Reduced Root Length Research Articles

Rapid screening of pea (Pisum sativum) genotypes against aluminium toxicity

Twenty-five pea genotypes were grown in trays under a controlled environment in the laboratory of Basic Sciences and Humanities, College of Horticulture and Forestry, CAU, Pasighat, Arunachal Pradesh (2018–2021) and evaluated at 3 levels of Al (0 ppm, 12 ppm and 24 ppm). Al treatment was given through Hoagland solution. Screening of pea genotypes was performed using growth characters, root tolerance index and haematoxylin staining. The genotypes Kashi Samridhi, CHFGP-1 and CHFGP‑14 exhibited an increase in root and shoot biomass. Nearly all the genotypes exhibited reduction in root and shoot length. Based on the K-clustering score P.S.M.3, Kashi Samrath, Kashi Samridhi, CHFGP-1, CHFGP-7 and CHFGP-55 were observed as tolerant at 24 ppm Al level. Matar Ageta-7, Pb-89, AP-3, Pusa Pragati, Arka Priya, Kashi Shakti, CHFGP-6, VRPE- 29, NO-17 and CHFGP-15 were categorized as susceptible genotypes.a

The evaluation of lateral incisor adjacent to treated labial inversely impacted maxillary central incisor: A retrospective follow-up study

This retrospective study aimed to evaluate the further development of the lateral incisor and its associated periodontium adjacent to the treated labial inversely impacted maxillary central incisor. We enrolled 23 participants (average age, 8.24 ± 1.43 years) undergoing a mean follow-up period of 31.10 ± 13.05 months. Each participant had an unimpacted lateral incisor and a successfully treated unilateral labial inversely impacted maxillary central incisor. The contralateral lateral incisors served as controls. Cone-beam computed tomography data were available for treatment completion and follow-up stages. The variables (including root length, dental age, root canal width, root-crown angulation, and alveolar bone loss and thickness) were evaluated with Dolphin Imaging software (version 11.95; Dolphin Imaging and Management Solutions, Chatsworth, Calif). At the follow-up stage, the lateral incisors in the impacted side had significantly longer root lengths, smaller root canal widths, and thinner labial bone widths at the apex than at the posttreatment stage (P<0.001, P= 0.036, and P= 0.001, respectively). A significant lateral incisor root length reduction was noted when comparing the impacted and contralateral sides, although no variation was observed in root canal width. Similarly, crown-root angulation of the lateral incisor on the impacted side was significantly larger than that of the contralateral lateral incisor. The lateral incisor on the impacted side also had thicker labial and thinner lingual bone widths at the apex than the contralateral lateral incisor. The lateral incisor adjacent to the successfully treated labial inversely impacted maxillary central incisor showed continuous growth during follow-up stages, exhibiting a similar morphology and alveolar bone quality but shorter root length, larger root angulation, and thinner lingual bone width at the apex than those of the contralateral lateral incisors.

Phytotoxicity of Bisphenol A to Allium cepa Root Cells Is Mediated through Growth Hormone Gibberellic Acid and Reactive Oxygen Species

The aim of this study was to test the phytotoxicity and mode of action of bisphenol A (BPA) on Allium cepa using a multibiomarker approach. A. cepa roots were exposed to BPA in concentration range 0-50 mg L-1 for 3 days. BPA even in the lowest applied concentration (1 mg L-1) reduced root length, root fresh weight, and mitotic index. Additionally, the lowest BPA concentration (1 mg L-1) decreased the level of gibberellic acid (GA3) in root cells. BPA at concentration 5 mg L-1 increased production of reactive oxygen species (ROS) that was followed by increase in oxidative damage to cells' lipids and proteins and activity of enzyme superoxide dismutase. BPA in higher concentrations (25 and 50 mg L-1) induced genome damage detected as an increase in micronucleus (MNs) and nuclear buds (NBUDs). BPA at >25 mg L-1 induced synthesis of phytochemicals. Results of this study using multibiomarker approach indicate that BPA is phytotoxic to A. cepa roots and has shown genotoxic potential to plants, thus its presence in the environment should be monitored.

