Total Root Length Research Articles

Cultivar mixtures of maize enhance grain yield and nitrogen use efficiency by promoting canopy photosynthetically active radiation and root growth

Cultivar mixtures increases crop diversification and grain yield stability. It is a major challenge to achieve high grain yield and nitrogen use efficiency with environmentally friendly practices. However, it is currently unclear whether the cultivar mixtures of maize can improve nitrogen use efficiency. A two-year field experiment was conducted using two maize cultivars with different roots angles and leaf angles planted in monoculture or in mixtures under four nitrogen levels N0 (0 kg N ha-1), N140 (140 kg N ha-1), N280 (280 kg N ha-1) and N340 (340kg N ha-1). Cultivar mixtures significantly increased light interception of middle canopy, dry matter accumulation and total roots length under N0, N140, and N280 conditions. Light interception of middle canopy positively related to dry matter accumulation and thus increased grain yield. And light interception of whole canopy positively related to total lateral root length, while the increased total lateral root length of outer nodal roots significantly improved nitrogen accumulation and nitrogen use efficiency. Thus, cultivar mixtures promoted an optimal canopy structure and good root growth, then improved grain yield and nitrogen use efficiency. These findings could deepen our understanding of the facilitating effect of canopy structure and root traits of cultivar mixtures on the collaborative promotion of grain yield and nitrogen use efficiency.

Effects of soil physical ameliorants on the growth and root morphology of Prunus yedoensis and Ginkgo biloba seedlings in compacted soils

ABSTRACT Soil compaction is prevalent in forest ecosystems, it alters the physical structure of the soil and impedes tree growth. Although ameliorants are known to enhance soil properties and positively influence tree growth, studies remain limited on the effects of potential factors on root development in compacted soils after amelioration. This study aimed to examine the effects of the physical ameliorant treatments BIOC (compaction + biochar) and ORGF (compaction + organic fertilizer) on the soil properties, growth, and root development of Prunus yedoensis and Ginkgo biloba seedlings in compacted soils. We found that ameliorant treatments improved physicochemical soil conditions, such as bulk density, porosity, permeability, pH, total carbon, and total nitrogen, which in turn influence seedling growth. Specifically, in P. yedoensis, the relative growth rate of height was significantly higher in BIOC (46.19 ± 3.47%) compared to the control (29.58 ± 3.22%). The ameliorants did not significantly affect root morphological traits; however, we found that the total fine root length was positively correlated with shoot biomass in G. biloba (R = 0.97), but not in P. yedoensis. Root length tended to increase in BIOC, with measurements of 288.12 ± 68.97 m for P. yedoensis and 65.96 ± 25.08 m for G. biloba, while the mean fine root diameter tended to decrease in ORGF (1.25 ± 0.04 mm) and BIOC (1.37 ± 0.08 mm) for G. biloba. We conclude that biochar and organic fertilizer positively affect both soil properties and plant growth, highlighting that enhanced root development through ameliorants can improve plant growth in compacted soil.

Application of Arbuscular Mycorrhizal Fungi for Improved Growth and Acclimatization of Micropropagated Fegra Fig (Ficus palmata Forssk.) Plantlets

Fegra fig (Ficus palmata) is an important fruit-yielding crop and potential rootstock for grafting Ficus carica. The acclimatization phase is a pivotal step during the micropropagation of plants. During this study, the mycorrhization of micropropagated fegra fig plants with two arbuscular mycorrhizal fungi (AMF; Gigaspora margarita and Gigaspora albida) to enhance their growth and survival during the acclimatization stage was investigated. The AMF were mixed in equal proportions and the acclimatizing fegra fig plantlets were treated for 8 weeks. The leaf pigments, i.e., chlorophyll a [2.56 mg·g−1 fresh weight (FW)], chlorophyll b (1.08 mg·g−1 FW), total chlorophyll (3.67 mg·g−1 FW), and carotenoid (1.34 mg·g−1 FW), of AMF-treated plants were higher than those of non-AMF plants. The number of stomata per unit was higher in the AMF-treated plants (16.00), the density of stomata per unit area (88.40 mm2) of AMF-treated plants was similar to that of non-AMF treated plants, and the number of epidermal cells (79.00) was higher in the AMF-treated plants. The AMF-treated plants were taller and had more leaves, a greater leaf area, and higher shoot FW and dry weight. The AMF-treated plants also had the greatest total root length values, greatest surface areas of roots, and greatest total root volume and diameter compared to those of non-AMF plants. Additionally, the AMF-treated plants had a 100% survival rate, whereas a survival rate of 95% was recorded for non-AMF plants. These findings emphasize the importance of biological acclimatization of micropropagated fegra fig plants with AMF.

