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Shrubs are usually adapted to stressful environments in which soil resources are limited, and thus, roots are fundamental for their biological success. However, root measures are challenging to collect, especially in field conditions and at the individual level. For this study, we collected data on the three‐dimensional distribution of fine root biomass of twenty‐three individuals belonging to three shrub species in a mediterranean shrubland in central Spain: gum rockrose Cistus ladanifer, rosemary Salvia rosmarinus, and hairy‐fruited broom Cytisus striatus. Our goal was to determine the soil‐foraging strategies adopted by the plants. We hypothesized that plants would show stabilizing niche differences explaining the high plant biodiversity characteristic of mediterranean shrublands and that they would follow the game theory model's prediction of exploitative segregation of roots behaving territorially but also over‐proliferating roots close to their stem and engaging in a root tragedy of the commons. We found that two‐thirds to three‐fourths of the biomass was belowground, and the system's productivity was roughly 500–600 g C m−2 year−1. Only rosemary plants competed with neighbors following the exploitative segregation predictions. Broom plants had the shallowest and most widespread root systems but significantly reduced their root range toward competing neighbors. Gum rockrose presented deep, narrow root systems avoiding extensive overlap with neighbors but did not appear to respond to competitive pressure levels. Shrubs appeared to stratify their roots at different soil depths, supporting the niche segregation hypothesis. [ABSTRACT FROM AUTHOR]

Summary: Barley (Hordeum vulgare) is an important global cereal crop and a model in genetic studies. Despite advances in characterising barley genomic resources, few mutant studies have identified genes controlling root architecture and anatomy, which plays a critical role in capturing soil resources.Our phenotypic screening of a TILLING mutant collection identified line TM5992 exhibiting a short‐root phenotype compared with wild‐type (WT) Morex background. Outcrossing TM5992 with barley variety Proctor and subsequent SNP array‐based bulk segregant analysis, fine mapped the mutation to a cM scale. Exome sequencing pinpointed a mutation in the candidate gene HvPIN1a, further confirming this by analysing independent mutant alleles.Detailed analysis of root growth and anatomy in Hvpin1a mutant alleles exhibited a slower growth rate, shorter apical meristem and striking vascular patterning defects compared to WT. Expression and mutant analyses of PIN1 members in the closely related cereal brachypodium (Brachypodium distachyon) revealed that BdPIN1a and BdPIN1b were redundantly expressed in root vascular tissues but only Bdpin1a mutant allele displayed root vascular defects similar to Hvpin1a.We conclude that barley PIN1 genes have sub‐functionalised in cereals, compared to Arabidopsis (Arabidopsis thaliana), where PIN1a sequences control root vascular patterning. [ABSTRACT FROM AUTHOR]

This article explores the impact of salinity on two different maize cultivars and their ability to tolerate salt stress. The study reveals that the more salt-tolerant cultivar is better at excluding sodium (Na+) and retaining potassium (K+), which are crucial for minimizing Na+ uptake. The researchers also discovered that the salt-tolerant cultivar experienced a net influx of hydrogen ions (H+) under severe salt stress, while the salt-sensitive cultivar did not. This suggests that net H+ influx is an important but often overlooked trait in salt tolerance. Additionally, the study found that K+ efflux and Na+ influx help maintain charge balance during H+ influx. [Extracted from the article]

Understanding how plant nutrient acquisition strategies respond to grazing at the community level is critical understanding ecosystem structure and functioning in grasslands. However, few studies have simultaneously compared the difference in above‐ground (leaf) and below‐ground (root) nutrient‐acquisition strategies in response to long‐term grazing, especially at the regional scale.Here, we measured a set of leaf and fine‐root traits that correspond to the fast‐slow economic spectrum at the community level in 10 experimental sites from paired grazed and ungrazed grasslands across a soil nutrient gradient covering three major types of grasslands in northern China.We found that patterns of variations of leaf and fine‐root traits were consistent with both a leaf and root economic spectrum at the community level for both grazed and non‐grazed plots. Grazing had minor effect on community‐level leaf nutrient‐acquisition strategies but strongly influenced community‐level root nutrient‐acquisition strategies. Specifically, root nutrient‐acquisition strategies were shifted to more exploitative resource use in grazed communities. Moreover, soil nutrient contributed to the changes in both leaf and root nutrient‐acquisition strategies, which tended towards a more resource acquisition strategy with increasing soil nutrient levels. Grazing significantly interacted with soil nutrient to affect root nutrient‐acquisition strategies, and grazing contributed more to root nutrient‐acquisition strategies than soil nutrient.Synthesis. Our results demonstrated completely inconsistent responses of community‐level above‐ and below‐ground resource acquisition strategies to long‐term grazing, and below‐ground acquisition strategies were more sensitive to long‐term grazing. Our findings also suggest that high intensity anthropogenic activities such as grazing may strongly modify below‐ground resource acquisition strategies. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Objectives: Oro‐dental manifestations of hyperoxaluria and dental management of affected patients are rarely reported in the literature. We describe a new oral presentation of primary hyperoxaluria (PH) and review relevant literature about oro‐dental manifestations and management of dental complications of hyperoxaluria. Methods: A case report of a 44‐year‐old female who presented with symptoms of temporomandibular joint dysfunction due to hyperoxaluria was described according to the CARE guidelines. In addition, an extensive search of biomedical databases (PubMed, Medline, Google Scholar, and Embase) for articles describing oro‐dental manifestations and/or dental management in patients with hyperoxaluria was performed using the key words ("oral" and/or "hyperoxaluria" and/or "dental" and/or "oxalosis"). Included articles were reviewed and data about patient demographics, disease type and stage, oral and dental manifestations, and dental treatment outcome were retrieved and analyzed. Results: A total of 14 articles describing the oral and dental manifestations in 15 patients with hyperoxaluria were included. Tooth mobility, root resorption, and radiographic alterations were consistently described in all cases. Oral manifestations were described mainly in PH at late stages, and only after the onset of chronic renal disease. Dental management in all reported cases was palliative and aimed to relive pain and treat periodontal infection. Tooth loss due to extraction or uncontrolled mobility was the ultimate outcome in almost all reported cases. Conclusion: Oral and dental manifestations in hyperoxaluria are rarely reported in the literature. Management of tooth mobility and root resorption in hyperoxaluria is challenging and clinical guidelines and evidence‐based recommendations are lacking. Early diagnosis and treatment of hyperoxaluria might be the only effective approach to prevent dental and periodontal complications of the disease. [ABSTRACT FROM AUTHOR]

Summary Single‐cell proteomics (SCP) is an emerging approach to resolve cellular heterogeneity within complex tissues of multi‐cellular organisms. Here, we demonstrate the feasibility of SCP on plant samples using the model plant Arabidopsis thaliana. Specifically, we focused on examining isolated single cells from the cortex and endodermis, which are two adjacent root cell types derived from a common stem cell lineage. From 756 root cells, we identified 3763 proteins and 1118 proteins/cell. Ultimately, we focus on 3217 proteins quantified following stringent filtering. Of these, we identified 596 proteins whose expression is enriched in either the cortex or endodermis and are able to differentiate these closely related plant cell types. Collectivity, this study demonstrates that SCP can resolve neighboring cell types with distinct functions, thereby facilitating the identification of biomarkers and candidate proteins to enable functional genomics. [ABSTRACT FROM AUTHOR]

SUMMARY: Plants partly optimize their water recruitment from the growth medium by directing root growth toward a moisture source, a phenomenon termed hydrotropism. The default mechanism of downward growth, termed gravitropism, often functions to counteract hydrotropism when the water‐potential gradient deviates from the gravity vector. This review addresses the identity of the root sites in which hydrotropism‐regulating factors function to attenuate gravitropism and the interplay between these various factors. In this context, the function of hormones, including auxin, abscisic acid, and cytokinins, as well as secondary messengers, calcium ions, and reactive oxygen species in the conflict between these two opposing tropisms is discussed. We have assembled the available data on the effects of various chemicals and genetic backgrounds on both gravitropism and hydrotropism, to provide an up‐to‐date perspective on the interactions that dictate the orientation of root tip growth. We specify the relevant open questions for future research. Broadening our understanding of root mechanisms of water recruitment holds great potential for providing advanced approaches and technologies that can improve crop plant performance under less‐than‐optimal conditions, in light of predicted frequent and prolonged drought periods due to global climate change. Significance Statement: Understanding the mechanisms that plant roots utilize to resist the strong tendency to grow downward in order to grow toward a moisture source, holds great potential for unveiling research approaches and technologies to improve crop performance. Herein, we assess the complex interplay between major regulators of root growth, development, and responses to myriad internal and external cues, that function to attenuate downward root growth, thereby enabling the root to reach water. [ABSTRACT FROM AUTHOR]