Opposite Root Morphological Responses of Chinese Cabbage to Poly-γ-glutamic Acid When Applied with Urea and Ammonium Sulphate

Poly-γ-glutamic acid (γ-PGA) significantly promotes the fertilizer N uptake efficiency of crops and evidently affects soil available N (nitrate, ammonium and glutamate) status. As an adaptive strategy to forage N, root morphology responds variably to soil available N dynamics. Detailed knowledge of how root morphology responds to γ-PGA remains unexplored. A pot trial was conducted to investigate the response of root morphological traits to γ-PGA when applied with CO(NH2)2 or (NH4)2SO4. The results showed that γ-PGA significantly improved the dry weight, total carbon and total nitrogen content of roots, and with a higher improvement with CO(NH2)2 compared to (NH4)2SO4. γ-PGA significantly increased the root length, total surface area, tips and forks with CO(NH2)2. Contrarily, γ-PGA significantly reduced root length, specific root length, specific root area, root volume, tips and forks with (NH4)2SO4, with its inhibition on root growth mainly caused by the high ammonium content in soil. In conclusion, γ-PGA gives opposite effects on root morphological traits when applied with CO(NH2)2 or (NH4)2SO4. This finding provides a new insight to reveal the promotion mechanism of γ-PGA on plant N acquisition in the rhizosphere and offers a practical reference for optimizing γ-PGA and fertilizer application management.

Systematic stress persistence and recovery patterns of rice (Oryza sativa L.) roots in response to molybdenum disulfide nanosheets

The increasing application of engineered nanomaterials (ENMs) unavoidably leads to environmental release and biological exposure. Understanding the potential hazards of ENMs on crops is essential for appropriate utilization and management. Herein, rice seedlings were hydroponically exposed to molybdenum sulfide (MoS2, a typical ENM) nanosheets at 5−20 mg/L for 7 days and then depurated for another 7 days in a fresh culture medium. Exposure to MoS2 triggered irreversible reductions in root length (by 26.3%–69.9%) and tip number (by 22.2%–66.0%). Integration of biochemical assays, transcriptomic and metabolomics found that oxidative stress induced by MoS2 in roots was persistent, whereas the activation of aquaporins, ionic transportation, and energy synthesis was normalized due to the recovery of nutrient uptake. The down-regulated levels of genes and metabolites associated with peroxidases, hemicellulose synthesis, expansins, and auxins caused persistent structural damages (sclerosis and rupture) of root cell walls. Approximately 64.5%–84.8% of internalized MoS2 nanosheets were degraded, and the successive up-regulation of genes encoding cytochrome P450s and glutathione S-transferases reflected the biotransformation and detoxification of MoS2 in the depuration period. These findings provide novel insights into the persistence and recovery of MoS2 phytotoxicity, which will help advance the risk assessment of MoS2 application on environment.

Transcriptomic and physiological effects of polyethylene microplastics on Zea mays seedlings and their role as a vector for organic pollutants

The widespread employment of plastics in recent decades has resulted in the accumulation of plastic residues in all ecosystems. Their presence and degradation into small particles such as microplastics (MPs) may have a negative effect on plant development and therefore on crop production. In this study, the effects of two types of polyethylene MPs on Zea mays seedlings cultured in vitro were analysed. In addition, four organic pollutants (ibuprofen, simazine, sertraline, and amoxicillin) were adsorbed by the MPs to evaluate their capacity as other contaminant vectors. The development of the plants was negatively affected by MPs alone or with the organic compounds. The strongest effect was observed in the W-MPs treatments, with a reduction in leaf and root length near 70%. Chlorophyll content was also differentially affected depending on the treatment. Transcriptome analysis showed that MPs affected gene expression in the roots of maize seedlings. As observed in the physiological parameters analysed, some gene expression changes were associated with specific treatments, such as changes in sugar transport genes in the B-MIX treatment. These results contribute to a better understanding of the molecular mechanisms of plants in regard to plastic stress responses.

