Chickpea Roots Research Articles

Appraising Endophyte–Plant Symbiosis for Improved Growth, Nodulation, Nitrogen Fixation and Abiotic Stress Tolerance: An Experimental Investigation with Chickpea (Cicer arietinum L.)

Chickpea is an important leguminous crop that improves soil fertility through atmospheric nitrogen fixation with the help of rhizobia present in nodules. Non-rhizobia endophytes are also capable of inducing nodulation and nitrogen fixation in leguminous crops. The aim of the current study was to isolate, characterize and identify the non-rhizobia endophytic bacterial strains from root nodules of chickpea. For this purpose, more than one hundred isolates were isolated from chickpea root nodules under aseptic conditions and were confirmed as endophytes through re-isolating them from root nodules of chickpea after their inoculation. Nineteen confirmed endophytic bacterial strains revealed significant production of indole acetic acid (IAA) both in presence and absence of L-tryptophan and showed their ability to grow under salt, pH and heavy metal stresses. These strains were evaluated for in vitro plant growth promoting (PGP) traits and results revealed that seven strains showed solubilization of P and colloidal chitin along with possessing catalase, oxidase, urease and chitinase activities. Seven P-solubilizing strains were further evaluated in a jar trial to explore their potential for promoting plant growth and induction of nodulation in chickpea roots. Two endophytic strains identified as Paenibacillus polymyxa ANM59 and Paenibacillus sp. ANM76 through partial sequencing of the 16S rRNA gene showed the maximum potential during in vitro PGP activities and improved plant growth and nodulation in chickpea under the jar trial. Use of these endophytic strains as a potential biofertilizer can help to reduce the dependence on chemical fertilizers while improving crop growth and soil health simultaneously.

Seed bacterization stimulated resistance in chickpea against Fusarium oxysporum f. sp. ciceris

The study envisaged at eliciting defense in chickpea plants challenged with and without Fusarium oxysporum f. sp. ciceris on prior inoculating seeds with two bioagents, Bacillus sp. and Brevibacillus brevis alone and in conglomeration with rhizobia. Spectrophotometric analysis for defense-related enzymes demonstrated higher accrual of peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), phenols and total proteins in bacterized plants compared to uninoculated control and only pathogen inoculated chickpea roots. Nevertheless, activities of PAL, PO and PPO were found to be higher in the bacterized root tissue of the plants challenged with F. oxysporum compared to only bacterized plants. Combined administration of bacterial isolates with rhizobia resulted in stimulated expression of defense enzymes than with either agent alone. The steady increase in synthesis of defense enzymes was recorded up to 15 days which reached maximum by 20th day and then declined drastically. Native-polyacrylamide gel electrophoresis analysis for PO and PPO anionic forms following activity staining revealed higher expression of PO3, PO5, PO4, PO7, PPO1 and PPO3 isoforms in bacterized chickpea root tissues challenge inoculated with the pathogen. Higher expression of enzymes could be associated with defense against ingressing pathogen.

Identification and pathogenicity of Rhizoctonia solani AG-4 causing root rot on chickpea in Turkey

In the 2016-17 growing seasons, surveys were conducted in the Isparta, Uşak, Kütahya and Denizli provinces of Turkey to identify the Rhizoctonia solani AG-4 associated with root and crown rot of chickpea. A total of 75 isolates of Rhizoctonia were obtained from surveyed areas. Visual diagnostic, isolation and microscopic observation identified the causal organism as R. solani. Sequence data of the ITS rDNA region confirmed the species identity and revealed that the anastomosis group of the 23 isolates were AG-4 HGII. The isolates were variable in their morphological characters. The sequences generated during this study were clustered in the same branch with the reference isolates of R. solani AG-4 HGII based on their ITS sequencing on chickpea and the isolate grouping was not related to their geographic origins or virulence pattern. Pathogenicity tests revealed that all AG-4 isolates were pathogenic on chickpea and the disease severity values of 23 isolates varied between 42.8% and 100%. Based on the virulence, the isolates were grouped into two categories: 5 of them exhibited moderately virulence and 18 of them exhibited highly virulence reaction on chickpea. The high virulent isolate level (>50% disease severity) was determined as 78.2% of all 23 isolates. This is the first report of R. solani AG-4 as a pathogen of chickpea in Turkey.