In this study, we investigated the genetic mapping of root biomass and root/shoot ratio. We utilized a large (n = 345) bi‐parental recombinant inbred line (RIL) population from the 'Penny' × 'Yecora‐Rojo' cross to investigate the partitioning of biomass above‐ and belowground and to identify the quantitative trait loci (QTL) that influence root biomass and root/shoot ratio. Genotyping of 345 RILs by using genotyping by sequencing produced 2918 single‐nucleotide polymorphism markers by which a genome‐wide map of 3507 cM was constructed. Phenotyping was conducted in an augmented design with large pots in controlled environment. We identified two significant QTL regions, QRt.peye‐5A and QRt.peye‐5B, which control root biomass and the root/shoot ratio. QRt.peye‐5A, marking a 3.15 Mbp region on chromosome 5A, explained 11% of variations in root biomass and 9.5% of variations in root/shoot ratio, with the narrow region harbouring 28 genes. QRt.peye‐5B, marking a 12.2 Mbp region on chromosome 5B, explained 7% of variations in root/shoot ratio and harbours 104 genes. The root/shoot ratio enhancing alleles at QRt.peye‐5A and QRt.peye‐5B come from 'Penny' and 'Yecora‐Rojo' respectively. These QTL regions contains genes such as the two MADS box transcription factors on the 5A QTL that are candidate genes for Vrn1 locus, and other genes previously postulated for root traits such as a COBRA‐like COBL2 and landmark hormonal responses genes such as IAA16, IAA4 and BRI1, DREB2A‐INTERACTING PROTEIN2 (DRIP2) and bHLH92 which has a role in amelioration of stress conditions. [ABSTRACT FROM AUTHOR]

Summary: Phloem sieve elements (PSE), the primary conduits collaborating with neighboring phloem pole pericycle (PPP) cells to facilitate unloading in Arabidopsis roots, undergo a series of developmental stages before achieving maturation and functionality. However, the mechanism that maintains the proper progression of these differentiation stages remains largely unknown.We identified a gain‐of‐function mutant altered phloem pole pericycle 1 Dominant (app1D), producing a truncated, nuclear‐localized active form of NAC with Transmembrane Motif 1‐like (NTL9). This mutation leads to ectopic expression of its downstream target CALLOSE SYNTHASE 8 (CalS8), thereby inducing callose accumulation, impeding SE differentiation, impairing phloem transport, and inhibiting root growth.The app1D phenotype could be reproduced by blocking the symplastic channels of cells within APP1 expression domain in wild‐type (WT) roots. The WT APP1 is primarily membrane‐tethered and dormant in the root meristem cells but entries into the nucleus in several cells in PPP near the unloading region, and this import is inhibited by blocking the symplastic intercellular transport in differentiating SE.Our results suggest a potential maintenance mechanism involving an APP1‐CalS8 module, which induces CalS8 expression and modulates symplastic communication, and the proper activation of this module is crucial for the successful differentiation of SE in the Arabidopsis root. [ABSTRACT FROM AUTHOR]

The identification of soybean genotypes tolerant to soil compaction makes it possible to reduce productivity loss under stress conditions. Added to this, the prior selection of these genotypes will result in greater assertiveness in the positioning of cultivars in the field. Thus, the objective was to evaluate the susceptibility of soybean genotypes to compaction in greenhouse and field conditions; verify which characteristics of seedlings under high resistance to root penetration are correlated with crop production in compacted soil; and to validate the substrate mechanical impedance method for evaluating the susceptibility of plant genotypes to soil compaction. Seeds of 20 genotypes were sown in a substrate mechanical impedance system under controlled conditions. The characteristics evaluated were total root length, total root surface area, mean root diameter, total root volume, taproot length, shoot length, root dry matter and seedling shoot dry matter. In the field experiment, half of the planting area was compacted, constituting two treatments, soil with and without compaction. The percentage of seedling emergence, initial plant height, stem diameter, number of nodes, internode length, number of lateral branches, shoot dry matter, final plant height, absolute and relative growth rate, number of pods, weight of 100 seeds and grain yield. In addition, the number of days between soybean sowing until plant flowering and grain harvest was recorded according to genotype and soil compaction level. In a controlled environment, genotypes tolerant to soil compaction show greater plasticity of root characteristics and smaller alterations in the shoot of seedlings. In the field, these genotypes show smaller reductions in growth rate, height, number of pods and grain yield. The shoot dry matter and the root dry matter of soybean seedlings in a mechanical impedance system present a positive and negative correlation, respectively, with soybean yield in compacted soil, indicating that the genetically determined susceptibility to soil compaction stress was similar throughout ontogenesis. The substrate mechanical impedance system used to evaluate the performance of soybean seedlings under stress, facilitates the decision‐making in breeding programs focused on identifying genotypes expressing soil compaction tolerance. [ABSTRACT FROM AUTHOR]

Ferns are primitive vascular plants with diverse morphologies and structures. Plant anatomical traits and their linkages can reflect adaptation to the environment; however, these remain are still poorly understood in ferns. The main objective of this study was to explore whether there was structural coordination among and within organs in fern species. We measured 16 hydraulically related anatomical traits of pinnae, petioles, and roots of 24 representative fern species from the tropical and subtropical forest understory and analyzed trait correlation networks. In addition, we examined phylogenetic signals for the anatomical traits and analyzed co-evolutionary relationships. These results indicated that stomatal density and all petiole anatomical traits exhibited significant phylogenetic signals. Evolutionary correlations were observed between the tracheid diameter and wall thickness of the petiole and between the water transport capacity of the petiole and stomatal density. Conversely, anatomical traits of roots (e.g., root diameter) showed no phylogenetic signals and were not significantly correlated with those of the pinnae and petioles, indicating a lack of structural coordination between the below- and above-ground organs. Unlike angiosperms, vein density is unrelated to stomatal density or pinna thickness in ferns. As root diameter decreased, the cortex-to-stele diameter ratio decreased significantly (enhanced water absorption) in angiosperms but remained unchanged in ferns. These differences lead to different responses of ferns to climate change and improve our knowledge of the water adaptation strategies of ferns. [ABSTRACT FROM AUTHOR]

To better understand the dynamics and functional roles of root pressure, we represent a novel and the first complete analytical model for root pressure, which can be applied to complex roots/shoots. The osmotic volume of a single root is equal to that of the vessel lumen in fine roots and adjacent apoplastic spaces. Water uptake occurs via passive osmosis and active solute uptake (Js*, osmol s−1), resulting in the osmolyte concentration Cr (mol·kg−1 of water) at a fixed osmotic volume. Solute loss occurs via two passive processes: radial diffusion of solute Km (Cr− Csoil) from fine roots to soil, where Km is the diffusional constant and Csoil is the soil–solute concentration, and the mass flow of solute and water into the plant from the fine roots. The proposed model predicts the quadratic function of root pressure (Pr), Pr2+bPr+c=0, where b and c are the functions of plant hydraulic resistance, soil water potential, solute flux and gravitational potential. The model demonstrates the root pressure‐mediated distribution of water through the hydraulic architecture of a 6.8‐m‐tall bamboo shoot. This model provides a theoretical basis to test the functional roles of root pressure in shaping the hydraulic architecture and refilling potential xylem embolisms. Summary statement: An analytical solution for root pressure is derived and illustrated by applying it to the measured hydraulic architecture of a 7‐m bamboo shoot. [ABSTRACT FROM AUTHOR]

