Root Border Cells Research Articles

Flg22-facilitated PGPR colonization in root tips and control of root rot.

Plant root border cells (RBCs) prevent the colonization of plant growth-promoting rhizobacteria (PGPR) at the root tip, rendering the PGPR unable to effectively control pathogens infecting the root tip. In this study, we engineered four strains of Pseudomonas sp. UW4, a typical PGPR strain, each carrying an enhanced green fluorescent protein (EGFP)-expressing plasmid. The UW4E strain harboured only the plasmid, whereas the UW4E-flg22 strain expressed a secreted EGFP-Flg22 fusion protein, the UW4E-Flg(flg22) strain expressed a non-secreted Flg22, and the UW4E-flg22-D strain expressed a secreted Flg22-DNase fusion protein. UW4E-flg22 and UW4E-flg22-D, which secreted Flg22, induced an immune response in wheat RBCs and colonized wheat root tips, whereas the other strains, which did not secrete Flg22, failed to elicit this response and did not colonize wheat root tips. The immune response revealed that wheat RBCs synthesized mucilage, extracellular DNA, and reactive oxygen species. Furthermore, the Flg22-secreting strains showed a 33.8%-93.8% higher colonization of wheat root tips and reduced the root rot incidence caused by Rhizoctonia solani and Fusarium pseudograminearum by 24.6%-35.7% compared to the non-Flg22-secreting strains in pot trials. There was a negative correlation between the incidence of wheat root rot and colonization of wheat root tips by these strains. In contrast, wheat root length and dry weight were positively correlated with the colonization of wheat root tips by these strains. These results demonstrate that engineered secretion of Flg22 by PGPR is an effective strategy for controlling root rot and improving plant growth.

Effects of Phloretin on Seedling Growth and Histochemical Distribution of Phenols, Polysaccharides and Lipids in Capsella bursa-pastoris (L.) Medik.

The present study evaluates the phytotoxic effects of phloretin, a prevalent secondary metabolite of apple trees, on the broadleaf weed Capsella bursa-pastoris (L.) Medik. known for its resistant myxospermous seeds that form a long-lasting soil bank. The results indicate a significant, dose-dependent inhibitory effect of phloretin on the growth and morphological parameters of weed seedlings grown in vitro. Although the applied phloretin concentrations (250-1000 µM) were not lethal to the C. bursa-pastoris seedlings after two weeks, the metabolism of the seedlings was impaired, resulting in an accumulation of lipid droplets in the root tips and root hairs. Histochemical analysis shows deposits of phenols in the root epidermal cells, which are probably aggregates of phloretin or its metabolic derivatives. The accumulation of pectin in the cell walls of root border cells in phloretin-treated seedlings indicates an attempt to reduce the uptake of phloretin and reduce its concentration in the cells. Inhibition of shoot growth associated with chlorosis and reduced photosynthetic pigment content is a consequence of seedling exposure to phloretin. This study provides a basis for further evaluation of phloretin as a new bioherbicidal compound and for elucidating the mechanism underlying its phytotoxic activity.

Receptor Plants Alleviated Allelopathic Stress from Invasive Chenopodium ambrosioides L. by Upregulating the Production and Autophagy of Their Root Border Cells.

Chenopodium ambrosioides L. is an invasive plant native to the Neotropics that has seriously threatened the ecological security of China, and allelopathy is one of the mechanisms underlying its successful invasion. Maize (Zea mays L.) and soybean (Glycine max (L.) Merr.), as the main food crops, are usually affected by C. ambrosioides in their planting areas. The purpose of this study was to investigate the ultrastructure, autophagy, and release-related gene expression of receptor plant root border cells (RBCs) after exposure to volatile oil from C. ambrosioides and its main component α-terpene, which were studied using maize and soybean as receptor plants. The volatiles inhibited root growth and promoted a brief increase in the number of RBCs. As the volatile concentration increased, the organelles in RBCs were gradually destroyed, and intracellular autophagosomes were produced and continuously increased in number. Transcriptomic analysis revealed that genes involved in the synthesis of the plasma membrane and cell wall components in receptor root cells were significantly up-regulated, particularly those related to cell wall polysaccharide synthesis. Meanwhile, polygalacturonase and pectin methylesterases (PME) exhibited up-regulated expression, and PME activity also increased. The contribution of α-terpene to this allelopathic effect of C. ambrosioides volatile oil exceeded 70%. Based on these results, receptor plant root tips may increase the synthesis of cell wall substances while degrading the intercellular layer, accelerating the generation and release of RBCs. Meanwhile, their cells survived through autophagy of RBCs, indicating the key role of RBCs in alleviating allelopathic stress from C. ambrosioides volatiles.

