Root Structure Research Articles

A new dryolestid fossil from the Late Jurassic illuminates molar root structure of dryolestids

ABSTRACT We report a micro-CT study of a new specimen of Dryolestes priscus (Dryolestidae, Cladotheria) from the Upper Jurassic Morrison Formation of Wyoming. The fossil (KUVP 134101) is an incomplete lower jaw preserving eight intact teeth, including two premolars (p3, p4) and six molars (m1–6), along with double-alveoli for m7 and a single alveolus for m8. Its preserved teeth and molar alveoli are consistent with the dental formula in more complete jaws of this species (i4.c1.p4.m8–m9). Here we have newly characterized diagnostic features on the molar trigonid of Dryolestes priscus and other species of Dryolestidae. Our analysis places this specimen close to Dryolestes priscus in terms of phylogeny. CT scans and visualization made it possible to illustrate the distinctive root structures of lower molars of dryolestid species. The two-rooted lower molars of D. priscus show a hypertrophied anterior root that is spatulate and much broader and longer than the simpler posterior root of the same molar. The disparate shape and size of the two molar roots are a highly derived pattern of dryolestids, which is absent in closely related genera formerly assigned to “paurodontids.” It is also unique among all mammaliaforms with typically two-rooted molars. The hypertrophied anterior root corresponds to most of the molar crown, and likely provided better support for occlusal forces acting on the large trigonid of the molar.

Community responses of arbuscular mycorrhiza fungi to hydrological gradients in a riparian Phragmites australis wetland.

The hydrological regime is considered to be the major factor that affects the distribution of arbuscular mycorrhiza (AM) fungi in wetlands. We aimed to investigate the responses of AM fungal community to different hydrological gradients. Illumina Miseq sequencing technology was used to study the AM fungal community structure in roots and rhizosphere soils of Phragmites australis in different moisture areas (dry area, alternating wet and dry area, and flooded area) in Mengjin Yellow River wetland. The rhizosphere soils and roots hosted different AM fungal communities. In roots, the AM fungal colonization and Chao1 richness in dry area were significantly higher than that in alternating wet and dry area and flooded area, but the community composition did not vary clearly under different water conditions. In rhizosphere soils, the Chao1 richness of AM fungi in flooded area was significantly higher than that in alternating wet and dry area and dry area, and the AM fungal community structure obviously differed across different areas. The redundancy analyses indicated that changes in the AM fungal community in soils were associated with altered soil properties, and the abundance of the dominant genus Glomus was mostly positively correlated with alkali-hydrolyzable nitrogen in soils. This study helps us to understand the responses of AM fungal community to hydrological gradients in wetlands.

Rogue wave pattern of multi-component derivative nonlinear Schrödinger equations.

This paper studies the multi-component derivative nonlinear Schrödinger (n-DNLS) equations featuring nonzero boundary conditions. Employing the Darboux transformation method, we derive higher-order vector rogue wave solutions for the n-DNLS equations. Specifically, we focus on the distinctive scenario where the (n+1)-order characteristic polynomial possesses an explicit (n+1)-multiple root. Additionally, we provide an in-depth analysis of the asymptotic dynamic behaviors and pattern classification inherent to the higher-order vector rogue wave solution of the n-DNLS equations, mainly when one of the internal arbitrary parameters is extremely large. These patterns are related to the root structures in the generalized Wronskian-Hermite polynomial hierarchies.

Large-time lump patterns of Kadomtsev-Petviashvili I equation in a plasma analyzed via vector one-constraint method

In plasma physics, the Kadomtsev–Petviashvili I (KPI) equation is a fundamental model for investigating the evolution characteristics of nonlinear waves. For the KPI equation, the constraint method is an effective tool for generating solitonic or rational solutions from the solutions of lower-dimensional integrable systems. In this work, various nonsingular, rational lump solutions of the KPI equation are constructed by employing the vector one-constraint method and the generalized Darboux transformation of the (1 + 1)-dimensional vector Ablowitz–Kaup–Newell–Segur system. Furthermore, we investigate the large-time asymptotic behavior of high-order lumps in detail and discover distinct types of patterns. These lump patterns correspond to the high-order rogue wave patterns of the (1 + 1)-dimensional vector integrable equation and are associated with root structures of generalized Wronskian–Hermite polynomials.