Hydrotropism is an important adaptation of plant roots to the uneven distribution of water, with current research mainly focused on Arabidopsis thaliana. To examine hydrotropism in tomato (Solanum lycopersicum) primary roots, we used RNA sequencing to determine gene expression of root tips (apical 5 mm) on dry and wet sides of hydrostimulated roots grown on agar plates. Hydrostimulation enhances cell division and expansion on the dry side compared with the wet side of the root tip. In hydrostimulated roots, the abscisic acid (ABA) biosynthesis gene ABA4 was induced more on the dry than the wet side of root tips. The ABA biosynthesis inhibitor Fluridone and the ABA‐deficient mutant notabilis (not) significantly decreased hydrotropic curvature. Wild‐type, but not the ABA biosynthesis mutant not, root tips showed asymmetric H+ efflux, with greater efflux on the dry than on the wet side of root tips. Thus, ABA mediates asymmetric H+ efflux, allowing the root to bend towards the wet side to take up more water. Summary statement: ABA regulates asymmetric H+ efflux, which is required for the root hydrotropic bending. [ABSTRACT FROM AUTHOR]

Enhancing the productivity of seed potato production systems by improving the size of the tubers is a primary concern. Punjab, a state located in the northwest region of India, meets 60% of the country's seed requirements. In order to optimize the morpho‐physiological aspects, root structure, and overall yield of seed‐sized tubers, research trials were carried out at Punjab Agricultural University, Ludhiana over two consecutive years. The trial consisted of 11 different treatments and was conducted using a randomized complete block design with three replications. The application of Gibberellic acid at a concentration of 200 ppm, at 45 and 60 days after sowing (DAS), resulted in significantly higher yields of seed‐sized tubers measuring <4.5 cm. This treatment also exhibited superior root architecture parameters and accumulation of dry matter, outperforming all other growth regulation treatments. Compared to the untreated control group, the Gibberellic acid application led to a remarkable increase of 45.9% and 39.8% in seed‐sized tuber yields. Furthermore, it significantly boosted the protein, starch, antioxidant (total phenols), sugar (total and reducing), and mineral content (nitrogen, phosphorus, and potassium) in the tubers, surpassing the effects of all other growth regulation treatments. These results suggested that the exogenous use of gibberellic acid (200 ppm) at 45 and 60 DAS substantially improved the physiology, root architecture, and yield of seed‐sized tubers. [ABSTRACT FROM AUTHOR]

SUMMARY: Soil water uptake by roots is a key component of plant water homeostasis contributing to plant growth and survival under ever‐changing environmental conditions. The water transport capacity of roots (root hydraulic conductivity; Lpr) is mostly contributed by finely regulated Plasma membrane Intrinsic Protein (PIP) aquaporins. In this study, we used natural variation of Arabidopsis for the identification of quantitative trait loci (QTLs) contributing to Lpr. Using recombinant lines from a biparental cross (Cvi‐0 x Col‐0), we show that the gene encoding class 2 Sucrose‐Non‐Fermenting Protein kinase 2.4 (SnRK2.4) in Col‐0 contributes to >30% of Lpr by enhancing aquaporin‐dependent water transport. At variance with the inactive and possibly unstable Cvi‐0 SnRK2.4 form, the Col‐0 form interacts with and phosphorylates the prototypal PIP2;1 aquaporin at Ser121 and stimulates its water transport activity upon coexpression in Xenopus oocytes and yeast cells. Activation of PIP2;1 by Col‐0 SnRK2.4 in yeast also requires its protein kinase activity and can be counteracted by clade A Protein Phosphatases 2C. SnRK2.4 shows all hallmarks to be part of core abscisic acid (ABA) signaling modules. Yet, long‐term (>3 h) inhibition of Lpr by ABA possibly involves a SnRK2.4‐independent inhibition of PIP2;1. SnRK2.4 also promotes stomatal aperture and ABA‐induced inhibition of primary root growth. The study identifies a key component of Lpr and sheds new light on the functional overlap and specificity of SnRK2.4 with respect to other ABA‐dependent or independent SnRK2s. [ABSTRACT FROM AUTHOR]

Changes in water and nitrogen availability, as important elements of global environmental change, are known to affect the temporal stability of aboveground net primary productivity (ANPP). However, evidences for their effects on the temporal stability of belowground net primary productivity (BNPP), and whether such effects are consistent between belowground and aboveground, are rather scarce. Here, we investigated the responses of temporal stability of both ANPP and BNPP to water and nitrogen addition based on a 9‐year manipulative experiment in a temperate grassland in northern China. The results showed that the temporal stability of ANPP increased with water addition but decreased with nitrogen addition. By contrast, the temporal stability of BNPP decreased with water addition but increased with nitrogen enrichment. The temporal stability of ANPP was mainly determined by the soil moisture and inorganic nitrogen, which modulated species asynchrony, as well as by the stability of dominant species. On the other hand, the temporal stability of BNPP was mainly driven by the soil moisture and inorganic nitrogen that modulated ANPP of grasses, and by the direct effect of soil water availability. Our study provides the first evidence on the opposite responses of aboveground and belowground grassland temporal stability to increased water and nitrogen availability, highlighting the importance of considering both aboveground and belowground components of ecosystems for a more comprehensive understanding of their dynamics. [ABSTRACT FROM AUTHOR]

Summary: Lateral root (LR) positioning and development rely on the dynamic interplay between auxin production, transport but also inactivation. Nonetheless, how the latter affects LR organogenesis remains largely uninvestigated.Here, we systematically analyze the impact of the major auxin inactivation pathway defined by GRETCHEN HAGEN3‐type (GH3) auxin conjugating enzymes and DIOXYGENASE FOR AUXIN OXIDATION1 (DAO1) in all stages of LR development using reporters, genetics and inhibitors in Arabidopsis thaliana.Our data demonstrate that the gh3.1/2/3/4/5/6 hextuple (gh3hex) mutants display a higher LR density due to increased LR initiation and faster LR developmental progression, acting epistatically over dao1‐1. Grafting and local inhibitor applications reveal that root and shoot GH3 activities control LR formation. The faster LR development in gh3hex is associated with GH3 expression domains in and around developing LRs. The increase in LR initiation is associated with accelerated auxin response oscillations coinciding with increases in apical meristem size and LR cap cell death rates.Our research reveals how GH3‐mediated auxin inactivation attenuates LR development. Local GH3 expression in LR primordia attenuates development and emergence, whereas GH3 effects on pre‐initiation stages are indirect, by modulating meristem activities that in turn coordinate root growth with LR spacing. [ABSTRACT FROM AUTHOR]

SUMMARY: Plant growth and morphogenesis are determined by the mechanical properties of its cell walls. Using atomic force microscopy, we have characterized the dynamics of cell wall elasticity in different tissues in developing roots of several plant species. The elongation growth zone of roots of all species studied was distinguished by a reduced modulus of elasticity of most cell walls compared to the meristem or late elongation zone. Within the individual developmental zones of roots, there were also significant differences in the elasticity of the cell walls of the different tissues, thus identifying the tissues that limit root growth in the different species. In cereals, this is mainly the inner cortex, whereas in dicotyledons this function is performed by the outer tissues—rhizodermis and cortex. These differences result in a different behaviour of the roots of these species during longitudinal dissection. Modelling of longitudinal root dissection using measured properties confirmed the difference shown. Thus, the morphogenesis of monocotyledonous and dicotyledonous roots relies on different tissues as growth limiting, which should be taken into account when analyzing the localization of associated molecular events. At the same time, no matrix polysaccharide was found whose immunolabelling in type I or type II cell walls would predict their mechanical properties. However, assessment of the degree of anisotropy of cortical microtubules showed a striking correlation with the elasticity of the corresponding cell walls in all species studied. Significance Statement: Juxtaposing the nanomechanical properties of cell walls in growing roots with their composition and the organization of the cytoskeleton revealed key similarities and differences in root morphogenesis in monocots and dicots. [ABSTRACT FROM AUTHOR]