Strong effect of recovery period between hypoxia events on roots of chickpea (Cicer arietinum L)

Hypoxia as an environmental stress affects the physiological, metabolic, and anatomical parameters in plants. This experiment was conducted in order to evaluate the changes of these parameters in chickpea roots in response to hypoxia followed by recovery. With this aim, two periods of hypoxia (two and four days) and recovery subsequent (one and three days) were applied on chickpea roots in a hydroponic condition. Hypoxic condition significantly decreased the root dry weight of plants. However, the contents of anthocyanins, flavonoids, malondialdehyde (MDA), hydrogen peroxide (H2O2), as well as the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX)) were increased by hypoxia. In addition, anatomical changes were observed in the chickpea roots under the hypoxia and recovery treatments. Under the hypoxic condition, root's aerenchyma began to form and the thickness of the Casparian strip was decreased. Interestingly, the one-day recovery following two or four days of hypoxia could not reduce the hypoxia effects on the chickpea roots. In contrast, the three-day recovery period partly reduced the adverse effect of hypoxia. The pattern of physiological, metabolic, and anatomical changes during the recovery period following the four-day hypoxia was similar to the recovery period following the two-day hypoxia. These findings display a negative effect of hypoxia and one-day recovery following hypoxia on different parameters of chickpea roots. Nevertheless, prolonging the period of recovery (three-day recovery) has a positive effect on the chickpea roots after exposure to hypoxia.

Novel Sources of Resistance to Root-Lesion Nematode (Pratylenchus thornei) in a New Collection of Wild Cicer Species (C. reticulatum and C. echinospermum) to Improve Resistance in Cultivated Chickpea (C. arietinum).

Pratylenchus thornei, a nematode species that feeds and reproduces in chickpea (Cicer arietinum) roots, is widespread throughout the Mediterranean basin and Indian subcontinent. In Australia, it can cause yield losses up to approximately 25% of intolerant chickpea cultivars. Potential for improvement has been hindered by the narrow genetic diversity of cultivated chickpea and a limited world collection of original wild Cicer spp. in the primary gene pool, consisting of 18 C. reticulatum and 10 C. echinospermum accessions. Recently, collections of C. reticulatum and C. echinospermum from Turkey have substantially increased the number of accessions. This study evaluated 133 C. reticulatum and 41 C. echinospermum accessions from the new collection for resistance to P. thornei under controlled conditions in repeated glasshouse pot experiments. The aim of the study was to identify accessions with resistance superior to that currently available in Australian germplasm. Both wild Cicer spp. were found, on average, to be more resistant to P. thornei (P < 0.001) than C. arietinum. Combined analyses across experiments to determine genetic rankings showed that 13 (7%) wild accessions were significantly more resistant than the most resistant C. echinospermum reference ILWC 246, while another 40 (23%) accessions were significantly more resistant than the least susceptible Australian chickpea cultivar PBA Seamer. Mean P. thornei population densities differed significantly between collection sites in Turkey and within each of the genetic population groups. The sites Kayatepe and Baristepe1, and genetic population groups Ret_A and Ret_F associated with sites Oyali and Baristepe1, produced the lowest P. thornei population densities. This is the first report assessing the resistance to P. thornei of this new collection which offers novel sources of P. thornei resistance and untapped genetic diversity valuable for international chickpea breeding programs to exploit.

