Root Responses Research Articles

Defense responses and symbiotic functional initiation in trifoliate orange‒arbuscular mycorrhizal fungi interaction

Arbuscular mycorrhizal fungi (AMF) trigger beneficial effects on their hosts, but it is unknown how plants modulate their defense responses during root colonization of AMF and the symbiotic benefits are initiated. The purpose of this study was to analyze the root mycorrhizal colonization process of trifoliate orange and the responsive patterns of plant growth, root peroxide hydrogen (H2O2), antioxidant enzymes and their encoding gene expression, and sugar, lipid and phosphate transporter protein gene expression at 7‒56 days of inoculation (doi) with Funneliformis mosseae (Fm). Fm developed appressoriums on the root surface at 7 doi, followed by abundant arbuscules in root cortical cells at 28 doi, intracellular vesicles at 42 doi, and root mycorrhizal colonization rate of 41.54% at 56 doi. Plant growth improvement by Fm started at 28 doi. The immune defense response of roots was initiated at 7 doi, as evidenced by the increase of H2O2 levels and superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity, as well as the up-regulation of PtMn-SOD, PtCu/Zn-SOD, PtPOD, and PtCAT expression, which lasted until 14 doi. Starting at 28 doi, a sugar transporter gene (PtSWEET), a lipid transporter gene (PtSTR), and a phosphate transporter gene (PtPT6) were initiated to be up-regulated, followed by the up-regulation of PtSTR2, PtPT3, and PtPT5 at 42 doi and PtFe-SOD at 56 doi. Arbuscule formation and plant growth improvement together at 28 doi suggested that arbuscules trigger improved growth responses of host plants. This study also reveals the initiation of host immune defense response and function in early root AMF colonization.Graphical

Assessing Temperature Responses in Roots.

Due to global warming, it is important to understand how plants respond to high ambient temperature. Plant growth responses to high ambient temperature are termed thermomophogenesis and have been explored for more than a decade. However, this was mostly focused on the above-ground part of plants, the shoot. In this chapter, we describe a simple method to assess root growth phenotype to high ambient temperatures. In principle, this protocol can be applied for any other treatments to test overall seedling growth.

Initiation of Red Ginger Callus (Zingiber officinale var. rubrum Rosc.) from Various Explants

The increasing demand for red ginger (Zingiber officinale Roxb. var. rubrum Rosc.) both at the domestic and international levels has led to the need for gingerol production, a main compound of red ginger, which has various pharmacological activities. The urgency of this research is related to gingerol produced in cultivated red ginger, which often shows variability in quantity due to genetic variation and differences in geographical and environmental conditions where it is grown, so it requires gingerol standardization efforts. Through tissue culture techniques, it is possible to propagate plants in a controlled environment, ensuring genetic uniformity and minimizing variations caused by genetic factors. Red ginger raw materials that can be produced consistently, quickly, and land-efficiently with high gingerol content and pesticide-free have become an essential economic necessity. In this joint study with PT. Bintang Toedjoe, researchers intend to utilize root culture bioprocessing technology to increase gingerol production from red ginger. Root cultures have stabile genetics and growth faster; thus, these techniques imply the formation of organs or structures conducive to enhanced gingerol production. Our research has revealed successful protocols for inducing and multiplying suitable callus for organogenesis. Through the application of hormones, the best callus induction is using a combination of 3 ppm 2,4-D and 0.2 ppm BA with a callus production percentage of 67%. On the other hand, a satisfactory callus multiplication rate was used using 1 ppm 2,4-D with the most significant increase in explant area (79 mm2) by ruler alignment. Meanwhile, the rooting response was prominent at 1 ppm 2,4-D + 3 ppm BA.

