The absence of oxidized leghemoglobin in soybean root nodules during nodule development.
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The effects of NH4NO3 on the development of root nodules of Pisum sativum after infection with Rhizobium leguminosarum (strain PRE) and on the nitrogenase activity of the bacteroids in the nodule tissue were studied. The addition of NH4NO3 decreased the nitrogenase activity measured on intact nodules. This reduction of nitrogen fixation did not result from a reduced number of bacteroids or a decreased amount of bacteroid proteins per gram of nodule. The synthesis of nitrogenase, measured as the relative amount of incorporation of [35S]sulfate into the components I and II of nitrogenase was similarly not affected. The addition of NH4NO3 decreased the amount of leghemoglobin in the nodules and there was a quantitative correlation between the leghemoglobin content and the nitrogen-fixing capacity of the nodules. The conclusion is that the decrease of nitrogen-fixing capacity is caused by a decrease of the leghemoglobin content of the root nodules and not by repression of the nitrogenase synthesis.
In order to determine the number of structural genes expressed specifically in root nodules, the total complexities of poly(A) + polysomal RNA populations from uninfected roots and mature nodules were compared. Hybridization kinetics of nodule poly(A) + RNA (NRNA) to its cDNA (NcDNA) revealed a very abundant component comprising 18--20% of the NRNA. This component was shown to be leghaemoglobin (Lb) by the similarity of its kinetics of hybridization to that of purified Lb-cDNA. The hybridization kinetics of uninfected root cDNA (RcDNA) to root poly(A) + RNA (RRNA) indicate that this abundant RNA fraction is absent in RRNA. The extent of sequence homologies between root and nodule tissue was determined by heterologous hybridizations of RcDNA to NRNA and vice versa. The data suggest that the mRNA populations of the two tissues are substantially homologous, though shifts in abundance of certain sequences are quite marked. The hybridization of purified Lb-cDNA to total polysomal RNA from developing nodules shows that the increase in concentration of Lb-mRNA sequences parallels the leghaemoglobin synthesis in this tissue. Lb sequences appear to increase between 8 and 13 days after infection with Rhizobium.
We have developed a procedure for testing iduronate sulfatase, the enzyme deficient in Hunter syndrome, in single hair roots. Beta-Hexosaminidase was used as the reference enzyme. The ratio of iduronate sulfatase to beta--hexosaminidase, expressed in arbitrary units of activity, is near zero for Hunter patients and greater than 0.6 in almost all roots of normal individuals. Hair roots of Hunter heterozygotes show a characteristic continuum of activity ratios, ranging from totally deficient up to and including the normal range. The results are consistent with the origin of hair roots from a small number of progenitor cells which obey the Lyon hypothesis. The proportion of roots with low activity can be used to discriminate between normal and heterozygous individuals.
Understanding root system architecture is critical for improving crop productivity and resilience, yet phenotyping root traits such as root growth angle and rooting depth remains technically challenging, especially at high throughput. Here, we present ClearDepthIAS, a high-throughput imaging and analysis platform that enables nondestructive, automated quantification of root architecture traits in taproot system crops. By capturing and stitching 360° images of roots growing along the transparent walls of pots and applying deep learning-based segmentation (ClearDepth-WRT), we measured wall root shallowness (WRS)-a proxy for root growth angle-with high precision. We demonstrated for the tap root systems of soybean and canola that the system accurately detects root tips, quantifies their vertical distribution, and extracts biologically meaningful traits such as root area, distribution indices, and growth angles. Validation experiments in canola and soybean demonstrated that WRS can correlate with root crown architecture in mature plants, both in greenhouse and field settings. Furthermore, WRS and root distribution indices derived from ClearDepthIAS are predictors of early root architecture and can be correlated with root biomass distribution across soil depths under field conditions; however, environmental interactions may influence these relationships and weaken or even negate such correlations, as observed when comparing field to field variation in root system architecture. Our system enables efficient phenotyping of genetically diverse populations, with medium to high trait heritability, supporting its utility for genome-wide association studies and breeding. ClearDepthIAS accelerates the development of root ideotypes for improved resource acquisition and carbon sequestration, offering a scalable tool for supporting climate-resilient agriculture.