Integration of Root Border Cells in Salt Stress Response of Thai Jasmine Rice

Integration of Root Border Cells in Salt Stress Response of Thai Jasmine Rice

The competitive strategies of poisonous weeds Elsholtzia densa Benth. on the Qinghai Tibet Plateau: Allelopathy and improving soil environment.

The competitive strategies of plants play a crucial role in their growth. Allelopathy is one of the weapons that plants use to improve their competitive advantage. In order to explore the competitive strategy of a poisonous weed Elsholtzia densa Benth. (E. densa) on the Qinghai-Tibet Plateau (QTP), the effects of decomposing substances of E. densa on growth, root border cells (RBCs) characteristics of highland crop highland barley (Hordeum vulgare L.), and soil environment were determined. The decomposing allelopathic effect of E. densa on the germination and seedling growth of highland barley mainly occurred in the early stage of decomposing. The allelopathic effects were mainly on seed germination and root growth of highland barley. After treatment with its decomposing solution, the RBC's mucilage layer of highland barley thickened, and the RBC's activity decreased or even apoptosis compared with the control. However, only the above-ground part of the treatment group showed a significant difference. The effects of E. densa decomposed substances on the soil environment were evaluated from soil physicochemical properties and bacterial community. The results showed that soil bacteria varied greatly in the early stage of decomposion under different concentrations of E. densa. In addition, E. densa decomposing substances increased the soil nutrient content, extracellular enzyme activities, and bacterial community diversity. In the process of decomposition, the bacterial community structure changed constantly, but Actinobacteriota was always the dominant phylum. These results indicated that E. densa might adopt the following two strategies to help it gain an advantage in the competition: 1. Release allelochemicals that interfere with the defense function of surrounding plants and directly inhibit the growth and development of surrounding plants. 2. By changing the physical and chemical properties of soil and extracellular enzyme activity, residual plant decomposition can stimulate soil microbial activity, improve soil nutrition status, and create a more suitable soil environment for growth.