Root response and phosphorus acquisition under partial distribution of phosphorus and water‐soluble organic matter

AbstractUnderstanding how phosphorus and water‐soluble organic matter (WSOM) from animal manure compost contribute to root development is essential for enhancing phosphorus utilization efficiency under their combined application. This study aims to determine mechanisms underlying root responses and phosphorus acquisition based on the partially varying available phosphorus levels in root zone soil following WSOM. The plant growth test was performed using a specifically designed pot where the root elongation was guided into the soil of different root compartments with either phosphorus combined with WSOM or single phosphorus or WSOM. The results revealed high levels of available phosphorus in the root zone soil of individual plants in the presence of WSOM induced small root weight. Phosphorus concentrations in the root exhibited a negative correlation with root weight. Improved root structure development even in the presence of WSOM induced to increase uptake of phosphorus and other nutrients in the plant. Furthermore, a positive linear relationship was observed between nutrient uptake and aboveground dry weight. These findings provide pioneering experimental evidence demonstrating that root development varies to some extent depending on the level of available phosphorus induced by the combined application of phosphorus and WSOM, even within the root zone soil of individual plants. Given that plant growth varied based on partial root development even when phosphorus and WSOM were combined, this study suggests that implementing appropriate phosphorus fertilizer application while considering the augmented availability of phosphorus via the combined application of animal manure compost can promote root development and nutrient uptake, resulting in improved plant growth.

RNA-seq analysis reveals transcriptome reprogramming and alternative splicing during early response to salt stress in tomato root.

Salt stress is one of the dominant abiotic stress conditions that cause severe damage to plant growth and, in turn, limiting crop productivity. It is therefore crucial to understand the molecular mechanism underlying plant root responses to high salinity as such knowledge will aid in efforts to develop salt-tolerant crops. Alternative splicing (AS) of precursor RNA is one of the important RNA processing steps that regulate gene expression and proteome diversity, and, consequently, many physiological and biochemical processes in plants, including responses to abiotic stresses like salt stress. In the current study, we utilized high-throughput RNA-sequencing to analyze the changes in the transcriptome and characterize AS landscape during the early response of tomato root to salt stress. Under salt stress conditions, 10,588 genes were found to be differentially expressed, including those involved in hormone signaling transduction, amino acid metabolism, and cell cycle regulation. More than 700 transcription factors (TFs), including members of the MYB, bHLH, and WRKY families, potentially regulated tomato root response to salt stress. AS events were found to be greatly enhanced under salt stress, where exon skipping was the most prevalent event. There were 3709 genes identified as differentially alternatively spliced (DAS), the most prominent of which were serine/threonine protein kinase, pentatricopeptide repeat (PPR)-containing protein, E3 ubiquitin-protein ligase. More than 100 DEGs were implicated in splicing and spliceosome assembly, which may regulate salt-responsive AS events in tomato roots. This study uncovers the stimulation of AS during tomato root response to salt stress and provides a valuable resource of salt-responsive genes for future studies to improve tomato salt tolerance.

Transcriptomics and metabolomics revealed the synthesis and potential role of flavonoids in pea roots under continuous cropping obstacles

AbstractWith the continuation of intensive and monoculture production in modern agriculture, the harm of continuous cropping obstacles is becoming more prominent. Pea has important nutritional and economic value, but it is easy to have continuous cropping obstacles in production. However, there is limited knowledge of the regulatory mechanisms of pea to cope with continuous cropping obstacles. In this study, we found that the number of differential expressed genes (DEGs) and differential metabolites (DAMs) increased in the pea roots with increasing continuous cropping times, and the number of DEGs and DAMs in roots of sensitive pea was more than that of continuous cropping tolerant pea. Comprehensive analysis of the omics data revealed that the flavonoid and isoflavonoid biosynthesis pathways play key roles in the response of pea roots to the continuous cropping obstacles. Most of the DEGs involved in these two pathways were up‐regulated. Meanwhile, most of the flavonoid compounds and total flavonoid content increased. With increasing continuous cropping times, the isoflavones category in DAMs increased, and the isoflavones category in the roots of continuous cropping tolerant pea were higher than in sensitive pea. Additionally, the isoflavonoid (biochanin A, calycosin, genistein) in the roots of continuous cropping tolerant pea have the ability to inhibit the growth of fungi in pea soil and possess antioxidant activity. These findings revealed the important role of flavonoids in pea continuous cropping obstacles and laid a foundation for effectively alleviating pea continuous cropping obstacles in the future.

Automatic Root Length Estimation from Images Acquired InSitu without Segmentation.

