Root Surface Area Research Articles

Genetic Basis of Seedling Root Traits in Common Wheat (Triticum aestivum L.) Identified by Genome-Wide Linkage Mapping

Common wheat production is significantly influenced by abiotic stresses. Identifying the genetic loci for seedling root traits and developing the available molecular markers are crucial for breeding high yielding and stable varieties. In this study, five wheat seedling root traits, including root length (RL), root surface area (RA), root volume (RV), number of root tips (RT), and root dry weight (RW), were measured in the Wp-072/Wp-119 recombinant inbred line (RIL) population. Genotyping was conducted for the RIL population and their parents using the wheat 90K single-nucleotide polymorphism (SNP) chip. In total, three quantitative trait loci (QTLs) for RL (QRL.gau-1DS, QRL.gau-1DL and QRL.gau-4AL), two QTLs for RA (QRA.gau-1D and QRA.gau-2DL), one locus for RV (QRV.gau-6AS), two loci for RW (QRW.gau-2DL and QRW.gau-2AS), and two loci for RT (QRT.gau-3AS and QRT.gau-6DL) were identified, with each explaining 4.5–8.4% of the phenotypic variances, respectively. Among these, QRT.gau-3AS, QRL.gau-4AL, and QRV.gau-6AS overlapped with the previous reports, whereas the other seven QTLs were novel. The favorable alleles of QRL.gau-1DS, QRL.gau-1DL, QRL.gau-4AL, QRA.gau-1D, QRW.gau-2AS, QRV.gau-6AS, QRT.gau-3AS, and QRT.gau-6DL were contributed by Wp-072, whereas the other two loci originated from Wp-119. Additionally, five kompetitive allele-specific PCR (KASP) markers, KASP-RL-1DL for RL, KASP-RA-1D and KASP-RA-2DL for RA, KASP-RW-2AS and KASP-RW-2DL for RW, were developed and validated successfully in 149 wheat accessions. Furthermore, seven candidate genes mainly for plant hormones were selected and validated by quantitative real-time PCR (qRT-PCR). This study provides new loci, new candidate genes, available KASP markers, and varieties for optimizing wheat root system architecture.

Measurement of the root surface area in rat molars through three-dimensional modeling

Rats are used as animal models for basic and applied research related to orthodontic tooth movement (OTM). The magnitude of mechanical force in OTM rat models mainly depends on the supporting capability of the periodontal ligament (PDL), which is highly associated with the root surface area (RSA). But the size of rat RSA remains unknown, which is the reason why there are still debates on the magnitude of mechanical force in OTM rat models. This study aimed to explore a method for measuring the RSA in rat molars. The maxillary and mandibular samples of rats were scanned by Micro-CT to generate three-dimensional (3D) images, followed by 3D reconstruction of every molar through Mimics Medical 21.0. Geomagic Wrap 2021 and Unigraphics NX 12.0 were utilized to smooth teeth surface and mark the cementoenamel junction (CEJ). Finally, the RSA in rat molars was measured. The results showed that for the six-, eight-, or ten-week-old rats, the average RSA of maxillary first, second, and third molars was 25.90 ± 2.29 mm2, 15.92 ± 2.14 mm2, and 10.34 ± 1.94 mm2. The RSA of mandibular first, second, and third molars was 27.03 ± 2.63 mm2, 17.16 ± 1.61 mm2, and 11.39 ± 2.13 mm2. Through 3D modelling, we provided data of rat RSA, and observed the trend of increasing RSA mean values with age. These data are pivotal for determining the magnitude of mechanical force required to move rat molars, especially when conducting research related to OTM using rat models.

Integrating physiological, metabolome and transcriptome revealed the response of maize seeds to combined cold and high soil moisture stresses.

Combined cold and high moisture stress (CHS) is a prevalent abiotic stress during maize sowing in northeast China, severely affecting the growth of seedlings and seed germination. However, the mechanism underlying seed growth responses to CHS remains unclear. We used Jidan441 (JD441, CHS-resistant) and Jidan558 (JD558, CHS-sensitive) as experimental materials. Treatments of 5-day cold (4°C, CS), high moisture (25%, gravimetric water content, HH), and CHS were initiated at sowing, followed by a return to normal growth conditions (20°C during light/ 15°C during dark, 15%) at 7 days after sowing (DAS). CS, HH, and CHS decreased seed root length and surface area. The reduction in root length and surface area in JD441 due to CHS was less severe than in JD558. We found that the difference between CHS and control in JD441was less than that in JD558 at transcriptional and metabolic levels at 7 DAS. After CHS removal, JD441 exhibited a greater increase in α-amylase activity and antioxidant content than JD558, which facilitated starch decomposition and the rapid removal of O2 - and H2O2 in seeds. The rapid recovery of soluble sugar and soluble protein in JD441 helped maintain osmotic balance. Amino acids and genes related to amino acid metabolism were upregulated in response to combined stress in JD441, whereas they were downregulated in JD558. In conclusion, the stress tolerance of JD441 was attributed to its efficient recovery ability from CHS. This study provides a scientific foundation for exploring seed stress tolerance pathways and developing cold and high-moisture-tolerant hybrids.