Phytotoxicity of zinc oxide nanoparticles and multi-walled carbon nanotubes, alone or in combination, on Arabidopsis thaliana and their mutual effects on oxidative homeostasis.

The extensive use of engineered nanoparticles (ENPs) has raised concerns about their potentially harmful effects on the ecosystem. Despite previous reports of a variety of individual ENPs, the mutual effects of ENPs when used in combination were not well understood. In this study, we first investigated the effects of different sizes and concentrations of ZnO nanoparticles (ZnO NPs) or multi-walled carbon nanotubes (MWCNTs) on the growth performance of Arabidopsis thaliana seedlings. Then, two concentrations of ZnO NP (40 and 50 mg/L) with a diameter of 90 nm and MWCNTs (100 and 500 mg/L) with an outer diameter of 40-60 nm were used to evaluate their respective or simultaneous phytotoxicity to Arabidopsis. The results showed that seedlings exposed to either ZnO NPs or MWCNTs exhibited significant phytotoxic symptoms. ZnO NPs caused stronger inhibitory effects than MWCNTs on several plant growth indices, including reduced root length, chlorophyll content, and increased ROS concentration. When applied together, the concurrent effects of ZnO NPs and MWCNTs on Arabidopsis seedlings appeared to be more negative, as evidenced not only by the further deterioration of several growth indices but also by their synergistic or additive regulation of the activities of several antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR). Moreover, qRT-PCR analysis revealed that in the presence of ZnO NPs and MWCNTs, the expression of genes important for maintaining cellular ROS homeostasis was differentially regulated in shoots and roots of Arabidopsis seedlings. Overall, our data may provide new insights into how plants respond to more than one type of nanomaterial and help us better understand the associated environmental risks.

Effects of antibiotics stress on root development, seedling growth, antioxidant status and abscisic acid level in wheat (Triticum aestivum L.)

The veterinary antibiotics contamination in agroecosystems is a substantial problem globally. However, little is known about their toxicity to crops, especially in wheat. This study evaluated the phytotoxic effects of the two most representative antibiotics, namely oxytetracycline (OTC) and enrofloxacin (ENR), on seed germination, seedling growth, root elongation and antioxidant status in wheat, and investigated the response of abscisic acid (ABA) to antibiotic stress and its underlying mechanism. The results showed that OTC and ENR under the experimental concentrations (5, 10, 20, 40 and 80 mg·L−1) had no influence on seed germination of wheat. The reduced root length, fresh weight and surface area were observed when the concentrations of OTC and ENR were higher than 10 mg·L−1 and 5 mg·L−1, respectively. High concentrations (＞40 mg·L−1) of antibiotics dramatically decreased the root length, fresh weight, root numbers and surface area as well as the number of stele cells and stele area. The activity of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD), and malondialdehyde (MDA) content in shoots and roots were increased with the increasing OTC and ENR concentrations. High concentrations (＞40 mg·L−1) of antibiotics improved ABA content and enhanced the transcription levels of genes related to ABA biosynthesis (TaNCED1 and TaNCED2) and metabolism (TaABA8′OH1-A and TaABA8′OH2-A) in shoots and roots of wheat seedlings. Wheat seedlings had relatively strong sensitivity to low concentration (5 mg·L−1) of ENR. These results suggest that OTC and ENR modulate root development and seedling growth by regulating ABA level and antioxidant defense system in wheat.

