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Root anatomy plays a crucial role in regulating essential processes such as the absorption and movement of water and nutrients in plants. Root anatomy also impacts the energy costs of building and sustaining root tissues, tissue mechanics, and interactions with other organisms. Although several studies in maize have confirmed the functional utility of numerous root anatomical traits, such as that of cortical cell size and number for stress adaptation, there have been significant obstacles in measuring and analyzing root anatomical characteristics. This has resulted in gaps in our understanding of the genetic control and range of phenotypic variations among different cultivars, and how this diversity relates to overall fitness. Here, we review root anatomical phenotypes in maize and their function in stress adaptation, and briefly discuss phenotyping methods available for root anatomy. We further introduce a simple and accessible phenotyping approach that enables a comprehensive investigation of maize root anatomy. Detailed characterization of root traits and the implementation of robust methods for root anatomical phenotyping could have wide-ranging benefits across various areas of plant science, from fundamental research to enhancing crop breeding efforts.
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Root anatomy plays a critical structural and functional role in the maize root system, and regulates edaphic stress tolerance. The function and genetic basis of several maize root anatomical traits for stress tolerance have been demonstrated. Leveraging root anatomical traits in maize thus holds great potential for developing cultivars with greater nutrient and water efficiency. Key for such approaches is the ability to characterize the root anatomy of plants of interest. Here, we outline a systematic method for preparing, imaging, and analyzing maize root cross-sections. The protocol describes root sectioning (by hand or using a vibratome), preparation of microscope slides and toluidine blue staining, imaging under a light microscope, and both manual and semiautomated methods for anatomical feature extraction from images. The protocol enables the visualization and quantification of various anatomical tissues and traits, and its simplicity, adaptability, and accessibility make it an ideal choice for both small- and large-scale phenotyping studies in maize and other plant species. This standardized protocol provides researchers with a comprehensive methodology to accurately dissect root structures, enabling in-depth analyses that are essential for understanding plant growth, development, and adaptive value for stress tolerance.
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A diet lacking dietary fibers promotes the expansion of gut microbiota members that can degrade host glycans, such as those on mucins. The microbial foraging on mucin has been associated with disruptions of the gut-protective mucus layer and colonic inflammation. Yet, it remains unclear how the co-utilization of mucin and dietary fibers affects the microbiota composition and metabolic activity. Here, we used 14 dietary fibers and porcine colonic and gastric mucins to study the dynamics of mucin and dietary fiber utilization by the human fecal microbiota in vitro. Combining metaproteome and metabolites analyses revealed the central role of the Bacteroides genus in the utilization of complex fibers together with mucin while Akkermansia muciniphila was the main utilizer of sole porcine colonic mucin but not gastric mucin. This study gives a broad overview of the colonic environment in response to dietary and host glycan availability.
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Plant phenotypic plasticity plays an important role in nitrogen (N) acquisition and use under nitrogen-limited conditions. However, this role has never been quantified as a function of N availability, leaving it unclear whether plastic responses should be considered as potential targets for selection. A combined modelling and experimentation approach was adopted to quantify the role of plasticity on N uptake and plant yield. Based on a greenhouse experiment we considered plasticity in two maize traits: root-to-leaf biomass allocation ratio and emergence rate of axial roots. In a simulation experiment we individually enabled or disabled both plastic responses for maize stands grown across six N levels. Both plastic responses contributed to maintaining a higher N uptake and plant productivity as N-availability declined, compared to stands in which plastic responses were disabled. We conclude that plastic responses quantified in this study may be a potential target trait in breeding programs for greater N uptake across N levels while it may only be important for the internal use of N under N-limited conditions in maize. Given the complexity of breeding for plastic responses, an a priori model analysis is useful to identify which plastic traits to target for enhanced plant performance.