荞麦、高粱根系分泌物对玉米根边缘细胞和根生长的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 荞麦、高粱根系分泌物对玉米根边缘细胞和根生长的影响 DOI: 10.5846/stxb202204090929 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 山西省重点研发计划项目(201803D221011-5) Effects of root exudates from buckwheat and sorghum on the root border cells and root growth of Maize Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:植物的根系分泌物是植物根系与周围环境之间的化学媒介,通过传递特定的信息,调节根际微环境,影响周围植物的生长。玉米(Zea mays L.)和荞麦(Fagopyrum esculentum Moench)是农作物间套作体系中典型的不能搭配的组合,其障碍因素尚不清楚。以玉米为受体植物,采用根悬空培养的方法,研究了荞麦、高粱(Sorghum bicolor (L.) Moench)根系分泌物对玉米根边缘细胞和根生长的影响。结果发现,玉米根边缘细胞离体培养条件下,用荞麦根系分泌物中的小分子物质处理4、8 h显著诱导边缘细胞凋亡、死亡,细胞活率分别比对照降低了71.6%和72.3%;荞麦根系分泌物中的小分子物质对玉米根产生氧化胁迫,诱导根SOD、POD和CAT活性分别比对照高22.6%、33.9%和107.2%,根中超氧阴离子(O-.2)和脯氨酸含量分别比对照高33.9%和49.8%;荞麦根系分泌物中小分子物质的胁迫使根细胞膜透性增大,与对照相比升高80.0%,丙二醛(MDA)含量比对照升高31.5%;荞麦根系分泌物中小分子物质诱导根内源激素(IAA)含量降低,根系活力下降,根生长受到抑制,与对照比IAA含量降低44.2%,根系活力降低14.4%,根长减少36.9%;高粱根系分泌物对玉米根边缘细胞和根生长无显著的化感胁迫影响。由此可得,荞麦根系分泌物中的小分子物质诱导玉米根边缘细胞凋亡死亡,使其失去边缘细胞的保护作用,进一步诱导根产生氧化胁迫,诱导根内吲哚乙酸(IAA)含量降低,根的生长和发育受到抑制,这可能是玉米荞麦不能间套作的原因所在。 Abstract:Plant root exudates act as the chemical mediators between root systems and the surrounding environment. Root exudates regulate the rhizosphere microenvironment and affect the growth of nearby plants by transmitting specific information. Zea mays L. (Maize) and Fagopyrum esculentum Moench (buckwheat) are the typically unsuitable combination in intercropping system of crops, however, the obstacle factors are still unclear. In this study, using maize as a recipient plant, the effects of root exudates from buckwheat or Sorghum bicolor (L.) Moench (sorghum) on the root border cells (RBCs) and root growth of maize were investigated by the method of root suspension culture. Results indicated that the viability of RBCs of maize treated with the small molecular substances in the root exudates of buckwheat for 4 and 8 hours decreased by 71.6% and 72.3%, respectively, compared with the control. The small molecular substances in buckwheat root exudates generated oxidative stress on the roots of maize, and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were 22.6%, 33.9% and 107.2% higher than those of the control, respectively. In addition, the content of the superoxide anion (O-.2) was 33.9% higher than that of the control, while the proline content in the root was 49.8% higher. Furthermore, the small molecular substances in root exudates of buckwheat increased the permeability of root cell membrane by 80.0% and the content of malondialdehyde (MDA) by 31.5% compared with those of the control. The small molecular substances in buckwheat root exudates decreased root endogenous hormone (IAA) content, root activity, and root growth. More specifically, the IAA content decreased by 44.2%, TTC reduction strength decreased by 14.4%, and root length decreased by 36.9%. Sorghum root exudates had no significant allelopathic stress effect on maize root border cells and root growth. Therefore, the small molecular substances in the root exudates of buckwheat can induce the apoptosis and death of maize root border cells, which can make them lose the protective effect of root border cells, further induce the root to produce oxidative stress, reduce the content of IAA in the root, and inhibit the growth and development of the root. We speculate that this is one of the reasons why maize and buckwheat cannot be intercropped. 参考文献 相似文献 引证文献

In situ control of root-bacteria interactions using optical trapping in transparent soil.

Bacterial attachment on root surfaces is an important step preceding the colonization or internalization and subsequent infection of plants by pathogens. Unfortunately, bacterial attachment is not well understood because the phenomenon is difficult to observe. Here we assessed whether this limitation could be overcome using optical trapping approaches. We have developed a system based on counter-propagating beams and studied its ability to guide Pectobacterium atrosepticum (Pba) cells to different root cell types within the interstices of transparent soils. Bacterial cells were successfully trapped and guided to root hair cells, epidermal cells, border cells, and tissues damaged by laser ablation. Finally, we used the system to quantify the bacterial cell detachment rate of Pba cells on root surfaces following reversible attachment. Optical trapping techniques could greatly enhance our ability to deterministically characterize mechanisms linked to attachment and formation of biofilms in the rhizosphere.

Nitrogen fixation and mucilage production on maize aerial roots is controlled by aerial root development and border cell functions.

Exploring natural diversity for biological nitrogen fixation in maize and its progenitors is a promising approach to reducing our dependence on synthetic fertilizer and enhancing the sustainability of our cropping systems. We have shown previously that maize accessions from the Sierra Mixe can support a nitrogen-fixing community in the mucilage produced by their abundant aerial roots and obtain a significant fraction of their nitrogen from the air through these associations. In this study, we demonstrate that mucilage production depends on root cap and border cells sensing water, as observed in underground roots. The diameter of aerial roots correlates with the volume of mucilage produced and the nitrogenase activity supported by each root. Young aerial roots produce more mucilage than older ones, probably due to their root cap’s integrity and their ability to produce border cells. Transcriptome analysis on aerial roots at two different growth stages before and after mucilage production confirmed the expression of genes involved in polysaccharide synthesis and degradation. Genes related to nitrogen uptake and assimilation were up-regulated upon water exposure. Altogether, our findings suggest that in addition to the number of nodes with aerial roots reported previously, the diameter of aerial roots and abundance of border cells, polysaccharide synthesis and degradation, and nitrogen uptake are critical factors to ensure efficient nitrogen fixation in maize aerial roots.