Ectopic Expression of PvHMA2.1 Enhances Cadmium Tolerance in Arabidopsis thaliana

Cadmium (Cd) in soil inhibits plant growth and development and even harms human health through food chain transmission. Switchgrass (Panicum virgatum L.), a perennial C4 biofuel crop, is considered an ideal plant for phytoremediation due to its high efficiency in removing Cd and other heavy metals from contaminated soil. The key to understanding the mechanisms of switchgrass Cd tolerance is to identify the genes involved in Cd transport. Heavy-metal ATPases (HMAs) play pivotal roles in heavy metal transport, including Cd, in Arabidopsis thaliana and Oryza sativa, but little is known about the functions of their orthologs in switchgrass. Therefore, we identified 22 HMAs in switchgrass, which were distributed on 12 chromosomes and divided into 4 groups using a phylogenetic analysis. Then, we focused on PvHMA2.1, which is one of the orthologs of the rice Cd transporter OsHMA2. We found that PvHMA2.1 was widely expressed in roots, internodes, leaves, spikelets, and inflorescences, and was significantly induced in the shoots of switchgrass under Cd treatment. Moreover, PvHMA2.1 was found to have seven transmembrane domains and localized at the cell plasma membrane, indicating that it is a potential transporter. The ectopic expression of PvHMA2.1 alleviated the reduction in primary root length and the loss of fresh weight of Arabidopsis seedlings under Cd treatment, suggesting that PvHMA2.1 enhanced Cd tolerance in Arabidopsis. The higher levels of relative water content and chlorophyll content of the transgenic lines under Cd treatment reflected that PvHMA2.1 maintained water retention capacity and alleviated photosynthesis inhibition under Cd stress in Arabidopsis. The roots of the PvHMA2.1 ectopically expressed lines accumulated less Cd compared to the WT, while no significant differences were found in the Cd contents of the shoots between the transgenic lines and the WT under Cd treatment, suggesting that PvHMA2.1 reduced Cd absorption from the environment through the roots in Arabidopsis. Taken together, our results showed that PvHMA2.1 enhanced Cd tolerance in Arabidopsis, providing a promising target that could be engineered in switchgrass to repair Cd-contaminated soil.

NtPIN3 positively regulates low phosphorus tolerance by changing root elongation, Pi concentration and antioxidant capacity in tobacco

Phosphorus (P) is a critical nutrient for plants, and inorganic orthophosphate (Pi) deficiency results in declining crop quality and yields. Auxin plays a key regulatory effect on plant growth in response to Pi deficiency, yet the regulatory mechanisms remain poorly understood. In this study, we cloned and identified an auxin efflux transporter, NtPIN3, involved in the low phosphate response of tobacco (Nicotiana tabacum). NtPIN3 is located on the cytoplasmic membrane, and high expression levels of NtPIN3 were observed under phosphorus deficiency conditions. Moreover, NtPIN3 overexpression in tobacco could dramatically enhance low Pi tolerance by increasing the root length, which was consistent with the GUS activity and the auxin concentration in the root. Notably, Pi concentration and antioxidant capacity in overexpression transgenic tobacco were significantly increased compared with the wild type (WT) under low Pi stress conditions due to Pi uptake (NtPT1 and NtPT2) and antioxidant capacity (superoxide dismutase, peroxidase, and catalase). In contrast, compared with WT, the ntpin3 mutant significantly reduced root length, auxin concentration, Pi concentration, and antioxidant capacity under low Pi stress conditions, suggesting that NtPIN3 is a positive regulator of low phosphate in tobacco. In addition, the yeast-two-hybrid and luciferase complementation imaging assay confirmed that NtPIN3 interacted with NtPIN2. Altogether, the NtPIN3 involved in low Pi response and overexpression of NtPIN3 contributed to enhanced tolerance to low Pi stress, which proved an underlying gene for breeding low Pi-stress tolerant plants.