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We describe how increased root cortical parenchyma wall width (CPW) can improve tolerance to drought stress in maize by reducing the metabolic costs of soil exploration. Significant variation (1.0 to 5.0 µm) for CPW was observed in maize germplasm. The functional-structural model RootSlice predicts that increasing CPW from 2 to 4 µm is associated with ca. 15% reduction in root cortical cytoplasmic volume, respiration rate, and nitrogen content. Analysis of genotypes with contrasting CPW grown with and without water stress in the field confirms that increased CPW is correlated with ca. 32 to 42% decrease in root respiration. Under water stress in the field, increased CPW is correlated with 125% increased stomatal conductance, 325% increased leaf CO2 assimilation rate, 73 to 78% increased shoot biomass, and 92 to 108% increased yield. CPW was correlated with leaf mesophyll midrib parenchyma wall width, indicating pleiotropy. GWAS analysis identified candidate genes underlying CPW. OpenSimRoot modeling predicts that a reduction in root respiration due to increased CPW would also benefit maize growth under suboptimal nitrogen, which requires empirical testing. We propose CPW as a new phene that has utility under edaphic stress meriting further investigation.
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Mexican native maize (Zea mays ssp. mays) is adapted to a wide range of climatic and edaphic conditions. Here, we focus specifically on the potential role of root anatomical variation in this adaptation. Given the investment required to characterize root anatomy, we present a machine-learning approach using environmental descriptors to project trait variation from a relatively small training panel onto a larger panel of genotyped and georeferenced Mexican maize accessions. The resulting models defined potential biologically relevant clines across a complex environment that we used subsequently for genotype-environment association. We found evidence of systematic variation in maize root anatomy across Mexico, notably a prevalence of trait combinations favoring a reduction in axial hydraulic conductance in varieties sourced from cooler, drier highland areas. We discuss our results in the context of previously described water-banking strategies and present candidate genes that are associated with both root anatomical and environmental variation. Our strategy is a refinement of standard environmental genome-wide association analysis that is applicable whenever a training set of georeferenced phenotypic data is available.
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BACKGROUND AND AIMS: About 20% of patients develop cardiac decompensation within the first year after transjugular intrahepatic portosystemic shunt (TIPS) insertion. However, risk factors for cardiac decompensation remain poorly defined. We aimed to evaluate predictors of cardiac decompensation after TIPS insertion in a large, well-defined cohort of patients with liver cirrhosis. METHODS: 234 cirrhotic patients who received a TIPS at Hannover Medical School were retrospectively followed up for one year to assess the incidence of cardiac decompensation. Echocardiographic parameters and established diagnostic criteria for cardiac impairment (e.g. by the American Society of Echocardiography/ European Association of Cardiovascular Imaging (ASE/EACVI)) were investigated for an association with cardiac decompensation in a competing risk analysis. Survival was analyzed using a multivariable cox regression analysis adjusting for Freiburg index of post-TIPS survival. RESULTS: Predominant TIPS indication was ascites (83%). Median age was 59 years, median MELD-score 12% and 58% were male. Overall, 41 patients (18%) developed cardiac decompensation within one year after TIPS insertion. Diastolic dysfunction according to the ASE/EACVI was diagnosed in 26% of patients at baseline and was linked to a significantly higher risk for cardiac decompensation (p = 0.025) after TIPS. When investigating individual echocardiographic baseline parameters, only pathological E/A (<0.8 or >2) was identified as a risk factor for cardiac decompensation (p = 0.015). Mortality and liver transplantation (n = 50) were significantly higher among patients who developed cardiac decompensation (HR = 5.29, p < 0.001) as well as in patients with a pathological E/A (HR = 2.34, p = 0.006). Cardiac high-risk status (44% of patients) was strongly linked to cardiac decompensation (HR = 2.93, p = 0.002) and mortality (HR = 2.24, p = 0.012). CONCLUSION: Cardiac decompensation after TIPS is a frequent and important complication and is associated with reduced survival. American Society of Echocardiography/EACVI criteria and E/A seem to be the best parameters to predict the cardiac risk in cirrhotic patients undergoing TIPS insertion.
