Number Of Root Hairs Research Articles

Functional\xa0characterization of the PHT1 family transporters of foxtail millet with development of a novel Agrobacterium-mediated transformation procedure

Phosphate is an essential nutrient for plant growth and is acquired from the environment and distributed within the plant in part through the action of phosphate transporters of the PHT1 family. Foxtail millet (Setaria italica) is an orphan crop essential to the food security of many small farmers in Asia and Africa and is a model system for other millets. A novel Agrobacterium-mediated transformation and direct plant regeneration procedure was developed from shoot apex explants and used to downregulate expression of 3 members of the PHT1 phosphate transporter family SiPHT1;2 SiPHT1;3 and SiPHT1;4. Transformants were recovered with close to 10% efficiency. The downregulation of individual transporters was confirmed by RT-PCR. Downregulation of individual transporters significantly reduced the total and inorganic P contents in shoot and root tissues and increased the number of lateral roots and root hairs showing they have non-redundant roles. Downregulation of SiPHT1;2 had the strongest effect on total and inorganic P in shoot and root tissues. Complementation experiments in S. cerevisiae provide evidence for the ability of SiPHT1;1, 1;2, 1;3, 1;7 and 1;8 to function as high affinity Pi transporters. This work will aid development of improved millet varieties for global food security.

The interaction between glucose and cytokinin signaling in controlling Arabidopsis thaliana seedling root growth and development

ABSTRACTCytokinin (CK) and glucose (GLC) control several common responses in plants. There is an extensive overlap between CK and GLC signal transduction pathways in Arabidopsis. Physiologically, both GLC and CK could regulate root length in light. CK interacts with GLC via HXK1 dependent pathway for root length control. Wild-type (WT) roots cannot elongate in the GLC free medium while CK-receptor mutant ARABIDOPSIS HISTIDINE KINASE4 (ahk4) and type B ARR triple mutant ARABIDOPSIS RESPONSE REGULATOR1, 10,11 (arr1, 10,11) roots could elongate even in the absence of GLC as compared with the WT. The root hair initiation was also found defective in CK signaling mutants ahk4, arr1,10,11 and arr3,4,5,6,8,9 on increasing GLC concentration (up to 3%); and lesser number of root hairs were visible even at 5% GLC as compared with the WT. Out of 941 BAP regulated genes, 103 (11%) genes were involved in root growth and development. Out of these 103 genes, 60 (58%) genes were also regulated by GLC. GLC could regulate 5736 genes, which include 327 (6%) genes involved in root growth and development. Out of these 327 genes, 60 (18%) genes were also regulated by BAP. Both GLC and CK signaling cannot alter root length in light in auxin signaling mutant AUXIN RESPONSE3/INDOLE-3-ACETIC ACID17 (axr3/iaa17) suggesting that they may involve auxin signaling component as a nodal point. Therefore CK- and GLC- signaling are involved in controlling different aspects of root growth and development such as root length, with auxin signaling components working as downstream target.

Light Sheet Fluorescence Microscopy Quantifies Calcium Oscillations in Root Hairs of Arabidopsis thaliana.

Calcium oscillations play a role in the regulation of the development of tip-growing plant cells. Using optical microscopy, calcium oscillations have been observed in a few systems (e.g. pollen tubes, fungal hyphae and algal rhizoids). High-resolution, non-phototoxic and rapid imaging methods are required to study the calcium oscillation in root hairs. We show that light sheet fluorescence microscopy is optimal to image growing root hairs of Arabidopsis thaliana and to follow their oscillatory tip-focused calcium gradient. We describe a protocol for performing live imaging of root hairs in seedlings expressing the cytosol-localized ratiometric calcium indicator Yellow Cameleon 3.6. Using this protocol, we measured the calcium gradient in a large number of root hairs. We characterized their calcium oscillations and correlated them with the rate of hair growth. The method was then used to screen the effect of auxin on the properties of the growing root hairs.

