Changes in hormonal balance and meristematic activity in primary root tips on the slowly rotating clinostat and their effect on the development of the rapeseed root system

Abstract Rhizotaxis is established under changing environmental conditions via periodic priming of lateral root (LR) initiation at the root tips and adaptive LR formation along the primary root (PR). In contrast to the adaptable LR formation in response to nutrient availability, there is little information on root development during interactions with beneficial microbes. The Arabidopsis root system is characteristically modified upon colonization by the root endophytic fungus Serendipita indica, accompanied by a marked stimulation of LR formation and the inhibition of PR growth. This root system modification has been attributed to endophyte-derived indole-3-acetic acid (IAA). However, it has yet to be clearly explained how fungal IAA affects the intrinsic LR formation process. In this study, we show that diffusible compounds (chemical signals) other than IAA are present in the coculture medium of Arabidopsis and S. indica and induce auxin-responsive DR5::GUS expression in specific sections within the pericycle layer. The DR5::GUS expression was independent of polar auxin transport and the major IAA biosynthetic pathways, implicating unidentified mechanisms responsible for the auxin response and LR formation. Detailed metabolite analysis revealed the presence of multiple compounds that induce local auxin responses and LR formation. We found that benzoic acid (BA) cooperatively acted with exogenous IAA to generate a local auxin response in the pericycle layer, suggesting that BA is one of the chemical signals involved in adaptable LR formation. Identification and characterization of the chemical signals will contribute to a greater understanding of the molecular mechanisms underlying adaptable root development and to unconventional technologies for sustainable agriculture.

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Comprehensive Genome-Wide Association Analysis Reveals the Genetic Basis of Root System Architecture in Soybean

Frontiers in Plant Science ◽

10.3389/fpls.2020.590740 ◽

2020 ◽

Vol 11 ◽

Author(s):

Waldiodio Seck ◽

Davoud Torkamaneh ◽

François Belzile

Keyword(s):

Root System ◽

System Architecture ◽

Phenotypic Variation ◽

Genetic Basis ◽

Genome Wide Association Study ◽

Primary Root ◽

Root System Architecture ◽

Genome Wide Association ◽

Nucleotide Polymorphisms ◽

Genome Wide

Increasing the understanding genetic basis of the variability in root system architecture (RSA) is essential to improve resource-use efficiency in agriculture systems and to develop climate-resilient crop cultivars. Roots being underground, their direct observation and detailed characterization are challenging. Here, were characterized twelve RSA-related traits in a panel of 137 early maturing soybean lines (Canadian soybean core collection) using rhizoboxes and two-dimensional imaging. Significant phenotypic variation (P < 0.001) was observed among these lines for different RSA-related traits. This panel was genotyped with 2.18 million genome-wide single-nucleotide polymorphisms (SNPs) using a combination of genotyping-by-sequencing and whole-genome sequencing. A total of 10 quantitative trait locus (QTL) regions were detected for root total length and primary root diameter through a comprehensive genome-wide association study. These QTL regions explained from 15 to 25% of the phenotypic variation and contained two putative candidate genes with homology to genes previously reported to play a role in RSA in other species. These genes can serve to accelerate future efforts aimed to dissect genetic architecture of RSA and breed more resilient varieties.

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Effect of earthworms on mycorrhization, root morphology and biomass of silver fir seedlings inoculated with black summer truffle (Tuber aestivum Vittad.)

Scientific Reports ◽

10.1038/s41598-021-85497-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tina Unuk Nahberger ◽

Gian Maria Niccolò Benucci ◽

Hojka Kraigher ◽

Tine Grebenc

Keyword(s):