MYB30-INTERACTING E3 LIGASE 1 regulates LONELY GUY 5-mediated cytokinin metabolism to promote drought tolerance in cotton

Abstract Ubiquitination plays important roles in modulating the abiotic stress tolerance of plants. Drought seriously restricts agricultural production, but how ubiquitination participates in regulating drought tolerance remains largely unknown. Here, we identified a drought-inducible gene, MYB30-INTERACTING E3 LIGASE 1 (GhMIEL1), which encodes a RING E3 ubiquitin ligase in cotton (Gossypium hirsutum). GhMIEL1 was strongly induced by polyethylene glycol (PEG-6000) and the phytohormone abscisic acid (ABA). Overexpression and knockdown of GhMIEL1 in cotton substantially enhanced and reduced drought tolerance, respectively. GhMIEL1 interacted with the MYB transcription factor GhMYB66 and could ubiquitinate and degrade it in vitro. GhMYB66 directly bound to the LONELY GUY 5 (GhLOG5) promoter, a gene encoding cytokinin riboside 5'-monophosphate phosphoribohydrolase, to repress its transcription. Overexpression of GhMIEL1 and silencing of GhMYB66 altered the homeostasis of cytokinin of plant roots, increased total root length and number of root tips, and enhanced plant drought tolerance. Conversely, silencing GhLOG5 decreased total root length and number of root tips and reduced plant drought tolerance. Our studies reveal that the GhMIEL1-GhMYB66-GhLOG5 module positively regulates drought tolerance in cotton, which deepens our understanding of plant ubiquitination-mediated drought tolerance and provides insights for improving drought tolerance.

Biological Acclimatization of Micropropagated Al-Taif Rose (Rosa damascena f. trigintipetala (Diek) R. Keller) Plants Using Arbuscular Mycorrhizal Fungi Rhizophagus fasciculatus

Tissue culture is used to multiply Al-Taif rose (Rosa damascena f. trigintipetala (Diek) R. Keller) plants in order to meet the demands of the fragrance, cosmetic, and floriculture industries. The use of arbuscular mycorrhizal fungus (AMF) could potentially improve plant growth and acclimatization performance to ex vitro conditions. Thus, in the current study, we investigated how AMF Rhizophagus fasciculatus influences the growth, establishment, and physiological performance of micropropagated Al-Taif rose plants during the acclimatization stage. The growth and physiological parameters of the AMF-treated plants were evaluated after a 12 week growth period in the growth chambers. The plants treated with AMF exhibited greater height (25.53 cm) and biomass growth values for both shoot fresh weight (0.93 g/plant) and dry weight (0.030 g/plant), more leaves (11.3/plant), more leaf area (66.15 cm2), longer main roots (15.05 cm/plant), total root length (172.16 cm/plant), total root area (64.36 cm2/plant), and biomass from both fresh weight (383 mg/plant) and dry weight (80.00 mg/plant) of the plants. The plants treated with AMF also exhibited increased rates of net CO2 assimilation, stomatal conductance, and transpiration compared to the control plants. The proline content in the leaves and roots was significantly lower in the AMF-treated plants than untreated plants. The Fv/Fm ratio, which serves as an indicator of the intrinsic or maximal efficacy of Photosystem II (PSII) demonstrated a notable decline in the untreated Al-Taif rose plants. These results elucidate the advantageous impact of AMF colonization on micropropagated Al-Taif rose plants, thereby enhancing their resilience against adverse ex vitro conditions.