Image-based root phenotyping technologies, including the minirhizotron (MR), have expanded our understanding of the insitu root responses to changing environmental conditions. The conventional manual methods used to analyze MR images are time-consuming, limiting their implementation. This study presents an adaptation of our previously developed convolutional neural network-based models to estimate the total (cumulative) root length (TRL) per MR image without requiring segmentation. Training data were derived from manual annotations in Rootfly, commonly used software for MR image analysis. We compared TRL estimation with 2 models, a regression-based model and a detection-based model that detects the annotated points along the roots. Notably, the detection-based model can assist in examining human annotations by providing a visual inspection of roots in MR images. The models were trained and tested with 4,015 images acquired using 2 MR system types (manual and automated) and from 4 crop species (corn, pepper, melon, and tomato) grown under various abiotic stresses. These datasets are made publicly available as part of this publication. The coefficients of determination (R2), between the measurements made using Rootfly and the suggested TRL estimation models were 0.929 to 0.986 for the main datasets, demonstrating that this tool is accurate and robust. Additional analyses were conducted to examine the effects of (a) the data acquisition system and thus the image quality on the models' performance, (b) automated differentiation between images with and without roots, and (c) the use of the transfer learning technique. These approaches can support precision agriculture by providing real-time root growth information.

Cooperative advertising and coordination in a supply chain: the role of Nash bargaining fairness concerns

This study constructs a game-theoretic model of cooperative advertising in a supply chain with Nash bargaining solutions as the fairness reference point. We use a square root response function to describe the saturation effect of advertising. We find that the retailer’s Nash bargaining fairness concerns (NBFC) improve the local advertising investment even more than the level of the centralized case. The effect of NBFC on the retailer’s profit is inverted U-shaped, rising first and then falling, and vice versa for the manufacturer. As the fairness-concerned coefficient increases from small to large, the efficiency of the supply chain changes from improvement to decline. Moreover, we find that a two-way subsidy mechanism in cooperative advertising still works on coordination although the retailer possesses NBFC. The study offers practical management insights into the operational strategies of supply chain members.

Unveiling nutrient flow-mediated stress in plant roots using an on-chip phytofluidic device.

The initial emergence of the primary root from a germinating seed is a pivotal phase that influences a plant's survival. Abiotic factors such as pH, nutrient availability, and soil composition significantly affect root morphology and architecture. Of particular interest is the impact of nutrient flow on thigmomorphogenesis, a response to mechanical stimulation in early root growth, which remains largely unexplored. This study explores the intricate factors influencing early root system development, with a focus on the cooperative correlation between nutrient uptake and its flow dynamics. Using a physiologically as well as ecologically relevant, portable, and cost-effective microfluidic system for the controlled fluid environments offering hydraulic conductivity comparable to that of the soil, this study analyzes the interplay between nutrient flow and root growth post-germination. Emphasizing the relationship between root growth and nitrogen uptake, the findings reveal that nutrient flow significantly influences early root morphology, leading to increased length and improved nutrient uptake, varying with the flow rate. The experimental findings are supported by mechanical and plant stress-related fluid flow-root interaction simulations and quantitative determination of nitrogen uptake using the total Kjeldahl nitrogen (TKN) method. The microfluidic approach offers novel insights into plant root dynamics under controlled flow conditions, filling a critical research gap. By providing a high-resolution platform, this study contributes to the understanding of how fluid-flow-assisted nutrient uptake and pressure affect root cell behavior, which, in turn, induces mechanical stress leading to thigmomorphogenesis. The findings hold implications for comprehending root responses to changing environmental conditions, paving the way for innovative agricultural and environmental management strategies.

Unravelling the Functional Role of GthGAPC2 in Cotton's Defense Against Verticillium dahliae through Proteome

