitious root porosity than sensitive genotypes but also much faster development of aerenchyma. The greatest difference in adventitious root porosity among genotypes was observed after 7 days of waterlogging treatment. At the same time, antioxidant enzyme activities in leaves, GABA and lactic acid contents in roots did not correlate with waterlogging tolerance. A faster formation of aerenchyma in adventitious roots is one of the key factors for waterlogging tolerance in barley. This protocol is recommended to be applied in future studies to identify molecular markers linked to this trait using appropriate mapping populations.

Capparidaceous Medicinal Plants of North-West Rajasthan: Good Sources of Ascorbic Acid

Ascorbic acid contents of roots, shoots and fruits of three selected medicinal plants like Capparis decidua, Cleome gynandra and Cleome viscosa of family Capparidaceae have been analysed. Maximum ascorbic acid contents were found in the fruits of Capparis decidua (108.12mg/100g.d.w.) while, minimum in the roots of Cleome viscosa (62.25mg/100g.d.w).