Pathogen Identification and Evaluation of Chickpea Varieties for Resistance Against the Pathogens in West Shewa, Oromia Regional State, Ethiopia

Chickpea (Cicer arietinum L) is one of the economically important grain legume crops in Africa particularly in Ethiopia which widely grown in marginal soils and usually as rotational crops in highland and semi-highland regions of the country and also as a source of cash to the farmers and foreign currency in Ethiopia. However, its production is affected by many pest and diseases. Among them wilt or root rot diseases are considered as the major problems in chickpea production. Therefore, the present study was conducted to identify chickpea wilt or root rot causing pathogens and evaluate of chickpea varieties resistance against identified pathogens in West Shewa, Oromia regional state, Ethiopia. The pathogenicity test revealed that three fungal pathogens, Fusarium oxysporum, Fusarium solani and Rhizoctonia bataticola were identified as wilt/root rot causing pathogens. The percentage frequency of occurrence of Fusarium oxysporum, Fusarium solani and Rhizoctonia bataticola regardless of the districts were 50.7%, 26.76% and 14.08%, respectively. Among seven chickpea varieties, host resistance were evaluated against the identified wilt /root rot causing fungal pathogens, the variety, Arerti was the only resistant to all identified wilt causing pathogenic isolates. The varieties, Arerti and Shasho were resistant and Habru was moderately resistant reaction to Fusarium oxysporum. But local and Dz-10-4 cultivars were found to be highly susceptible. The cultivars, Arerti, Acos dube and Dz-10-4 were found to be resistant and Shasho and Chefe were moderately resistant to Rhizoctonia bataticola. Except Arerti variety, all inoculated varieties were susceptible to Fusarium solani isolate. Only local variety was highly susceptible to all identified pathogenic isolates. The remaining varieties were susceptible to tested pathogenic isolates with varying degrees. Therefore, from the artificial inoculation test, resistance of chickpea varieties to specific isolates could be further deployed for sustainable wilt or root rots management. Further, the effective and feasible integrated management options need to be developed on chickpea wilt /root rot diseases in the country. Keywords : Chickpea Wilt or Root rots Pathogens, isolation, varieties, host resistance. DOI : 10.7176/ALST/73-04 Publication date : April 30 th 2019

Proteomic analysis of chickpea roots reveal differential expression of abscisic acid responsive proteins.

Seeds of chickpea are nutritious and alleged to be a preferred source of protein next only to milk. Some of the biotic and abiotic factors reduce chickpea production worldwide. Plant roots are the first to perceive stress signals. The wild root free radical scavenging activity measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method was 28.06±1.43% and 25.12±0.95% in cultivated chickpea type. The root proteins were resolved on 7cm IPG strip having a pH gradient 5-8 and subsequently separated on the basis of mass using SDS-PAGE in second dimension. A total of eight representative spots were subjected for identification by MALDI-TOF-MS. A protein-protein association network analysis using STRING software permitted to build an interactomic map of all detected proteins, characterised by 16 interactions. The findings may provide a better understanding of the biochemical mechanism of different root pathways and stress-responses in chickpea. PRACTICAL APPLICATIONS: Information pertaining to stress resistance is essential from breeder's perspectives. Chickpea is prone to high yield losses due to recurring droughts. MALDI-TOF-MS coupled with MASCOT query search found significant correlations with abscisic acid responsive proteins associated to drought stress using comparative proteomics. This report will assist researchers a ready reference for executing further studies concerning chickpea root proteins. The findings may provide a better understanding of the biochemical mechanism of different root pathways and stress-responses in chickpea.

Diversity and Functionality of Culturable Endophytic Bacterial Communities in Chickpea Plants.

The aims of this study were to isolate, identify and characterize culturable endophytic bacteria from chickpea (Cicer arietinum L.) roots grown in different soils. In addition, the effects of rhizobial inoculation, soil and stress on the functionality of those culturable endophytic bacterial communities were also investigated. Phylogenetic analysis based on partial 16S rRNA gene sequences revealed that the endophytic bacteria isolated in this work belong to the phyla Proteobacteria, Firmicutes and Actinobacteria, with Enterobacter and Pseudomonas being the most frequently observed genera. Production of indoleacetic acid and ammonia were the most widespread plant growth-promoting features, while antifungal activity was relatively rare among the isolates. Despite the fact that the majority of bacterial endophytes were salt- and Mn-tolerant, the isolates obtained from soil with Mn toxicity were generally more Mn-tolerant than those obtained from the same soil amended with dolomitic limestone. Several associations between an isolate’s genus and specific plant growth-promoting mechanisms were observed. The data suggest that soil strongly impacts the Mn tolerance of endophytic bacterial communities present in chickpea roots while rhizobial inoculation induces significant changes in terms of isolates’ plant growth-promoting abilities. In addition, this study also revealed chickpea-associated endophytic bacteria that could be exploited as sources with potential application in agriculture.