Alleviation of NaCl Stress on Growth and Biochemical Traits of Cenchrus ciliaris L. via Arbuscular Mycorrhizal Fungi Symbiosis

Soil salinization, especially in arid and semi-arid regions, is one of the major abiotic stresses that affect plant growth. To mediate and boost plant tolerance against this abiotic stress, arbuscular mycorrhizal fungi (AMF) symbiosis is commonly thought to be an effective tool. So, the main purpose of this study was to estimate the role of AMF (applied as a consortium of Claroideoglomus etunicatum Claroideoglomus eutinicatum, Funneliformis mosseae Funliformis mosseae, Rhizophagus fasciculatum, and R. intraradices species) symbiosis in mitigating deleterious salt stress effects on the growth parameters (shoot length (SL), root length (RL), shoot dry weight (SDW), root dry weight (RDW), root surface area (RSA), total root length (TRL), root volume (RV), root diameter (RD), number of nodes and leaves) of Cenchrus ciliaris L. plants through improved accumulations of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll), proline and phenolic compounds. The results of this experiment revealed that the roots of C. ciliaris plants were colonized by AMF under all the applied salinity levels (0, 75, 150, 225, and 300 mM NaCl). However, the rate of colonization was negatively affected by increasing salinity as depicted by the varied colonization structures (mycelium, vesicles, arbuscules and spores) which were highest under non-saline conditions. This association of AMF induced an increase in the growth parameters of the plant which were reduced by salinity stress. The improved shoot/root indices are likely due to enhanced photosynthetic activities as the AMF-treated plants showed increased accumulation of pigments (chlorophyll a, chlorophyll b and total chlorophyll), under saline as well as non-saline conditions, compared to non-AMF (N-AMF) plants. Furthermore, the AMF-treated plants also exhibited enhanced accumulation of proline and phenolic compounds. These accumulated metabolites act as protective measures under salinity stress, hence explaining the improved photosynthetic and growth parameters of the plants. These results suggest that AMF could be a good tool for the restoration of salt-affected habitats. However, more research is needed to check the true efficacy of different AMF inoculants under field conditions.

Rice homolog of Arabidopsis Xylem NAC domain 1 (OsXND1), a NAC transcription factor regulates drought stress responsive root system architecture in indica rice.

Rice yield is greatly constrained by drought stress. In Arabidopsis, XYLEM NAC DOMAIN 1 (XND1) gene regulates the xylem formation, efficiency of water transport, and the delicate equilibrium between drought tolerance and resistance to pathogens. However, diversity and the role of rice homologs of OsXND1 is not reported so far. This study hypothesized that the rice homolog of OsXND1 also regulates drought stress tolerance through modulation of root architecture. Initially, phylogenetic analysis identified two OsXND1 homologs (Os02g0555300 and Os04g0437000) in rice. Further, 14 haplotypes were identified in the OsXND1 of which Hap1 and Hap3 were major haplotypes. The association analysis of OsXND1 with 16 different traits, including 10 root traits, showed three SNPs (Chr02:20972728-Promoter variant; Chr02:20972791-5' UTR variant, and Chr02:20973745-3' UTR variant) were significantly associated with root area, root surface area, total root length, and convex hull area only under drought stress in indica rice. Besides, the superior haplotype of OsXND1 increased the root area, root surface area, total root length, and convex hull area by 46%, 40%, 38%, and 42%, respectively, under drought stress conditions. Therefore, the identified superior haplotype of OsXND1 can be utilized in haplotype breeding programs for the improvement of drought tolerance in rice.

Integrated deep banding and fertigation of phosphorus improves cotton yield by regulating root spatial distribution and growth