Agrobacterium T-DNA insertion in the rice DWARF SHOOT AND DEFECTIVE PANICLE1 (DSDP1) gene causes a severe dwarf phenotype, reduces plant vigour, and affects seed germination

We report a new T-DNA-tagged rice plant chi7, which displays a severe dwarf phenotype, reduced plant vigour, and impaired panicle development in the homozygous state. By chromosome walking, T-DNA integration was mapped in chromosome 2, 1054-bp upstream of the translation start site of a gene (Os02g0820400), which we designate as DWARF SHOOT AND DEFECTIVE PANICLE1 (DSDP1). DSDP1 expression was unexpectedly higher in the homozygous mutant leaves than in the hemizygous mutant and control plant leaves. Mutant dsdp1 seeds, stored for 24 weeks, failed to germinate in soil. The growth vigour of the dsdp1 mutant reduced with increasing seed storage period. The dsdp1 mutant plants, grown in vitro on MS medium, formed short, stout, and ageotropic roots with lesser number of root hairs. The findings suggest that DSDP1 may function as a negative regulator of many developmental processes in rice.

Efficient Irrigation Water Management in Sugarcane Through Alteration of Field Application Parameters Under Subtropical India

Field experiments were conducted during consecutive spring seasons of 2013–2014 and 2014–2015 at ICAR-Indian Institute of Sugarcane Research, Lucknow, in subtropical India to find the best irrigation application parameters that lead to significant reduction in total water use and to characterize soil moisture spread along the furrow. The soil of the experimental site is categorized as Inceptisol neutral in reaction (pH 7.6), low in organic carbon (0.33%) and available N (187.5 kg/ha), medium in available P (19.7 kg/ha) and K (239.4 kg/ha). The treatment consisted of two length of furrows (F1-50 m and F2-75 m) and six discharge and cut-off length (D1: Furrow-8 L per second – lps + 75% cut-off length, D2: Furrow-10 lps + 75% cut-off length, D3: Furrow-8 lps + 85% cut-off length, D4: Furrow-10 lps + 85% cut-off length, D5: Border-75% cut-off length and D6: Border-85% cut-off length). Experiment was laid out in split plot design with three replications. The number of millable canes (109.27 t/ha), cane length (169.21 cm), average cane weight (0.68 kg), cane yield (50.93 t/ha) and sugar yield (6.75 t/ha) were found significantly higher under longer furrow length (75 m). Significantly highest number of shoot counts (168.61 t/ha at 180 DAP), millable canes (106.61 t/ha), cane yield (54.02 t/ha) and sugar yield (7.03 t/ha) were recorded with discharge of 10 lps + 85% cut-off length. Moisture flow pattern showed a clear downward movement of water in all the furrow irrigation combinations methods with required water availability at tail end region. Significantly voluminous root (53.25 cc/clump), longer root length (33.90 cm), higher number of root hairs (918.9 cm), wider horizontal spread (27.0 cm) and root efficiency (22.84) were observed under discharge of 10 lps at cut-off of 85% discharge of water at 10 lps with 85 m cut-off length recorded highest IWUE (2239.71 kg/ha cm). Under conventional method of irrigation, IWUE was very low. Thus, it may be concluded that to conserve and save irrigation water, a cut-off at 85% furrow length and discharge of 10 lps are efficient to soak the soil at tail end of the field. Further, the length of the furrow may be kept up to 75 m under sandy loam alluvial soils having slope less than 1%.

A Legume TOR Protein Kinase Regulates Rhizobium Symbiosis and Is Essential for Infection and Nodule Development.