Background Aims Methods Results Conclusions Boron (B) is an essential micronutrient for plants. Dicot plants respond to insufficient B supply by altering root architecture and root hair growth. How root systems of rather low‐B demanding monocot species such as maize (Zea mays L.) respond to B deficiency in terra has not been experimentally resolved, yet.The study aims to investigate root responses and their physiological consequences under B deficiency during the vegetative growth of maize.B73 wild‐type (WT) maize and its root hairless rth3 mutant were grown under varying B supply conditions in soil columns and in an automated root phenotyping facility. Biomass data, root system architecture traits, the mineral elemental composition and molecular B‐deficiency responses were quantified.Though having very low leaf B concentrations, no major growth deficit, apart from chlorotic stripes on leaves, was recorded on maize root and shoot development, with or without root hairs, on B‐deficient conditions. Although leaf B concentration of the rth3 mutant is significantly lower under B‐deficient and under B‐surplus conditions compared to the WT, the rth3 mutant neither developed a larger total root length, more fine roots nor displayed a higher expression of B uptake transporters as compensatory adaptations.Strikingly, maize plants did neither react with an inhibited root growth nor by a compensatory root foraging behaviour to severe B‐deficient in terra growth conditions. This is rather atypical for plants. The performance and altered leaf B concentrations of rth3 mutants may be biased by secondary effects, such as an overall reduced root growth. [ABSTRACT FROM AUTHOR]

Summary: Nutrient allocation is central to understanding plant ecological strategies and forest roles in biogeochemical cycles. Thought to be mainly driven by environmental conditions, nutrient allocation to woody organs, especially to living tissues, is poorly understood.To examine the role of differences in living tissues (sapwood, SW, vs inner bark, IB), organs, ecological strategies, and environmental conditions in driving nutrient allocation and scaling in woody plants, we quantified nitrogen and phosphorus in main stems and coarse roots of 45 species from three tropical ecosystems with contrasting precipitation, fire regime, and soil nutrients.Nutrient concentration variation was mostly explained by differences between IB and SW, followed by differences between species and, in the case of phosphorus, soil nutrient availability. IB nutrient concentrations were four times those of SW, with root tissues having slightly higher concentrations than stem tissues. Scaling between IB and SW, and between stems and roots, was generally isometric. In cross‐sections, IB contributed half of total nutrients in roots and a third in stems.Our results highlight the important role of IB and SW for nutrient storage, the coordination in nutrient allocation across tissues and organs, and the need to differentiate between IB and SW to understand plant nutrient allocation. [ABSTRACT FROM AUTHOR]

The United Nations Decade of Ecosystem Restoration was announced in 2021 to highlight the need for collective efforts to revive degraded ecosystems. Plant above‐ and belowground microbiomes are fundamental to plant health and ecosystem functioning. Plant aboveground microbiomes have received considerably more attention than the belowground microbiome, especially in the context of coastal plant restoration. Thus, there is fundamental gap in our understanding of the role belowground microbiomes play in restoration success in saltmarsh and mangrove ecosystems. Here, we outline potential pathways and challenges associated with including the belowground microbiome in mangrove and saltmarsh restoration via a conceptual framework and an overview of current literature. We highlight the large gap of knowledge that exists in plant–microbe literature as it pertains to coastal restoration warranting future research. More research is needed to significantly advance both fundamental and applied knowledge through better understanding of the importance of coastal microbiomes to restoration success by stakeholders and funding bodies. [ABSTRACT FROM AUTHOR]

With ongoing climate change and the increase in extreme weather events, especially droughts, the challenge of maintaining food security is becoming ever greater. Locally adapted landraces of crops represent a valuable source of adaptation to stressful environments. In the light of future droughts—both by altered soil water supply and increasing atmospheric water demand (vapor pressure deficit [VPD])—plants need to improve their water efficiency. To do so, plants can enhance their access to soil water by improving rhizosphere hydraulic conductivity via the exudation of mucilage. Furthermore, plants can reduce transpirational water loss via stomatal regulation. Although the role of mucilage and stomata regulation on plant water management have been extensively studied, little is known about a possible coordination between root mucilage properties and stomatal sensitivity as well as abiotic drivers shaping the development of drought resistant trait suits within landraces. Mucilage properties and stomatal sensitivity of eight Mexican landraces of Zea mays in contrast with one inbred line were first quantified under controlled conditions and second related to water demand and supply at their respective site of origin. Mucilage physical properties—namely, viscosity, contact angle, and surface tension—differed between the investigated maize varieties. We found strong influences of precipitation seasonality, thus plant water availability, on mucilage production (R2 =.88, p <.01) and mucilage viscosity (R2 =.93, p <.01). Further, stomatal sensitivity to increased atmospheric water demand was related to mucilage viscosity and contact angle, both of which are crucial in determining mucilage's water repellent, thus maladaptive, behavior upon soil drying. The identification of landraces with pre‐adapted suitable trait sets with regard to drought resistance is of utmost importance, for example, trait combinations such as exhibited in one of the here investigated landraces. Our results suggest a strong environmental selective force of seasonality in plant water availability on mucilage properties as well as regulatory stomatal effects to avoid mucilage's maladaptive potential upon drying and likely delay critical levels of hydraulic dysfunction. By this, landraces from highly seasonal climates may exhibit beneficial mucilage and stomatal traits to prolong plant functioning under edaphic drought. These findings may help breeders to efficiently screen for local landraces with pre‐adaptations to drought to ultimately increase crop yield resistance under future climatic variability. [ABSTRACT FROM AUTHOR]

We prove that for any fixed k$$ k $$, the probability that a random vertex of a random increasing plane tree is of rank k$$ k $$, that is, the probability that a random vertex is at distance k$$ k $$ from the leaves, converges to a constant ck$$ {c}_k $$ as the size n$$ n $$ of the tree goes to infinity. We prove that 1−∑j≤kck<22k+3(2k+4)!$$ 1-{\sum}_{j\le k}{c}_k<\frac{2^{2k+3}}{\left(2k+4\right)!} $$, so that the tail of the limiting rank distribution is super‐exponentially narrow. We prove that the latter property holds uniformly for all finite n$$ n $$ as well. More generally, we prove that the ranks of a finite uniformly random set of vertices are asymptotically independent, each with distribution {ck}$$ \left\{{c}_k\right\} $$. We compute the exact value of ck$$ {c}_k $$ for 0≤k≤3$$ 0\le k\le 3 $$, demonstrating that the limiting expected fraction of vertices with rank ≤3$$ \le 3 $$ is 0.9997$$ 0.9997 $$... We show that with probability 1−n−0.99ε$$ 1-{n}^{-0.99\varepsilon } $$ the highest rank of a vertex in the tree is sandwiched between (1−ε)logn/loglogn$$ \left(1-\varepsilon \right)\log n/\mathrm{loglog}n $$ and (1.5+ε)logn/loglogn$$ \left(1.5+\varepsilon \right)\log n/\mathrm{loglog}n $$, and that this rank is asymptotic to logn/loglogn$$ \log n/\mathrm{loglog}n $$ with probability 1−o(1)$$ 1-o(1) $$. [ABSTRACT FROM AUTHOR]

Cochlospermum spp. root powder is widely used by local populations in Sudanian zone of Benin as food ingredient. This study aims at documenting the mineral profile of Cochlospermum spp. root powder and the consumption frequencies of foods enriched with this species in the three phytodistricts of Sudanian zone of Benin. A consumption frequency survey was conducted among 449 women of reproductive age and their children (n = 406) aged 6 to 59 months. Processing follow‐up was performed among twelve (12) selected processors per phytodistict and samples were collected for minerals (Ca, Mg, Na, P, Fe, Zn, Cu, and Mn) analysis. Results showed that most (>75%) women and their children consumed foods enriched with Cochlospermum spp. root powder at least two times per day. The mineral contents (expect Ca and P) of Cochlospermum spp. root powder do not vary significantly according to phytodistricts. High mineral content was obtained for iron (54.1 ± 21.5 mg/100 g dry weight) and calcium (573.7 ± 98 and 802.5 ± 49.9 mg/100 g dry weight, respectively in Atacora Chain and Northern Borgou phytodistricts). Cochlospermum spp. root powder could be used to alleviate iron and calcium deficiencies among populations. Further studies should focus on the bioavailability of minerals and anti‐nutrients content of this plant food. [ABSTRACT FROM AUTHOR]