Chitosan nanoparticles loaded with thiamine stimulate growth and enhances protection against wilt disease in Chickpea

Nanoencapsulation is considered as one of the unique technique for increasing the bioavailability, solubility and retention time of bioactive compounds. In this study, thiamine was incorporated into the chitosan nanoparticles and characterized through FTIR, DLS, SEM, TEM and XRD analyses. Zeta potential of the synthesized nanoparticles was found to be 37.7 mV. The encapsulation efficiency of chitosan nanoparticle was 90 ± 3%. Application of thiamine loaded chitosan nanoparticle enhanced seed germination and growth of chickpea seedlings when compared to untreated control seeds. Treated seedlings showed enhanced production of indole acetic acid (IAA). Foliar application of synthesized nanoparticle induced defense enzymes in leaves and roots of chickpea plants. Decreased cell death in the chickpea roots of treated plants was observed when compared to control under green house condition. These results showed that the thiamine loaded chitosan nanoparticle can be used as a growth stimulator as well as a defense activator in chickpea.

Diversity of endomycorrhizal fungi in the rhizosphere of chickpea in Morocco

The endomycorrhizal fungi diversity in the rhizosphere of chickpea (Cicer arietinum L.) and the evaluation of root mycorrhizal level were studied in six regions of Morocco: Tahla, Sefrou, Souk Larbae, Souk Tlat, Ouazzane and Jarf Melha. All chickpea roots are carrying endomycorrhizal structures. Root mycorrhizal parameters varied from one site to another, and the highest frequency and intensity of mycorrhization was recorded in the roots of chickpea plants at the two sites Tahla and Jarf Melha respectively, 83%, 33% and 25.03%. In addition, the highest arbuscular content was also noted in the roots of plants growing in the site of Tahla (22.18%) while the lowest content was noted at the site of Sefrou (2.07%). However, the vesicles were not observed in all the sites. The highest numbers of endomycorrhizal spores were recorded in the rhizosphere of plants collected in Jarf Melha and Tahla, respectively, 74 and 41 spores / 100 g soil. All spores found in the studied sites are represented by 22 morphotypes belonging to 7 genera: Glomus (13 species), Acaulospora (4 species), Gigaspora (one species), Radekera (one species), Entrophospora (one species), Pacispora (one species), Dentiscutata (one species).

Genome-wide profiling reveals extensive alterations in Pseudomonas putida-mediated miRNAs expression during drought stress in chickpea (Cicer arietinum L.)

Pseudomonas putida strain MTCC5279 (RA) is a plant growth promoting rhizobacteria which improves growth and development of plants by colonizing their root surface and also confers drought stress tolerance. Further, along with several stress responsive genes, microRNAs are also well known for their crucial involvement in drought stress response. Considering the above, in this study, we performed identification and expression profiling of small RNAs in chickpea roots either uninoculated or inoculated with P. putida RA under drought stress through high-throughput sequencing. We identified 923 conserved and 216 novel miRNAs from all four libraries. Out of these, 431 and 332 conserved miRNAs; and 60 and 39 novel miRNAs were found to be differentially expressed in RA and drought with RA-inoculated plants, respectively. A total of 4647 and 551 target genes involved in various biological, cellular and molecular processes were predicted to be targets of conserved and novel miRNAs, respectively. Stem-loop quantitative real-time PCR analysis of selected nine miRNAs showed their expression patterns in consistence with those obtained from Illumina-sequencing. Besides, the expression patterns of miRNAs showed inverse correlation to that of their respective targets. Our results indicate that RA plays a very crucial role in regulating the expression of miRNAs and their targets during drought stress in chickpea paving the way for further characterization and utilization of miRNAs in crop improvement programmes.