Transcriptome analysis reveals the key pathways and candidate genes involved in salt stress responses in Cymbidium ensifolium leaves

BackgroundCymbidium ensifolium L. is known for its ornamental value and is frequently used in cosmetics. Information about the salt stress response of C. ensifolium is scarce. In this study, we reported the physiological and transcriptomic responses of C. ensifolium leaves under the influence of 100 mM NaCl stress for 48 (T48) and 96 (T96) hours.ResultsLeaf Na+ content, activities of the antioxidant enzymes i.e., superoxide dismutase, glutathione S-transferase, and ascorbate peroxidase, and malondialdehyde content were increased in salt-stressed leaves of C. ensifolium. Transcriptome analysis revealed that a relatively high number of genes were differentially expressed in CKvsT48 (17,249) compared to CKvsT96 (5,376). Several genes related to salt stress sensing (calcium signaling, stomata closure, cell-wall remodeling, and ROS scavenging), ion balance (Na+ and H+), ion homeostasis (Na+/K+ ratios), and phytohormone signaling (abscisic acid and brassinosteroid) were differentially expressed in CKvsT48, CKvsT96, and T48vsT96. In general, the expression of genes enriched in these pathways was increased in T48 compared to CK while reduced in T96 compared to T48. Transcription factors (TFs) belonging to more than 70 families were differentially expressed; the major families of differentially expressed TFs included bHLH, NAC, MYB, WRKY, MYB-related, and C3H. A Myb-like gene (CenREV3) was further characterized by overexpressing it in Arabidopsis thaliana. CenREV3’s expression was decreased with the prolongation of salt stress. As a result, the CenREV3-overexpression lines showed reduced root length, germination %, and survival % suggesting that this TF is a negative regulator of salt stress tolerance.ConclusionThese results provide the basis for future studies to explore the salt stress response-related pathways in C. ensifolium.

Effect of Innovative Bio-Based Plastics on Early Growth of Higher Plants

Plastic particles are widespread in the environment including the terrestrial ecosystems. They may change the physicochemical properties of soil and subsequently affect plant growth. In recent decades, traditional, petroleum-derived plastics have been increasingly replaced by more environmentally friendly bio-based plastics. Due to the growing role of bio-based plastics it is necessary to thoroughly study their impact on the biotic part of ecosystems. This work aimed for the assessment of the effect of five innovative bio-based plastics of different chemical composition and application on the early growth of higher plants (sorghum, cress and mustard). Each bio-based plastic was tested individually. It was found that the early stages of growth of monocotyledonous plants were usually not affected by any of plastic materials studied. At the same time, the presence of some kinds of bio-based plastics contributed to the inhibition of root growth and stimulation of shoot growth of dicotyledonous plants. Two PLA-based plastics inhibited root growth of dicotyledonous plants more strongly than other plastic materials; however, the reduction of root length did not exceed 22% compared to the control runs. PBS-based plastic contributed to the stimulation of shoot growth of higher plants (sorghum, cress and mustard) at the concentrations from 0.02 to 0.095% w/w. In the case of cress shoots exposed to this plastic the hormetic effect was observed. Lepidium sativum turned out to be the most sensitive plant to the presence of bio-based plastic particles in the soil. Thus, it should be included in the assessment of the effect of bio-based plastics on plant growth.

PATHOGENICITY OF RENIFORM NEMATODE (ROTYLENCHULUS RENIFORMIS, LINFORD AND OLIVEIRA, 1960) ON COWPEA (VIGNA UNGUICULATA)

– Studies on the pathogenicity of reniform nematode (Rotylenchulus reniformis Linford &amp; Oliveira, 1940) on cowpea (Vigna unguiculata) under greenhouse conditions showed that there was a progressive decrease in the plant growth parameters as the inoculum level of Rotylenchulus reniformis increased, i.e., 10, 100, 500, 1000, 5000, and 10,000 nematodes per pot (1kg). An initial inoculum level of 1000 nematodes per kg of soil caused a significant reduction in shoot length, root length, shoot and root weight and proved to be pathogenic to cowpea (var. local). With an increase in the inoculum level, there was a gradual increase in the number of females, egg masses per root system, and nematode population of Rotylenchulus reniformis in 1 kg of soil. The reproductive rates were found to be inversely proportional with inoculum levels, with the highest at 100 and the lowest at 10,000 nematodes per pot. Based on these results, it can be concluded that the threshold level of reniform nematode, Rotylenchulus reniformis was 1000 nematodes per kg of soil.