Effects of Cadmium Stress on Root and Root Border Cells of Some Vegetable Species with Different Types of Root Meristem.

Cadmium is one of the most toxic heavy metals and can be easily absorbed by plants, affecting root growth. Root border cells (RBCs), that are located in the periphery of the root cap and originate from the root cap meristem, represent a convenient tool to study the toxic effects of Cd on root performance. In this work, vegetables with contrasting types of root apical meristem (RAM) organizations were used. The open RAM organizations included pea and cucumber, and the closed RAM organizations included tomato, chili, and eggplant. The number of RBCs were significantly higher in the species possessing open RAM organization: pea (11,330 cells per root) > cucumber (8200) > tomato (2480) > eggplant (1830) > chili (1320). The same trend was observed for cell viability: pea (61%) > cucumber (59%) > tomato (49%) > eggplant (44%) > chili (42%). Pea and cucumber had higher relative radicle elongation rates and a lower increase in stress-induced accumulation of malondialdehyde (MDA), making them more resistant to Cd stress than the vegetables with close RAM organization. Under Cd treatment, the number and viability of RBCs in vegetables with both types of RAM organization were significantly decreased. However, the decreasing ratio of the number and viability of RBCs in pea and cucumber was higher than in tomato, chili, and eggplant. Taken together, the plants with the open-type RAM are more tolerant to Cd, and it can be speculated that the cadmium tolerance of the vegetables may be correlated with the number and viability of RBCs in response to cadmium stress.

Root Border Cells as a Convenient Single Cell System to Study Plant-Environmental Interactions: A Case Study for Aluminum Tolerance

Root border cells (RBCs) are a group of cells that originated from the root cap meristem, which are developed by genetic regulation and play a variety of biological functions. Being composed of a homologous single cell population with high metabolic activity and intact cell walls, RBCs represent a highly useful tool for studying various aspects of plant mineral absorption and utilization, as well as plant-soil-microbiome interactions in the rhizosphere. Research on RBCs also promise to become a hotspot in the context of understanding root adaptive responses to hostile environments. In order to take advantage of RBCs as an ideal single cell system in plant-environmental interactions, we summarized the production and function of RBCs and built-up the methodology for RBCs culturing, purification, and quantity control for plant research. The latter is done by using a case study of the application of RBCs to study mechanisms of Al toxicity in plants. This work offers plant scientists a new cognition of adopting RBCs as a convenient single cell system for the multidisciplinary research including (but not limited to) plant physiology, development and genetics, nutrition, and stress and adaptation. Root border cells (RBCs) are derived from the root cap and represent a population of living cells with special physiological activity and biological roles that are different from the root cap cells per se. After being separated from the root cap, RBCs become more active in metabolism than the progenitor root cap cells; for example, they incorporate labeled amino acids into protein 2.6-fold more efficiently than the cells of the root cap. In addition, mRNA and protein were differentially expressed between root cap cells and RBCs. Since the production of RBCs is genetically regulated and RBCs played a variety of biological functions in resistance to biotic and abiotic stresses occurred in the rhizosphere, RBCs were suggested as an ideal single cell system for the study the response of plant root cells to nutrient availability, environmental stresses, and in plant-microbial interactions. Some studies revealed that RBCs, which development is regulated by endogenous and exogenous signals, are biologically viable in the majority of higher plant species. This work reviews the research on RBCs in plant environment interaction and describes the case study of RBCs as a convenient single cell system to study plant responses to Al toxicity.