In this study, we aimed to identify long noncoding RNAs (lncRNAs) in root tips of the model legume Medicago truncatula using previously generated nuclear, total polyA, ribosome‐associated polyA, and Riboseq RNA datasets, which might shed light on their localization and potential regulatory roles. RNA‐seq data were mapped to the version 5 of the M. truncatula A17 genome and analyzed to identify genome annotated lncRNAs and putative new root tip (NRT) lncRNAs. lncRNAs were classified according to their genomic location relative to chromatin accessible regions, protein‐coding genes and transposable elements (TE), finding differences between annotated lncRNAs and NRT lncRNAs, both in their genomic position as well as in the type of TEs in their vicinity. We investigated their response to submergence and found a set of regulated lncRNAs that were preferentially upregulated in the nucleus, some of which were located nearby genes of the conserved submergence upregulated gene families, and chromatin accessible regions suggesting a potential regulatory role. Finally, the accumulation of lncRNAs under submergence was validated by reverse transcription quantitative polymerase chain reaction on nuclear RNA, providing additional evidence of their localization, which could ultimately be required for their function. [ABSTRACT FROM AUTHOR]

Roots are highly plastic organs enabling plants to adapt to a changing below‐ground environment. In addition to abiotic factors like nutrients or mechanical resistance, plant roots also respond to temperature variation. Below the heat stress threshold, Arabidopsis thaliana seedlings react to elevated temperature by promoting primary root growth, possibly to reach deeper soil regions with potentially better water saturation. While above‐ground thermomorphogenesis is enabled by thermo‐sensitive cell elongation, it was unknown how temperature modulates root growth. We here show that roots are able to sense and respond to elevated temperature independently of shoot‐derived signals. This response is mediated by a yet unknown root thermosensor that employs auxin as a messenger to relay temperature signals to the cell cycle. Growth promotion is achieved primarily by increasing cell division rates in the root apical meristem, depending on de novo local auxin biosynthesis and temperature‐sensitive organization of the polar auxin transport system. Hence, the primary cellular target of elevated ambient temperature differs fundamentally between root and shoot tissues, while the messenger auxin remains the same. Synopsis: Plant root growth is influenced by temperature variation. This article shows that elevated temperatures directly promote primary root growth through an auxin‐mediated response that increases cell division rates in the root apical meristem. Plant roots respond to warmer temperatures by promoting primary root growth.Roots are able to sense and respond to elevated temperature independently of shoot‐derived signals through an as yet unknown root thermosensor.Growth promotion in roots is primarily achieved by increasing cell division rates in the root apical meristem.Auxin mediates a temperature‐dependent increase in cell division rate depending on de novo local auxin biosynthesis and temperature‐sensitive organization of the polar auxin transport system. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Escobedia grandiflora is a medicinal hemiparasite that occurs naturally in non‐forested communities in Central and South America. Parasitic plants accumulate high levels of a water‐soluble orange pigment in roots that was once among the most important food dyes in the Andean region. We conclusively address the chemical identification of this pigment and provide molecular and cellular insights on its biosynthesis and possible function. Summary: The herbaceous hemiparasite Escobedia grandiflora (Orobanchaceae) is used in traditional medicine in the Andean region. Escobedia roots accumulate high levels of an orange pigment with a significant relevance as a cooking dye that exhibits antioxidant and cardioprotective properties. Here, we aimed to confirm the chemical identity of the pigment and investigate its biosynthesis and function in Escobedia roots.We combined metabolic and cytological analyses with de novo transcriptome assembly, gene expression studies, and phylogenetic analyses.The pigment was conclusively shown to be azafrin, an apocarotenoid likely derived from the cleavage of β‐carotene. RNA‐seq supported by multispecies comparative transcriptome analysis and qRT‐PCR allowed to propose candidate genes for the production of azafrin in Escobedia roots. We also showed that azafrin is delivered to the root apoplast and that it accumulates in the area where the Escobedia haustorium contacts the host's root.Our data suggest that azafrin production might rely on a carotenoid cleavage dioxygenase (CCD) different from CCD7 and that this apocarotenoid might function in the parasitism process. Together, our work represents an unprecedented step forward in our understanding of the Escobedia parasitization system. [ABSTRACT FROM AUTHOR]

Maize yield reduction occurs frequently due to soil drought. Abscisic acid (ABA) is an important hormonal signal indicating drought. However, it remains unclear about the specific roles of root ABA in the adaptation to soil drought in maize. This study applied five different soil water potentials (SWP), referring to maintaining SWP at −15, −30, −45, −60, and −75 kPa, respectively, and investigated the ABA content in roots and the activities and gene expression levels of key enzymes involved in the ABA biosynthesis, the leaf photosynthetic properties, root traits, and kernel yield. The results showed that maize root ABA content, the activities and gene expressions of key enzymes involved in the ABA biosynthesis were increased with the decrease of SWP. The leaf transpiration rate, and root dry weight, length, volume, surface area, and activity, and kernel yield of maize were increased first and then decreased with the severity of soil drying. The leaf photosynthetic rate was not significantly reduced with ABA accumulation at a low ABA content in roots. Root ABA content was significantly positively correlated with leaf transpiration efficiency and root activity when ABA content was relatively low (9.03–22.02 nmol g−1 DW), whereas root ABA content was negatively correlated with leaf photosynthetic rate, leaf transpiration efficiency, root volume, and root activity when ABA content was high (28.32–39.23 nmol g−1 DW). The results indicate that maize root ABA exhibit differential roles in the adaptation to soil drought, and can positively regulate the drought‐resistance of maize at an appropriate level. [ABSTRACT FROM AUTHOR]

Aluminum (Al) toxicity is one of the most serious hazards of soil acidification, which limits root formation and hinders crop growth. Soil acidification in orchards has been widely reported. However, there is little information about the effect of Al3+ on citrus roots in acidified red soil. Taking pomelo (Citrus grandis), the main citrus variety in Southeast China, as an example, soil surveys were conducted to analyze the status and characteristics of acidification in pomelo orchards. Subsequently, we explored whether optimized fertilization and liming can effectively reduce Al toxicity in roots and increase yield by three treatments, including farmer fertilization practice (FFP), NPK optimization (OPT), and OPT combined with lime (OPT+L). The results showed that (1) rapid soil acidification occurred in pomelo orchards in the past 40 years (with a decrease of 0.81 units). The severity of soil acidification increases with orchard age. In addition, the soil pH and base saturation (BS) at the drip line (DL; i.e., fertilization site) were the lowest, while the concentration of exchangeable acid (Ex.Acid) and exchangeable Al (Ex.Al), and the ratio of Ex.Al to cation exchange capacity (Ex.Al%) was highest compared to other locations away from DL. Random forest analysis indicated Ex.Al was the most important factor to reflect soil acidification. (2) Under the OPT+L treatment, the concentrations of soil Ex.Acid and Ex.Al decreased, and BS increased, which markedly reduced the Al3+ concentration in the roots and promoted root growth. OPT+L significantly decreased the Al concentrations in soils (by 71.3%) and roots (by 47.8%) but increased root activity, root length, root tips and root surface area by 119.2%, 80.3%, 124.6% and 136.6%, respectively. In addition, structural equation modeling further proved that increasing soil pH and BS while decreasing Ex.Al was beneficial to citrus production in acidic soil, and optimized fertilization and lime application are necessary. [ABSTRACT FROM AUTHOR]

Plant functional traits are increasingly recognised as being impacted by soil abiotic and biotic factors. Yet, the question to what extent the coupling between community‐level above‐ and below‐ground traits is affected by soil conditions remains open.In a field experiment in dune grassland, we quantified the responses of both community‐level leaf and root traits to changes in soil abiotic and biotic conditions using soil inoculation by living and sterile soil inocula originated from different dune ecosystems.Altered soil conditions resulted in a strong decoupling in responses of community‐level leaf and root traits. Changes in soil abiotic conditions imposed by soil inoculation were more important in determining the decoupling of the leaf vs root relationships than additions of soil biota. Altered soil abiotic factors influenced both leaf and root traits at the community level and caused the entire community‐level trait spectrum to shift, while experimental additions of living soil inocula only significantly influenced root traits towards longer and thinner roots.Synthesis. Our results bring direct evidence that, at a plant community level, the dynamics of plant above‐ground traits are not informative of below‐ground traits. Particularly, below‐ground abiotic processes are a major driver of commonly observed trait spectra. We suggest that future study is required to test the general pattern of leaf and root correlations across different ecosystems under field conditions. [ABSTRACT FROM AUTHOR]