Allelopathic Effect of Barley (Hordeum vulgare) and Rapeseed (Brassica napus) Crops on Early Growth of Acetolactate Synthase (ALS)-Resistant Glebionis Coronaria

Glebionis coronaria is a serious threat to cereal production in Northern Tunisia. Previous results showed that G. coronaria has developed resistance to acetolactate synthase (ALS)-inhibiting herbicides which limits their use in cereal cropping systems. The use of allelopathic crops has been reported as a potential alternative to herbicides to control resistant weed populations. The aim of this study is to evaluate the effect of five allelopathic crops on the early growth of G. coronaria. In vitro experiments using aqueous extracts of different crops and in pots experiments with increasing rates of barley (Hordeum vulgare) and rapeseed (Brassica napus) residues were performed for this purpose. All tested crops showed allelopathic effects on G. coronaria and were able to reduce its root length at the concentration of 50 g/L. Barley and rapeseed were the most effective crops, with 70% and 60% of root length reduction, respectively. An aqueous extract concentration study with five increasing concentrations of 12.5, 25, 50, 75, and 100 % was performed with these two crops, and root length was significantly reduced with increasing concentration, being up to 80% with the highest aqueous extract concentration of barley. The in vitro results were supported by the in pots experiment: Shortest roots length and highest dry mass reduction were obtained by the highest barley (0.64 g/kg) and rapeseed (8 g/kg) residue concentrations. This study confirmed the allelopathic potential of both barley and rapeseed in reducing the early growth of ALSresistant G. coronaria, suggesting the effectiveness of these crops if integrated with other control measures for the management of resistant population of G. coronaria in cereal fields.

Cardiolipin synthesis in Pseudomonas fluorescens UM270 plays a relevant role in stimulating plant growth under salt stress

Membrane cardiolipin (CL) phospholipids play a fundamental role in the adaptation of bacteria to various environmental conditions, including saline stress. Here, we constructed deletion mutants of two CL synthetase genes, clsA (UM270 ∆clsA) and clsB (UM270 ∆clsB), in the rhizobacterium Pseudomonas fluorescens UM270, and evaluated their role in plant growth promotion under salt stress. UM270 ∆clsA and UM270 ∆clsB mutants showed a significant reduction in CL synthesis compared to the P. fluorescens UM270 wild-type (UM270 wt) strain (58% ∆clsA and 53% ∆clsB), and their growth rate was not affected, except when grown at 100 and 200 mM NaCl. Additionally, the root colonization capacity of both mutant strains was impaired compared with that of the wild type. Concomitant with the deletion of clsA and clsB genes, some physiological changes were observed in the UM270 ∆clsA and UM270 ∆clsB mutants, such as a reduction in indole acetic acid and biofilm production. By contrast, an increase in siderophore biosynthesis was observed. Further, inoculation of the UM270 wt strain in tomato plants (Solanum lycopersicum) grown under salt stress conditions (100 and 200 mM NaCl) resulted in an increase in root and shoot length, chlorophyll content, and dry weight. On the contrary, when each of the mutants were inoculated in tomato plants, a reduction in root length was observed when grown at 200 mM NaCl, but the shoot length, chlorophyll content, and total plant dry weight parameters were significantly reduced under normal or saline conditions (100 and 200 mM NaCl), compared to UM270 wt-inoculated plants. In conclusion, these results suggest that CL synthesis in P. fluorescens UM270 plays an important role in the promotion of tomato plant growth under normal conditions, but to a greater extent, under salt-stress conditions.