The target of rapamycin (TOR) protein kinase regulates metabolism, growth, and life span in yeast, animals, and plants in coordination with nutrient status and environmental conditions. The nutrient-dependent nature of TOR functionality makes this kinase a putative regulator of symbiotic associations involving nutrient acquisition. However, TOR's role in these processes remains to be understood. Here, we uncovered the role of TOR during the bean (Phaseolus vulgaris)-Rhizobium tropici (Rhizobium) symbiotic interaction. TOR was expressed in all tested bean tissues, with higher transcript levels in the root meristems and senesced nodules. We showed TOR promoter expression along the progressing infection thread and in the infected cells of mature nodules. Posttranscriptional gene silencing of TOR using RNA interference (RNAi) showed that this gene is involved in lateral root elongation and root cell organization and also alters the density, size, and number of root hairs. The suppression of TOR transcripts also affected infection thread progression and associated cortical cell divisions, resulting in a drastic reduction of nodule numbers. TOR-RNAi resulted in reduced reactive oxygen species accumulation and altered CyclinD1 and CyclinD3 expression, which are crucial factors for infection thread progression and nodule organogenesis. Enhanced expression of TOR-regulated ATG genes in TOR-RNAi roots suggested that TOR plays a role in the recognition of Rhizobium as a symbiont. Together, these data suggest that TOR plays a vital role in the establishment of root nodule symbiosis in the common bean.

A repressor motif-containing poplar R3 MYB-like transcription factor regulates epidermal cell fate determination and anthocyanin biosynthesis in Arabidopsis

Single-repeat R3 MYB transcription factors (R3 MYBs) regulate epidermal cell fate determination in Arabidopsis through a lateral inhibition mechanism. Previously we have shown that poplar R3 MYB genes regulate trichome formation when expressed in Arabidopsis. Here we report the identification and functional characterization of a poplar R3 MYB-like protein, Populus trichocarpa R3 MYB-LIKE1 (PtrRML1). So far all the MYB transcription factors identified have a highly conserved N-terminal DNA-binding domain composed of MYB repeats and a highly variable C-terminal domain. However, PtrRML1 has a single R3 MYB repeat at its C-terminal and an LxLxL repressor motif-containing N-terminal, and with amino acids about twice of that of the known R3 MYBs. PtrRML1 is localized in nuclear in transgenic Arabidopsis plants expressing PtrRML1-GFP. PtrRML1 repressed reporter gene expression in protoplasts, and it interacted with GL3 in plant cells. Expression of PtrRML1 in Arabidopsis resulted in glabrous phenotypes, increased number of root hairs, and decreased anthocyanin accumulation. Consist with these observation, the expression levels of some MBW component genes and some of their target genes involved in the regulation of epidermal cell fate determination and anthocyanin biosynthesis, including TRY, CPC, ETC1, GL1, GL2, DFR, UF3GT and TT8 were reduced in the transgenic plants.

The Root Hair Specific SYP123 Regulates the Localization of Cell Wall Components and Contributes to Rizhobacterial Priming of Induced Systemic Resistance.

Root hairs are important for nutrient and water uptake and are also critically involved the interaction with soil inhabiting microbiota. Root hairs are tubular-shaped outgrowths that emerge from trichoblasts. This polarized elongation is maintained and regulated by a robust mechanism involving the endomembrane secretory and endocytic system. Members of the syntaxin family of SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) in plants (SYP), have been implicated in regulation of the fusion of vesicles with the target membranes in both exocytic and endocytic pathways. One member of this family, SYP123, is expressed specifically in the root hairs and accumulated in the growing tip region. This study shows evidence of the SYP123 role in polarized trafficking using knockout insertional mutant plants. We were able to observe defects in the deposition of cell wall proline rich protein PRP3 and cell wall polysaccharides. In a complementary strategy, similar results were obtained using a plant expressing a dominant negative soluble version of SYP123 (SP2 fragment) lacking the transmembrane domain. The evidence presented indicates that SYP123 is also regulating PRP3 protein distribution by recycling by endocytosis. We also present evidence that indicates that SYP123 is necessary for the response of roots to plant growth promoting rhizobacterium (PGPR) in order to trigger trigger induced systemic response (ISR). Plants with a defective SYP123 function were unable to mount a systemic acquired resistance in response to bacterial pathogen infection and ISR upon interaction with rhizobacteria. These results indicated that SYP123 was involved in the polarized localization of protein and polysaccharides in growing root hairs and that this activity also contributed to the establishment of effective plant defense responses. Root hairs represent very plastic structures were many biotic and abiotic factors can affect the number, anatomy and physiology of root hairs. Here, we presented evidence that indicates that interactions with soil PGPR could be closely regulated by signaling involving secretory and/or endocytic trafficking at the root hair tip as a quick way to response to changing environmental conditions.