The process of root hair formation has been studied by light-, transmission-and scanning electron microscopy. In the course of root hair development a break of the outer cell wall is observed by electron microscopy. It apparently occurs after the break of the fibrillar layer. The break of the outer layer of the cell wall is assumed to represent the break of the outer mucilage, the cuticle and the adjoining amorphous matrix with irregularly oriented cellulose microfibrils. The scheme of successive ultrastructural changes in the outer cell wall pattern during root hair formation is presented.
The inoculation of the European Alnus glutinosa (L.) Gaertn. host plant by a crushed-nodule inoculum, prepared with the North-American Alnus crispa var. mollis Fern. root nodule, was successful. Fluorescein- and ferritin-labelled antibodies, specific against the A. crispa var. mollis root nodule endophyte (Lalonde et al. 1975), demonstrated the idenity of this endophyte in the resulting nodules. The nodulation process of this abnormal host-endophyte system was studied by light and electron microscopy. An excretion of host blebs containing electron-dense polysaccharide material, resulting in the formation of exo-encapsulation threads containing presumptive endophytic bacterial cells, was associated with deformed root hairs. Originating from an exoencapsulation thread, the endophyte penetrates the root hair cell and then migrates as a hypha toward the cortical cells of the root. Its migration in the cortical cells of the primary nodule results in the induction of a lateral root which develops as the true nodule. The ultrastructure of the A. crispa var. mollis endophyte developing in the primary and true nodule of the abnormal A. glutinosa host was similar to the one induced inside its normal A. crispa var. mollis host. The actinomycetal intruder was a branched and septate hypha able to produce septate vesicles. The endophyte was always encapsulated in an electron-dense polysaccharide material surrounded by a host plasma membrane envelope. However, in this abnormal host-endophyte system, the number of primary nodules formed per root system was drastically reduced, and their appearance was delayed by 1 to 2 weeks. The delayed nodules were effective in fixing nitrogen and able to support satisfactory plant growth in a nitrogen-free medium.
Small nucleolar RNAs (snoRNAs) function in ribosome biogenesis, and many ribosome biogenesis-related genes were downregulated by osmotic stress, implying a negative role of snoRNAs in drought tolerance. A snoRNA, namely, the NON-CODING RNA 1 (NCR1) was studied for its roles in drought tolerance in Arabidopsis. In comparison with wild-type (WT) plants, the loss-of-function ncr1 mutant plants showed enhanced drought tolerance, which was restored in the NCR1-complemented plants, whereas the NCR1-overexpressing plants revealed a drought-sensitive phenotype. Physiological analyses revealed that the ncr1 plants had a higher leaf surface temperature, lower water loss rates, and improved cell membrane integrity compared with WT. Comparative leaf transcriptomics and proteomics suggested that wax biosynthesis, anthocyanin metabolism, and leaf senescence processes are regulated by NCR1 under both normal and water-deficit conditions. Under drought, an increase in wax and anthocyanin accumulations and a delay in leaf senescence in ncr1 plants, when compared with WT, supported the transcriptome and proteomics data. Additionally, the ncr1 plants exhibited higher abscisic acid (ABA) sensitivity and longer root hairs than WT. Collectively, our results suggest that NCR1 negatively regulates drought tolerance through modification of wax biosynthesis, anthocyanin accumulation, leaf senescence, cell membrane integrity, ABA responses, and root hair development.