Transcriptomic and metabolomic analyses reveal defense mechanism in ‘Beta’ grapevine root border cells under ρ-hydroxybenzoic acid stress

Autotoxins are a major cause of grapevine replant disease. Root border cells (RBCs) of ‘Beta’ grapevine seedlings were selected to investigate the mechanism underlying the changes in the composition of grapevine root secretions mediated by autotoxins ρ-hydroxybenzoic acid (4-HBA) and their effect on harmful soil fungi (Fusarium solani). The results showed that, compared with control, the root length and number of RBCs were increased under 50 μg·mL–1 4-HBA treatment but inhibited under 200 μg·mL–1 treatment (T200), and no significant difference was found under 100 μg·mL–1 treatment (T100). In the T100 vs CK group, RBCs enhanced metabolites involved in the respiratory pathway and released carbon source substances, such as saccharides and organic acids. In addition, most metabolites of the flavonoid biosynthesis pathway and gallic acid (GA) of tannins were abundant in the RBC mucilage possibly due to the action of shikimate dehydrogenase (SDH). In the T200 vs CK group, abundance of some metabolites of the respiratory pathway decreased, and dihydroquercetin (DHQ), catechin (C), epicatechin gallate (ECG), quercetin derivative, and hesperetin derivative abundances of flavonoid biosynthesis pathway were inhibited possibly due to the declined expression level of PAL and CHS genes. Tannins [such as GA and ellagic acid (EA)] were also decreased in the mucilage of RBCs. Plate confrontation experiments showed that flavonoids [C, DHQ, and naringenin (NAR)] and tannin (GA) inhibited the growth of Fusarium solani to some extent. RBCs may also resist 4-HBA stress by increasing the expression level of lignin synthesis and SOD genes. Our research indicates that RBCs and their mucilage play an important role in protecting the root tips of grapevine against 4-HBA stress.

Silicon prevents aluminum from entering root tip by promoting formation of root border cells in rice

Root border cells (RBCs) and their mucilage are considered to play an important role in protecting root tip from aluminum (Al) toxicity, but their interactions with silicon (Si) under Al stress still remain unclear. Here, we investigated the effect of Si on the formation of RBCs under Al stress and the related detoxification mechanism in hydroponically grown rice (Oryza sativa L.). The results showed that Si could prevent the separation of RBCs from each other by increasing the degree of pectin methylesterification in root tip cell wall, thereby keeping more RBCs around the root tip. Also, Si maintained the viability of RBCs, increased the amount of mucilage, and reduced the content of total Al and free Al in root tips. Moreover, the RBCs accumulated more Al and Si simultaneously than root tip in the Al treatments with Si supply. Overall, these results indicated that Si reduced the toxicity of Al to RBCs through formation of Si–Al complex on the RBCs, thereby improving the viability of RBCs and promoting the secretion of mucilage. Concomitantly, Si, RBCs and their mucilage could form a protective sheath at the root tip, which prevented Al from diffusing into the root tip, thereby alleviating Al toxicity in rice root tips.

Proteolytic and Structural Changes in Rye and Triticale Roots under Aluminum Stress.

Proteolysis and structural adjustments are significant for defense against heavy metals. The purpose of this study was to evaluate whether the Al3+ stress alters protease activity and the anatomy of cereale roots. Azocaseinolytic and gelatinolytic measurements, transcript-level analysis of phytocystatins, and observations under microscopes were performed on the roots of Al3+-tolerant rye and tolerant and sensitive triticales exposed to Al3+. In rye and triticales, the azocaseinolytic activity was higher in treated roots. The gelatinolytic activity in the roots of rye was enhanced between 12 and 24 h in treated roots, and decreased at 48 h. The gelatinolytic activity in treated roots of tolerant triticale was the highest at 24 h and the lowest at 12 h, whereas in treated roots of sensitive triticale it was lowest at 12 h but was enhanced at 24 and 48 h. These changes were accompanied by increased transcript levels of phytocystatins in rye and triticale-treated roots. Light microscope analysis of rye roots revealed disintegration of rhizodermis in treated roots at 48 h and indicated the involvement of root border cells in rye defense against Al3+. The ultrastructural analysis showed vacuoles containing electron-dense precipitates. We postulate that proteolytic-antiproteolytic balance and structural acclimation reinforce the fine-tuning to Al3+.

Salt stress of two rice varieties: root border cell response and multi-logistic quantification.