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Derivación Portosistémica Intrahepática Transyugular , Humanos , Masculino , Estados Unidos , Persona de Mediana Edad , Femenino , Derivación Portosistémica Intrahepática Transyugular/efectos adversos , Estudios Retrospectivos , Resultado del Tratamiento , Cirrosis Hepática/complicaciones , Cirrosis Hepática/diagnóstico , Cirrosis Hepática/epidemiología , Factores de RiesgoRESUMEN
Background & Aims: Hepatic encephalopathy (HE) is a frequent and severe complication in patients after transjugular intrahepatic portosystemic shunt (TIPS) insertion. However, risk factors for post-TIPS HE remain poorly defined. Minimal HE (mHE) is a well-known risk factor for overt HE in patients with cirrhosis without TIPS. We aimed to evaluate three tools frequently used for diagnosing mHE for their dynamic changes and their predictive value for overt HE after TIPS. Methods: We prospectively recruited 84 consecutive patients before TIPS insertion and monitored them for 180 days for post-TIPS HE. Before TIPS insertion, the patients underwent the portosystemic encephalopathy (PSE) syndrome test, the animal naming test (ANT), and the critical flicker frequency (CFF). Patients were retested after TIPS insertion. Results: The majority of patients were male (67.9%), and the predominant indication for TIPS was refractory ascites (75%). Median age was 59 years, model for end-stage liver disease score was 12, and 66.3%, 64.6%, and 28.4% patients had evidence for mHE according to the PSE syndrome test, ANT, and CFF, respectively. Overall, 25 patients developed post-TIPS HE within 180 days after TIPS insertion. Post-TIPS incidence of overt HE was 22.2, 28.6, 45.5, and 55.6% in those with no, one, two, and three pathological tests at baseline, respectively. However, none of the three tests was significantly associated with post-TIPS HE. Of note, mean performance in all tests remained stable over time after TIPS insertion. Conclusions: PSE syndrome test, ANT and CFF, which are frequently used for diagnosing mHE have limited value for predicting HE after TIPS insertion. We could not find evidence that TIPS insertion leads to a psychometric decline in the long term. Impact and implications: This prospective observational study compared three diagnostic tests for mHE and showed the limited value of these tests for predicting overt HE in patients with cirrhosis undergoing TIPS insertion. In addition, the results suggest that cognitive performance generally remains stable after TIPS insertion. These results are important for physicians and researchers involved in the management of patients with cirrhosis undergoing TIPS procedures. The study's findings serve as a starting point for further investigations on the development of more effective strategies for predicting and managing post-TIPS HE. Clinical trial number: ClinicalTrials.gov NCT04801290.
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OBJECTIVES: Diffusion-weighted imaging (DWI) enhances specificity in multiparametric breast MRI but is associated with longer acquisition time. Deep learning (DL) reconstruction may significantly shorten acquisition time and improve spatial resolution. In this prospective study, we evaluated acquisition time and image quality of a DL-accelerated DWI sequence with superresolution processing (DWI DL ) in comparison to standard imaging including analysis of lesion conspicuity and contrast of invasive breast cancers (IBCs), benign lesions (BEs), and cysts. MATERIALS AND METHODS: This institutional review board-approved prospective monocentric study enrolled participants who underwent 3 T breast MRI between August and December 2022. Standard DWI (DWI STD ; single-shot echo-planar DWI combined with reduced field-of-view excitation; b-values: 