Context or problemTraditionally, 100 % phosphorus (P) fertilizer application as a band at various depths before sowing significantly influenced crop root growth and yield by reducing P fixation and optimizing its spatial distribution. However, with the advent of drip fertigation in Xinjiang, China, P fertilization practices have shifted from 100 % basal to a combination of basal and fertigation for enhanced P nutrition in cotton. Despite this, the impact of pre-sowing P band application on cotton growth under drip fertigation remains unclear. Objective or research questionThis study aimed to determine the optimal P fertilizer banding depth for cotton under a drip fertigation system. MethodsField trials were conducted comparing different basal P fertilizer application depths (5 cm, 15 cm, and 25 cm, denoted as D5, D15, and D25, respectively) with 50 % of the P rate and the remaining 50 % applied as topdressing via drip fertilization. A control (CK) involving 50 % broadcasted P fertilizer and 50 % topdressed P was included. The study focused on the effects of P application depth on soil P availability, root growth patterns, P utilization, and cotton yield. ResultsAt the boll opening stage, the D15 treatment exhibited a significant 18.69 %-49.76 % increase in available phosphorus in the 10–40 cm soil layer compared to the CK. During the peak boll to boll opening stage, the D15 treatment significantly outperformed the CK in terms of total root biomass density (11.62 %-17.54 %), total root length (16.75 %-24.81 %), total root surface area (23.07 %-37.59 %), and total root volume (20.69 %-26.23 %). Moreover, root activity and growth parameters were notably higher in the D15 treatment within the 10–40 cm soil layer. ConclusionsApplying 50 % of the P fertilizer as a band at a 15 cm depth before planting drip-irrigated cotton is optimal. This practice enhances soil P availability, stimulates root growth and distribution, and ultimately improves P utilization and cotton yield. Implications or significanceBanding P fertilizer at a 15 cm depth in combination with drip fertigation demonstrates superior yield benefits. This technology offers a novel approach to fertilizer application, enhancing nutrient use efficiency and crop productivity in drip-irrigated systems.

Enhancing Growth of Upland Rice in Low-Phosphorus Soil by Leveraging Root Morphological Traits

Low phosphorus (P) in the upland ecosystems negatively, influence rice growth and causes significant yield losses. In the present study, 9 upland rice genotypes were screened to identify root traits that support the growth in low P soil in a cement tank. Rice genotypes showed significant (p = ≤ 0.05) variation for number of root tips (NRT), number of root branching points (NBP), total root length (TRL), whole root network area (NA), average root diameter, root volume (RV), root surface area (RSA), first order root length (FORL), and second order root length (SORL). BW01 and ITA01 recorded the highest NRT, NBP, TRL, RV, NA, RSA, FORL and SORL while NERICA04 had the lowest representing 5.8, 8.0, 7.6, 6.8, 9.0, 5.8, and 9.3 differences in these traits under low P soil. NRT significantly positively correlated with NBP, TRL, NA, RV, RSA, FORL indicating the role of different root traits in foraging for soil nutrients. The principal component analysis (PCA) showed that the NRT, NBP, TRL, RSA and SORL are important and effective root traits for selection in rice breeding under low P soil supply. BW01 and ITA01 recorded well developed root system indicating that they are P-efficient than P-inefficient NERICA04 under low P soil conditions. Therefore, BW01 and ITA01 can targeted for cultivation in P deficient soils and also used as donor of novel root traits to improve P-inefficient rice cultivars.

PGPR alleviated the negative effects of low temperature and low light stress on the growth and physiology of violet plants

Plants in greenhouses are often exposed to low temperature and low light conditions in the winter, and this has a major effect on flower cultivation. Inoculation of plant growth-promoting rhizobacteria (PGPR) can improve the growth of plants under stress. Here, we examined the effects of Pseudomonas fluorescens on the growth, photosynthesis, chlorophyll fluorescence parameters, and antioxidant enzyme systems of violet plants (Matthiola incana) exposed to normal temperature and normal light intensity (18 °C/11 °C, 500 μmol·m-2·s-1, NN), low temperature and normal light intensity (4 °C/1 °C, 500 μmol·m-2·s-1, LN), normal temperature and low light intensity (18 °C/11°C, 100 μmol·m-2·s-1, NL), and low temperature and low light intensity (4 °C/1 °C, 100 μmol·m-2·s-1, LL). The results showed that the plant height, stem diameter, leaf area, shoot fresh/dry weight, and underground fresh/dry weight of violet inoculated with PGPR were 40%, 17%, 13%, 25%, 41%, 30%, and 38% higher than the control, respectively. In addition, the total root length, mean root diameter, number of root tips, number of bifurcated root tips, and root vigor were 24%, 23%, 14%, 30%, and 21% higher in the inoculated group than in the control group, respectively. PGPR promoted chlorophyll accumulation in plants, and the net photosynthetic rate of violets was 32% higher in plants inoculated with PGPR than in control plants. PGPR also significantly promoted the maximum photochemical conversion efficiency of photosystem II (PSII) and the potential activity of PSII under UV light. After inoculation with PGPR, the content of MDA decreased by 16.8%, and the activities of superoxide dismutase and peroxidase increased by 19.2% and 20.0%, respectively. Therefore, PGPR can promote the growth of violet plants by increasing the photosynthetic capacity, activating the antioxidant enzyme system, and reducing damage induced by exposure to low light intensity.