Study on the Morphology and Mechanical Properties of Cynodon dactylon in the Riparian Zone Slopes of a Large Reservoir

The stability of riverbank slopes is crucial in watershed ecology. The morphology and tensile strength properties of plant roots play a significant role in slope stability, which is of great importance for the ecological stability of riverbanks. The Jinsha and Yalong River basins are the largest hydropower bases in China and are in the ecologically fragile areas of the dry and hot river valleys, yet fewer studies are available on these basins. Further studies on the growth morphology and root mechanical properties of plant roots in the riparian zone at different elevations have not been reported. Therefore, we selected the dominant species of Cynodon dactylon root as the research subject, analyzed the root morphology, and conducted indoor single-root tensile tests to study its root structure and mechanical properties at various elevations. The results showed that the root morphology of Cynodon dactylon was positively correlated with elevation. Compared to low elevations (L and M), the root length increased by 57.3% and 21.47%, the root diameter increased by 24.85% and 13.92%, the root surface area increased by 93.5% and 67.37%, and the total root volume increased by 119.91% and 107.36%. As the elevation gradient increased, the flooding time decreased, leading to more developed plant roots for Cynodon dactylon. The Young’s modulus ranged from 148.43 to 454.18 MPa for Ertan Cynodon dactylon roots and 131.31 to 355.53 MPa for Guanyingyan Cynodon dactylon roots. The maximum tensile strength, ultimate tensile strength, ultimate elongation, and Young’s modulus of the plant root of the Cynodon dactylon showed a power function relationship with the diameter. The maximum tensile strength increased as the diameter increased, while the remaining properties decreased following a power function relationship. The maximum tensile strength, ultimate tensile strength, and Young’s modulus of Cynodon dactylon were positively correlated with elevation, while the ultimate elongation was negatively correlated with elevation. The results elucidate the influence of elevation on the root morphology and mechanical properties of dominant riparian species. This provides a theoretical basis for managing and protecting riparian slopes in ecologically fragile areas.

Exogenous application of mycotoxin fusaric acid improve the morphological, cytogenetic, biochemical and anatomical parameters in salt (NaCl) stressed Allium cepa L.

Salinity is one of the most important abiotic stress factors that negatively affect plant growth and development. In contrast, fusaric acid (FA), a mycotoxin produced by Fusarium and Giberella fungal genera, has biological and metabolic effects in various plants. In this study, it was aimed to investigate the protective effect of externally applied FA (0.1 nM) against the damage caused by salt (0.15 M NaCl) stress in onion (Allium cepa L.) plant. Salt stress resulted in an increase in the chromosomal aberrations (CAs) and micronucleus (MN) frequency, a decrease in the mitotic index (MI), fresh weight, root number, germination percentage, and root length. It promoted CAs such as irregular mitosis, bilobulated nuclei, chromosome loss, bridge, unequal seperation of chromosome, vagrant chromosome and polar slip in root meristem cells. In addition, salt stress caused a enhancement in free proline (PR), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) contents in the roots of onion plant. Moreover, it revealed damage and changes that include the accumulation of some chemical substances such as proline and sugars in epidermis and cortex layer cells, epidermal cell injury, flattening of the cell nucleus, wall thickening in cortex cells, necrotic areas and indistinct transmission tissue in the anatomical structure of onion roots. On the other hand, FA application promoted bulb germination and mitotic activity, strengthened the antioxidant defense system, and reduced chromosome and anatomical structure damages. In conclusion; it has been revealed that exogenous FA application may have a positive effect on increasing the resistance of onion plants to salt stress.

Effects of Root Architecture on Uprooting Properties between Deciduous and Evergreen Species with Different Growth Habits

Roots anchor plants firmly to the soil, enabling them to effectively resist soil erosion and shear failure. Vegetation restoration has been acknowledged as one of the most useful measures for controlling soil loss; however, which root system characteristics were most beneficial for plant anchoring in the soil remains unclear. In the black soil region of northeastern China, which frequently experiences serious soil erosion, pullout tests were carried out on six species of soil and water conservation woody plants with different growth habits (deciduous shrubs, deciduous trees and evergreen trees), and the root geometry and topology of each species were determined. The results showed that the maximum uprooting force and activation displacement (the displacement at the maximum peak in the relationship curve between pulling force and displacement) of shrubs were significantly greater than those of trees, while deciduous trees were significantly greater than evergreen trees. Therefore, the ability of the whole root system to anchor the soil was the largest for shrubs, followed by deciduous trees, and the smallest for evergreen trees. The uprooting force and activation displacement were mainly affected by the root topological index, total root length and the number of inclined roots. The total root length had the greatest influence on the maximum uprooting force, and the root topology had the greatest influence on the activation displacement, both of which can be used as important predictors of plant root anchorage strength. In addition, the plants with the R-type root structure may have a greater ability to anchor the soi, and can be prioritized for vegetation restoration with black soils. These findings provide references and implications for identifying the effective plant strategies for eroded soil restoration in the black soil region of northeastern China and other areas with similar soil types and bioclimates.