How to capture the rice varieties salt stress sensitivity? Here, we measure responses of root border cells (1 day, ± 60 mM NaCl) and apply multi-logistic quantification of growth variables (21 days, ± 60 mM NaCl) to two rice varieties, salt-sensitive IR29 and tolerant Pokkali. Thus, logistic models determine the maximum response velocities (Vmax) and times of half-maximum (T0) for root border cell (RBC) and growth parameters. Thereof, seven variables show logistic models (0.58 < R ≤ 1) and monotonous responses in both Pokkali and IR29: root to shoot ratio by water content, primary root length, shoot water, adventitious root number, shoot dry and fresh weight, and root dry weight. Moreover, the regression to lognormal distribution (R = 0.99) of these seven Vmax fractionated by T0 represents the rice variety's comprehensive response. Its quotient IR29/Pokkali is peaking at 98-fold higher velocity of IR29, thus capturing the variety's sensitivity. Consequently, our finding of 66-fold higher Vmax of primary root length response of IR29 indicates an essential salt sensor in the root, including RBC. Finally, the effects of salt stress on RBC confirm multi-logistic quantification, showing 36% decrease of RBC mucilage layer in IR29, without change in Pokkali. Inversely, RBC number of Pokkali increases 43% without change in IR29. Briefly, this suggests both RBC and multi-logistic quantification for the screening for salt tolerance in two thousand rice varieties.

Root border cells: A pioneer’s of plant defence in rhizosphere

The environment around the root in rhizosphere is a complex region where multiple interactions take place among soil, plant and microorganisms. Plant growth and architecture of entire plant, in fact depends upon the roots which provide sufficient amount of nutrients and water. Root tips while sensing the rhizosphere for availability nutrients counteract with array of harmful microorganisms in the soil. In order to protect from these stresses plant roots have evolved specialized cells known as root border cells which act as front line defence mechanism in rhizosphere. Border cells are individual or bunch of programmed viable cells released from root tip which forms protective sheath between root and external environment. Border cells secret hydrated mucilage that contains antimicrobial compounds and extracellular DNA which governs the behaviour of microbiome in the soil. Production of border cell is regulated by number of factors such as phytohormones, PME enzyme and transcription factor NLP7. Plant breeding and genetic engineering could be used to exploit border cells defence mechanism as a new avenue for disease control. This review summarizes about the importance, properties of border cells, mechanism, and regulation of border cells production and role of RETs as element of plant defence.

Root Border Cells and Mucilage Secretions of Soybean, Glycine Max (Merr) L.: Characterization and Role in Interactions with the Oomycete Phytophthora Parasitica.

Root border cells (BCs) and their associated secretions form a protective structure termed the root extracellular trap (RET) that plays a major role in root interactions with soil borne microorganisms. In this study, we investigated the release and morphology of BCs of Glycine max using light and cryo-scanning electron microscopy (SEM). We also examined the occurrence of cell-wall glycomolecules in BCs and secreted mucilage using immunofluorescence microscopy in conjunction with anti-glycan antibodies. Our data show that root tips released three populations of BCs defined as spherical, intermediate and elongated cells. The mechanism of shedding seemed to be cell morphotype-specific. The data also show that mucilage contained pectin, cellulose, extracellular DNA, histones and two hemicellulosic polysaccharides, xyloglucan and heteromannan. The latter has never been reported previously in any plant root secretions. Both hemicellulosic polysaccharides formed a dense fibrillary network embedding BCs and holding them together within the mucilage. Finally, we investigated the effect of the RET on the interactions of root with the pathogenic oomycete Phytophthora parasitica early during infection. Our findings reveal that the RET prevented zoospores from colonizing root tips by blocking their entry into root tissues and inducing their lysis.

Cytotoxic and genotoxic evaluation and the toxicological mechanism of uranium in Vicia faba root

This study revealed the cytotoxicity, genotoxicity and toxicity mechanism of uranium (U) in plants. The cytotoxic effect of U was evaluated by detecting the survival status of root border cells; the genotoxic effect was evaluated by micronuclear experiments; and the toxicity mechanism of U to plants was primarily revealed by combining with transcriptome. Results showed that after U exposure, the proportion of late apoptotic cells and dead cells was significantly higher than the control, indicating that U could induce the apoptosis or necrosis of root border cells. The micronucleus rate increased dramatically after U exposure, reaching a maximum of 4.89 times the control, whereas the mitotic index decreased significantly, reaching a minimum of 26.00% of the control. Moreover, the activities of superoxide dismutase and peroxidase decreased, triggering severe oxidative stress. Combined with the transcriptome data, this study showed that U interfered with the expression of genes related to antioxidant enzymes, the cell cycle and the DNA repair system. In conclusion, U strongly terminated the root border cells and blocked the mitosis, therefore inhibiting the growth of the Vicia faba root. It also caused DNA damage by interfering with the antioxidant enzymes to trigger oxidative stress and prevented DNA self-repair by interfering with the DNA repair system.