Effects of rhizobacteria on seed germination of water spinach (Ipomoea aquatica)

Rhizobacteria are considered as the most useful microorganism based on their properties in nitrogen fixing, phosphate and potassium solubilizing, IAA and other plant hormones which improve the germination of seed. However, seed germination varied depending on stimulator such as bacterial strains, bacterial growing media. This investigation focused on testing the germination of Ipomoea aquatica vegetable by using three rhizobacteria isolates including H1-702, C1-112, P1-5071 and their growing media. Percentage of seed germination, shoot length, root length and number of root hairs of I. aquatica were lowest found in nutrient media treatments without bacteria (50%, 1.67 cm, 1.47 cm, and 1.47, respectively) while the highest numbers were obtained from the treatment of soaked seed with bacterial suspension which gave rise 90%, 4.88 cm, 3.01 cm and 19.26, respectively. Among all treatments, percentage of seed germination was highest (83%) in the single inoculums treatments C1-112 and H1-702. In day 5, the highest root length (2.4 cm) and root hair number (22.05) was showed in H1-702 treatment while C1-112 treatment revealed the highest shoot length (4.52 cm). The combination of two bacterial isolates did not stimulate the germination of I. aquatica , especially, P-H treatment which got the lowest number in all observation data.

Soybean SPX1 is an important component of the response to phosphate deficiency for phosphorus homeostasis

Phosphate (Pi) homeostasis is required for plant growth and development, but the Pi-signaling pathways in plants still remain largely unknown. Proteins only containing the SPX domain are very important in phosphate (Pi) homeostasis and signaling transduction. In the T-DNA insertion Arabidopsis mutant spx3, AtPHT1-4, AtPHT1-5, AtACP5, AtRNS, and AtAT4 expression levels were increased under Pi-sufficient condition and low Pi condition compared with WT. Meanwhile, the expression levels of these phosphate starvation genes was inhibited in OXSPX1 and spx3/OXSPX1 compared with WT, only under Pi-sufficient condition. These imply that GmSPX1 may negatively control the transcription of Pi starvation responsive genes indirectly. However, there were no differences between expression levels of these PSI genes in spx3 and those in WT under −Pi conditions. These facts imply that the negative regulation of GmSPX1 and AtSPX3 on PSI genes is depending on Pi concentration. Consistent with this, GmSPX1 overexpression in the WT and spx3 decreased the total Pi concentration in plants and changed root hair morphology, suppressing the elongation and number of root hairs compared with the WT and spx3. The yeast two-hybrid assays and BiFC assays demonstrated that GmSPX1 could interact with GmMYB48.The qRT-PCR analysis showed that GmMYB48 is a new phosphate starvation induced transcription factor in soybean. Also, GmSPX1 overexpression led to decreased transcripts of AtMYB4, an ortholog of GmMYB48, in OXSPX1. Together, these results suggest that GmSPX1 is a negative regulator in the Pi signaling network of soybean, and the interaction of GmSPX1/GmMYB48 can be considered a potential candidate suppressor.

Influence of biocontrol agents and fungicides on vegetative parameters of groundnut (Arachis hypogaea L.) under greenhouse conditions