Effect of Exogenous IBA on Root Morphology and Endogenous Hormone Metabolic Pathways in Castor Seedlings Under Pb/Zn Stress

Ricinus communis, a plant of significant industrial value for its oil, is renowned for its robust root system and vigorous growth, qualities that render it an exemplary candidate for the ecological remediation of soils contaminated with heavy metals. The impact of heavy metal stress on root development is characterized by inhibition, a phenomenon whose underlying mechanisms are not fully elucidated. To shed light on this, a study was conducted wherein varying concentrations of the exogenous auxin, IBA, were applied to the roots of Ricinus communis to scrutinize its influence on the endogenous indole-3-acetic acid (IAA) metabolism in seedlings and to delineate the molecular underpinnings of its effects on root morphology. It was observed that IBA significantly amplified the total root surface area by a factor of 1.29 and increased the number of root tips by 40.11% under lead (Pb) stress, and by 32.29% and 91.19%, respectively, under zinc (Zn) stress. These findings underscore the efficacy of IBA in promoting the proliferation of lateral roots in seedlings subjected to stress induced by either Pb or Zn. Further analysis of auxin signaling pathways revealed that the presence of Pb or Zn impedes root growth and lateral root formation by perturbing auxin transporters and signaling molecules. Notably, IBA was found to foster the development of lateral roots by modulating the expression of specific transporters. Post-application of IBA, the endogenous levels of IAA in roots exhibited a 2.80-fold elevation under Pb stress, IBA stimulated the activity of key biosynthetic enzymes, such as RcNIT and RcTAR, culminating in elevated IAA levels. Conversely, under Zn stress, IBA was observed to diminish the levels of RcTAR, which in turn led to reduced IAA levels. These outcomes contribute to a deeper comprehension of the modulatory role of IBA in the context of heavy metal stress.

Occurrence of Rhizoctonia solani AG-5 Causing Root Rot on Astragalus mongholicus in Northwestern China.

Astragalus mongholicus is a perennial Chinese medicinal herb in the family Leguminosae widely cultivated in China. In September 2023, A. mongholicus plants in a field in Weiyuan County, Gansu Province, showed symptoms of circular or irregular brown, sunken and necrotic lesions, multiple lesions coalesced, and brown longitudinal cracks in the roots. An investigation was performed in a 1998 m2 field with a root rot incidence of 10%, and the severity ranged from 5 to 60% of root surface area. Five rotted root samples were collected. Fragments of symptomatic roots were surface sterilized with 75% ethanol for 10 s, 2% sodium hypochlorite for 2 min, washed three times with sterilized distilled water, and then blotted dry on sterile filter paper. Fragments were placed on potato dextrose agar (PDA) medium and incubated at 25 ± 1°C in darkness for 5 days and five isolates were purified by transferring single hyphal tips to new PDA plates. Isolates WY23AM01 and WY23AM05, two of five isolates with similar morphology, were randomly selected for morphological and molecular identification and pathogenicity tests. Colonies of the fungus were white initially, then turned light brown to brown, raised, and with entire or undulate edges. Sclerotia were brown and produced on PDA after 20 days of incubation at 25 ± 1°C in the dark. Genomic DNA from each of the two isolates was extracted, and the internal transcribed spacer (ITS) region was amplified and sequenced with the primer pair ITS5/ITS4 (White et al. 1990). The sequences of isolates WY23AM01 and WY23AM05 were deposited in GenBank (PQ362092 and PQ362093). Phylogenetic analyses were performed by the maximum likelihood method with ITS sequences for anastomosis groups (AG) of Rhizoctonia solani using MEGA 10.0. The phylogenetic tree grouped the two isolates within the R. solani AG-5 clade with high bootstrap support (99%). PCR analysis was performed with 21 primers specifically designed to detect individual anastomosis groups or anastomosis subgroups of R. solani (Carling et al., 2002; Misawa and Kurose, 2019; Misawa et al., 2020; Okubara et al., 2008). Among the 21 specific primer pairs, only AG-5 specific primer amplified the fungal DNA, indicating that the two isolates belonged to the R. solani AG-5. For pathogenicity tests, two isolates were grown individually on sterile wheat kernels at 25 ± 1°C for 10 days. Certified pathogen-free seedling stage roots were grown in the plastic pot filled with the commercially available sterilized horticultural soil and inoculated by burying twenty infested wheat kernels in the soil adjacent to the roots. Control plants were inoculated with sterile wheat kernels using the same procedure. Each pot had three roots, and each treatment had 12 pots as replicates. All plants were placed in a greenhouse with 60% relative humidity and a 12h/12h light/dark photoperiod at 15 to 30°C. Sixty days after inoculation, typical root rot symptoms developed on all inoculated plants, similar to symptoms observed in the field, whereas control plants remained symptomless. The pathogenicity test was performed three times and symptoms were similar to those observed in the field. Finally, fungal isolates were reisolated from the symptomatic roots of all inoculated plants and identified as R. solani AG-5 by molecular analysis as the isolates used for inoculation, thus fulfilling Koch's postulates. To our knowledge, this is the first confirmed report of R. solani AG-5 causing root rot on A. mongholicus in China. Our findings improve knowledge about R. solani AGs occurring in A. mongholicus fields in China and broadens the host range of R. solani AG-5. Due to serious damages caused by this disease in recent years in China, further studies should be conducted to investigate the diversity, prevalence, disease control measures and fungicide sensitivity of AGs distributed in the main A. mongholicus-producing areas in China.