Root System ◽

Root Biomass ◽

Fine Root ◽

Abies Alba ◽

Fine Root Biomass ◽

Root Tip ◽

Silver Fir ◽

Tuber Aestivum ◽

Root Tips ◽

Root Parameters

AbstractSpecies of the genus Tuber have gained a lot of attention in recent decades due to their aromatic hypogenous fruitbodies, which can bring high prices on the market. The tendency in truffle production is to infect oak, hazel, beech, etc. in greenhouse conditions. We aimed to show whether silver fir (Abies alba Mill.) can be an appropriate host partner for commercial mycorrhization with truffles, and how earthworms in the inoculation substrate would affect the mycorrhization dynamics. Silver fir seedlings inoculated with Tuber. aestivum were analyzed for root system parameters and mycorrhization, how earthworms affect the bare root system, and if mycorrhization parameters change when earthworms are added to the inoculation substrate. Seedlings were analyzed 6 and 12 months after spore inoculation. Mycorrhization with or without earthworms revealed contrasting effects on fine root biomass and morphology of silver fir seedlings. Only a few of the assessed fine root parameters showed statistically significant response, namely higher fine root biomass and fine root tip density in inoculated seedlings without earthworms 6 months after inoculation, lower fine root tip density when earthworms were added, the specific root tip density increased in inoculated seedlings without earthworms 12 months after inoculation, and general negative effect of earthworm on branching density. Silver fir was confirmed as a suitable host partner for commercial mycorrhization with truffles, with 6% and 35% mycorrhization 6 months after inoculation and between 36% and 55% mycorrhization 12 months after inoculation. The effect of earthworms on mycorrhization of silver fir with Tuber aestivum was positive only after 6 months of mycorrhization, while this effect disappeared and turned insignificantly negative after 12 months due to the secondary effect of grazing on ectomycorrhizal root tips.

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QTL mapping of root traits in wheat under different phosphorus levels using hydroponic culture

BMC Genomics ◽

10.1186/s12864-021-07425-4 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Mengjiao Yang ◽

Cairong Wang ◽

Muhammad Adeel Hassan ◽

Faji Li ◽

Xianchun Xia ◽

...

Keyword(s):

Root System ◽

Phenotypic Diversity ◽

Nutrient Use Efficiency ◽

Snp Array ◽

P Uptake ◽

Hydroponic Culture ◽

Seedling Stage ◽

Root Surface Area ◽

Root Tips ◽

Phenotypic Effect

Abstract Background Phosphorus (P) is an important in ensuring plant morphogenesis and grain quality, therefore an efficient root system is crucial for P-uptake. Identification of useful loci for root morphological and P uptake related traits at seedling stage is important for wheat breeding. The aims of this study were to evaluate phenotypic diversity of Yangmai 16/Zhongmai 895 derived doubled haploid (DH) population for root system architecture (RSA) and biomass related traits (BRT) in different P treatments at seedling stage using hydroponic culture, and to identify QTL using 660 K SNP array based high-density genetic map. Results All traits showed significant variations among the DH lines with high heritabilities (0.76 to 0.91) and high correlations (r = 0.59 to 0.98) among all traits. Inclusive composite interval mapping (ICIM) identified 34 QTL with 4.64–20.41% of the phenotypic variances individually, and the log of odds (LOD) values ranging from 2.59 to 10.43. Seven QTL clusters (C1 to C7) were mapped on chromosomes 3DL, 4BS, 4DS, 6BL, 7AS, 7AL and 7BL, cluster C5 on chromosome 7AS (AX-109955164 - AX-109445593) with pleiotropic effect played key role in modulating root length (RL), root tips number (RTN) and root surface area (ROSA) under low P condition, with the favorable allele from Zhongmai 895. Conclusions This study carried out an imaging pipeline-based rapid phenotyping of RSA and BRT traits in hydroponic culture. It is an efficient approach for screening of large populations under different nutrient conditions. Four QTL on chromosomes 6BL (2) and 7AL (2) identified in low P treatment showed positive additive effects contributed by Zhongmai 895, indicating that Zhongmai 895 could be used as parent for P-deficient breeding. The most stable QTL QRRS.caas-4DS for ratio of root to shoot dry weight (RRS) harbored the stable genetic region with high phenotypic effect, and QTL clusters on 7A might be used for speedy selection of genotypes for P-uptake. SNPs closely linked to QTLs and clusters could be used to improve nutrient-use efficiency.

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Root System Architecture Plasticity of Bread Wheat in Response to Oxidative Burst under Extended Osmotic Stress

Plants ◽

10.3390/plants10050939 ◽

2021 ◽

Vol 10 (5) ◽

pp. 939

Author(s):

Omar Azab ◽

Abdullah Al-Doss ◽

Thobayet Alshahrani ◽

Salah El-Hendawy ◽

Adel M. Zakri ◽

...