AbstractCotton (Gossypium spp.) is an economically important crop, but its productivity is often hindered by the soil‐borne pathogen Verticillium dahliae. This study aimed to investigate the response of cotton roots to V. dahliae infection by analysing the proteome of Gossypium thurberi (resistant) and Gossypium raimondii (susceptible) at 0 h, 24 h, and 48 h post‐infection. Through weighted protein coexpression network analysis, fifteen hub proteins crucial for defense against V. dahliae were identified. Expression analysis revealed the pivotal role of GthGAPC2, encoding GLYCERALDEHYDE‐3‐PHOSPHATE DEHYDROGENASE 2, in conferring resistance to V. dahliae in cotton. Virus‐induced gene Silencing (VIGS) of GthGAPC2 increased susceptibility to V. dahliae, which was supported by oxidant and antioxidant enzyme activities. Furthermore, GthGAPC2 silencing influenced lignin content, indicating its involvement in lignin biosynthesis regulation. Transient overexpression of GthGAPC2 in tobacco supported its role in cell death processes. Subcellular localization studies showed predominant nuclear localization of GthGAPC2. Overexpression of GthGAPC2 in Arabidopsis also confirms its significant role in V. dahliae resistance. These findings shed light on the molecular mechanisms of disease resistance in Gossypium thurberi. Identification of GthGAPC2, as a key protein involved in V. dahliae resistance, and its functional implications can aid breeding strategies for enhancing cotton's disease resistance.

Soil erosion rates based on anatomical changes in exposed roots - case study from southwest Bulgaria

In recent years different methods for soil erosion assessment have been used. Because of its high accuracy in estimations, dendrogeomorphology was selected as one suitable and reliable scientific method to achieve the main goals of this study.  The main goal of the study is to date denudation events using anatomical responses of the tree-rings of the roots. We analyze the histological changes that occur in the roots of two tree species, along the river banks of the Sedelska River, which is a tributary of Struma River. The significant differences between homogenous groups of measurements in pre-exposed and exposed roots was established, and it shows a remarkable response of roots to sheet erosion.

Integrated Bulk Segregant Analysis, Fine Mapping, and Transcriptome Revealed QTLs and Candidate Genes Associated with Drought Adaptation in Wild Watermelon.

Drought stress has detrimental effects on crop productivity worldwide. A strong root system is crucial for maintaining water and nutrients uptake under drought stress. Wild watermelons possess resilient roots with excellent drought adaptability. However, the genetic factors controlling this trait remain uninvestigated. In this study, we conducted a bulk segregant analysis (BSA) on an F2 population consisting of two watermelon genotypes, wild and domesticated, which differ in their lateral root development under drought conditions. We identified two quantitative trait loci (qNLR_Dr. Chr01 and qNLR_Dr. Chr02) associated with the lateral root response to drought. Furthermore, we determined that a small region (0.93 Mb in qNLR_Dr. Chr01) is closely linked to drought adaptation through quantitative trait loci (QTL) validation and fine mapping. Transcriptome analysis of the parent roots under drought stress revealed unique effects on numerous genes in the sensitive genotype but not in the tolerant genotype. By integrating BSA, fine mapping, and the transcriptome, we identified six genes, namely L-Ascorbate Oxidase (AO), Cellulose Synthase-Interactive Protein 1 (CSI1), Late Embryogenesis Abundant Protein (LEA), Zinc-Finger Homeodomain Protein 2 (ZHD2), Pericycle Factor Type-A 5 (PFA5), and bZIP transcription factor 53-like (bZIP53-like), that might be involved in the drought adaptation. Our findings provide valuable QTLs and genes for marker-assisted selection in improving water-use efficiency and drought tolerance in watermelon. They also lay the groundwork for the genetic manipulation of drought-adapting genes in watermelon and other Cucurbitacea species.

Facilitative and competitive interactions between mycorrhizal and nonmycorrhizal plants in an extremely phosphorus-impoverished environment: role of ectomycorrhizal fungi and native oomycete pathogens in shaping species coexistence.

Nonmycorrhizal cluster root-forming species enhance the phosphorus (P) acquisition of mycorrhizal neighbours in P-impoverished megadiverse systems. However, whether mycorrhizal plants facilitate the defence of nonmycorrhizal plants against soil-borne pathogens, in return and via their symbiosis, remains unknown. We characterised growth and defence-related compounds in Banksia menziesii (nonmycorrhizal) and Eucalyptus todtiana (ectomycorrhizal, ECM) seedlings grown either in monoculture or mixture in a multifactorial glasshouse experiment involving ECM fungi and native oomycete pathogens. Roots of B. menziesii had higher levels of phytohormones (salicylic and jasmonic acids, jasmonoyl-isoleucine and 12-oxo-phytodienoic acid) than E. todtiana which further activated a salicylic acid-mediated defence response in roots of B. menziesii, but only in the presence of ECM fungi. We also found that B. menziesii induced a shift in the defence strategy of E. todtiana, from defence-related secondary metabolites (phenolic and flavonoid) towards induced phytohormone response pathways. We conclude that ECM fungi play a vital role in the interactions between mycorrhizal and nonmycorrhizal plants in a severely P-impoverished environment, by introducing a competitive component within the facilitation interaction between the two plant species with contrasting nutrient-acquisition strategies. This study sheds light on the interplay between beneficial and detrimental soil microbes that shape plant-plant interaction in severely nutrient-impoverished ecosystems.