Finite element analysis of stress distribution on residual root structure in socket shield procedure following immediate dental implant placement: an in vitro study

BackgroundThe success of implants in the socket shield technique relies on stress experienced by root fragments within the socket. Although there is no consensus on optimal root fragment thickness, varying thicknesses and dynamic implant placement induce stress in various directions and degrees. This study aimed to assess biomechanical response and stress distribution across different root fragment thicknesses in the socket shield procedure.MethodsThis in vitro study was conducted to assess and compare the stress distribution on residual root structures of varying thicknesses positioned within the labial aspect of the maxillary incisor socket during immediate implant placement of standard dimensions. The procedure involved applying an insertional torque of 40 Ncm, and the analysis was conducted using finite element analysis software.ResultsUtilizing the Numerical Technique with Abaqus software for explicit dynamics, von Mises stress and principal strain were analyzed on the root structure and bone under nonlinear contact conditions during implant torque application. For Model A, a loading torque of 40 Ncm was applied vertically on the implant, along with a horizontal force of 20 N on the root structure and bone. Results indicated maximum stress of 12.68 MPa on the root structure with a thickness of 0.5 mm and 5.61 MPa on the bone, with principal strains of 6.82E-03 and 4.10E-03, respectively. In Model B, with a root structure thickness of 1.0 mm, the maximum stress increased to 19.70 MPa, while the bone stress rose to 9.51 MPa, with principal strains of 1.03E-02 and 6.09E-03. Model C, with a root structure thickness of 1.5 mm, exhibited a maximum stress of 21.58 MPa on the root and 10.12 MPa on the bone, with principal strains of 1.16E-02 and 6.10E-03. Lastly, in Model D, with a root structure thickness of 2.0 mm, the maximum stress on the root structure and bone escalated to 28.74 MPa and 11.38 MPa, respectively, with principal strains of 1.55E-02 and 8.31E-03.ConclusionsAs the thickness of the shield increases (ranging from 0.5 to 2 mm) in socket shield procedures with immediate implant placement, both stress on the root fragment and bone and principal micro-strain escalate. However, employing a shield thickness within the range of 0.5 to 2 mm does not lead to any adverse stress generation on the residual root fragment. However, for enhanced safety, it is recommended to restrict the maximum diameter and extension of the root fragment to 1.5 mm when considering implant sizes and socket diameter for the socket shield technique.

The leaf micromorphology and anatomy of gamba grass, Andropogon gayanus Kunth (Poaceae: Panicoideae)

Context Andropogon gayanus, commonly known as gamba grass, is one of the declared weeds of national significance in Australia. Past studies have focused on gross morphology of root structures, biogeochemical behaviour, and ecology, but there has been limited work on comparative descriptions of leaf micromorphology and anatomy. Aims We investigated and described its leaf micromorphology and anatomy to understand weed biology and ecophysiology. Methods Optical and scanning electron microscope examination of the adaxial and abaxial leaf surfaces of A. gayanus was carried out. We identified and generated a list of morphological characters that were used to compare several dried herbarium specimens of A. gayanus. Key results The leaf characters were consistent across all specimens examined, with minor differences in leaf pubescence, indicating this could be a plastic trait. Conclusions Andropogon gayanus leaves are well adapted to wet and dry tropical conditions. Plasticity in leaf surface pubescence possibly enhances its adaptability, increasing its success as a weed in Australian ecosystems. The success of A. gayanus in Australia could be because the environment compares favourably with the native environment of the species in Africa, where it has adapted to extremes of wet and dry conditions over a large geographical range. Implications Plant morphological and taxonomic studies of A. gayanus focused on describing characters of spikelets and caryopses are recommended to understand how reproductive structures aid in its successful proliferation.