In the present study the compatibility of various plant growth promoting organisms [Pseudomonas fluorescens (Pf), Trichoderma viride (Tv) and Rhizobium (Rhi)] along with fungicides (mancozeb, tebuconazole and carbendazim + mancozeb) was tested on groundnut crop (cv. K-6) variety under greenhouse conditions. At 45 days after sowing (DAS), maximum (109) number of root nodules was observed in plants treated with combination of biocontrol agents Pf, Tv and Rhi. Maximum (1314.7 mm) root length was observed in Pf and Rhi combination while root area was recorded to be maximum (1341.8 mm2) in Rhi treatment. Root diameter (3.7 mm), root hairs (79.5) and chlorophyll content (51.7) were significant in Pf and Rhi combination. At 90 DAS, boosting effect on root nodules with maximum number (111) was seen in seeds treated with combination of biocontrol agents Pf, Tv and Rhi. Root length was prominent (1775.5 mm) in Tv treated plants whereas root area was maximum (1865.6 mm2) in Pf and Rhi combination. Maximum root diameter (4.8 mm) was found in Pf and Rhi combination whereas Pf, Tv and Rhi combination showed significant (108.5) root hair number. Pf treated plants showed remarkable (60.3) chlorophyll content compared to other treatments. The study showed increase in overall growth parameters in biocontrol agents treated plants followed by fungicides.

A Complex Molecular Interplay of Auxin and Ethylene Signaling Pathways Is Involved in Arabidopsis Growth Promotion by Burkholderia phytofirmans PsJN.

Modulation of phytohormones homeostasis is one of the proposed mechanisms to explain plant growth promotion induced by beneficial rhizobacteria (PGPR). However, there is still limited knowledge about the molecular signals and pathways underlying these beneficial interactions. Even less is known concerning the interplay between phytohormones in plants inoculated with PGPR. Auxin and ethylene are crucial hormones in the control of plant growth and development, and recent studies report an important and complex crosstalk between them in the regulation of different plant developmental processes. The objective of this work was to study the role of both hormones in the growth promotion of Arabidopsis thaliana plants induced by the well-known PGPR Burkholderia phytofirmans PsJN. For this, the spatiotemporal expression patterns of several genes related to auxin biosynthesis, perception and response and ethylene biosynthesis were studied, finding that most of these genes showed specific transcriptional regulations after inoculation in roots and shoots. PsJN-growth promotion was not observed in Arabidopsis mutants with an impaired ethylene (ein2-1) or auxin (axr1–5) signaling. Even, PsJN did not promote growth in an ethylene overproducer (eto2), indicating that a fine regulation of both hormones signaling and homeostasis is necessary to induce growth of the aerial and root tissues. Auxin polar transport is also involved in growth promotion, since PsJN did not promote primary root growth in the pin2 mutant or under chemical inhibition of transport in wild type plants. Finally, a key role for ethylene biosynthesis was found in the PsJN-mediated increase in root hair number. These results not only give new insights of PGPR regulation of plant growth but also are also useful to understand key aspects of Arabidopsis growth control.

MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex

In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species (ROS). MES, 2-(N-morpholino)ethanesulfonic acid as one of the Good’s buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v) because the buffer capacity of MES ranging pH 5.5–7.0 (for Arabidopsis, pH 5.8). However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone, and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone). Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the ROS homeostasis in root apex.

Root Responses to Boron Deficiency Mediated by Ethylene

Low boron (B) supply alters the architecture of the root system in Arabidopsis thaliana seedlings, leading to a reduction in the primary root growth and an increase in the length and number of root hairs. At short-term (hours), B deficiency causes a decrease in the cell elongation of the primary root, resulting in a lower growth. Experimental approaches using ethylene insensitive Arabidopsis mutants, inhibitors of ethylene response, and GUS reporter lines suggest that ethylene is involved in these responses of the primary root to B deficiency. Furthermore, it has been shown that auxin participates in the inhibition of cell elongation under short-term B deprivation. These results support that an interaction between ethylene and auxin plays an important role in controlling the primary root elongation, in which a number of genes related to the synthesis, transport, and signaling of both phytohormones could modulate this effect. Evidence for a root cross-talk among both hormones and other possible intermediates (abscisic acid, calcium sensors, and reactive oxygen species) in response to B deficiency is provided and discussed.