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The stable 3St(3D) substitution line offers promising genetic potential for improving drought tolerance in wheat during critical reproductive stages. The flowering stage is highly susceptible to drought, which significantly reduces wheat grain yield globally. Low genetic diversity in wheat further limits the discovery of optimal gene variants for breeding climate-resilient varieties. The substitution of chromosome 3D by a group 3 chromosome pair from Thinopyrum intermedium × Th. ponticum artificial hybrid was identified using in situ hybridization and genotyping-by-sequencing. This homoeologous substitution showed good functional compensation for grain yield and fertility, similar to the wheat parents ('Mv9kr1' and 'Mv Karizma') in field and greenhouse trials. The substitution line exhibits a semidwarf phenotype due to the Rht8 and Rht2 dwarfing alleles. Automated shoot phenotyping after a 10-day water withdrawal at flowering revealed efficient water preservation allowing to maintain photosynthetic functions, sustained photosynthetic activity, and less chlorophyll degradation, indicated by Normalized Difference Vegetation Index (NDVI) and modified Normalized Difference Index (mND705) values and moderate level of protective functions shown by the expression of stress-related genes. Compared to the wheat parents, the substitution line developed thicker roots with increased volume under drought, resulting in a lower surface-to-volume ratio. This may enhance water storage efficiency and help reduce yield loss under drought conditions.
In contrast with patients with herniations of the nucleus pulposus, those with spinal stenosis experience onset of symptoms at a slightly older age; more males are affected than females. The symptoms tend to be somewhat more chronic, and therefore, the patients will have symptoms of back pain for a longer period of time before developing radiating root pains and will not come to surgical treatment until relatively late. Bilateral root symptomatology is more common although examination shows multiple nerve root involvement only slightly more frequently as well as involvement of the L1 to L4 nerve roots. The spinal movements tend to be somewhat better and straight leg raising tests are usually symmetrical and somewhat less restricted in those patients than in the acute disk syndrome. Postfusion and post-chemonucleolysis spinal stenosis will, of course, have the symptomatology of the initial problem, but their recurrent problems would tend to parallel those of spinal stenosis rather than disk herniation.
Huanglongbing (HLB) disease, associated with the fastidious bacterium Candidatus Liberibacter asiaticus (CLas), has a significant impact on citrus production worldwide. Conventional biochemical and genetic evaluation studies to identify potential disease resistance strategies have been mainly hindered due to the inability to culture CLas in a defined medium and the general recalcitrance of Citrus cultivars (grapefruits and oranges) to Agrobacterium-mediated plant transformation. We previously demonstrated the utility of plant hairy roots to co-cultivate CLas. In this study, we developed a hairy root transformation system using citron (Citrus medica L.), which is highly amenable to Rhizobium-mediated hairy root transformation. The explant survival and hairy root transformation efficiencies were up to 100% and 73%, respectively, and transgenic roots can be attained in as little as 30-60 days. We demonstrate the utility of this citron-based hairy root transformation for rapid CRISPR/Cas9-mediated gene editing, transgene evaluation, and antimicrobial efficacy testing. The citron-based hairy root transformation system will significantly help the research community to speed-track the assessment of potential HLB disease resistance strategies.
The purpose of the investigation was clinically, microbiologically and radiologically to assess the effect of calcium hydroxide as a temporary root-filling inserted in the same sitting as root canal debridement in non-vital permanent incisors with mature and immature root, infected or uninfected root canal and with or without radiologically demonstrated periapical bone changes. The material consisted of 141 teeth divided in 3 groups in which mechanical cleansing was accompanied by flushing with sterile saline and sodium hypochlorite solutions giving 0.5% or 5.0% active chlorine, respectively. Microbiological samples were taken from root canals after extirpation of necrotic pulp tissue, after completed cleansing of the root canal and 3 and 6 month after treatment. Results of treatment were evaluated from the radiographs taken before treatment and at the 3 and 6 month follow-ups. Complication, pain and an abscess, occurred in 2 cases, 2 and 5 days, respectively, after treatment. No statistical correlation between occurrence of samples that gave growth, taken from the root canals at 3 (8%) or 6-month control (9%) and 1) bacteriological status of the root canal prior to filling with calcium hydroxide, 2) the development of the root or 3) periapical healing at 3 or 6 month follow-up could be ascertained. Periapical bone healing at the end of 6-months observation period was noted in 61 teeth (46%), regression of periapical bone lesions in 64 (49%) and no periapical healing in 6 (5%). The only difference in healing pattern, statistically significant on 0.1% level, was found in the group of teeth flushed with 5.0% sodium hypochlorite. At 3 month control they showed percentually less cases with regression and more cases with no healing of periapical bone lesions than the teeth in the other two groups. It was concluded that treatment in one sitting can be done routinely, irrespective of the initial status, in all those cases where no other treatment is possible. If the periodontium or the periapical bone are injured during cleansing procedures or if necrotic rests are not pressed out through the apical foramen, no complications after treatment need to be feared.