The long‐term dynamics of the transcriptome under natural field conditions remain unclear. We conducted comprehensive gene expression analyses of rice leaves and roots grown under natural field conditions for a long period, from the tillering stage to the ripening stage. In this experiment, changes in the transcriptome were captured in relation to microclimatic parameters, particularly potential evaporation (Ep), which is a multiple meteorological factor and acts as an indicator of transpirational demand. The results indicated that many genes were regulated by changes in temperature and Ep in both leaves and roots. Furthermore, the correlation between gene expression and meteorological factors differed significantly between the vegetative and reproductive stages. Since Ep triggers transpiration, we analyzed aquaporin gene expression, which is responsible for water transport, and found that many aquaporin genes in leaves were positively correlated with Ep throughout the growth period, whereas in roots, two plasma membrane intrinsic aquaporins, PIP2;4 and PIP2;5 were strongly correlated with Ep during reproductive growth. Other genes closely related to productivity, such as those involved in nutrient absorption and photosynthesis, exhibited different responses to meteorological factors at different growth stages. The stage‐dependent shift in the microclimate response provides an important perspective on crop physiology in light of climate change. [ABSTRACT FROM AUTHOR]

Summary: The processes that contribute to plant organ morphogenesis are spatial–temporally organized. Within the meristem, mitosis produces new cells that subsequently engage in cell expansion and differentiation programs. The latter is frequently accompanied by endoreplication, being an alternative cell cycle that replicates the DNA without nuclear division, causing a stepwise increase in somatic ploidy.Here, we show that the Arabidopsis SCL28 transcription factor promotes organ growth by modulating cell expansion dynamics in both root and leaf cells.Gene expression studies indicated that SCL28 regulates members of the SIAMESE/SIAMESE‐RELATED (SIM/SMR) family, encoding cyclin‐dependent kinase inhibitors with a role in promoting mitotic cell cycle (MCC) exit and endoreplication, both in response to developmental and environmental cues. Consistent with this role, mutants in SCL28 displayed reduced endoreplication, both in roots and leaves. We also found evidence indicating that SCL28 co‐expresses with and regulates genes related to the biogenesis, assembly, and remodeling of the cytoskeleton and cell wall.Our results suggest that SCL28 controls, not only cell proliferation as reported previously but also cell expansion and differentiation by promoting MCC exit and endoreplication and by modulating aspects of the biogenesis, assembly, and remodeling of the cytoskeleton and cell wall. [ABSTRACT FROM AUTHOR]

It is important that both clinicians and patients are aware of the risk of displacement of a maxillary tooth into the sinus. Appropriate warnings should be given preoperatively and steps should be taken to reduce the chance of this occurring. Despite this, the introduction of a foreign body into the sinus is an unfortunate but real possibility during extraction of teeth. In the event that this occurs appropriate steps should be taken to manage this. We present a case of a patient that underwent extraction of his maxillary first molar, with the displacement of the disto‐buccal root into his maxillary sinus during the procedure. Subsequently the patient was referred to the Oral Surgery Department at Birmingham Dental Hospital and retrieval of the root was planned. However, the root was spontaneously cleared prior to surgery. Investigations, management and complications of this case are discussed. The importance of preoperative imaging to avoid unnecessary treatment is highlighted by this case. [ABSTRACT FROM AUTHOR]

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Ricinus communis is an important oilseed crop worldwide and is also considered one of the best potential plants for salt‐affected soil improvement in northeast China. However, little is known about photosynthesis and carbohydrate metabolism in this plant, nor the distribution of carbohydrates in cotyledons and roots under salinity stress.In the present study, seedling growth, gas exchange parameters (PN, E, gs and Ci), carbohydrate (fructose, sucrose, glucose, soluble sugar and starch) metabolism and related enzymes and genes were measured in Ricinus plants.Under salt stress, PN of cotyledons decreased significantly (P < 0.05), resulting in weak photosynthetic capacity. Furthermore, salt stress increased sucrose and glucose content in cotyledons, but decreased soluble sugar and starch content. However, sucrose increased and starch decreased in roots. This may be correlated with the increasing sugar metabolism under salinity, including notable changes in sugar‐related enzyme activities (SPS, SuSy, α‐amylase and β‐amylase) and gene expression of RcINV, RcSUS, RcAmY, RcBAM and RcGBE1.The results suggest that salinity reduces photosynthesis of cotyledons, alters carbohydrate allocation between cotyledons and roots and also promotes starch utilization in cotyledons and starch biosynthesis in roots, leading to a functional imbalance between cotyledons and roots. Together, these findings provide insights into the crucial role of sugar metabolism in improving salt‐tolerance of Ricinus during the early seedling growth stage. [ABSTRACT FROM AUTHOR]

Premise: Plant disease severity assessments are used to quantify plant–pathogen interactions and identify disease‐resistant lines. One common method for disease assessment involves scoring tissue manually using a semi‐quantitative scale. Automating assessments would provide fast, unbiased, and quantitative measurements of root disease severity, allowing for improved consistency within and across large data sets. However, using traditional Root System Markup Language (RSML) software in the study of root responses to pathogens presents additional challenges; these include the removal of necrotic tissue during the thresholding process, which results in inaccurate image analysis. Methods: Using PlantCV, we developed a Python‐based pipeline, herein called RootDS, with two main objectives: (1) improving disease severity phenotyping and (2) generating binary images as inputs for RSML software. We tested the pipeline in common bean inoculated with Fusarium root rot. Results: Quantitative disease scores and root area generated by this pipeline had a strong correlation with manually curated values (R2 = 0.92 and 0.90, respectively) and provided a broader capture of variation than manual disease scores. Compared to traditional manual thresholding, images generated using our pipeline did not affect RSML output. Discussion: Overall, the RootDS pipeline provides greater functionality in disease score data sets and provides an alternative method for generating image sets for use in available RSML software. [ABSTRACT FROM AUTHOR]

Global banana production is affected by Fusarium wilt, a devastating disease caused by the soilborne root‐infecting fungus, Fusarium oxysporum f. sp. cubense (Foc). Fusarium wilt is notoriously difficult to manage because infection arises through complex below‐ground interactions between Foc, the plant, and the soil microbiome in the root–soil interface, defined as the rhizosphere. Interactions in the rhizosphere play a pivotal role in processes associated with pathogen development and plant health. Modulation of these processes through manipulation and management of the banana rhizosphere provides an auspicious prospect for management of Fusarium wilt. Yet, a fundamental understanding of interactions in the banana rhizosphere is still lacking. The objective of this review is to discuss the state‐of‐the‐art of the relatively scant data available on banana below‐ground interactions in relation to Fusarium wilt and, as a result, to highlight key research gaps. Specifically, we seek to understand (a) the biology of Foc and its interaction with banana; (b) the ecology of Foc, including the role of root‐exuded metabolites in rhizosphere interactions; and (c) soil management practices and how they modulate Fusarium wilt. A better understanding of molecular and ecological factors influencing banana below‐ground interactions has implications for the development of targeted interventions in the management of Fusarium wilt through manipulation of the banana rhizosphere. [ABSTRACT FROM AUTHOR]

Summary: Efficient root‐to‐shoot delivery of water and nutrients in plants relies on the correct differentiation of xylem cells into hollow elements. While auxin is integral to the formation of xylem cells, it remains poorly characterized how each subcellular pool of this hormone regulates this process.Combining genetic and cell biological approaches, we investigated the bipartite activity of nucleoplasmic vs plasma membrane‐associated phosphatidylinositol 4‐phosphate kinases PIP5K1 and its homolog PIP5K2 in Arabidopsis thaliana roots and uncovered a novel mechanism by which phosphoinositides integrate distinct aspects of the auxin signaling cascade and, in turn, regulate the onset of xylem differentiation.The appearance of undifferentiated cells in protoxylem strands of pip5k1 pip5k2 is phenomimicked in auxin transport and perception mutants and can be partially restored by the nuclear residence of PIP5K1. By contrast, exclusion of PIP5K1 from the nucleus hinders the auxin‐mediated induction of the xylem master regulator VASCULAR RELATED NAC DOMAIN (VND) 7. A xylem‐specific increase of auxin levels abolishes pip5k1 pip5k2 vascular defects, indicating that the establishment of auxin maxima is required to activate VND7‐mediated xylem differentiation.Our results describe a new mechanism by which distinct subcellular pools of phosphoinositides integrate auxin transport and perception to initiate xylem differentiation in a spatiotemporal manner. [ABSTRACT FROM AUTHOR]