Exploration of Biomass-related Genes in the FOX-superroot Lines of Lotus corniculatus and its Impact on Agronomic Traits

Background: Identifying biomass-related genes to meet the increasing demand for food supply is important approach for agricultural and scientific efforts. In this study, we employed the Full-length cDNA Over-eXpressing gene hunting system (FOX hunting system) to identify biomass-related genes through ectopic expression of Arabidopsis thaliana full-length cDNA in bird’s-foot trefoil (Lotus corniculatus). Methods: A total of 66 FOX superroot lines (FSLs) from Lotus corniculatus cv. Viking were transferred in vermiculite after two weeks in half-strength Murashige and Skoog (MS) medium. These FSLs were then grown in a growth chamber for four weeks, during which their plant length and root length were measured. High biomass lines were selected from this group. FSL #83 and #121 were then grown for an additional four months in a greenhouse until they reached maturity, at which point they were evaluated for their agronomic traits. Result: Out of the 66 analyzed FSLs, 15 displayed superior growth characteristics in plant length and total root length. Arabidopsis cDNA, categorized into genes related to various functions such as membrane transport, photosystems, phytohormone synthesis, amino acid synthesis and unknown genes, was introduced into these lines. Two lines were grown to maturity in the greenhouse and their agronomic traits were analyzed in detail. FSL #83 expressed brassinosteroid biosynthetic pathway gene (CPD) led to significant differences in internode length, number of stems, number of flowers and above-ground dry matter weight compared to non-transgenic Super-growing roots (SR). On the other hand, FSL #121 expressed Asparaginyl-tRNA synthetase (SYNC1) gene exhibited increases in plant length and the number of stem nodes.

Combined Genome-Wide Association Studies (GWAS) and Linkage Mapping Identifies Genomic Regions Associated with Seedling Root System Architecture (RSA) under Different Nitrogen Conditions in Wheat (Triticum aestivum L.)

The nitrogen (N) use efficiency (NUE) in the roots of seedlings is beneficial for increasing crop yield. Creating marker-assisted selection for wheat root traits can assist wheat breeders in choosing robust roots to maximize nutrient uptake. Exploring and identifying the effect of different N supply conditions on root system architecture (RSA) is of great significance for breeding N efficient wheat varieties. In this study, a total of 243 wheat varieties native to the Yellow and Huai Valley regions of China were utilized for genome-wide association studies (GWAS). Furthermore, a recombinant inbred line (RIL) population of 123 lines derived from the cross between Avocet and Chilero was utilized for linkage examination. A hydroponic seedling experiment using a 96-well tray was conducted in the lab with two treatments: normal N (NN) and low N (LN). Five RSA traits, including the relative number of root tips (RNRT), relative total root length (RTRL), relative total root surface area (RTRS), relative total root volume (RTRV), and relative average root diameter (RARD), were investigated. GWAS and linkage analysis were performed by integrating data from the wheat 660 k single nucleotide polymorphism (SNP) chip and diversity arrays technology (DArT) to identify genetic loci associated with RSA. The results showed that, based on the ratio of RSA-related traits under two N supply conditions, a total of 497 SNP markers, which are significantly associated with RSA-related traits, were detected at 148 genetic loci by GWAS. A total of 10 QTL loci related to RSA were discovered and identified by linkage mapping. Combining two gene localization methods, three colocalized intervals were found: AX-95160997/QRtrl.haust-3D, AX-109592379/QRnrt.haust-5A, and AX-110924288/QRtrl.haust-7D/QRtrs.haust-7D. According to the physical location of the colocalization of these two sites, between 39.61 and 43.74 Mb, 649.97 and 661.55 Mb, and 592.44 and 605.36 Mb are called qRtrl-3D, qRnrt-5A, and qRtrl-7D. This study has the potential to enhance the effectiveness of selecting root traits in wheat breeding programs, offering valuable insights into the genetic underpinnings of NUE in wheat. These results could help in breeding wheat varieties with higher NUE by implementing focused breeding strategies.