Keyword(s):

Oxidative Stress ◽

Membrane Potential ◽

Osmotic Stress ◽

Root System ◽

Bread Wheat ◽

System Architecture ◽

Mitochondrial Membrane ◽

Root System Architecture ◽

Root Tips ◽

Scavenging Capacity

There is a demand for an increase in crop production because of the growing population, but water shortage hinders the expansion of wheat cultivation, one of the most important crops worldwide. Polyethylene glycol (PEG) was used to mimic drought stress due to its high osmotic potentials generated in plants subjected to it. This study aimed to determine the root system architecture (RSA) plasticity of eight bread wheat genotypes under osmotic stress in relation to the oxidative status and mitochondrial membrane potential of their root tips. Osmotic stress application resulted in differences in the RSA between the eight genotypes, where genotypes were divided into adapted genotypes that have non-significant decreased values in lateral roots number (LRN) and total root length (TRL), while non-adapted genotypes have a significant decrease in LRN, TRL, root volume (RV), and root surface area (SA). Accumulation of intracellular ROS formation in root tips and elongation zone was observed in the non-adapted genotypes due to PEG-induced oxidative stress. Mitochondrial membrane potential (∆Ψm) was measured for both stress and non-stress treatments in the eight genotypes as a biomarker for programmed cell death as a result of induced osmotic stress, in correlation with RSA traits. PEG treatment increased scavenging capacity of the genotypes from 1.4-fold in the sensitive genotype Gemmiza 7 to 14.3-fold in the adapted genotype Sakha 94. The adapted genotypes showed greater root trait values, ∆Ψm plasticity correlated with high scavenging capacity, and less ROS accumulation in the root tissue, while the non-adapted genotypes showed little scavenging capacity in both treatments, accompanied by mitochondrial membrane permeability, suggesting mitochondrial dysfunction as a result of oxidative stress.

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AT-HOOK MOTIF NUCLEAR LOCALISED PROTEIN 18 as a Novel Modulator of Root System Architecture

10.20944/preprints202003.0046.v1 ◽

2020 ◽

Author(s):

Marek Šírl ◽

Tereza Šnajdrová ◽

Dolores Gutiérrez-Alanís ◽

Joseph G. Dubrovsky ◽

Jean Phillipe Vielle-Calzada ◽

...

Keyword(s):

Root System ◽

System Architecture ◽

Lateral Root ◽

Apical Meristem ◽

Lateral Roots ◽

Primary Root ◽

Root System Architecture ◽

Root Apical Meristem ◽

Root Initiation ◽

Lateral Root Initiation

The AT-HOOK MOTIF NUCLEAR LOCALIZED PROTEIN (AHL) gene family encodes embryophyte-specific nuclear proteins with DNA binding activity. They modulate gene expression and affect various developmental processes in plants. We identify AHL18 (At3G60870) as a developmental modulator of root system architecture and growth. AHL18 regulates the length of the proliferation domain and number of dividing cells in the root apical meristem and thereby, cell production. Both primary root growth and lateral root development respond according to AHL18 transcription level. The ahl18 knock-out plants show reduced root systems due to a shorter primary root and a lower number of lateral roots. This change results from a higher number of arrested and non-developing lateral root primordia (LRP) rather than from decreased initiation. Overexpression of AHL18 results in a more extensive root system, longer primary roots, and increased density of lateral root initiation events. Formation of lateral roots is affected during the initiation of LRP and later development. AHL18 regulate root apical meristem activity, lateral root initiation and emergence, which is in accord with localization of its expression.