The Role and Mechanism of Spinal NF-κB-CXCL1/CXCR2 in Rats with Nucleus Pulposus-induced Radicular Pain.

Experimental study of the role and mechanism of spinal NFκB-CXCL1/CXCR2 in rats with nucleus pulposus-induced radicular pain. This study investigated the role and mechanism of spinal NFκB-CXCL1/CXCR2 in autologous nucleus pulposus-induced pain behavior in rats and to clarify the involvement and regulation of spinal NFκB as an upstream molecule of CXCL1 in autologous nucleus pulposus-induced radicular pain in rats. The inflammatory response of nerve roots is an important mechanism for the occurrence of chronic pain. NFκB-CXCL1/CXCR2 pathway plays an important role in the development of radicular pain, but its regulatory mechanism in the model of radicular pain induced by autologous nucleus pulposus is still unclear. We established a rat model of autologous medullary nucleus transplantation. We observed and recorded the changes in 50% mechanical withdrawal threshold and thermal withdrawal latency before and after the administration of CXCL1-neutralizing antibodies, CXCR2 inhibitor, and NFκB inhibitor in each group of rats and evaluated the expression of NFκB, CXCL1, and CXCR2 in the spinal dorsal horn using immunofluorescence and Western blot. To compare differences between groups in behavioral testing, analysis of variance was employed. Dunnett's method was used to compare differences at different time points within a group and between different groups at the same time point. A comparison of the relative concentration of protein, relative concentration of mRNA, and semiquantitative data from immunofluorescence staining was conducted utilizing one-way ANOVA and Dunnett's pairwise comparison. Autologous nucleus pulposus transplantation can induce radicular pain in rats and upregulate the expression of CXCL1, CXCR2, and NFκB in the spinal cord. CXCL1 is co-expressed with astrocytes, CXCR2 with neurons, and NFκB with both astrocytes and neurons. The application of CXCL1 neutralizing antibodies, CXCR2 inhibitors, and NFκB inhibitors can alleviate pain hypersensitivity induced by autologous nucleus pulposus transplantation in rats. Inhibitors of NFκB could downregulate the expression of CXCL1 and CXCR2. We found that spinal NFκB is involved in NP-induced radicular pain in rats through the activation of CXCL1/CXCR2, enriching the mechanism of medullary-derived radicular pain and providing a possible new target and theoretical basis for the development of more effective anti-inflammatory and analgesic drugs for patients with chronic pain following LDH.

The primacy of temporal dynamics in driving spatial self-organization of soil iron redox patterns.

This study investigates mechanisms that generate regularly spaced iron-rich bands in upland soils. These striking features appear in soils worldwide, but beyond a generalized association with changing redox, their genesis is yet to be explained. Upland soils exhibit significant redox fluctuations driven by rainfall, groundwater changes, or irrigation. Pattern formation in such systems provides an opportunity to investigate the temporal aspects of spatial self-organization, which have been heretofore understudied. By comparing multiple alternative mechanisms, we found that regular iron banding in upland soils is explained by coupling two sets of scale-dependent feedbacks, the general principle of Turing morphogenesis. First, clay dispersion and coagulation in iron redox fluctuations amplify soil Fe(III) aggregation and crystal growth to a level that negatively affects root growth. Second, the activation of this negative root response to highly crystalline Fe(III) leads to the formation of rhythmic iron bands. In forming iron bands, environmental variability plays a critical role. It creates alternating anoxic and oxic conditions for required pattern-forming processes to occur in distinctly separated times and determines durations of anoxic and oxic episodes, thereby controlling relative rates of processes accompanying oxidation and reduction reactions. As Turing morphogenesis requires ratios of certain process rates to be within a specific range, environmental variability thus modifies the likelihood that pattern formation will occur. Projected changes of climatic regime could significantly alter many spatially self-organized systems, as well as the ecological functioning associated with the striking patterns they present. This temporal dimension of pattern formation merits close attention in the future.