Larger shrubs can maintain high infiltration and evapotranspiration rates in experimental biofiltration systems impacted by high sediment loads

Biofiltration systems can fail over time due to clogging by fine sediments in stormwater. Infiltration can be maintained by plant roots, but species selection for biofiltration to date has largely been driven by pollutant removal efficiency and tolerance of conditions. As a result, plant species diversity in biofilters is typically low and dominated by sedges and rushes. Increased use of woody species could in theory improve plant diversity, aesthetic appeal, infiltration under high sediment loads and volumetric runoff reduction via higher evapotranspiration, without jeopardising nutrient pollutant removal. We tested whether shrubs could maintain infiltration and evapotranspiration in biofiltration profiles treated with a high sediment load, by comparing them with biofilters subjected to tap water without sediment. Following sediment application, biofilter columns planted with shrubs with high total biomass and total root length showed higher infiltration and evapotranspiration than those receiving tap water. These results indicate that shrub species are likely to alleviate clogging and increase stormwater retention in biofiltration systems. However, shrubs with a high root diameter also had low total biomass and total root length and showed 33–51 % lower infiltration rates after sediment application compared with those receiving tap water. As all shrubs had higher root diameters than typical sedges and rushes, we suggest that shrubs need a combination of higher total biomass, total root length and average root diameter to effectively maintain infiltration. While shrubs which maintained infiltration had traits associated with high nutrient removal, nutrient removal efficiency of shrubs needs to be quantified. Although root traits were related to maintenance of infiltration, above-ground stems likely created flow pathways through sediment which requires further investigation. Overall, selecting shrub species with high total biomass has the potential to maintain infiltration and increase evapotranspiration in biofiltration systems impacted by high sediment loads.

Fe toxicity tolerance is advantageous in rice growth recovery after Fe stress alleviation

AbstractBackgroundFe toxicity often inhibits rice growth on acid sulfate soils in tropical coastal lowlands. Previous studies in plant physiology and breeding have focused on high‐Fe stress, but not on growth recovery after stress alleviation.AimsThe objective of this study was to elucidate the morphophysiological characteristics in rice growth recovery from high‐Fe stress.MethodsWe evaluated the seedling growths of Taichung65 (T65) (Fe toxicity‐tolerant) and Ciherang (susceptible) in hydroponic culture, during the period of high‐Fe stress (250 mg Fe2+ L−1 for 12 or 18 days) and after stress alleviation.ResultsThe plant growth rate during recovery was negatively correlated with the leaf bronzing score (damage symptoms due to Fe toxicity) at the end of high‐Fe stress, which in turn was negatively correlated with the shoot Fe concentration. After 18‐day stress, T65 showed greater growth recovery than Ciherang, attributable to its higher net assimilation rate, higher transpiration rate (water uptake/green leaf area), and greater increase in total root length during recovery. In particular, T65 showed vigorous lateral root development in nodal roots that emerged during the stress period and vigorous growth of nodal roots that emerged during recovery.ConclusionsOur results suggest that tolerance to high‐Fe stress confers an advantage in growth recovery. It is likely that tolerance to Fe toxicity contributes not only to the maintenance of green leaf area at the end of stress but also to quick root growth recovery, leading to vigorous water uptake and high photoassimilation capacity after stress alleviation.