The polarized and dynamic actin cytoskeleton is essential for root cell growth. Here, we report the key role of thiol‐disulfide oxidoreductase PDI1;1 in actin structures. Microscopic analyses revealed that after Oryza sativa roots were exposed to H2O2, both actin and PDI1;1 were depolarized and arranged in a meshwork. In H2O2‐exposed cells, actin formed intermolecularly disulfide‐bonded high‐molecular‐weight structures, which were thiol‐trapped by PDI1;1. Recombinant PDI1;1 exhibited the ability to recognize actin in an in vitro binding assay. During recovery from H2O2 exposure, the amount of disulfide‐bonded high‐molecular‐weight structures of actin decreased over time, but deficiency of PDI1;1 inhibited the decrease. These results suggest a PDI1;1‐dependent pathway that reduces disulfide bonds in high‐molecular‐weight structures of actin, thus promoting their degradation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Plant growth‐promoting rhizobacteria may significantly impact the soil microbial community and the growth of plant roots and have critical roles in soil ecosystem functioning. However, the interactions between rhizobacteria and plants are extremely complicated and remain understudied. RESULTS: In this study, a Bacillus strain was isolated from a long‐term maize colonization soil and identified as Bacillus aryabhattai strain LAD. Laboratory tests showed that B. aryabhattai LAD had phosphate‐solubilizing and nitrogen‐fixing functions that benefit plant growth. The effects of LAD cultures on the root system development of corn seedlings and the structure of rhizosphere bacterial communities were studied. The most significant stimulations of LAD culture on plant growth were observed at a cell density of 102 CFU mL−1. Treatment with LAD culture in hydroponics caused an increase of 107%, 197%, and 25% in the shoot length, total root length, and main root thickness respectively. The LAD treatment also significantly affected the rhizosphere microbial abundance and community structure. The rhizobacterial abundance and species richness in the corn seedlings treated with LAD culture were significantly lower than those in the control group. However, the LAD‐treated samples had higher relative abundances of plant growth‐promoting rhizobacteria like Bacillus and Burkholderia than the control samples did, suggesting that LAD treatment may facilitate the mutualistic relation between the rhizosphere microbiome and the plant. CONCLUSION: These results collectively demonstrated that LAD is capable of shaping the rhizosphere microbial community structure and functions as a plant growth‐promoting agent, which makes it a strong candidate for application as bio‐fertilizer in agricultural systems. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: Salinity is detrimental to plants and developmental adjustments limiting salt uptake and transport is therefore important for acclimation to high salt. These parameters may be influenced by xylem morphology, however how plant root xylem development is affected by salt stress remains unclear.Using molecular and genetic techniques and detailed phenotypic analyses, we demonstrate that salt causes distinct effects on Arabidopsis seedling root xylem and reveal underlying molecular mechanisms.Salinity causes intermittent inhibition of protoxylem cell differentiation, generating protoxylem gaps, in Arabidopsis and several other eudicot seedlings. The extent of protoxylem gaps in seedlings positively correlates with salt tolerance. Reduced gibberellin signalling is required for protoxylem gap formation. Mutant analyses reveal that the xylem differentiation regulator VASCULAR RELATED NAC DOMAIN 6 (VND6), along with secondary cell wall producing and cell wall modifying enzymes, including EXPANSIN A1 (EXP1), are involved in protoxylem gap formation, in a DELLA‐dependent manner.Salt stress is likely to reduce levels of bioactive gibberellins, stabilising DELLAs, which in turn activates multiple factors modifying protoxylem differentiation. Salt stress impacts seedling survival and formation of protoxylem gaps may be a measure to enhance salt tolerance. [ABSTRACT FROM AUTHOR]

Ecological resilience to ungulate overbrowsing is an important issue in forest ecosystems. After chronic herbivory, the recovery rate of understory vegetation and its related functions can be slow even with decreasing grazing intensity; thus, detecting elasticity during alternative successional trajectories is fundamental to understanding state perturbations. In this context, we focused on physical plant–soil feedback (functional interactions between plant growth and soil physical conditions) and evaluated elasticity and recovery processes according to deer density. The effects of 40 years of chronic herbivory by sika deer (average density 14.7 individuals km−2) on the recovery of understory plant communities and associated changes in soil physical properties in headwater catchments were assessed. Using 8 years of catchment‐wide exclusion (fenced) and reduction (only culled; average 4.3 individuals km−2) treatments, plot sampling was conducted in 2010 (before treatment) and 2018 (after treatment). The recovery of vegetation and soil physical properties were evaluated, and functional plant–soil relationships and spatial variability were assessed to detect recovery processes during alternative successional trajectory. Woody species increased only under the exclusion treatment and the average soil bulk density was lower than that under reduction treatments. Soil bulk density was negatively correlated with root biomass in the fenced catchment, and root biomass was positively associated with woody species richness. Reduced soil bulk density (~0.5 g cm−3) was observed with greater root biomass and woody species richness on upper hillslopes in the deer‐excluded catchment where plant coverage was minimal. Successional failure under the reduction treatment suggested slow recovery with a depressed threshold according to deer density, indicating a clockwise hysteretic response to deer density. Unlike plant coverage during the earlier period of overbrowsing, woody species root development led the recovery of functional physical plant–soil feedback; however, this was probably limited by the higher soil erosion rate in riparian areas and an under‐developed herb layer. Our results highlight an alternative recovery trajectory of physical plant–soil feedback driven by an alternative plant element (woody roots) to recovery trajectory with increasing plant cover. However, riparian erosion and herb layer would still suppress recovery. Therefore, recovery might be slower at the landscape scale. [ABSTRACT FROM AUTHOR]

For over a century, deep roots have been assumed to allow trees to avoid competition with grasses (i.e., the two‐layer hypothesis). Yet, in part because it remains difficult to measure water uptake in the field, there has been a shift in savanna ecology away from the two‐layer hypothesis and towards alternative explanations of tree‐grass coexistence. Here, we combine hydrologic tracer experiments and soil water flow models to demonstrate how the distribution of active roots affects water uptake across a range of savanna conditions. Grass roots were shallower and provided pre‐emptive access to enough soil water to allow nearly continuous grass cover, but slightly deeper roots provided trees with more total water under most conditions. This 'some water now or more water later' tradeoff varied with precipitation amount, soil texture, and tree and grass relative root abundance in ways that helped explain tree and grass landscape abundance. [ABSTRACT FROM AUTHOR]

Extracellular ATP (eATP) increases cytosolic free calcium ([Ca2+]cyt) as a specific second messenger 'signature' through the plasma membrane DORN1/P2K1 receptor. Previous studies revealed a biphasic signature in Arabidopsis thaliana roots that is altered by inorganic phosphate (Pi) deprivation. The relationship between the two phases of the signature and possible wave formation have been tested as a function of Pi nutrition.The bioluminescent aequorin and intensiometric GCaMP3 reporters were used to resolve the spatial origin of the eATP [Ca2+]cyt signature in Arabidopsis root tips. Application of eATP only to the root apex allowed [Ca2+]cyt wave resolution without the confounding effects of eATP delivery by superfusion.The first apical millimetre of the root generates the first [Ca2+]cyt increase by eATP, regardless of nutritional status. The second increase occurs sub‐apically in the root hair zone, has some autonomy and is significantly reduced in Pi‐starved roots. A significant component of the Pi‐replete signature does not require DORN1/P2K1, but Pi‐starved roots appear to have an absolute requirement for that receptor. Application of eATP specifically to the root apex provides evidence for cell‐to‐cell propagation of a [Ca2+]cyt wave that diminishes sub‐apically.The apex maintains a robust [Ca2+]cyt increase (even under Pi starvation) that is the basis of a propagative wave, with implications for the ability of the root's eATP signalling systems to signal systemically. Partial autonomy of the sub‐apical region may be relevant to the perception of eATP from microbes. eATP‐induced [Ca2+]cyt increase may not have always have an obligate requirement for DORN1/P2K1. [ABSTRACT FROM AUTHOR]