Root system architecture change in response to waterlogging stress in a 448 global collection of rapeseeds (Brassica napus L.).

A novel image-based screening method for precisely identifying genotypic variations in rapeseed RSA under waterlogging stress was developed. Five key root traits were confirmed as good indicators of waterlogging and might be employed in breeding, particularly when using the MFVW approach. Waterlogging is a vital environmental factor that has detrimental effects on the growth and development of rapeseed (Brassica napus L.). Plant roots suffer from hypoxia under waterlogging, which ultimately confers yield penalty. Therefore, it is crucially important to understand the genetic variation of root system architecture (RSA) in response to waterlogging stress to guide the selection of new tolerant cultivars with favorable roots. This research was conducted to investigate RSA traits using image-based screening techniques to better understand how RSA changes over time during waterlogging at the seedling stage. First, we performed a t-test by comparing the relative root trait value between four tolerant and four sensitive accessions. The most important root characteristics associated with waterlogging tolerance at 12 h are total root length (TRL), total root surface area (TRSA), total root volume (TRV), total number of tips (TNT), and total number of forks (TNF). The root structures of 448 rapeseed accessions with or without waterlogging showed notable genetic diversity, and all traits were generally restrained under waterlogging conditions, except for the total root average diameter. Additionally, according to the evaluation and integration analysis of 448 accessions, we identified that five traits, TRL, TRSA, TRV, TNT, and TNF, were the most reliable traits for screening waterlogging-tolerant accessions. Using analysis of the membership function value (MFVW) and D-value of the five selected traits, 25 extremely waterlogging-tolerant materials were screened out. Waterlogging significantly reduced RSA, inhibiting root growth compared to the control. Additionally, waterlogging increased lipid peroxidation, accompanied by a decrease in the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). This study effectively improves our understanding of the response of RSA to waterlogging. The image-based screening method developed in this study provides a new scientific guidance for quickly examining the basic RSA changes and precisely predicting waterlogging-tolerant rapeseed germplasms, thus expanding the genetic diversity of waterlogging-tolerant rapeseed germplasm available for breeding.

Extraction of Sesquiterpene Lactones from Inula helenium Roots by High-Pressure Homogenization and Effects on Antimicrobial, Antioxidant, and Antiglycation Activities

The sesquiterpene lactones (SL) of Inula helenium (I. helenium) roots were extracted using high-pressure homogenization (HPH) and compared against those derived from maceration. The effect of process conditions on the extraction efficiency of bioactive compounds (alantolactone, isoalantolactone, total phenols, and flavonoids); the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging activity, ferric-reducing antioxidant power (FRAP), and antimicrobial activity of the extract; and the inhibition of advanced glycated end product (AGE) formation were assessed. The HPH of 90 MPa for 4 passes demonstrated the highest alantolactone (38.1 ± 0.7 mg/g) and isoalantolactone yields (34.4 ± 0.2 mg/g), respectively, which were significantly higher than the rates obtained using maceration (20.0 ± 0.2 mg/g and 18.9 ± 0.7 mg/g). Under optimal extraction conditions of 90 MPa for 4 passes, inhibition of AGE formation in the extract reached a rate of 97.16 ± 1.86%, with the highest DPPH and FRAP of 231.63 ± 2.96 µg/mL and 949.43 ± 1.86 µmol TE/100 mL, respectively. HPH exhibited lethal activity against all tested bacteria and fungi strains (Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Aspergillus niger, Fusarium oxysporum, and Penicillum expansum) at a concentration of 15 µL. SEM results proved that HPH severely damaged the cell structures of roots, increased solvent permeability, and improved the extraction rate of bioactive compounds. Additionally, this study also demonstrated that HPH yields high recovery with a specific energy consumption of 0.22 kWh/kg, which is close to the recommended minimum energy demand for an extraction procedure within industrial production processes. Therefore, these findings showed that HPH can be used as an efficient extraction technique for the production of SL in related industries.