Silicon Nutrition Improves Lodging Resistance of Rice Under Dry Cultivation

Silicon (Si) has been proven to enhance the stress resistance of rice, but its effect on the lodging resistance of rice under dry cultivation (DCR) is still unclear. The purpose of this experiment is to clarify the appropriate amount of silicon fertilizer for DCR to resist lodging and to elucidate how it coordinates lodging resistance and yield. This experiment used the ‘Suigeng 18’ cultivar as the material and set six silicon fertilizers (SiO2) with dosages of 0, 15, 30, 45, 60, and 75 kg·ha−1 (Si0, Si1, Si2, Si3, Si4, Si5). Analyze the effects and key indicators of silicon on lodging resistance of DCR from the perspectives of plant weight distribution, stem structure and composition, and root architecture. The results showed that the Si3 treatment had the highest yield and the lowest lodging index (LI). Si3 increases the weight of the upper three leaves and 4–5 internodes, thereby promoting panicle weight and yield. An increase of 13.38% in 2/3PWSI (weight of the 4th–5th stems and upper three leaves/weight of the 1st–3rd stems and lower leaves) can reflect the promoting effect of silicon on stem and leaf development near the panicle. Si3 reduces the GA/IAA value, shortens the length of the second internode, and increases the diameters of the major and minor axes, thereby increasing culm thickness and section modulus (SM), achieving the effect of “short and thick”. Si3 also increases the content of silicon and non-structural carbohydrates (NSCs) in the second internode, and increases lignin and cellulose content by upregulating the expression levels of CAD7, PAL, COMT, and CesA4 genes, thereby increasing fullness and flexural strength (M), achieving “short, thick, and strong” and reducing LI. The 38.95% reduction in IFL (second internode length/fullness) reflects the positive effect of silicon on the “short, thick, and strong” stem. In the underground part, adding silicon reduces the CTK/IAA value of roots, and increases root length, root tip number, root surface area, and root weight. The key to coordinating the lodging resistance and yield of DCR with appropriate silicon dosage is to reduce the IFL in the second internode and increase 2/3 PWSI and root growth. The key to DCR and breeding is to focus on the relationship between basal internode length and fullness, as well as stem and leaf growth near the panicle.

Broad-spectrum applications of plant growth-promoting rhizobacteria (PGPR) across diverse crops and intricate planting systems.