Receptor‐like kinases (RLKs) play key roles in regulating various physiological aspects in plant growth and development. In Arabidopsis thaliana, there are at least 223 leucine‐rich repeat (LRR) RLKs. The functions of the majority of RLKs in the LRR XI subfamily were previously revealed. Only three RLKs were not characterized. Here we report that two independent triple mutants of these RLKs, named ROOT ELONGATION RECEPTOR KINASES (REKs), exhibit increased cell numbers in the root apical meristem and enhanced cell size in the elongation and maturation zones. The promoter activities of a number of Quiescent Center marker genes are significantly up‐regulated in the triple mutant. However, the promoter activities of several marker genes known to control root stem cell niche activities are not altered. RNA‐seq analysis revealed that a number of cell wall remodeling genes are significantly up‐regulated in the triple mutant. Our results suggest that these REKs play key roles in regulating root development likely via negatively regulating the expression of a number of key cell wall remodeling genes. [ABSTRACT FROM AUTHOR]

Vegetation plays a crucial role in gully headcut erosion. However, little is known about how grass influences runoff hydraulics, soil erosion and headcut erosion processes. A series of rainfall and scouring experiments were conducted on four plots to elucidate the effect of the density of Agropyron cristatum (L.) Gaertn (planting spaces: 20 × 20 cm2, GA1; 15 × 15 cm2, GA2; 10 × 10 cm2, GA3; bare land as control, BL) on runoff hydraulics and soil erosion during gully headcut erosion. The velocity, Reynolds number (Re), runoff shear force (τ) and stream power (ω) of the BL increased exponentially with time (P < 0.01). However, for the grassland, most parameters increased linearly with time (P < 0.01). The Froude number (Fr) of the BL and grassland significantly decreased linearly and exponentially, respectively, with time (P < 0.01). For τ, the grass tableland needed to develop for a period of time to restrain it. The runoff of the BL tableland and gully head was supercritical turbulent, while that of the grassland was more dispersed. The existence of a gully head increased the jet velocity by 2.97%–67.19%, which increased the dispersion degree of the runoff. The runoff energy showed a significant exponential increase with time (P < 0.05). Compared with that of the BL, the energy consumption of the runoff from the grassland increased by 4.10%–31.81%. During gully headcut erosion, the BL was primarily cut down to the tableland by runoff, while the grassland was cut down to the headwall by on‐wall flow. As the density increased, the benefit of sediment reduction increased, reaching a maximum of 66.79%. The collapse of the BL primarily occurred in the upper part of the headwall during the early experimental stage. The frequency and space–time ranges of the collapse of the grassland were larger than those of the BL. The gravity erosion types of the BL were headwall collapse and gully bank collapse, while those of the grasslands were headwall collapse and root‐soil composite collapse. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Bowles et al. (2022), 235: 732–742. [ABSTRACT FROM AUTHOR]

Identification of water flow through non‐root soil macropores and along roots using X‐ray computed tomography (CT) is still challenging because of limited methods to quantify roots and pore structures. This study selected shrub‐encroached grassland consisting of a mosaic of shrub patches and interspace grass patches and the original grassland as a control treatment. Twelve intact soil columns (0–30 cm deep) were excavated, which included four replicates each from the soils under the original grassland, the shrub patches and interspace grass patches. Three‐dimensional networks of soil macropores and roots were quantified using CT scanning and image analysis techniques, and active flow pathways were identified through KI tracing experiment using CT scanning. The results showed that the tracer depths of soils under the shrub patches and interspace grass patches were deeper than those of the original grassland, which was attributed to the well‐developed root system. The tracer volume density was significantly and positively correlated with soil macropore node density and root volume density (p < 0.05), and significantly and negatively correlated with root mean angle (p < 0.05). Soils under the shrub patches had lower tracer volume density than that under the interspace grass patches, which was attributed to the horizontal‐oriented roots under the shrub patches. The relative contribution of water flow along roots was larger than that through non‐root soil macropores 35 min after dye application. This provided direct evidence that shrub roots were the main pathway of macropore flow resulting in water flow into deep soil layers in the shrub‐encroached grassland. Highlights: The tracer depths of shrub‐encroached grassland were deep due to well‐developed root system.Shrub patches had low tracer volume density due to the horizontal‐oriented roots.The contribution of water flow along roots was larger than that through non‐root soil macropores.Shrub roots were the main pathway of water flow. [ABSTRACT FROM AUTHOR]

SUMMARY: Rhizobiome confer stress tolerance to ruderal plants, yet their ability to alleviate stress in crops is widely debated, and the associated mechanisms are poorly understood. We monitored the drought tolerance of maize (Zea mays) as influenced by the cross‐inoculation of rhizobiota from a congeneric ruderal grass Andropogon virginicus (andropogon‐inoculum), and rhizobiota from organic farm maintained under mesic condition (organic‐inoculum). Across drought treatments (40% field capacity), maize that received andropogon‐inoculum produced two‐fold greater biomass. This drought tolerance translated to a similar leaf metabolomic composition as that of the well‐watered control (80% field capacity) and reduced oxidative damage, despite a lower activity of antioxidant enzymes. At a morphological‐level, drought tolerance was associated with an increase in specific root length and surface area facilitated by the homeostasis of phytohormones promoting root branching. At a proteome‐level, the drought tolerance was associated with upregulation of proteins related to glutathione metabolism and endoplasmic reticulum‐associated degradation process. Fungal taxa belonging to Ascomycota, Mortierellomycota, Archaeorhizomycetes, Dothideomycetes, and Agaricomycetes in andropogon‐inoculum were identified as potential indicators of drought tolerance. Our study provides a mechanistic understanding of the rhizobiome‐facilitated drought tolerance and demonstrates a better path to utilize plant–rhizobiome associations to enhance drought tolerance in crops. Significance Statement: The rhizobiome from a drought‐tolerant ruderal plant (Andropogon virginicus) alleviates drought‐induced physiological stress of maize (Zea mays) through modifications in root morphology driven by homeostasis of phytohormones and stress‐related proteome upregulations. Thus our study captures the underlying mechanisms through which rhizobiome facilitates drought tolerance in maize, and highlight the importance of cross‐inoculation of rhizobiota from stress‐resilient cogeneric species. [ABSTRACT FROM AUTHOR]

SUMMARY: Protein tracking in living plant cells has become routine with the emergence of reporter genes encoding fluorescent tags. Unfortunately, this imaging strategy is not applicable to glycans because they are not directly encoded by the genome. Indeed, complex glycans result from sequential additions and/or removals of monosaccharides by the glycosyltransferases and glycosidases of the cell's biosynthetic machinery. Currently, the imaging of cell wall polymers mainly relies on the use of antibodies or dyes that exhibit variable specificities. However, as immunolocalization typically requires sample fixation, it does not provide access to the dynamics of living cells. The development of click chemistry in plant cell wall biology offers an alternative for live‐cell labeling. It consists of the incorporation of a carbohydrate containing a bio‐orthogonal chemical reporter into the target polysaccharide using the endogenous biosynthetic machinery of the cell. Once synthesized and deposited in the cell wall, the polysaccharide containing the analog monosaccharide is covalently coupled to an exogenous fluorescent probe. Here, we developed a metabolic click labeling approach which allows the imaging of cell wall polysaccharides in living and elongating cells without affecting cell viability. The protocol was established using the pollen tube, a useful model to follow cell wall dynamics due to its fast and tip‐polarized growth, but was also successfully tested on Arabidopsis root cells and root hairs. This method offers the possibility of imaging metabolically incorporated sugars of viable and elongating cells, allowing the study of the long‐term dynamics of labeled extracellular polysaccharides. Significance Statement: This paper reports a protocol for the metabolic‐click mediated dynamic imaging of a pollen tube, a rapidly elongating plant cell. This method results in the fluorescent labelling of cell wall polysaccharides in living cells, allowing the study of their long‐term dynamics. [ABSTRACT FROM AUTHOR]