Root hair formation at the root-hypocotyl junction in CPC-LIKE MYB double and triple mutants of Arabidopsis

In Arabidopsis thaliana, R3-type MYB genes, CAPRICE (CPC) and its family of genes including TRIPTYCHON (TRY), ENHANCER OF TRY AND CPC1 (ETC1), ETC2 and CPC-LIKE MYB3 cooperatively regulate epidermal cell differentiation. Root hair formation is greatly reduced by a mutation in CPC, and try and etc1 enhance this phenotype. In this study, we demonstrate that CPC, TRY and ETC1 are also involved in root hair formation at the root-hypocotyl junction. The cpc try and cpc etc1 double mutants showed a reduced number of root hairs in that area. Additionally, the expression of ETC1::GUS was higher near this area. These results suggest that CPC family of genes also cooperatively regulates root hair formation at the root-hypocotyl junction in unique ways.

The histone deacetylase HDA19 controls root cell elongation and modulates a subset of phosphate starvation responses in Arabidopsis.

The length of root epidermal cells and their patterning into files of hair-bearing and non-hair cells are genetically determined but respond with high plasticity to environmental cues. Limited phyto-availability of the essential mineral nutrient phosphate (Pi) increases the number of root hairs by longitudinal shortening of epidermal cells and by reprogramming the fate of cells in positions normally occupied by non-hair cells. Through analysis of the root morphology and transcriptional profiles from transgenic Arabidopsis lines with altered expression of the histone deacetylase HDA19, we show that in an intricate interplay of Pi availability and intrinsic factors, HDA19 controls the epidermal cell length, probably by altering the positional bias that dictates epidermal patterning. In addition, HDA19 regulates several Pi-responsive genes that encode proteins with important regulatory or metabolic roles in the acclimation to Pi deficiency. In particular, HDA19 affects genes encoding SPX (SYG1/Pho81/XPR) domain-containing proteins and genes involved in membrane lipid remodeling, a key response to Pi starvation that increases the free Pi in plants. Our data add a novel, non-transcriptionally regulated component of the Pi signaling network and emphasize the importance of reversible post-translational histone modification for the integration of external signals into intrinsic developmental and metabolic programs.

Distillery effluent as a liquid fertilizer: a win–win option for sustainable agriculture

A promising approach to recycle the residual distillery waste as a potential liquid fertilizer has been discussed in this paper. Field studies were conducted on Brassica compestris to assess the potential of the diluted post- methanated distillery effluent. The results indicated that there was not much variation in pH, conductivity and nitrate of soil, whereas total dissolved solids, conductivity, nitrate and chemical oxygen demand of the well water increased slightly but well within the permissible limit. However, there was a significant increase in the plant biomass, diameter of the shoot and root, area of leaf, as well as number and length of pods and root hairs. The hydrophilic colloids of the seed increased significantly (p < .01) and the yield of mustard seeds was increased by 30% as compared to the conventional fertilizer. The carbohydrate, chlorophyll and ascorbic acid content of the leaf, stem and root were also analysed and its morpho- physiological significance is also presented in this paper.

Phytotoxic interference of volatile organic compounds and water extracts of Tinospora tuberculata Beumee on growth of weeds in rice fields

Tinospora tuberculata Beumee is an aromatic shrub with pharmacological properties and belongs to the Menispermaceae family. We assessed T. tuberculata for its ability to suppress growth of weeds in rice fields. In seedling bioassays, the rate of seed germination and the radicle and hypocotyl lengths of barnyardgrass, rice and weedy rice seedlings were reduced as the concentration of aqueous water extracts and volatile organic compounds increased compared to the control. In a glasshouse experiment, T. tuberculata leaf powder also exhibited effective reduction in the emergence and growth of weeds in rice fields. Applications at rates of 4tha−1 completely suppressed emergence of barnyardgrass, sprangletop and smallflower umbrella. The chemical compositions of extracts and volatiles were analyzed by GC–MS and HS-SPME-GC–MS. The results showed that 7 of 43 components in the leaf aqueous extract, as compared to 5 of 15 compounds in the stem aqueous extract, are known to be toxic compounds. Moreover, eight main volatile organic compounds were identified, which accounted for 97 and 95% of the whole fresh and dry leaf volatiles, respectively. We observed qualitative and quantitative differences in the compounds present in the dry and fresh leaf. Confocal laser scanning microscope images showed that the volatile emissions and aqueous extracts also inhibited the main root diameter, and the number and elongation of root hairs of tested weeds in rice fields. These results suggest that T. tuberculata contains a significant source of plant growth inhibitors. Hence, it can be used as a mulch to suppress weeds in rice fields and for developing new herbicide based on phytotoxic compounds release by this plant.