Multi-imaging platform for rhizosphere studies: Phosphorus and oxygen fluxes

Rhizosphere is a soil volume of high spatio-temporal heterogeneity and intensive plant-soil-microbial interactions, for which visualization and process quantification is of highest scientific and applied relevance, but still very challenging. A novel methodology for quick assessment of two-dimensional distribution of available phosphorus (P) in rhizosphere was suggested, tested, and development up to the application platform. Available P was firstly trapped by an in-situ diffusive gradients in thin-films (DGT) sampler with precipitated zirconia as the binding gel, and subsequently, the loaded gel was analyzed with an optimized colorimetric imaging densitometry (CID). The imaging platform was established linking: i) DGT, ii) planar optode, and iii) soil zymography techniques to simultaneously determine available P, oxygen, and acid phosphatase in rhizosphere at sub-millimeter spatial scales. The DGT identified available P level in rice rhizosphere were spatially overlapping to the localized redox hotspots and phosphatase activity. The spatial relationship between available P and acid phosphatase activity was dependent on root development. The root radial oxygen loss (ROL) remained active during the experimental observations (2–3 days), while a flux of available P of 10 pg cm−2 s−1 was visualized within 2–3 mm of roots, confirming the correlative response of rice roots to oxygen secretion and P uptake. Summarizing, the established imaging platform is suitable to capture spatial heterogeneity and temporal dynamics of root activities, nutrient bioavailability, ROL and enzyme activities in rhizosphere.

Aloe monticola Reynolds: A refugee of the mountains − contributing towards its conservation through in vitro propagation

In vitro micropropagation study of Aloe monticola Reynolds was conducted using offshoots in Murashige and Skoog (MS) media enriched with plant growth regulators (PGRs). Initiation experiment, carried out by culturing sterilized explants in full-strength MS media enriched with 0.0–1.0 mg/L benzyl amino purine (BAP) alone and in combination with 0.10 mg/L indole-3-butyric acid (IBA), resulted in 89 − 100 % healthy and live (i.e., initiated) explants in 9–29 days. Regeneration study, conducted by culturing initiated explants in full-strength MS media supplemented with 0.0–3.0 mg/L BAP alone and in combination with 0.50 mg/L IBA, showed that treatments enriched with 1.0–3.0 mg/L BAP in combination with 0.50 mg/L IBA yielded better shooting responses than the rest of the treatments. The rooting responses of the shoots were also tested by culturing in half-strength MS media enriched with 0.0–4.0 mg/L NAA alone and in combination with 0.25 mg/L IBA. Better rooting responses were observed in treatments supplemented with 1.0–4.0 mg/L NAA in combination with 0.25 mg/L IBA with two exceptions. The responses of A. monticola plantlets to primary and secondary acclimatization in greenhouse, nursery shade, and direct sunlight in coco peat, composted soil, and manured soil were excellent – with survival percentages of 90–98 %. The findings of this empirical research are important for developing refined protocol of in vitro micropropagation of this ecologically important but endangered plant.

Shoot and root responses to low phosphorus and their genotypic variability in selected cultivars of Japanese core collections of maize and soybean