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DEVELOPMENTAL STUDIES ON EUPHORBIA ESULA L.: MORPHOLOGY OF THE ROOT SYSTEM

Canadian Journal of Botany ◽

10.1139/b63-049 ◽

1963 ◽

Vol 41 (5) ◽

pp. 579-589 ◽

Cited By ~ 20

Author(s):

M. V. S. Raju ◽

T. A. Steeves ◽

R. T. Coupland

Keyword(s):

Root System ◽

Lateral Roots ◽

Primary Root ◽

Cambial Activity ◽

Euphorbia Esula ◽

Developmental Studies ◽

Limited Growth ◽

Mode Of Reproduction ◽

Shoot Buds ◽

Adverse Conditions

The significance of Euphorbia esula L. as a weed is related to its capacity to persist under adverse conditions and to its mode of reproduction. In both these properties, the root system plays an important role. The root system is initially established by seedlings. The seedling has a vigorous primary root with extensive longitudinal growth and considerable cambial activity. Such a root has been designated a "long" root. By contrast, the first lateral roots produced on the primary root have limited growth and no cambial activity. These roots have been termed "short" roots. Thus, the seedling exhibits a "heterorhizic" pattern. Lateral long roots also arise on the primary root of seedlings but their origin is delayed until cambial activity has begun. Such lateral long roots arise much earlier on seedlings growing in denuded areas than on those growing in areas covered by dense vegetation. The mature root system is described in terms of horizontal and vertical long roots, which make up the conspicuous framework of the system, and of the short roots which they produce. Long roots produce shoot-buds and the origin of these structures is delayed until cambial activity has started. Short roots do not give rise to shoot-buds. Cambial activity in long roots appears to be connected with bud production and its absence in short roots probably underlies their inability to produce buds.L'importance de Euphorbia esula L. comme mauvaise herbe est connexé a son capacité de persister dans les situations hostiles et à sa methode de reproduction. Dans ces deux caractéristiques, le système des racines a une signification profunde. Initialement le système des racines s'établit dans le semis. Le semis a une racine primaire très forte avec beaucoup de croissance longitudinale et avec une activité considérable du cambium. Une racine de cette espèce s'appelle une "longue" racine (long root). Par contre, les premières racines latérales que poussent sur la racine primaire ont croissance limité et aucun activité du cambium. Ces racines s'appellent les "courtes" racines (short roots). De cette façon, le semis montre un dessin "heterorhizique" (heterorhizic). Les longues racines latérales ont aussi leur origine sur la racine primaire du semis, mais l'origine est retardé jusqu'au commencement de l'activité du cambium. Les racines de cette espèce apparaissent beaucoup plus tôt sur les semis qui sont situés en terre sans autre végétation, que sur ceux qui sont situés au milieu des autres plantes. Le système adulte des racines se décrit sous forme des longues racines de l'espèce horizontale et verticale, lesquelles constituent la charpente bien visible du système, et des courtes racines que sont produites par les longues racines. Les longues racines produisent les bourgeons, mais l'origine des bourgeons est retardé jusqu'au commencement de l'activité du cambium dans les racines. Les courtes racines ne produisent pas les bourgeons. Il paraît que l'activité du cambium dans les longues racines soit corrélative avec l'initiation des bourgeons et l'absence du cambium dans les courtes racines explique probablement leur incapacité à produire les bourgeons.

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A biochemical study of BAS 517 using excised corn and soybean root systems

Weed Science ◽

10.1017/s0043174500090615 ◽

1999 ◽

Vol 47 (1) ◽

pp. 28-36

Author(s):

Hwei-Yiing Li ◽

Chester L. Foy

Keyword(s):

Root System ◽

Biochemical Study ◽

Lipid Fraction ◽

Root Systems ◽

Water Soluble ◽

Root Tips ◽

Soybean Root ◽

Corn Roots ◽

Tracer Techniques ◽

High Degree

The mode of action of BAS 517 in a susceptible plant species, corn, was investigated using an excised root system and14C-tracer techniques. The root system of a tolerant species, soybean, was used for comparison. When UL-14C- glucose was used as a precursor,14C incorporation into lipids was reduced in BAS 517-treated corn roots, although14C incorporation from UL-14C-glucose into lipids was relatively low. Inhibition of14C incorporation into water-soluble compounds was not definite because of a high degree of variability. Using14C-acetate as a precursor, 49, 43, and 34% of the recovered radioactivity was found in the lipid fractions of root tips treated with 0, 1.0, and 10 μM BAS 517, respectively. In nontreated soybean root tips, 47% of the recovered radioactivity was found in the lipid fraction compared to 49% in root tips treated with 10 μM BAS 517. Further analysis of lipids showed that BAS 517 inhibited the incorporation of14C from14C-acetate into phosphatidylethanolamine, a phospholipid, whereas the labeling of sterols in treated corn roots was not adversely affected. Acetyl CoA carboxylase extracted from root systems of corn and soybean showed different sensitivity to BAS 517, suggesting its role as the herbicide target site and as a basis for the selectivity.