Root cell fate and patterning in plants are orchestrated by the expression of cell-type-specific genes, including WEREWOLF (WER). Phylogenetic analysis of WER, functional WER homologs in Type III species (Rhodiola rosea and Boehmeria nivea), and related R2R3 MYB proteins identified in the cotton genome revealed that GhMYB109-a known regulator of fiber development in cotton ovules-clustered in a clade with Arabidopsis thaliana WER. To determine whether GhMYB109 is a functional homolog of WER, we expressed GhMYB109 under the control of the CaMV 35S promoter in the Arabidopsis thaliana wer-1 mutant and analyzed root epidermal cell patterning by counting root hairs. GhMYB109 expression significantly decreased the percentage of root hairs at both H and N positions. We found that most epidermal cells in the cotton root develop into root hairs (Type I pattern) although the cotton genome contains a functional WER homolog, GhMYB109. Additionally, GhMYB109 has been reported not to be expressed in cotton roots. These support the idea that GhMYB109 is a functional homolog of WER and that Arabidopsis thaliana and cotton diverged in root epidermal morphology through modifications in cis-regulatory elements rather than a functional divergence of their WER-like R2R3 MYB transcription factors.
Although the potential of microbial inoculants for sustainable agriculture and environmental restoration has been widely recognized, their field performance remains highly variable and often unpredictable. Current research and development frameworks for microbial inoculants primarily focus on their plant growth-promoting functions and metabolic traits, often overlooking the ecological processes that determine whether introduced strains can successfully disperse, access, and establish within the rhizosphere. Increasing evidence suggests that successful dispersal and establishment cannot be assumed in the highly heterogeneous conditions of soil systems. Here, we summarize the key mechanisms underlying bacterial motility and discuss its role within the broader framework of microbial dispersal, highlighting how motility-mediated processes contribute to rhizosphere colonization. We propose that bacterial motility represents a key mechanistic determinant of biofertilizer efficacy. Its role extends beyond the ability of inoculant strains to physically reach the rhizosphere, encompassing competitive colonization on the root surface, long-term persistence, and the ability to respond to dynamic root-derived chemical gradients associated with newly developing root tissues. We argue that inoculant motility should be elevated from a passive descriptive trait to a core design parameter that can be systematically incorporated and regulated during the development and optimization of microbial inoculants. We outline a multi-tiered strategic framework for next-generation biofertilizer engineering that integrates strain selection, community design, motility regulation, and deployment strategies, thereby unlocking the full potential of synthetic microbial consortia for sustainable agriculture, ecosystem restoration, and climate change mitigation.
Transplantation of 28 maxillary canines was followed up in 22 patients with an average age of 25.2 s.d. 9.9 years. The root was fully developed. The mean immobilization time was 6.6 weeks and the mean follow-up period 17.8 months. Results seemed to be better in the age group of 13--20 years than in 21--30 and 31--47 years. Statistically significant better results were found in the youngest than in the older groups in the return of vitality, vertical bone resorption, periodontal space in the lamina dura. Four of the 28 teeth were extracted because of great mobility caused by poor bone regeneration and vertical resorption of the alveolar bone: three in the middle age group and one in the oldest. Pulp extirpation was performed on nine teeth: six in the oldest group and three in the middle group. Vitality returned in only three teeth, all of which belonged to the youngest group. Root resorption was observed in all age groups; in 76% of the cases it occurred in the apical third, and was generally inflammatory. The causes of the failure of transplantation were considered to include damage of the transplant during removal from deep palatal malposition, poor regeneration of the bone around the transplant and chronic periodontal infection. The prognosis for transplantation was found to be fairly good for patients under 20 years of age but poorer for older age groups.