Multifunctional plant growth-promoting rhizobacteria (PGPR) have garnered significant attention in agricultural applications; however, a few have applied them in crop rotation or intercropping fields. To identify PGPR with strong colonization ability and broad spectrum benefit, we screened strains from the local tobacco rhizosphere and evaluated their growth-promoting effects across various crops and farming systems. In this study, strain L8, identified as Bacillus thuringiensis, was selected as a multifunctional PGPR capable of producing indole-3-acetic acid (IAA), solubilizing potassium, and mobilizing both organic and inorganic phosphorus. Compared with the control group, the soil treated with strain L8 in tobacco pot experiments showed significantly higher levels of IAA, available potassium, and available phosphorus. Furthermore, tobacco plants inoculated with L8 exhibited significantly improved growth parameters compared with the uninoculated control. The results indicated that compared with the control, strain L8 increased tobacco fresh weight (by 83.18%), plant height (by 29.32%), relative chlorophyll content (by 14.33%), as well as plant phosphorus (by 23.78%) and potassium (by 30.81%). Interestingly, L8 not only enhanced tobacco growth but also improved tobacco root morphology, significantly increasing root length (1.55-fold), root surface area (1.78-fold), and root volume (2.05-fold) compared with the control. These findings provide valuable insights into utilizing plant growth-promoting bacteria for tobacco production. Moreover, the inoculation strain L8 enriched soil organic matter and nutrient content in both wheat (Triticum aestivum)-maize (Zea mays) rotation and peanut (Arachis hypogaea)-maize intercropping systems. Furthermore, within the intricate tillage systems of wheat-corn rotation and peanut-corn intercropping, multifunctional PGPR strain L8 can play a crucial role in crop growth promotion, yield increase, and higher soil nutrient availability.IMPORTANCEThese findings aim to study the application of plant growth-promoting rhizobacteria (PGPR) in diverse crops and complex planting systems, showing their adaptability and effectiveness in various agricultural contexts. The study suggests that this strain improves nutrient utilization in the soil, enhances soil health, and plays a significant role in plant growth through the secretion of substances like auxin (IAA). In parallel, we observed that applying this strain improved the production efficiency of wheat, corn, and peanuts within complex farming systems, indicating that this method holds the potential for enhancing both the yield and quality of various crops.

Efficient and rapid identification of tropical maize inbred lines tolerant to waterlogging stress

Waterlogging (WL) is an important abiotic stress, severely affecting plant growth and development, inhibiting root respiration and degradation of chlorophyll, senescence of leaves and chlorosis leading to substantial yield loss. These intensities of yield losses generally depend on the duration of WL and crop growth stages. Maize being a dry land crop is particularly sensitive to WL. Systematic screening techniques to identify parameters linked with tolerance are not well established which serves as a major bottleneck in the identification of promising genotypes. In this study, 120 maize inbred lines belonging to diverse genetic backgrounds were evaluated for WL tolerance both at pre-emergence as well as the seedling stage. Results based on percentage germination at pre-emergence and percentage survival at the seedling stage under WL established that pre-germination tolerance is independent of seedling stage tolerance. Membership function value based on WL tolerance coefficient of shoot and root fresh weights, dry weights, lengths, root surface area, shoot area and root volume was used to identify tolerant lines. Established mathematical models were used and identified root dry weight as a single reliable parameter to judge the tolerance level of genotypes. The use of BLPSI and ESIM selection indices as well as MTSI to judge the stability as well as genetic worth of genotypes further strengthens the selection efficiency. Lines thus performing best across all the models included I 185, I 172 and SE 503 and were identified as tolerant lines for WL. A combination of these different selection approaches would further strengthen selection efficiency and is believed to be a rapid and effective selection approach.

Effects of Serendipita indica on the Morphological and Physiological Characteristics of Agrostis stolonifera L. Under Drought Stress

This study investigates the effect of Serendipita indica inoculation on the growth, structural characteristics of leaf epidermis, photosynthetic parameters, and antioxidant and osmoregulation capacities of Agrostis stolonifera L. under different drought stresses (normal moisture management: at 70–75% of the field capacity, low drought: at 55–60% field capacity, moderate drought: at 40–45% of the field capacity, and severe drought: at 25–30% of the field capacity). The results showed that inoculation with S. indica significantly enhanced the growth potential of A. stolonifera compared to uninoculated controls, and then under drought stress conditions, inoculation with S. indica significantly alleviated the inhibition of the growth and development of A. stolonifera, especially under mild and moderate drought stresses. These improvements were evident in both aboveground and underground parts, leaf relative water content, total root length, and root surface area after 25 days of drought treatments. Inoculated plants also exhibited higher levels of photosynthetic pigments, net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) under drought conditions. Additionally, S. indica inoculation significantly increased the activities of catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX), as well as the soluble sugar, soluble protein, and proline levels under drought-stressed and non-stressed conditions. In addition, the increases in the malondialdehyde (MDA) content and relative conductivity (RC) of leaves were significantly lower in the inoculated group compared to the control group. In conclusion, the symbiosis with S. indica promotes the growth of A. stolonifera under drought stress, likely by enhancing photosynthesis, osmoregulatory substances, and antioxidant enzyme activities.

Effects of Intercropping and Mowing Frequency on Biological Nitrogen Fixation Capacity, Nutritive Value, and Yield in Alfalfa (Medicago sativa L. cv. Vernal).