Against semantic features: the view from derivational affixes

This paper builds a systematic argument against the existence of semantic features, although these would in principle conform with the understanding of features in Chomsky (1995) as instructions to the interfaces, to the Conceptual-Intentional Interface in this case. I first lay out their superfluous character as well as their redundancy in separationist / realisational approaches, and in non-lexicalist models of grammar, more generally. Under the assumption that lexical meaning in natural language is mediated by grammatical structure containing roots, (purely) semantic features would inevitably be restricted to “non-lexical” elements only, i.e. those derivational affixes that encode rich conceptual content. This makes the positing of semantic features methodologically suspect and, ultimately, redundant.Accordingly, the rich content of derivational affixes, which can involve pretty much any nominal concept (as in Acquaviva 2009) from ‘profession’, ’tree’, and ‘place’ to body parts, will be argued not to be encoded in terms of semantic features. On the contrary, this paper makes the case for derivational affixes not belonging to a unitary syntactic category, with some derivational affixes actually being roots interpreted in particular structural contexts, as has been argued already since De Belder (2011). The chapter closes by offering a taxonomy of the elements that grammar manipulates and sketches the division of labour between root structures and formal features.

Initial Biomass Effect of Azolla caroliniana Culture on Performance in the Southern Kyrgyzstan Conditions

The object of the study was Azolla caroliniana Willd., collected from reservoirs of collector-drainage networks in the vicinity of Osh (Ak-Buura river basin), and also grown in laboratory conditions. To determine the initial biomass of the culture, Azolla caroliniana was grown outdoors in tray units with an area of 1 m2 of water surface, a capacity of 500 l, a depth of 50 cm and a nutrient medium prepared from chicken manure (5 g/l), which was renewed every 5 days. The initial biomass of the Azolla culture added to the trays in option I was 100 g/m2, in option II 200 g/m2, option III 300 g/m2, option IV 400 g/m2, option V 500 g/m2, option VI 600 g/m2, VII option 700 g/m2. The A. caroliniana high performance in variants III and IV is the result of its daily growth rate. As a result, the daily increase was 129.0±0.4 g/m2in option III, and 112.4±0.3 in option IV. With a low biomass (in options I and II), azolla does not have time to fully use the available nutrient medium; due to the excess nutrient medium, other aquatic plants and algae develop strongly. In this regard, the growth and development of Azolla shoots and rhizoids slows down. In the III and IV variants of the Azolla experiment, due to the complete absorption of nutrients, normal development of the root structure and shoots occurs; accordingly, the daily growth rate of raw biomass was higher than in the other variants. Thus, when growing Azolla caroliniana in field conditions or in greenhouses, it is advisable to use 300-400 g of initial biomass per 1 m2 of water surface.

Complexation and immobilization of arsenic in maize using green synthesized silicon nanoparticles (SiNPs)

Arsenic (As) is a heavy metal that is toxic to both plants and animals. Silicon nanoparticles (SiNPs) can alleviate the detrimental effects of heavy metals on plants, but the underlying mechanisms remain unclear. The study aims to synthesize SiNPs and reveal how they promote plant health in Arsenic-polluted soil. 0 and 100% v/v SiNPs were applied to soil, and Arsenic 0 and 3.2 g/ml were applied twice. Maize growth was monitored until maturity. Small, irregular, spherical, smooth, and non-agglomerated SiNPs with a peak absorbance of 400 nm were synthesized from Pycreus polystachyos. The SiNPs (100%) assisted in the development of a deep, prolific root structure that aided hydraulic conductance and gave mechanical support to the maize plant under As stress. Thus, there was a 40–50% increase in growth, tripled yield weights, and accelerated flowering, fruiting, and senescence. SiNPs caused immobilization (As(III)=SiNPs) of As in the soil and induced root exudates Phytochelatins (PCs) (desGly-PC2 and Oxidized Glutathione) which may lead to formation of SiNPs=As(III)–PCs complexes and sequestration of As in the plant biomass. Moreover, SiNPs may alleviate Arsenic stress by serving as co-enzymes that activate the antioxidant-defensive mechanisms of the shoot and root. Thus, above 70%, most reactive ROS (OH) were scavenged, which was evident in the reduced MDA content that strengthened the plasma membrane to support selective ion absorption of SiNPs in place of Arsenic. We conclude that SiNPs can alleviate As stress through sequestration with PCs, improve root hydraulic conductance, antioxidant activity, and membrane stability in maize plants, and could be a potential tool to promote heavy metal stress resilience in the field.