The growth‐promoting effects of Bacillus amyloliquefaciens W82T‐44 on soybean and its biocontrol potential against soybean Phytophthora root rot

AbstractThe most devastating soilborne disease of soybean is Phytophthora root rot (PRR) caused by Phytophthora sojae. Biological control has emerged as an effective method of reducing soilborne diseases. The present study isolated the bacterial strain W82T‐44 from the rhizosphere soil of a resistant soybean variety Williams 82. This strain was identified as Bacillus amyloliquefaciens and exhibited a 92.4% inhibition of mycelial growth of P. sojae. W82T‐44 produced cellulase, siderophore and protease and significantly promoted soybean growth. W82T‐44 treatment, compared to the negative control, was found to significantly (p < 0.05) increase soybean plant height (22.34 vs. 18.47 cm), fresh weight of the whole plant (2.57 vs. 2.05 g), dry weight (0.43 vs. 0.32 g), total root length (266.80 vs. 182.53 cm), root area (27.10 vs. 17.84 cm2) and root volume (1.88 vs. 1.16 cm3). The fermentation filtrate of W82T‐44 had significant inhibitory effects on mycelial growth, oospore formation and cyst germination in P. sojae and additionally promoted zoospore encystment. W82T‐44 possessed genes involved in lipopeptide synthesis, including bacilysin, surfactin, fengycin and bacillomycin. Moreover, it significantly upregulated pathogenesis‐related genes (β‐1,3‐glucanase, nonexpressor of pathogenesis‐related gene 1, chitinase) and genes encoding defence enzymes (polyphenol oxidase, phenylalanine ammonia‐lyase, peroxidase) in soybean roots (p < 0.05). The PRR disease index of soybean treated with the W82T‐44 strain was significantly lower (11.67) than the negative control (40.00; p < 0.05). The present study indicates the potential of B. amyloliquefaciens W82T‐44 as a biological control agent against PRR from various perspectives.

Effects of Ecotypes and Reduced N Fertilization on Root Growth and Aboveground Development of Ratooning Sorghum × Sudangrass Hybrids

Reduced N input while maintaining biomass production of sorghum × sudangrass hybrids (Sorghum bicolor L. × Sorghum sudanense; SSG) is essential; however, its effects on root sustainability and photosynthetic capacity during the ratooning period are not well defined in a multiple harvests system. The physiological response and root morphology of SSG were investigated under different N application levels during the ratooning period in a two-year field experiment. Treatments were all combinations of two ecotypes (late-flowering, Greenstar; early-flowering, Honeychew) and four N levels (0, 50, 100, 150 kg N ha−1). The total root length, surface area, volume, tips, and dry matter (DM) were significantly influenced by both ecotype and N level, with Greenstar outperforming Honeychew. Specifically, Greenstar’s root length increased by up to three times with reduced N application (50 kg N ha−1), while Honeychew showed significant root length increases only at higher N levels (100 and 150 kg N ha−1). Our data support the conclusion that a low level of N (50–100 kg N ha−1) was the optimal rate for ratooning root sustainability. The findings highlight the critical role of root development in sustaining biomass production and suggest that the late-flowering ecotype, Greenstar, is more suitable for a multiple harvests system with a robust root system.

Use of the Sulfur-Containing Growth Regulator Tiaton for Rooting Micro-Gears of Grapes in Culture in vitro

The study was carried out to evaluate the effect of a nutrient solution for the rhizogenesis of grape micro–gears in the Murasiga-Skuga medium (MS) with the addition of various concentrations of the drug Tiaton (0.1, 0.15, 0.20 and 0.25 ml/l). In experiments, the effect of different concentrations of the drug Tiaton on the rooting and vegetative growth of grapes of the Khasansky and Moskovsky White hybrids in vitro was studied. When the Tiaton preparation was added to the MS nutrient medium in various concentrations, the rooting capacity of the micro-gears of the Khasansky hybrid grape increased by 40%, the total root length increased by 2.4 times compared with the control. In the Moscow White hybrid, when using the Triaton growth regulator, an increase in the rooting capacity of micro gears up to 25% and the total root length by 1.5 times is shown. The optimal concentrations of the Triaton preparation for addition to the MS nutrient solution for optimal rhizogenesis of micro-gears and the development of vegetative growth of cuttings of the studied grape hybrids have been established. Thus, for Khasansky hybrid grapes, the most optimal medium for improving rooting and root development of micro gears was ½ MS + 0.15 ml/l of Tiaton preparation. In the Moscow White hybrid, a significant increase in the rooting capacity of micro-gears and good development of the root system was obtained when Tiaton was added to the nutrient medium for rhizogenase of micro-gears in concentrations (0.15 and 0.20 ml/l).