Intercropping with legume forages is recognized as an effective strategy for enhancing nitrogen levels in agroforestry, while mowing may influence nitrogen fixation capacity and yield. This study investigated the rooting, nitrogen fixation, nutritive value, and yield of alfalfa (Medicago sativa L.) under intercropping and varying mowing frequencies (CK, 2, and 3) from 2021 to 2023, using walnut (Juglans regia L.) and alfalfa as experimental subjects. The results indicated that intercropping suppressed root growth, whereas increased mowing frequency stimulated root development in the topsoil (0-20 cm). Specifically, the average root length density, root surface area, and root volume from the twice- and thrice-mowed treatments increased by 18.26, 17.45, and 4.15%, respectively, in comparison to the control. The δ15N values of the intercropped alfalfa were significantly lower than those of the monocropped alfalfa (p < 0.05), with the δ15N values of the mowing-thrice treatment increasing by an average of 38.61% compared to the control. Intercropping suppressed alfalfa yield but did not affect the total nitrogen content in the leaves or the nutritive value, and all mowing treatments resulted in land equivalent ratios (LERs) greater than 1. Furthermore, increased mowing frequency enhanced both the nutritive value and yield of alfalfa. Our study suggests that intercropping with walnut can improve biological nitrogen fixation in alfalfa, and that adopting a mowing-thrice regime can optimize yield and nutritive value.

The Effect of Mulching on the Root Growth of Greenhouse Tomatoes Under Different Drip Irrigation Volumes and Its Distribution Model

Despite the continuous development of greenhouse cultivation technology, the influence mechanism of covering conditions on the root distribution of greenhouse crops remains unclear, which is emerging as a significant research topic at present. The interaction between mulching and irrigation plays a key role in the root growth of greenhouse tomatoes, but its specific impact awaits in-depth exploration. To explore the response patterns of greenhouse crop root distribution to the drip irrigation water amount under mulching conditions, the tomato was chosen as the research object. Three experimental treatments were set up: mulched high water (Y0.9), non-mulched high water (N0.9), and mulched low water (Y0.5) (where 0.9 and 0.5 represent the cumulative evaporation from a 20 cm standard evaporation pan). We analyzed the water and thermal zone of tomato roots as well as the root distribution. Based on this, a root distribution model was constructed by introducing a mulching factor (fm) and a water stress factor (Ks). After carrying out two years of experimental research, the following results were drawn: (1) The average soil water content in the 0–60 cm soil layer was Y0.9 &gt; N0.9 &gt; Y0.5, and the average soil temperature in the 0–30 cm soil layer was Y0.5 &gt; Y0.9 &gt; N0.9. (2) The interaction between mulching and irrigation had a significant impact on the distribution of tomato roots. In the absence of mulch, the root surface area, average root diameter, root volume, and root length density initially increased and then decreased with depth, with the maximum root distribution concentrated around the 20 cm soil layer. Under mulched conditions, roots were predominantly located in the top layer (0–20 cm). Under the film mulching condition, the distribution range of root length density of low water (Y0.5) was wider than that of high water (Y0.9). (3) Root length density exhibited a significant cubic polynomial relationship with both the soil water content and soil temperature. In the N0.9 treatment, root length density had a bivariate cubic polynomial relationship with soil water and temperature, with a coefficient of determination (R2) of 0.97 and a normalized root mean square error (NRMSE) of 20%. (4) When introducing the film mulching factor (fm) and water stress factor (Ks) into the root distribution model to simulate the root length density distribution of Y0.9 and Y0.5, it was found that the NRMSE was 22% and R2 was 0.90 under the Y0.9 treatment, and the NRMSE was 24% and R2 was 0.98 under the Y0.5 treatment. This study provides theoretical support for the formulation of scientifically sound irrigation and mulching management plans for greenhouse tomatoes.

Root decomposition and nutrient dynamics in multifunctional forage‐biomass buffer‐strip systems

AbstractPerennial crops are thought as a solution for enhancing food security and providing ecosystem services under a changing climate, including forage‐biomass production, reduced erosion and nutrient leaching, and soil C accumulation. However, the drivers of root decomposition and C allocation in perennial multifunctional forage‐biomass buffer‐strips as affected by fertility management are poorly elucidated. Thus, study objectives were to assess root decomposition and soil CO2 efflux on switchgrass (Panicum virgatum L.), eastern gamagrass (Tripsacum dactyloides L.), silphium (Silphium integrifolium Michx.), and intermediate wheatgrass Kernza (Thinopyrum intermedium [Host] Barkworth &amp; D.R. Dewey) treated with poultry litter (PL) relative to the unfertilized control. Root mass loss was greatest for silphium, owing to low neutral and acid detergent fibers and lignin contents (6%) relative to the other species (16%–25%). Root‐C loss was the greatest for intermediate wheatgrass (IW), mostly driven by hemicellulose degradation. Low root mass, surface area, and volume likely enhanced root decomposition for silphium and IW. Root mass loss and C, N, and P mineralization for novel perennial buffer‐strip species were greater in PL plots. Soil organic C stocks were mostly similar across forage‐biomass species × amendment combinations. Silphium‐PL had 27%–50% greater SOC stocks after 4 years, owing to higher root sloughing and C inputs to soil. Root decomposition rates were primarily affected by root chemical composition and morphology, while soil CO2 efflux was driven by soil moisture and temperature. Greater root sloughing, C inputs, and nutrient cycling showcase the potential for C storage and multiple purposes of novel perennial buffer‐strips.