THE EFFECT OF SEED INOCULATION BY RHIZOTORFIN STRAINS ON CHICKPEA PRODUCTIVITY IN THE SOUTHERN PART OF THE ROSTOV REGION

The article presents the study results of seed inoculation by specific strains Mesorhizobiumciceri on number and weight of chickpea root nodules, productivity and nutrition value of chickpea cultivated in the southern nature-climatic part of the Rostov region. The study was conducted on the fields of FSBSI “Agricultural Research Center “Donskoy” (in the laboratory of cultivation technology of row crops) located in the southern part of the Rostov region in 2015–2016. The soil of the plot was heavy loamy carbonate blackearth (chernozem) with 7.0 рН, 3.2% of humus, 18–25 of P2O5 mg/kg of soil and 350–400 of K2O mg/kg of soil. The object of the study was a chickpea variety ‘Volgogradsky 10’, approved to use in the Rostov region. The strains of nodule bacteria (Rhyzotorfin) were developed and presented by the FSBSI All-Russian Research Institute of Agricultural Microbiology (the laboratory of ecology of symbiotic and associative rhizobacteria). Agroclimatic conditions of chickpea vegetation period ranged throughout the years of study that allowed estimating chickpea productivity without fear or favor. The use of Rhyzotorfin strains resulted in increasing preservation of plants for harvesting, improving seed productivity (seed-weight per plant, 1000-kernel weight) and increasing grain productivity (with the increase on 0.24–0.51 t/ha compared with the control). Large yields of fodder units and raw protein per unit area testified the improvement of nutrition value of chickpea kernels, and the increase of these traits to the control was 0.33–0.68 t/ha and 26.5-93.1 kg/ha respectively.

Genotype-independent Agrobacterium rhizogenes-mediated root transformation of chickpea: a rapid and efficient method for reverse genetics studies

Background Chickpea (Cicer arietinum L.), an important legume crop is one of the major source of dietary protein. Developing an efficient and reproducible transformation method is imperative to expedite functional genomics studies in this crop. Here, we present an optimized and detailed procedure for Agrobacterium rhizogenes-mediated root transformation of chickpea.ResultsTransformation positive roots were obtained on selection medium after two weeks of A. rhizogenes inoculation. Expression of green fluorescent protein further confirmed the success of transformation. We demonstrate that our method adequately transforms chickpea roots at early developmental stage with high efficiency. In addition, root transformation was found to be genotype-independent and the efficacy of our protocol was highest in two (Annigiri and JG-62) of the seven tested chickpea genotypes. Next, we present the functional analysis of chickpea hairy roots by expressing Arabidopsis TRANSPARENT TESTA 2 (AtTT2) gene involved in proanthocyanidins biosynthesis. Overexpression of AtTT2 enhanced the level of proanthocyanidins in hairy roots that led to the decreased colonization of fungal pathogen, Fusarium oxysporum. Furthermore, the induction of transgenic roots does not affect functional studies involving infection of roots by fungal pathogen.ConclusionsTransgenic roots expressing genes of interest will be useful in downstream functional characterization using reverse genetics studies. It requires 1 day to perform the root transformation protocol described in this study and the roots expressing transgene can be maintained for 3–4 weeks, providing sufficient time for further functional studies. Overall, the current methodology will greatly facilitate the functional genomics analyses of candidate genes in root-rhizosphere interaction in this recalcitrant but economically important legume crop.