A Novel In Vitro Tool to Study Cyst Nematode Chemotaxis.

This study presents a novel three-dimensional (3D) tool “3D in vitro choice” for chemotaxis assays with cyst nematodes. The original 3D in vitro choice was customized through digital printing. Freshly hatched second stage juveniles (J2s) of the cyst nematode Globodera pallida were used as the nematode model to illustrate chemo-orientation behavior in the 3D system. The efficiency and reliability of the 3D in vitro choice were validated with 2% Phytagel as navigation medium, in three biological assays and using tomato root exudates or potato root border cells and their associated mucilage as a positive attractant as compared with water. For each biological assay, J2s were hatched from the same population of a single generation glasshouse-cultured cysts. This novel easy to use and low-cost 3d-device could be a useful replacement to Petri dishes assays in nematode behavioral studies due to the ease of deposition of nematodes and test substances, coupled with its distinctive zones that allow for precision in choice making by the nematodes.

The leaf extract of crofton weed (Eupatorium adenophorum) inhibits primary root growth by inducing cell death in maize root border cells

The extract of crofton weed (Eupatorium adenophorum) inhibits seed germination and weed growth; however, the physiological mechanisms underlying the effect of crofton weed extract on the modulation of seedling growth and root system development remain largely unclear. In this study, we investigated the effects of the leaf extract of crofton weed (LECW) on primary root (PR) growth in maize seedlings. Treatment with LECW markedly inhibited seed germination and seedling growth in a dose-dependent manner. Physiological analysis indicated that the LECW induced reactive oxygen species (ROS) accumulation in root tips, thereby leading to cell swelling and deformation both in the root cap and elongation zone of root tips, finally leading to cell death in root border cells (RBCs) and PR growth inhibition. The LECW also inhibited pectin methyl esterase (PME) activity, thereby decreasing the RBC number. Taken together, our results indicated that the LECW inhibited PR growth by inducing ROS accumulation and subsequent cell death in RBCs. The present study provides a better understanding of how the LECW modifies root system development and provides insight for evaluating the toxicity of crofton weed extracts in plants.

Phytohormones (Auxin, Gibberellin) and ACC Deaminase In Vitro Synthesized by the Mycoparasitic Trichoderma DEMTkZ3A0 Strain and Changes in the Level of Auxin and Plant Resistance Markers in Wheat Seedlings Inoculated with this Strain Conidia.

Both hormonal balance and plant growth may be shaped by microorganisms synthesizing phytohormones, regulating its synthesis in the plant and inducing plant resistance by releasing elicitors from cell walls (CW) by degrading enzymes (CWDE). It was shown that the Trichoderma DEMTkZ3A0 strain, isolated from a healthy rye rhizosphere, colonized the rhizoplane of wheat seedlings and root border cells (RBC) and caused approximately 40% increase of stem weight. The strain inhibited (in over 90%) the growth of polyphagous Fusarium spp. (F. culmorum, F. oxysporum, F. graminearum) phytopathogens through a mechanism of mycoparasitism. Chitinolytic and glucanolytic activity, strongly stimulated by CW of F. culmorum in the DEMTkZ3A0 liquid culture, is most likely responsible for the lysis of hyphae and macroconidia of phytopathogenic Fusarium spp. as well as the release of plant resistance elicitors. In DEMTkZ3A0 inoculated plants, an increase in the activity of the six tested plant resistance markers and a decrease in the concentration of indoleacetic acid (IAA) auxin were noted. IAA and gibberellic acid (GA) but also the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) enzyme regulating ethylene production by plant were synthesized by DEMTkZ3A0 in the liquid culture. IAA synthesis was dependent on tryptophan and negatively correlated with temperature, whereas GA synthesis was positively correlated with the biomass and temperature.