Combined Impact of Canada Goldenrod Invasion and Soil Microplastic Contamination on Seed Germination and Root Development of Wheat: Evaluating the Legacy of Toxicity.

The concurrent environmental challenges of invasive species and soil microplastic contamination increasingly affect agricultural ecosystems, yet their combined effects remain underexplored. This study investigates the interactive impact of the legacy effects of Canada goldenrod (Solidago canadensis L.) invasion and soil microplastic contamination on wheat (Triticum aestivum L.) seed germination and root development. We measured wheat seed germination and root growth parameters by utilizing a controlled potted experiment with four treatments (control, S. canadensis legacy, microplastics, and combined treatment). The results revealed that the legacy effects of S. canadensis and microplastic contamination affected wheat seed germination. The effects of different treatments on wheat seedling properties generally followed an "individual treatment enhances, and combined treatment suppresses" pattern, except for root biomass. Specifically, the individual treatment promoted wheat seedling development. However, combined treatment significantly suppressed root development, decreasing total root length and surface area by 23.85% and 31.86%, respectively. These findings demonstrate that while individual treatments may promote root development, their combined effects are detrimental, indicating a complex interaction between these two environmental stressors. The study highlights the need for integrated soil management strategies to mitigate the combined impacts of invasive species and microplastic contamination on crop productivity and ecosystem health.

Fine-root and leaf acquisitive traits decoupled from chloride accumulation in reflecting the differential salinity tolerance among Prunus hybrids.

Improving crop salinity management requires enhanced understanding of salinity responses of leaf and fine-root traits governing resource acquisition, ideally in relation to ion accumulation at intra- or inter-specific levels. We hypothesized that these responses are coupled towards integrated resource conservation for plants under prolonged salt treatment. We tested the hypothesis with a glasshouse experiment on saplings of six contrasting Prunus hybrids, subjected to either control or salt treatment (reverse osmosis water versus 3.3 dS m-1 chloride solution containing mixed cations). Sample collections were carried out at 30 and at 60 days after the start of treatments. All six hybrids showed significantly higher lamina chloride concentration in response to salt treatment, with GF677 accumulating a lower concentration than the other five hybrids. There was significantly lower specific leaf area (SLA) in 'Monegro' and lower root tissue density (RTD) in 'Nemaguard' after 60 days - but not 30 days - of salt treatment. No hybrid showed concurrent significant decrease of SLA and specific root surface area (SRA) under salt treatment. The a priori known salinity-sensitive hybrid 'Nemaguard' not only showed decreased RTD and a negative relationship between root biomass and salt treatment duration, but also showed increased SRA without notable change of average root diameter. Lamina chloride accumulation and leaf gas exchange response were closely correlated along a gradient towards resource conservation from control to salt-treated plants in all hybrids, which was orthogonal to another gradient characterized by a hybrid-dependent modification of SLA, SRA, RTD and percentage of root length within the finest diameter class. This study highlighted the intraspecific differential resource investment strategies, reflected by the hybrid-specific salinity-response coordination among leaf and fine-root acquisitive traits.

Effects of combined inoculation of arbuscular mycorrhizal fungi and plant growth-promoting rhizosphere bacteria on seedling growth and rhizosphere microecology.