Proteomic analysis of the promotive effect of plant-derived smoke on plant growth of chickpea

Plant-derived smoke plays a key role in seed germination and plant growth. To investigate the effect of plant-derived smoke on chickpea, a gel-free/label-free proteomic technique was used. Germination percentage, root/shoot length, and fresh biomass were increased in chickpea treated with 2000 ppm plant-derived smoke within 6 days. On treatment with 2000 ppm plant-derived smoke for 6 days, the abundance of 90 proteins including glycolysis-related proteins significantly changed in chickpea root. Proteins related to signaling and transport were increased; however, protein metabolism, cell, and cell wall were decreased. The sucrose synthase for starch degradation was increased and total soluble sugar was induced. The proteins for nitrate pathway were increased and nitrate content was improved. On the other hand, although secondary metabolism related proteins were decreased, flavonoid contents were increased. Based on proteomic and immuno-blot analyses, proteins related to redox homeostasis were decreased and increased in root and shoot, respectively. Furthermore, fructose‑bisphosphate aldolase was increased; while, phosphotransferase and phosphoglycero mutase were decreased in glycolysis. In addition, phosphoglyceraldehyde‑3‑phosphate dehydrogenase and glutamine synthetase related genes were up-regulated. These results suggest that plant-derived smoke improves early stage of growth in chickpea with the balance of many cascades such as glycolysis, redox homeostasis, and secondary metabolism. Biological significanceThe current study examined the effects of plant-derived smoke on root of chickpea seedlings using a gel-free/label-free proteomic technique. Based on functional categorization of results from proteomics, proteins related to glycolysis, signaling, transport, protein metabolism, cell wall, and cell were predominantly changed in chickpea. The proteins related to carbohydrate and nitrate pathways were increased, while, those of secondary metabolism were decreased. Physiological analysis indicated that flavonoid, total soluble sugar, and nitrate content were increased in root of chickpea treated with plant-derived smoke for 6 days. Moreover, accumulated protein abundance of glyceraldehyde‑3‑phosphate dehydrogenase and fructose-bisphosphate aldolase was in agreement with immuno-blot results, which suggests that glycolysis process might be enhanced in root of chickpea in response to plant-derived smoke.

Effects of long term exposure to aluminium stress on the accumulation and distribution of K+, Na+, Ca2+, Mg2+, Fe2+ and Clin rice and chickpea plants

Sand culture experiments were undertaken to examine the effect of increasing aluminium levels (50-150 μM) on the mineral nutrients uptake (K+, Na+, Ca2+, Mg2+, Fe2+ and Cl-). Increasing concentrations of Al inhibited the uptake of K+, Ca2+, Mg2+ and Fe2+ but enhanced that of Na+ and Cl- in the root and shoot of rice, and the root, stem and leaves of chickpea. 150 μM Al caused a maximum inhibition of K+ accumulation in the root and shoot of rice ranging from 25.5 to 49.0% and 33 to 55.5%, respectively, from 7 to 28 day of treatment. In the root, stem and leaves of chickpea, 150 μM Al inhibited K+ content by 23.9 to 84.0%, 13.2 to 54.4% and 25.3 to 61.2%, respectively, from 7 to 28 day of application. On the contrary, a dramatic 2.7 to 3.1-folds and 70.8% to 2.3-folds stimulation of Na+ accumulation was recorded in the root of rice and chickpea, respectively, following 100 μM Al treatment from 7 to 28 day of treatment. Different concentrations of aluminium led to a stimulation of Cl- accumulation in different parts of rice and chickpea plants. In rice and chickpea plants, the inhibitory effect of aluminium stress on the accumulation of Ca2+, Mg2+ and Fe2+ was enhanced with the increase in Al concentration from 50 to 150 μM.&#x0D; Dhaka Univ. J. Biol. Sci. 27(1): 37-48, 2018 (January)

Distribution and factors influencing chickpea wilt and root rot epidemics in Ethiopia