50 and 800 s/mm 2 ) was followed by DWI DL with similar acquisition parameters and reduced averages. Quantitative image quality was analyzed for region of interest-based signal-to-noise ratio (SNR) on breast tissue. Apparent diffusion coefficient (ADC), SNR, contrast-to-noise ratio, and contrast (C) values were calculated for biopsy-proven IBCs, BEs, and for cysts. Two radiologists independently assessed image quality, artifacts, and lesion conspicuity in a blinded independent manner. Univariate analysis was performed to test differences and interrater reliability. RESULTS: Among 65 participants (54 ± 13 years, 64 women) enrolled in the study, the prevalence of breast cancer was 23%. Average acquisition time was 5:02 minutes for DWI STD and 2:44 minutes for DWI DL ( P < 0.001). Signal-to-noise ratio measured in breast tissue was higher for DWI STD ( P < 0.001). The mean ADC values for IBC were 0.77 × 10 -3 ± 0.13 mm 2 /s in DWI STD and 0.75 × 10 -3 ± 0.12 mm 2 /s in DWI DL without significant difference when sequences were compared ( P = 0.32). Benign lesions presented with mean ADC values of 1.32 × 10 -3 ± 0.48 mm 2 /s in DWI STD and 1.39 × 10 -3 ± 0.54 mm 2 /s in DWI DL ( P = 0.12), and cysts presented with 2.18 × 10 -3 ± 0.49 mm 2 /s in DWI STD and 2.31 × 10 -3 ± 0.43 mm 2 /s in DWI DL . All lesions presented with significantly higher contrast in the DWI DL ( P < 0.001), whereas SNR and contrast-to-noise ratio did not differ significantly between DWI STD and DWI DL regardless of lesion type. Both sequences demonstrated a high subjective image quality (29/65 for DWI STD vs 20/65 for DWI DL ; P < 0.001). The highest lesion conspicuity score was observed more often for DWI DL ( P < 0.001) for all lesion types. Artifacts were scored higher for DWI DL ( P < 0.001). In general, no additional artifacts were noted in DWI DL . Interrater reliability was substantial to excellent (k = 0.68 to 1.0). CONCLUSIONS: DWI DL in breast MRI significantly reduced scan time by nearly one half while improving lesion conspicuity and maintaining overall image quality in a prospective clinical cohort.
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Neoplasias de la Mama , Femenino , Humanos , Neoplasias de la Mama/diagnóstico por imagen , Quistes , Aprendizaje Profundo , Imagen de Difusión por Resonancia Magnética/métodos , Imagen Eco-Planar/métodos , Imagen por Resonancia Magnética , Estudios Prospectivos , Reproducibilidad de los Resultados , Masculino , Adulto , Persona de Mediana Edad , Anciano , Mama/diagnóstico por imagenRESUMEN
INTRODUCTION/OBJECTIVE: Treatment results of anorexia nervosa (AN) are modest, with fear of weight gain being a strong predictor of treatment outcome and relapse. Here, we present a virtual reality (VR) setup for exposure to healthy weight and evaluate its potential as an adjunct treatment for AN. METHODS: In two studies, we investigate VR experience and clinical effects of VR exposure to higher weight in 20 women with high weight concern or shape concern and in 20 women with AN. RESULTS: In study 1, 90% of participants (18/20) reported symptoms of high arousal but verbalized low to medium levels of fear. Study 2 demonstrated that VR exposure to healthy weight induced high arousal in patients with AN and yielded a trend that four sessions of exposure improved fear of weight gain. Explorative analyses revealed three clusters of individual reactions to exposure, which need further exploration. CONCLUSIONS: VR exposure is a well-accepted and powerful tool for evoking fear of weight gain in patients with AN. We observed a statistical trend that repeated virtual exposure to healthy weight improved fear of weight gain with large effect sizes. Further studies are needed to determine the mechanisms and differential effects.