Micromorphology, physicochemical parameters, and phytochemical screening of Chloranthus flavus D.T. Liu & G. Chen (syn. C. nervosus Collett & Hemsl.) from Vietnam

Abstract. Chen TV, Lam DNX, Khai HD, Duc DPN, Nga NT, Hien NTT, Quynh TTT. 2024. Micromorphology, physicochemical parameters, and phytochemical screening of Chloranthus flavus D.T. Liu & G. Chen (syn. C. nervosus Collett & Hemsl.) from Vietnam. Biodiversitas 25: 846-858. Chloranthus flavus D.T. Liu & G. Chen (syn. C. nervosus Collett & Hemsl.) is a subshrub belonging to the family Chloranthaceae. Information on the anatomical structure and the powder features of C. flavus has not been noted. This study aimed to develop a monograph on the microscopic characteristics and physicochemical parameters of C. flavus, as well as a preliminary assessment of the phytochemical composition of this species. Anatomical characterizations of roots, stems, and leaves were performed using the iodine green-carmine staining method and then an optical microscope was used to observe the histology of these parts, similar to observing powder characteristics. Secondary metabolites were detected by chromogenic or precipitation reagents. Anatomically, the structural characteristics of the roots, stems, and leaves are similar to those of the Chloranthus species. Particularly, the root structure is characterized by six alternating xylem bundles, with six phloem bundles forming a ring. Polygonal to irregularly shaped cells of the upper epidermis and irregularly shaped ordinary cells, laterocytic and anomocytic stomata types, stomatal clusters, and the stomatal index (15.75±1.52%) of the lower epidermis were observed in leaves. Both powders found fragments of epidermal and parenchymatous cells, spiral xylem vessels, and scalariform xylem vessels. However, the root powder only observed solid-shaped sclereid cells, starch granules, starch clusters, and calcium oxalate crystals. The powders' moisture content, total ash, and acid-insoluble ash values all meet acceptable standards according to regulations on raw material purity. The whole C. flavus plant contains carotenoids, fatty acids, essential oils, flavonoids, tannins, coumarins, alkaloids, triterpenoids, amino acids, and carbohydrates. The current findings highlight the key characteristics for identifying C. flavus.

Diversity of endophytic bacterial community in rice roots and their roles in phosphate solubilization and plant growth

Root endophytic bacteria have significant beneficial effects on plant growth and health, while specific coexisting pathogenic bacteria can cause various diseases. In this study, we assessed the diversity and cultivability of the endophytic bacterial community in rice roots with a focus on their capacity for phosphate solubilization and impact on plant growth. Employing PacBio Single Molecule Real-Time (SMRT) and Sanger sequencing, we generated 16S rRNA gene libraries using metagenomic DNA extracted from the roots of three field-grown rice plants, along with genomic DNA from 156 associated bacterial isolates. QIIME 2-based microbiome analysis revealed dominant classified species at diverse taxonomic levels, including Arcobacter marinus, Paraburkholderia kururiensis, Lactobacillus plantarum, and Lactobacillus brevis. Furthermore, we effectively isolated 25.97% of rice root endophytic bacteria, with a notable 33.33% of pure culture endophytic bacteria exhibiting phosphate solubilization abilities. Finally, we revealed the inhibitory role of Burkholderia vietnamiensis and the growth promoting role of Paraburkholderia kururiensis subsp. Kururiensis in both the monocot model Brachypodium distachyon and the dicot Arabidopsis thaliana. Our study provided novel insight into the microbiome structure in rice roots and its potential to benefit rice cultivation and enhance overall crop health.

Genes involved in auxin biosynthesis, transport and signalling underlie the extreme adventitious root phenotype of the tomato aer mutant

The use of tomato rootstocks has helped to alleviate the soaring abiotic stresses provoked by the adverse effects of climate change. Lateral and adventitious roots can improve topsoil exploration and nutrient uptake, shoot biomass and resulting overall yield. It is essential to understand the genetic basis of root structure development and how lateral and adventitious roots are produced. Existing mutant lines with specific root phenotypes are an excellent resource to analyse and comprehend the molecular basis of root developmental traits. The tomato aerial roots (aer) mutant exhibits an extreme adventitious rooting phenotype on the primary stem. It is known that this phenotype is associated with restricted polar auxin transport from the juvenile to the more mature stem, but prior to this study, the genetic loci responsible for the aer phenotype were unknown. We used genomic approaches to define the polygenic nature of the aer phenotype and provide evidence that increased expression of specific auxin biosynthesis, transport and signalling genes in different loci causes the initiation of adventitious root primordia in tomato stems. Our results allow the selection of different levels of adventitious rooting using molecular markers, potentially contributing to rootstock breeding strategies in grafted vegetable crops, especially in tomato. In crops vegetatively propagated as cuttings, such as fruit trees and cane fruits, orthologous genes may be useful for the selection of cultivars more amenable to propagation.