Regulation of arbuscular mycorrhizal fungi in citrus root hairs mediated by auxin efflux carrier protein PtPINs

Arbuscular mycorrhizal fungi (AMF) and auxins are critical in the development of root hairs, but the interaction mechanism by which they jointly regulating the development of citrus needs further clarification. This study investigated the influence of Funneliformis mosseae on the growth, root architecture, root hair traits, indole-3-acetic acid (IAA) content and flow rate, and auxins efflux carrier protein genes (PtPINs) expression in potted trifoliate orange (Poncirus trifoliata L.) over 4, 6, 8, 10, and 12 weeks of inoculation. Results indicated continuous increases in mycorrhizal colonization and soil hyphae length over time. Compared with the non-AMF, AMF significantly enhanced plant growth and biomass, and notably increased total root length, projected area, surface area, volume, and the number of 2nd-order lateral roots, with these parameters improving further over the treatment duration. Whereas root hair growth was inhibited at 4 w, 6 w and 8 w, it was promoted at 10 w and 12 w following AMF treatment. AMF also significantly increased the content of indole-3-acetic acid (IAA) over time. And the expression patterns of auxins flow rate and PtPINs vary across different treatment periods, showing a strong correlation with citrus growth and root hair development. Specifically, PtPINs were significantly correlated with total IAA flow rate and total root hair growth, with PtPIN6 potentially playing a positive role in root hair development. These findings suggested that auxins are involved in AMF-regulated citrus root hair growth, with PtPIN6 identified as a potentially key gene in auxin transport regulation.

Transcriptomic and Hormonal Changes in Wheat Roots Enhance Growth under Moderate Soil Drying.

Understanding the mechanisms that regulate plant root growth under soil drying is an important challenge in root biology. We observed that moderate soil drying promotes wheat root growth. To understand whether metabolic and hormonic changes are involved in this regulation, we performed transcriptome sequencing on wheat roots under well-watered and moderate soil drying conditions. The genes upregulated in wheat roots under soil drying were mainly involved in starch and sucrose metabolism and benzoxazinoid biosynthesis. Various plant hormone-related genes were differentially expressed during soil drying. Quantification of the plant hormones under these conditions showed that the concentrations of abscisic acid (ABA), cis-zeatin (CZ), and indole-3-acetic acid (IAA) significantly increased during soil drying, whereas the concentrations of salicylic (SA), jasmonic (JA), and glycosylated salicylic (SAG) acids significantly decreased. Correlation analysis of total root length and phytohormones indicated that CZ, ABA, and IAA are positively associated with wheat root length. These results suggest that changes in metabolic pathways and plant hormones caused by moderate soil drying help wheat roots grow into deeper soil layers.

Metal(loid) uptake and physiological response of Coix lacryma-jobi L. to soil potentially toxic elements in a polluted metal-mining area

Coix lacryma-jobi L. is a traditional medicinal plant in east Asia and is an important crop in Guizhou province, southwest China, where there are elevated levels of soil mercury and arsenic (As). Exposure to multiple potentially toxic elements (PTEs) may affect plant accumulation of metal(loid)s and food safety in regions with high geological metal concentrations. Field experiments were conducted to study the effects of PTEs on metal(loid) accumulation and physiological response of C. lacryma in different plant parts at three pollution levels. Total root length, number of root tips, number of branches, and number of root crosses increased with increasing pollution level, with increases in highly polluted areas of 44.2, 57.0, 79.6, and 97.2%, respectively, compared to lightly polluted areas. Under multi-element stress the activity of C. lacryma antioxidant oxidase showed an increase at low and medium PTE concentrations and inhibition at high concentrations. The As contents were all below the maximum limit of cereal food contaminants in China (GB 2762-2022, As < 0.5 mg kg−1). The stems had high Tl bioconcentration factors but the translocation factors from stem to grain were very low, indicating that the stems may be a key plant part restricting Tl transport to the grains. C. lacryma increased root retention and reduced the transport effect, thus reducing metal accumulation in the grains. C. lacryma adapted to PTE stress through root remodeling and enhanced antioxidant enzyme activities.