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Anorexia Nerviosa , Realidad Virtual , Humanos , Femenino , Anorexia Nerviosa/terapia , Miedo , Resultado del Tratamiento , Aumento de PesoRESUMEN
Root anatomical phenotypes present a promising yet underexploited avenue to deliver major improvements in yield and climate resilience of crops by improving water and nutrient uptake. For instance, the formation of root cortical aerenchyma (RCA) significantly increases soil exploration and resource capture by reducing the metabolic costs of root tissue. A key bottleneck in studying such phenotypes has been the lack of robust high-throughput anatomical phenotyping platforms. We exploited a phenotyping approach based on laser ablation tomography, termed Anatomics, to quantify variation in RCA formation of 436 diverse maize lines in the field. Results revealed a significant and heritable variation for RCA formation. Genome-wide association studies identified a single-nucleotide polymorphism mapping to a root cortex-expressed gene-encoding transcription factor bHLH121. Functional studies identified that the bHLH121 Mu transposon mutant line and CRISPR/Cas9 loss-of-function mutant line showed reduced RCA formation, whereas an overexpression line exhibited significantly greater RCA formation when compared to the wild-type line. Characterization of these lines under suboptimal water and nitrogen availability in multiple soil environments revealed that bHLH121 is required for RCA formation developmentally as well as under studied abiotic stress. Overall functional validation of the bHLH121 gene's importance in RCA formation provides a functional marker to select varieties with improved soil exploration and thus yield under suboptimal conditions.
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Factores de Transcripción , Zea mays , Zea mays/metabolismo , Factores de Transcripción/metabolismo , Estudio de Asociación del Genoma Completo , Raíces de Plantas/metabolismo , Suelo , Agua/metabolismoRESUMEN
BACKGROUND: Genome wide association (GWA) studies demonstrate linkages between genetic variants and traits of interest. Here, we tested associations between single nucleotide polymorphisms (SNPs) in rice (Oryza sativa) and two root hair traits, root hair length (RHL) and root hair density (RHD). Root hairs are outgrowths of single cells on the root epidermis that aid in nutrient and water acquisition and have also served as a model system to study cell differentiation and tip growth. Using lines from the Rice Diversity Panel-1, we explored the diversity of root hair length and density across four subpopulations of rice (aus, indica, temperate japonica, and tropical japonica). GWA analysis was completed using the high-density rice array (HDRA) and the rice reference panel (RICE-RP) SNP sets. RESULTS: We identified 18 genomic regions related to root hair traits, 14 of which related to RHD and four to RHL. No genomic regions were significantly associated with both traits. Two regions overlapped with previously identified quantitative trait loci (QTL) associated with root hair density in rice. We identified candidate genes in these regions and present those with previously published expression data relevant to root hair development. We re-phenotyped a subset of lines with extreme RHD phenotypes and found that the variation in RHD was due to differences in cell differentiation, not cell size, indicating genes in an associated genomic region may influence root hair cell fate. The candidate genes that we identified showed little overlap with previously characterized genes in rice and Arabidopsis. CONCLUSIONS: Root hair length and density are quantitative traits with complex and independent genetic control in rice. The genomic regions described here could be used as the basis for QTL development and further analysis of the genetic control of root hair length and density. We present a list of candidate genes involved in root hair formation and growth in rice, many of which have not been previously identified as having a relation to root hair growth. Since little is known about root hair growth in grasses, these provide a guide for further research and crop improvement.
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Estudio de Asociación del Genoma Completo , Oryza , Fenotipo , Sitios de Carácter Cuantitativo/genética , Genómica , Diferenciación Celular , Oryza/genética , Polimorfismo de Nucleótido Simple/genéticaRESUMEN
Suboptimal nutrient and water availability are primary constraints to crop growth. Global agriculture requires crops with greater nutrient and water efficiency. Multiseriate cortical sclerenchyma (MCS), a root anatomical trait characterized by small cells with thick cell walls encrusted with lignin in the outer cortex, has been shown to be an important trait for adaptation in maize and wheat in mechanically impeded soils. However, MCS has the potential to improve edaphic stress tolerance in a number of different crop taxa and in a number of different environments. This review explores the functional implications of MCS as an adaptive trait for water and nutrient acquisition and discusses future research perspectives on this trait for incorporation into crop breeding programs. For example, MCS may influence water and nutrient uptake, resistance to pests, symbiotic interactions, microbial interactions in the rhizosphere and soil carbon deposition. Root anatomical phenotypes are underutilized; however, important breeding targets for the development of efficient, productive and resilient crops urgently needed in global agriculture.