The effects of rhizosphere microorganisms on plant growth and the associated mechanisms are a focus of current research, but the effects of exogenous combined inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on seedling growth and the associated rhizosphere microecological mechanisms have been little reported. In this study, a greenhouse pot experiment was used to study the effects of single or double inoculation with AM fungi (Funneliformis mosseae) and two PGPR (Bacillus sp., Pseudomonas sp.) on the growth of tobacco seedlings, together with high-throughput sequencing technology to reveal associated rhizosphere microecological mechanisms. All inoculation treatments significantly increased the aboveground dry weight; root dry weight; seedling nitrogen, phosphorus, and potassium uptake; plant height; stem thickness; maximum leaf area; chlorophyll content; total root length, surface area, and volume; and average root diameter. The highest values for these indices were observed in the combined treatment of F. mosseae and Pseudomonas sp. SG29 (A_SG29). Furthermore, the A_SG29 treatment yielded the highest diversity indexes and largest percentages of significantly enriched bacterial taxa, and significantly promoted the colonization of AMF in tobacco roots and Pseudomonas in rhizosphere soil. Differential metabolic-pathway predictions using PICRUSt2 showed that the A_SG29 treatment significantly increased the metabolic pathway richness of tobacco rhizosphere microorganisms, and significantly up-regulated some metabolic pathways that may benefit plant growth. Co-inoculation with F. mosseae and Pseudomonas sp. SG29 promoted tobacco-seedling growth by significantly improving rhizosphere microbial communities' structure and function. In summary, the combined inoculation of AMF and SG29 promotes tobacco seedling growth, optimizes the rhizosphere microbial community's structure and function, and serves as a sustainable microbial co-cultivation method for tobacco seedling production.

Root characteristics response to N, P, and K fertilization in creeping bentgrass

AbstractTurfgrass roots are essential for growth and development by taking up water and nutrients from the soil. Therefore, improving root characteristics such as root length, root volume, root density, root diameter, and root dry biomass is crucial for improving turfgrass growth and quality. Greenhouse experiments were conducted in 2023 to document the effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizers on the root morphological responses of Penncross creeping bentgrass (Agrostis stolonifera) during establishment. Turfgrasses were grown from seeds in sand‐filled acrylic tubes for around three months. Fertilizer treatments included N, P, K, PK, NK, NP, all three macronutrients (NPK), and a non‐fertilized control (non‐NPK). NP treatment resulted in a greater total root length, root surface area, root volume, and root dry biomass of creeping bentgrass than the other treatments except for NPK treatment. While it is critical to provide sufficient N, P, and K for the optimal development of creeping bentgrass roots during the establishment period, reducing K fertilization had the least impact on the root morphological response of creeping bentgrass. NPK application during turfgrass establishment is context‐dependent, particularly with regard to nutrient availability in the soil. Based on this study, applying a balanced starter fertilizer with adjustments per the soil test results would ensure proper root growth.

Histological and radiographic assessment of the regenerative potential of sodium hexametaphosphate (SHMP) as a novel direct pulp capping material in an animal model

BackgroundThis study aimed to assess the histological and radiographic effects of sodium hexametaphosphate (SHMP) as a direct pulp capping (DPC) agent in immature permanent dog premolars.MethodsA split-mouth design was employed with three healthy 4-month-old Mongrel dogs, each having 36 premolars. The premolars were randomly assigned to either SHMP or MTA. The specimens were stained with hematoxylin and eosin (H&E) and Masson’s trichrome, and histologically examined three months after the animals were sacrificed. To assess root maturity, radiographic changes in root length (RL), root surface area (RSA), and apical foramen width (AFW) were measured at baseline and after 3 months. Quantitative data were analyzed using the paired-sample t-test, while the qualitative data based on Stanley's histological scoring system were tested using the Monte Carlo exact test. The level of significance was set at 5%.ResultsHistological findings showed no significant differences between the two groups, except for the average thickness of the predentin and odontoblastic layers, which was significantly higher in the SHMP specimens (P < 0.0001). The frequencies of fully calcified dentin bridges and regularly arranged dentinal tubules were significantly higher in the SHMP specimens (P < 0.05). Both materials showed comparable radiographic measurements (P > 0.05), except for the change in RL, which was significantly longer in the SHMP group (P < 0.05).ConclusionsThere were no significant differences between SHMP and MTA in some respects. Histological evaluation showed that SHMP provided better bioinductive and biocompatible properties compared to MTA. Radiographically, both materials showed comparable root maturogenesis outcomes, except for the significant increase in RL in the SHMP group. SHMP may be a suitable alternative material for DPC in the treatment of immature permanent teeth.

Enterobacter-inoculation altered the C, N contents and regulated biomass allocation in Reaumuria soongorica to promote plant growth and improve salt stress tolerance.