Studies on the Effect of Water Stress on Root Traits in Redgram Genotypes

The experiment was conducted during July–November, 2019 at Regional Agriculture Research Station, Professor Jayashankar Telangana State Agricultural University, Palem, Nagarkurnool district, Telangana State, India. The main treatments had five red gram genotypes and water stress levels were taken as sub-treatment in 3 replications in factorial RBD using specialized root structure made with cement bricks. There was great variability in the yield performance of different Redgram genotypes under drought conditions. The experiment was conducted to select genotypes with efficient root architecture and associated traits under drought stress. Root studies were performed with the Delta T automatic root scanner. The SPAD chlorophyll meter was used to measure the SCMR value. The present study results revealed that genotype, Maruti showed significant superiority for character plant height and SCMR under non-stress, mild stress and severe stress conditions. The same genotype showed superior values for main root length under control and mild stress. Whereas, Laxmi recorded the highest plant height under severe stress and the same genotype also showed significant superiority for total plant dry weight, root dry weight and root area under severe stress. The genotype Laxmi showed significant character, root area and diameter superiority under mild stress. ICPL-20176 recorded significant superiority for main root length under severe stress and root tip for mild stress. The identified genotypes can be used as the parents in future drought-proof breeding useful for cultivating in water stress conditions.

The effect of root shaving and biostimulant application on the transplant success of six common Australian urban tree species

To enhance the establishment of container-grown trees, nursery and urban forest practitioners use root pruning to improve plant root structure. However, some methods of root pruning may cause stress to the plant and reduce shoot growth. One potential approach to mitigating tree stress is the application of biostimulants. This study aimed to determine the impact root shaving, a type of root pruning, has on the growth of urban plant species, and whether biostimulant application mitigates this impact. To address these aims, we applied root shaving (not shaved, shaved) and biostimulant (control, humic substance, protein hydrolysate, seaweed extract) treatments to six tree species that are commonly planted in the Sydney metropolitan area, Australia in a factorial design. The study consisted of a glasshouse and field experiment to simulate nursery production and urban field conditions, respectively. We found that the assimilation rate of the plants was not affected by root shaving but four of the species still experienced reductions in shoot growth in the short-term. This reduction was a result of the plants allocating resources to root growth to compensate for the root loss. However, in the long-term, the plants were able to compensate for this reduction in shoot growth. We found that biostimulant application did not mitigate the short-term impacts of root shaving on plant growth. We can conclude that root shaving and biostimulant application do not affect plant establishment in the long-term.

Forecasting Tree Root Architecture as a Complement to Proactive Urban Green Space Design

Abstract Background Stewarding newly planted urban trees to maturity involves consideration of above- and belowground factors. While landscape architects and urban planners often focus on aboveground tree aspects, understanding root structure and function is crucial, especially in urban areas with limited underground space and diverse soil conditions. To address the importance and challenges of belowground planning for urban tree roots, we propose a protocol for site assessment and demonstrate root growth forecasting as a complement to existing urban planning approaches. Methods This paper describes adaptations to a plant root architecture simulator, RootBox, and its subsequent application in 4 scenarios created to assess its efficacy as a complement to the phase of urban planning that prescribes vegetation type and planting location in the context of a myriad of other site considerations. RootBox was parameterized based on observed conformity of root growth simulations to generalized tree root architecture reported in the literature. Results Root growth forecasts for each scenario illustrate that plausible urban tree root system architectures—specifically, commonly observed root growth habits—can be produced by RootBox.In-situroot detection (e.g., with an air spade or hydro-vac) at predetermined time intervals can provide model validation and the opportunity to backward reconfigure RootBox parameters for forecast accuracy. Conclusion The adapted RootBox is a flexible, proof-of-concept solution for predicting urban tree root architecture, considering the site and soil conditions pre-established in the planning process. When used with other relevant tools, RootBox can offer valuable insights during the design or rejuvenation of urban spaces.