Pathogenicity study of Rhizoctonia solani and its integrated management on different crop species in Morocco

In this work, we aimed to develop an ecofriendly strategy to manage the R. solani damping-off incidence of Moroccan strains. After the assessment of damping-off incidence on different crops, a greenhouse experiments were carried out to assess the efficiency of chemical and biological agents on plant growth and damping-off control. Results revealed that R. solani MN191236 strain was the most virulent as it dramatically increased severity indexes and reduced root length and pods number by 23% and 58% respectively. On R. solani-infested bean seedlings, Trichoderma asperellum increased pods number by 169% and reduce the severity index up to 1.33. However, the Tolclofos-methyl and the hypovirulent F. oxysporum strain came in second place. The efficiency of chemical or biological agents was significantly related to the interaction ‘pathogenic strains*fungicide or biological agents’. These results are promising in term of integrally and eco-friendly management of R. solani damping-off.

Hexavalent chromium-reducing plant growth-promoting rhizobacteria are utilized to bio-fortify trivalent chromium in fenugreek by promoting plant development and decreasing the toxicity of hexavalent chromium in the soil

BackgroundFenugreek is known to have good anti-diabetes properties. Moreover, several studies accounted that the trivalent form of chromium [Cr(III)] also have anti-diabetic properties. However, its hexavalent form i.e., Cr(VI) is known to be highly toxic and carcinogenic to living beings and retarded plant growth even if it is present in low concentration in soil. Many plant growth-promoting rhizobacteria (PGPR) are reported to have the potential to reduce the Cr(VI) into Cr(III) in soil. In view of the above, the present objective was designed to effectively utilize Cr(VI) reducing PGPRs for the growth and development of fenugreek plant in Cr(VI) amended soil, apart from reducing Cr(VI) in soil and fortification of Cr(III) in the aerial part of plants. MethodsThe experiment was carried out to evaluate the effect of Cr(VI)-reducing PGPRs viz. Bacillus cereus (SUCR44); Microbacterium sp. (SUCR140); Bacillus thuringiensis (SUCR186) and B. subtilis (SUCR188) on growth, uptake and translocation of Cr as well as other physiological parameters in fenugreek grown under artificially Cr(VI) amended soil (100 mg kg−1 of Cr(VI) in soil). ResultsThe aforementioned concentration of Cr(VI) in soil cause severe reduction in root length (41 %), plant height (43 %), dry root (38 %) and herb biomass (48 %), when compared with control negative (CN; uninoculated plant not grown in Cr(VI) contaminated soil). However, the presence of Microbacterium sp.˗SURC140 (MB) mitigates the Cr toxicity resulting in improved root length (92 %), plant height (86 %), dry root (74 %) and herb biomass (99 %) as compared with control positive (CP; uninoculated plants grown in Cr(VI) contaminated soil). The maximum reduction in bioavailability (82 %) of Cr(VI) in soil and its uptake (50 %) by the plant were also observed in MB-treated plants. However, All Cr(VI)-reducing PGPRs failed to decrease the translocation of Cr to the aerial parts. Moreover, the plant treated with MB observed diminution in relative water content (13 %), electrolyte leakage (16%) and lipid peroxidation (38 %) as well as higher chlorophyll (37 %) carotenoids (17 %) contents and antioxidants (18%) potential. ConclusionThis study demonstrates that MB can lower the Cr(VI) toxicity to the plant by reducing the bioavailable Cr(VI), consequently reducing the Cr(VI) toxicity level in soil and helping in improving the growth and yield of fenugreek. Additionally, Cr(III) uptakes and translocation may improve the effectiveness of fenugreek in treating diabetes.