CHANGES IN THE MORPHOLOGY OF THE ROOT SYSTEM OF WHEAT INOCULATED WITH Azospirillum brasilense Sp7 AND BACTERIOPHAGE FAb-Sp7

The Azospirillum is one of the most common objects to study associative interactions between bacteria and plants. In the rhizosphere of cereals the Azospirillum cells form effective association and demonstrate a stimulating effect on plant growth and development, in particular in wheat. However, the details of these positive effects are still unknown. For example, there is no evidence of whether the Azospirillum cells are infected with bacteriophages, and little is known about the role that the bacteriohages of soil microorganisms can play in the development of associative relationship between microorganisms and plants. Nevertheless, the bacteriophages are well known to control the bacteria number in the population and be involved in genetic transduction. Note that the studied bacteriophages are mostly isolated from environment, in particular, from soil, while the bacteriphages of associative soil bacteria still remain poorly studied. To evaluated changes in the morphology of the wheat (Triticum aestivum L.) root system in Saratovskaya 29 variety after inoculation with Azospirillum brasilense Sp7 bacterial cells and bacteriophage FAb-Sp7, isolated from these cells, we first inoculated the 3-day old wheat seedlings with A. brasilense Sp7 at 108, 106, 104 cells per 1 ml. It resulted in a decrease in the length of the root, and the number of lateral roots grew considerably at 102 cells per 1 ml. After treatment wiht bacteriophage FAb-Sp7 an average number of roots remained unchanged. It was shown that wheat seedling inoculation with Azospirillum suspension resulted in a 3-fold decrease in root elongation zone, and the suction zone reduced 1.5 times. Treatment of wheat seedlings with a suspension containing Azospirillum and phages resulted in a 3.3-fold decrease in the tensile zone, but the root hair zone remained unchanged. Using confocal microscopy we demonstrated that incubation of wheat seedlings with Azospirillum at 102 cells per 1 ml significantly increased the number and length of root hairs (on average by 40 %) compared with the control. It was shown that a simultaneous inoculation with Azospirillum Sp7 cells and bacteriophage FAb-Sp7 also increased the number and length of root hairs (60 % on average) compared with control. It is suggested that bacteriophages of Azospirillum are involved into complex interaction of bacteria with wheat root system, and can influence on and, ultimately, determine the effectiveness of associative relationships between the plant and microorganisms.

Morphological and biochemical responses of Abelmoschus esculantus (L.) Moench to zinc nanoparticles

The increasing application and use of nanoparticles are directly related to their release in the environment. There has arisen the necessity to study the interactions of nanoparticles with plants and other organisms. The present investigation is an attempt to evaluate the morphological and biochemical responses of Abelmoschus esculentus (L.) Moench to zinc nanoparticles treatment. Seeds were treated with zinc nanoparticles at concentrations of 50 100, 200, 500 ppm. The morphological and biochemical responses recorded include germination percentage, root, shoot length, number of root hairs and number of leaves. Chlorophyll, protein, proline and carbohydrate contents in the leaves of 30-days-old treated plants were estimated. A greater amount of total dissolved solids (TDS) leached out from the seeds soaked in different concentrations of Zn nanoparticles compared to the control. Zinc nanoparticles executed a positive impact on the seed germination. The seed germination percentage increased in all the treatments compared to control. Increase in the chlorophyll and protein content was also observed in the treated plants. The proline content increased in treated plants indicating the stress. The carbohydrate content of leaves decreased drastically in response to the treatment.