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Soil compaction represents a major agronomic challenge, inhibiting root elongation and impacting crop yields. Roots use ethylene to sense soil compaction as the restricted air space causes this gaseous signal to accumulate around root tips. Ethylene inhibits root elongation and promotes radial expansion in compacted soil, but its mechanistic basis remains unclear. Here, we report that ethylene promotes abscisic acid (ABA) biosynthesis and cortical cell radial expansion. Rice mutants of ABA biosynthetic genes had attenuated cortical cell radial expansion in compacted soil, leading to better penetration. Soil compaction-induced ethylene also up-regulates the auxin biosynthesis gene OsYUC8. Mutants lacking OsYUC8 are better able to penetrate compacted soil. The auxin influx transporter OsAUX1 is also required to mobilize auxin from the root tip to the elongation zone during a root compaction response. Moreover, osaux1 mutants penetrate compacted soil better than the wild-type roots and do not exhibit cortical cell radial expansion. We conclude that ethylene uses auxin and ABA as downstream signals to modify rice root cell elongation and radial expansion, causing root tips to swell and reducing their ability to penetrate compacted soil.
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Ácido Abscísico , Etilenos , Ácidos Indolacéticos , Oryza , Raíces de Plantas , Ácido Abscísico/metabolismo , Etilenos/metabolismo , Ácidos Indolacéticos/metabolismo , Oxigenasas de Función Mixta/genética , Oxigenasas de Función Mixta/metabolismo , Mutación , Oryza/genética , Oryza/crecimiento & desarrollo , Oryza/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , SueloRESUMEN
BACKGROUND: Plastic responses of plants to the environment are ubiquitous. Phenotypic plasticity occurs in many forms and at many biological scales, and its adaptive value depends on the specific environment and interactions with other plant traits and organisms. Even though plasticity is the norm rather than the exception, its complex nature has been a challenge in characterizing the expression of plasticity, its adaptive value for fitness and the environmental cues that regulate its expression. SCOPE: This review discusses the characterization and costs of plasticity and approaches, considerations, and promising research directions in studying plasticity. Phenotypic plasticity is genetically controlled and heritable; however, little is known about how organisms perceive, interpret and respond to environmental cues, and the genes and pathways associated with plasticity. Not every genotype is plastic for every trait, and plasticity is not infinite, suggesting trade-offs, costs and limits to expression of plasticity. The timing, specificity and duration of plasticity are critical to their adaptive value for plant fitness. CONCLUSIONS: There are many research opportunities to advance our understanding of plant phenotypic plasticity. New methodology and technological breakthroughs enable the study of phenotypic responses across biological scales and in multiple environments. Understanding the mechanisms of plasticity and how the expression of specific phenotypes influences fitness in many environmental ranges would benefit many areas of plant science ranging from basic research to applied breeding for crop improvement.
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Evolución Biológica , Señales (Psicología) , Adaptación Fisiológica/genética , Fenotipo , Plantas/genéticaRESUMEN
(1) Background: Transjugular intrahepatic portosystemic shunt (TIPS) is a standard therapy for portal hypertension. We aimed to explore the association of established baseline scores with TIPS outcomes. (2) Methods: In total, 136 liver cirrhosis patients underwent TIPS insertion, mainly to treat refractory ascites (86%), between January 2016 and December 2019. An external validation cohort of 187 patients was chosen. (3) Results: The majority of the patients were male (62%); the median follow-up was 715 days. The baseline ChildTurcotte−Pugh stage was A in 14%, B in 75% and C in 11%. The patients' liver-transplant-free (LTF) survival rates after 3, 12 and 24 months were 87%, 72% and 61%, respectively. In the univariate analysis, neither bilirubin, nor the international normalized ratio (INR), nor liver enzymes were associated with survival. However, both the APRI (AST-to-platelet ratio index) and the FIB-4 (fibrosis-4 score) were associated with LTF survival. For patients with FIB-4 > 3.25, the hazard ratio for mortality after 2 years was 3.952 (p < 0.0001). Liver-related clinical events were monitored for 24 months. High FIB-4 scores were predictive of liver-related events (HR = 2.404, p = 0.001). Similarly, in our validation cohort, LTF survival was correlated with the APRI and FIB-4 scores. (4) Conclusions: Well-established scores that reflect portal hypertension and biochemical disease activity predict long-term outcomes after TIPS and support clinical decisions over TIPS insertion.