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Effects of Phosphate Shortage on Root Growth and Hormone Content of Barley Depend on Capacity of the Roots to Accumulate ABA

Plants ◽

10.3390/plants9121722 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1722

Author(s):

Lidiya Vysotskaya ◽

Guzel Akhiyarova ◽

Arina Feoktistova ◽

Zarina Akhtyamova ◽

Alla Korobova ◽

...

Keyword(s):

Root Growth ◽

Lateral Roots ◽

Primary Root ◽

Growth Responses ◽

Root Tips ◽

P Deficiency ◽

Root Branching ◽

Auxin Concentration ◽

Shoot Mass ◽

Primary Root Length

Although changes in root architecture in response to the environment can optimize mineral and water nutrient uptake, mechanisms regulating these changes are not well-understood. We investigated whether P deprivation effects on root development are mediated by abscisic acid (ABA) and its interactions with other hormones. The ABA-deficient barley mutant Az34 and its wild-type (WT) were grown in P-deprived and P-replete conditions, and hormones were measured in whole roots and root tips. Although P deprivation decreased growth in shoot mass similarly in both genotypes, only the WT increased primary root length and number of lateral roots. The effect was accompanied by ABA accumulation in root tips, a response not seen in Az34. Increased ABA in P-deprived WT was accompanied by decreased concentrations of cytokinin, an inhibitor of root extension. Furthermore, P-deficiency in the WT increased auxin concentration in whole root systems in association with increased root branching. In the ABA-deficient mutant, P-starvation failed to stimulate root elongation or promote branching, and there was no decline in cytokinin and no increase in auxin. The results demonstrate ABA’s ability to mediate in root growth responses to P starvation in barley, an effect linked to its effects on cytokinin and auxin concentrations.

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Morphological and developmental investigations of the underground system of Erythroxylum species from Brazilian cerrado

Australian Journal of Botany ◽

10.1071/bt07060 ◽

2007 ◽

Vol 55 (7) ◽

pp. 749 ◽

Cited By ~ 11

Author(s):

Alexandre Antonio Alonso ◽

Silvia Rodrigues Machado

Keyword(s):

Root System ◽

Primary Root ◽

Additional Stress ◽

Aluminium Content ◽

Brazilian Cerrado ◽

Aerial Shoot ◽

Stage Of Development ◽

Slow Development ◽

Shrubby Species ◽

Underground System

Brazilian cerrado, a neotropical savanna, is characterised by a strongly seasonal climate with distinctive wet and dry seasons, and deep and well drained soils that are acidic and with high aluminium content. Recurrent fires in the dry season place additional stress on the survival of plants, which exhibit an array of strategies of survival. The purpose of this work was to study the underground system of Erythroxylum nanum A.St-Hil. and E. campestre A.St-Hil., two sub-shrubby species, and E. tortuosum Mart., a shrubby species, verifying the possible relationship between the morphology of the underground organs and the resprouting ability of these plants. Anatomical analyses followed the usual techniques of plant anatomy. The cotyledons of the three species were green, foliaceous and photosynthesising. The two sub-shrubby species (Erythroxylum nanum and E. campestre) showed slow development of the aerial shoot system and extensive growth of the primary root in the initial stage of development. E. tortuosum presented the most pronounced development of the aerial system and a poorly developed primary root compared with the sub-shrubby species. The sub-shrubby species occurred in clumps and had underground systems interlinked, consisting of a deep axial primary root system besides soboles in E. nanum and xylopodium in E. campestre. Plants of the E. tortuosum were isolated, highly branched and their underground system consisted of a superficial primary root system. Abundance of reserves and the bud-forming potential of the soboles, xylopodium and roots resulted in production of vigorous branches that are highly valuable in the regeneration of the aerial biomass following fire or seasonal dry in cerrado.

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