Chickpea is a major food legume crop in the mid-highlands of Ethiopia where its yield is negatively impacted by the wilt and root rot disease complex. The pathogens associated with WRR complex and their associations with biophysical factors have not been well understood in the past. We report here a survey of five major chickpea-growing regions covering 30 districts in the central and northern highlands of Ethiopia. The associations between disease parameters and biophysical factors were assessed using logistic regression analyses. Moreover, pathogens associated with wilt and root rot were identified, and their frequency of occurrence was determined. Mean percent wilt and root rot incidence and percent severity index were the highest in Gojam followed by Gondar and the lowest in Shoa. The major pathogens associated with infected roots were Fusarium oxysporum f. sp. ciceris, Fusarium solani, Rhizoctonia bataticola, Sclerotium rolfsii, and Rhizoctonia solani. The most frequently isolated pathogen was F. oxysporum f. sp. ciceris followed by R. solani. Moreover, significant (P < .001) associations between disease parameters and planting date and between weeding practice and soil and chickpea types were observed. High disease incidence and percent severity index showed high probability of association with planting date and chickpea types. Desi chickpea and chickpea that were planted early in the season had approximately 2 and 9 times greater probability of experiencing a high disease incidence and a 6–5 times greater probability of experiencing high wilt and root rot severity, respectively. High disease incidence and percent severity index were also correlated with weed infestation and planting on heavy black soils. Therefore, late planting, appropriate weeding, and the use of chickpea cultivars with a high level of resistance are important options to manage WRR complex.

Effects of calcium and EGTA on thiol homeostasis and defense-related enzymes in Cd-exposed chickpea roots

Exposure of chickpea seeds (Cicer arietinum L.) to cadmium stress for 6 days resulted in growth reduction and oxidative stress installation as exemplified by a strong accumulation of H2O2 and a disruption of enzymatic and non-enzymatic defense systems. The enrichment of the seed germinating medium with calcium and ethylene glycol tetraacetic acid (EGTA) relieved the detrimental effect of Cd on root growth. This protective effect would be the result of (1) protein thiol protection, as evidenced by thioredoxin system activation, and of (2) the glutathione disulfide content decrease. The absence of corrective effect of effectors on glutathione redox state should be associated with the concomitant decrease in regeneration and consumption processes of reduced forms of glutathione, namely by glutathione reductase and glutathione peroxidase activities, respectively. Calcium and EGTA application led to oxidative stress alleviation as evidenced by H2O2 content decrease and the restoration of catalase and ascorbate peroxidase activities at a level similar to control roots. Moreover, the analysis of the transcriptional system relating to the up-cited enzymes revealed a decreased gene expression subsequent to the enrichment of germination medium with the effectors. The present research provided deeper insights into the mechanisms induced by Ca and EGTA to protect plant cell against Cd-induced oxidative injury.

Effect of Mesorhizobium in chickpea root nodulation using transcriptome profiling approach

Root nodule development is a key event in legume plants for nitrogen fixation. In this process, Mesorhizobium forms a symbiotic relationship with chickpea (legume) crop that can produce nodule to fix the environmental nitrogen for necessary vital activities. Mesorhizobium infected chickpea shows enhanced function at different stages. We studied high throughput sequencing (454/Roche) data of control and three stages, viz. early, middle and late stages of Mesorhizobium infection (Bioproject: PRJNA214031) during nodule formation to identify the key regulatory genes in nitrogen fixation process and long non-coding RNAs (lncRNAs) participating in Mesorhizobium inoculation of chickpea root nodule. De novo assembly of raw reads resulted in 38835 contigs with the N50 value of 1019 bp. Differential expression analysis of assembled transcripts showed that 5615 genes were expressed differentially, out of which 1696 genes were differentially expressed in early infection while 1338 and 2581 genes were expressed in middle stage and late stage of infection, respectively. On analysis of DEGs, it was found that 392 genes were common in all three stages, 1304 were present in both early and late infection while 946 genes were uniquely expressed in the middle stage of infection. It has been evident from studies that long non-coding RNAs participate in host responses to infection but many lncRNAs are still unknown at the level of Mesorhizobium inoculated root nodules of chickpea. The present study aimed at identification of the lncRNAs in chickpea root nodules and to understand the transcriptomic mechanism during Mesorhizobium inoculation. Findings of this study characterize differential expression of lncRNAs in Mesorhizobium infected chickpea root nodules and it further gives understanding of symbiotic association in both aspects of coding and non-coding regulation.