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Efforts to understand the phenotypic transition that gave rise to maize from teosinte have mainly focused on the analysis of aerial organs, with little insights into possible domestication traits affecting the root system. Archeological excavations in San Marcos cave (Tehuacán, Mexico) yielded two well-preserved 5,300 to 4,970 calibrated y B.P. specimens (SM3 and SM11) corresponding to root stalks composed of at least five nodes with multiple nodal roots and, in case, a complete embryonic root system. To characterize in detail their architecture and anatomy, we used laser ablation tomography to reconstruct a three-dimensional segment of their nodal roots and a scutellar node, revealing exquisite preservation of the inner tissue and cell organization and providing reliable morphometric parameters for cellular characteristics of the stele and cortex. Whereas SM3 showed multiple cortical sclerenchyma typical of extant maize, the scutellar node of the SM11 embryonic root system completely lacked seminal roots, an attribute found in extant teosinte and in two specific maize mutants: root with undetectable meristem1 (rum1) and rootless concerning crown and seminal roots (rtcs). Ancient DNA sequences of SM10a third San Marcos specimen of equivalent age to SM3 and SM11revealed the presence of mutations in the transcribed sequence of both genes, offering the possibility for some of these mutations to be involved in the lack of seminal roots of the ancient specimens. Our results indicate that the root system of the earliest maize from Tehuacán resembled teosinte in traits important for maize drought adaptation.
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Domesticación , Zea mays , México , Fenotipo , Zea mays/genéticaRESUMEN
BACKGROUND AND AIMS: Deep roots (i.e. >1 m depth) are important for crops to access water when the topsoil is dry. Root anatomy and hydraulic conductance play important roles in the uptake of soil water, particularly water located deep in the soil. We investigated whether root and xylem anatomy vary as a function of root type, order and length, or with soil depth in roots of two deep-rooted perennial crops: intermediate wheatgrass [Thinopyrum intermedium (Kernza®)] and alfalfa (Medicago sativa). We linked the expression of these anatomical traits to the plants' capacity to take up water from deep soil layers. METHODS: Using laser ablation tomography, we compared the roots of the two crops for cortical area, number and size of metaxylem vessels, and their estimated root axial hydraulic conductance (ERAHCe). The deepest roots investigated were located at soil depths of 2.25 and at 3.5 m in the field and in rhizoboxes, respectively. Anatomical differences were characterized along 1-m-long individual roots, among root types and orders, as well as between environmental conditions. KEY RESULTS: For both crops, a decrease in the number and diameter, or both, of metaxylem vessels along individual root segments and with soil depth in the field resulted in a decrease in ERAHCe. Alfalfa, with a greater number of metaxylem vessels per root throughout the soil profile and, on average, a 4-fold greater ERAHCe, took up more water from the deep soil layers than intermediate wheatgrass. Root anatomical traits were significantly different across root types, classes and growth conditions. CONCLUSIONS: Root anatomical traits are important tools for the selection of crops with enhanced exploitation of deep soil water. The development and breeding of perennial crops for improved subsoil exploitation will be aided by greater understanding of root phenotypes linked to deep root growth and activity.
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Medicago sativa , Suelo , Productos Agrícolas/metabolismo , Medicago sativa/metabolismo , Raíces de Plantas , Agua/metabolismo , Xilema/metabolismoRESUMEN
Anatomics is a novel phenotyping strategy focused on high-throughput imaging and quantification of plant anatomy from field-grown plants. Here we highlight its potential applications for genetic and physiological analysis of plant anatomical phenotypes.