Soil salinization poses a significant ecological and environmental challenge both in China and across the globe. Plant growth-promoting rhizobacteria (PGPR) enhance plants' resilience against biotic and abiotic stresses, thereby playing a vital role in soil improvement and vegetation restoration efforts. PGPR assist plants in thriving under salt stress by modifying plant physiology, enhancing nutrient absorption, and synthesizing plant hormones. However, the mechanisms through which PGPR regulate the contents of carbon (C) and nitrogen (N), and biomass allocation of desert plant in response to salt stress is still unclear. This study explores the impact of PGPR on biomass allocation, C, and N contents of R. soongorica seedlings through a pot experiment. Strains P6, N20, and N21, identified as Enterobacter, were isolated from the rhizosphere of R. soongorica, and they exhibited various beneficial traits such as indole-3-acetic acid (IAA) production, phosphate solubilization, nitrogen fixation, and tolerance to up to 8% NaCl stress. We found that under NaCl stress, R. soongorica seedlings exhibit significant reductions in plant height, basal diameter, and root surface area (P<0.05). However, inoculation with strains P6, N20, and N21 reverses these trends. Compared to NaCl treatment alone, co-treatment with these strains significantly increases the biomass of roots, stems, and leaves, particularly root biomass, which increases by 99.88%, 85.55%, and 141.76%, respectively (P<0.05). Moreover, N contents decrease significantly in the roots, stems and leaves, C contents increase significantly in the roots and leaves compared to NaCl treatment (P<0.05). Specifically, N contents in roots decrease by 14.50%, 12.47%, and 8.60%, while C contents in leaves increase by 4.96%, 4.45%, and 4.94%, respectively (P<0.05). Additionally, stem and leaf biomasses exhibit a significant positive correlation with C contents and a significant negative correlation with N contents in these tissues. In conclusion, inoculation of Enterobacter strains enhanced the biomass of R. soongorica seedlings, regulated the biomass distribution, and modifies C and N contents to promote plant growth and improve salt stress tolerance. This study provides a novel adaptive strategy for the integrated use of PGPR and halophytes in saline-alkali soil improvement and vegetation restoration efforts.

Noninvasive, Presymptomatic Detection of Potato Cyst Nematode Infection in Tomato Using Chlorophyll Fluorescence Analysis.

Potato cyst nematodes (PCNs) are notorious pathogens in all major potato production areas worldwide. Mainly due to the low mobility of this soil pathogen, PCN infestations are mostly observed as patches ("foci") that only cover a fraction of the acreage. In-field presymptomatic localization of these pathogens is valuable, as it would allow for the localized application of control measures. Although the mapping of foci is technically feasible, it is unpractical, as it would require the analysis of numerous soil samples. We investigated whether chlorophyll fluorescence (Chl-F) could be suitable as a rapid, nondestructive method for early PCN detection. To this end, the impact of four Globodera pallida densities on the Chl-F of tomato was investigated in a phenotyping greenhouse for 26 days. Furthermore, the classical plant performance indicators of biomass and root surface area were compared with Chl-F. Thermal dissipation (NPQ) and an estimate of the photosynthetic rate (ΦPSII) responded at 1 day postinoculation, and ΦPSII was most sensitive to low PCN infection levels. Chl-F parameters responded more readily to PCN infection than biomass and root surface area. The maximum quantum yield of photosystem II (Fv/Fm) and the potential activity of photosystem II (Fv/F0) initially increased at low PCN infection levels, whereas a sharp decrease was observed at higher infestation levels. Hence, our data suggest that low PCN levels promoted plant performance before becoming detrimental at higher levels. Although Chl-F allowed for early and sensitive PCN detection, it remains to be investigated whether these signals can be distinguished from those produced by other belowground stressors in the field. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Impact of polystyrene nanoplastics on physiology, nutrient uptake, and root system architecture of aeroponically grown citrus plants

The widespread presence of plastic pollution has become a challenge for both aquatic and terrestrial plants. Notably, nanoplastics (NPs) have been found to enter the root tissues and translocate to different organs of plants; however, most previous studies were performed using crop or vegetable seedlings, and the extent NPs accumulation in fruit tree plants, particularly citrus, and their impacts remains unclear. This study was designed to fill this gap by determining the uptake and accumulation of green, fluorescent polystyrene nanoplastics (PS-NPs) of two different sizes (20nm and 50nm in diameter) in citrus rootstock ('US-942') in an aeroponic system and their impact on plant growth and physiological functions, nutrient uptake, and root system architectural and anatomical traits. The 20nm PS-NPs negatively impacted the root system architecture (total root length, root surface area, number of root forks) and nutrient contents (N, P, K, Mg, S, B, Fe, Cu, Mn) at both 15 and 30days after treatment; however, no significant differences were recorded for growth and physiological parameters. Microscopic analysis of roots revealed that under both the PS-NPs treatments, root apoplastic barriers were fully developed near the root tips. Furthermore, PS-NPs are predominantly adhered to the root surface, and no signs of uptake and translocation were recorded in root sections. However, alterations to the external root cell layers were observed. This research sheds light on the impact of PS-NPs on plant roots and their physiology and contributes to a better understanding of these emerging pollutants on tree crop horticulture.