Endophytic Bacteria Improve Plant Growth, Symbiotic Performance of Chickpea (Cicer arietinum L.) and Induce Suppression of Root Rot Caused by Fusarium solani under Salt Stress.

Salinity causes disturbance in symbiotic performance of plants, and increases susceptibility of plants to soil-borne pathogens. Endophytic bacteria are an essential determinant of cross-tolerance to biotic and abiotic stresses in plants. The aim of this study was to isolate non–rhizobial endophytic bacteria from the root nodules of chickpea (Cicer arietinum L.), and to assess their ability to improve plant growth and symbiotic performance, and to control root rot in chickpea under saline soil conditions. A total of 40 bacterial isolates from internal root tissues of chickpea grown in salinated soil were isolated. Four bacterial isolates, namely Bacillus cereus NUU1, Achromobacter xylosoxidans NUU2, Bacillus thuringiensis NUU3, and Bacillus subtilis NUU4 colonizing root tissue demonstrated plant beneficial traits and/or antagonistic activity against F. solani and thus were characterized in more detail. The strain B. subtilis NUU4 proved significant plant growth promotion capabilities, improved symbiotic performance of host plant with rhizobia, and promoted yield under saline soil as compared to untreated control plants under field conditions. A combined inoculation of chickpea with M. ciceri IC53 and B. subtilis NUU4 decreased H2O2 concentrations and increased proline contents compared to the un-inoculated plants indicating an alleviation of adverse effects of salt stress. Furthermore, the bacterial isolate was capable to reduce the infection rate of root rot in chickpea caused by F. solani. This is the first report of F. solani causing root rot of chickpea in a salinated soil of Uzbekistan. Our findings demonstrated that the endophytic B. subtilis strain NUU4 provides high potentials as a stimulator for plant growth and as biological control agent of chickpea root rot under saline soil conditions. These multiple relationships could provide promising practical approaches to increase the productivity of legumes under salt stress.

Ensifer adhaerens for heavy metal bioaccumulation, biosorption, and phosphate solubilization under metal stress condition

Abstract In this study, a bacterial strain was recovered from the chickpea root surface and its heavy metal tolerance ability, bioaccumulation, biosorption, chromium reduction potential, and phosphate solubilization activity were determined. Bacterial strain (OS3) was molecularly characterized through 16S rRNA partial gene sequencing and confirmed strain sequences belonged to the Ensifer adhaerens , inveterate by the BLASTn and phylogenetic analysis and achived accession number from Genbank # HE681418.1. Strain OS3 was able to tolerate up to 250 µg/ml Cd, 500 µg/ml Cr, 800 µg/ml each of Cu and Zn and 1000 µg/ml Ni. Moreover, strain OS3 was able to bioaccumulate and biosorb varying concentrations of heavy metals and showed maximum accumulation of Ni (95%) and least accumulation of Pb (74%) at a temperature of 34 °C and pH 7. The Langmuir and Freundlich adsorption constants were evaluated from the isotherms with a correlation coefficient ( r 2 > 0.98). The strain reduced 200 µg/ml of Cr (VI) completely after 96 h growth at 35 °C. Apart from bioremedaition ability, bacterial strain OS3 expressed a significant inorganic phosphate (P) solubilizing activity and solubilized inorganic P upto 303 µg/ml with a 2.2 solubilization index. Also, strain OS3 demonstrated plant growth promoting traits even under metal stress and secreted IAA, siderophore, HCN and ammonia under in vitro conditions. This study demonstrated that E. adhaerens survived well, even when exposed to higher concentrations of heavy metals and retained plant growth promoting activities. The biosorption ability, chromium reducing potential and ability to secrete plant growth regulators makes this organisms an interesting choice for metal removal (bioremediation) and enhancing crop production even in metal polluted soils.