ABSTRACT Low phosphorus (P) stress in agricultural soils is a global problem in crop production. A greater understanding of the genotype-specific responses under low P stress is imperative for producing P-efficient genotypes. This study first evaluated Japanese core collections of maize (86 landraces) and soybean (94 landraces) to low P under hydroponic conditions. Ten cultivars of each species were further evaluated in a pot experiment with two P supply rates: low P (10 mg P kg−1) and high P (50 mg P kg−1). Root morphology, acid phosphatase (ACP) activity, and rhizosphere soil pH were characterized 30 days after planting. A sufficient genotypic variation was found in both species under both P conditions. A significant decrease in biomass, except in maize cultivar JMC 76 and soybean cultivar GmJMC033, and increased phosphorus use efficiency (PUE) under low P conditions were observed. The maize cultivars: JMC 76, JMC 57, JMC 58, and JMC 8 and soybean cultivars: GmJMC033, GmJMC040, and GmJMC085 showed distinctive root modifications characterized by the high root-to-shoot ratio (RRS), total root length (TRL) and specific root length (SRL) under low P stress indicating their low P tolerance. Maize had more significant ACP activity compared to soybean under low P stress. The maize cultivars, which showed low P tolerance, were highly dependent on root morphological traits rather than physiological traits (ACP activity, rhizosphere acidification, and PUE), whereas soybean cultivars were dependent on both traits. In conclusion, the plasticity of the root system is crucial in both maize and soybean to tolerate P deficiency. These genotype-specific adaptations could be combined with agronomic strategies to enhance the overall P-use efficiency in cropping systems.

Exploring cadmium stress responses in sisal roots: Insights from biochemical and transcriptome analysis.

Sisal is a leaf fiber crop with a high integrated value and a wide range of uses in the application of soil remediation of heavy metal contamination. This study provides a preliminary understanding of how sisal responds to Cd stress and presents a theoretical basis for exploring the potential of sisal in the remediation of Cd-contaminated soils. In this work, the activities of the antioxidant enzymes (SOD, POD, and CAT) of sisal were measured by hydroponics with the addition of CdCl2·2.5H2O and different concentrations of Cd stress. Whole transcriptome sequencing (RNA-Seq) analysis was performed with lllumina sequencing technology, and qRT-PCR was conducted to verify the differential genes. The results obtained were as follows: (1) Short-term low concentration of Cd stress (20 mg/kg) had a transient promotion effect on the growth of sisal roots, but Cd showed a significant inhibitory effect on the growth of sisal roots over time. (2) Under different concentrations of Cd stress, the Cd content in sisal root was greater than that in sisal leaf, and Cd accumulated mainly in sisal roots. (3) With the increase of Cd stress concentration, the antioxidant enzyme catalase activity increased, peroxidase activity showed a decreasing trend, and superoxide dismutase showed a trend of increasing and then decreasing. (4) Transcriptome sequencing analysis detected 123 differentially expressed genes (DEGs), among which 85 genes were up-regulated and 38 genes were down-regulated. The DEGs were mainly concentrated in flavonoid biosynthesis and glutathione metabolism, and both processes had some regulatory effects on the Cd tolerance characteristics of sisal. This study elucidated the physiological, biochemical and transcriptomic responses of sisal under cadmium stress, and provided a theoretical basis for the ecological restoration function of sisal.

An efficient direct organogenesis protocol for in vitro clonal propagation of Rubia cordifolia L.

This comprehensive study delves into the intricate process of in vitro clonal propagation of R. cordifolia, with a particular focus on optimizing a method of direct organogenesis. The choice of direct organogenesis over indirect organogenesis is driven by the propensity for somaclonal variations associated with the latter. The presented research explores the critical factors influencing direct organogenesis, including the selection of appropriate explants and the optimum use of plant growth regulators. Notably, nodal explants have demonstrated great potential for regeneration, and the choice of cytokinins such as kinetin (KIN) and 2-isopentenyladenine (2-iP) for shoot induction has proven highly effective, with 1.0 mg/L KIN supplementation to MS media emerging as the most favourable choice resulting in 12.14 ± 1.58 shoots and 29.78 ± 1.93 axillary buds. Subsequent adventitious rooting using indole-3 butyric acid (IBA) and indole-3-acetic acid (IAA) resulted in a 100% rooting response. Among the concentrations tested, 1.0 mg/L IBA was found most effective, yielding the best rooting response (22.9 ± 1.06 roots/ micro-shoot). Acclimatization of in vitro cultures was achieved by gradually exposing them to natural conditions, maintaining high humidity and minimizing photorespiration. The morphological transformations observed, including robust leaf development contributed to the high acclimatization success (100% survival). Additionally, the genetic stability was confirmed using DNA-based ISSR markers, with complete monomorphism indicating no variations among the regenerants. The efficient direct organogenesis protocol developed in this study may prove a valuable contribution towards the mass clonal propagation and conservation of R. cordifolia, an industrially and medicinally important plant.