Low nitrogen supply inhibits root growth but prolongs lateral root lifespan in cotton

Primary and lateral roots are the main components of the root system in cotton, and their development and lifespan are critical for the uptake of water and nutrients (e.g., nitrogen). However, the responses of the daily growth dynamics and lifespan of cotton roots to low nitrogen are poorly understood. In this study of the whole growth period of cotton plants, two cotton cultivars (K836 and K837) were grown in pots in a greenhouse with 138 mg·kg-1 nitrogen fertilizer as the control (normal nitrogen) and no nitrogen fertilizer as the low nitrogen treatment. The growth of primary and lateral roots was investigated using the in situ root phenotyping platform RhizoPot. The root responses of both cultivars to low nitrogen were consistent except for the correlation between lateral root diameter and length on the 11th d after lateral root emergence. Root growth was significantly inhibited under low nitrogen, manifested as substantial reductions in root length, surface area, volume, and dry matter weight, which decreased by 23.91–26.88 %, 34.92–37.59 %, 32.71–37.94 %, and 17.92–21.62 %, respectively, in comparison with the control. Low nitrogen treatment reduced the diameter of primary roots by shortening the duration of its rapid accumulation, by 7.54–10.92 d. The smaller diameter of lateral roots was owing to low nitrogen treatment increasing the proportion of finer roots compared to the control. The effect of low nitrogen on the thickening rate of lateral roots showed stage-specific differences accompanied by elongation of lateral roots. In the early stage, the lateral root length of the low nitrogen treatment was longer than that of the control because lateral root elongation was higher, while the opposite pattern was observed in the later stage. Low nitrogen treatment significantly increased the lifespan of both the primary and secondary lateral roots, by 3.84–3.93 d and 4.95–5.46 d, respectively. Detailed studies revealed that low nitrogen treatment induced the greatest increase in the survival of lateral roots with larger diameters. Collectively, the results of this study indicate low nitrogen treatment not only reduced primary root thickness, but also resulted in shorter and thinner lateral roots with a longer lifespan relative to the normal nitrogen treatment.

An open source plant kinase chemogenomics set.

One hundred twenty-nine protein kinases, selected to represent the diversity of the rice (Oryza sativa) kinome, were cloned and tested for expression in Escherichia coli. Forty of these rice kinases were purified and screened using differential scanning fluorimetry (DSF) against 627 diverse kinase inhibitors, with a range of structures and activities targeting diverse human kinases. Thirty-seven active compounds were then tested for their ability to modify primary root development in Arabidopsis. Of these, 14 compounds caused a significant reduction of primary root length compared with control plants. Two of these inhibitory compounds bind to the predicted orthologue of Arabidopsis PSKR1, one of two receptors for PSK, a small sulfated peptide that positively controls root development. The reduced root length phenotype could not be rescued by the exogenous addition of the PSK peptide, suggesting that chemical treatment may inhibit both PSKR1 and its closely related receptor PSKR2. Six of the compounds acting as root growth inhibitors in Arabidopsis conferred the same effect in rice. Compound RAF265 (CHIR-265), previously shown to bind the human kinase BRAF (B-Raf proto-oncogene, serine/threonine kinase), also binds to nine highly conserved rice kinases tested. The binding of human and rice kinases to the same compound suggests that human kinase inhibitor sets will be useful for dissecting the function of plant kinases.

Mitochondria Specific Antioxidant, MitoTEMPO, Modulates Cd Uptake and Oxidative Response of Soybean Seedlings

Numerous reports find that Cd induces formation of reactive oxygen species (ROS) in plants. However, a general ROS pool is usually studied, without distinction of their production site. In the present study, we applied a mitochondria-specific antioxidant, MitoTEMPO, to elucidate the role of mitochondria-derived ROS in the response of soybean seedlings to short-term (48 h) Cd stress. The obtained results showed that Cd caused a reduction in root length and fresh weight and increase in the level of superoxide anion, hydrogen peroxide, markers of lipid peroxidation (thiobarbituric reactive substances, TBARS) and markers of RNA oxidation (8-hydroxyguanosine, 8-OHG) in seedling roots. Application of MitoTEMPO affected Cd uptake in a dose-dependent manner and diminished the Cd-dependent induction of superoxide anion and lipid peroxidation.