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PubMed1993

Root canal morphology of maxillary permanent first molar teeth at various ages.

The root canal anatomy and pulp chamber morphology of 216 maxillary permanent first molar teeth of known age was examined using a radiographic technique after infusion of the root canal system with a radiopaque sodium iothalomate gel. This technique proved to be a rapid and effective method for the examination of root canal morphology and is recommended when root canal anatomy needs to be examined before further investigations are carried out. Over 95% of palatal and disto-buccal roots contained a single root canal. The mesio-buccal root was more complex. All types of configurations were seen. Only 26% of mesio-buccal roots showed a single canal. The pulp canal in all roots appeared to narrow at an early age. In the mesio-buccal root, a definite two-directional calcification pattern was apparent in most teeth by the age of 10. The rate of progress of root formation was very variable. There was no apparent relationship between the type of canal system in the mesio-buccal root and the type of canal orifice present. The transverse cross-sectional shape of the pulp chamber was trapezoidal in 81% of teeth.

Adolescent↗
PubMed2004

Nonsurgically retreated root filled teeth--radiographic findings after 20-27 years.

AIM: To identify periapical changes in nonsurgically retreated root-filled teeth 20-27 years after root canal treatment. METHODOLOGY: From an original material of 429 roots, retreated by undergraduate students in a teaching clinic, 112 roots in 70 individuals could be evaluated radiographically 20-27 years after treatment. The same roots had been studied 10-17 years earlier. The periapical condition was registered and compared by three observers in two series of intraoral radiographs taken 10-17 and 20-27 years after treatment. A retrospective analysis was performed to gain information about probable endodontic and nonendodontic reasons for extractions of lost roots, by evaluating their periapical status immediately after retreatment and at the 10-17-year follow-up. RESULTS: Favourable outcomes were observed in 11 roots that had radiolucencies at the 10-17-year follow-up. Eight of these roots had periapical pathosis preoperatively, five of them filled with surplus root filling material. The percentage of cases recorded as normal condition at the final follow-up was 95.5%, including five cases initially recorded with increased width of the apical periodontal space. Delayed healing as a result of surplus root filling material explained most of the cases with favourable outcome assessed many years after treatment. Twenty-eight roots were lost because of extraction during the observation period, 17 during the last 10 years. Based on status at previous follow-ups, endodontic failure seems to represent a minor reason for extraction in the material. CONCLUSION: Late periapical changes, with more successful cases, were recorded when a 10-17-year follow-up after root canal treatment was extended for another 10 years. Persistent asymptomatic periapical radiolucencies, especially those with overfill, should generally not be classified as failures, as many of them will heal after an extended observation period.

Dental Pulp Cavity↗
PubMed2005

Comparison of root canal preparation using RaCe and ProTaper rotary Ni-Ti instruments.

AIM: To compare various parameters of root canal preparation using RaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium (Ni-Ti) instruments. METHODOLOGY: Fifty extracted mandibular molars with mesial root canal curvatures between 20 degrees and 40 degrees were embedded in a muffle system. All root canals were prepared to size 30 using RaCe or ProTaper rotary instruments in low-torque motors with torque control and constant speed of 300 r.p.m. (ProTaper with ATR Tecnika, Advanced Technology Research, Pistoia, Italy; RaCe with EndoStepper, S.E.T., Olching, Germany). In both groups irrigation was performed with 2 mL NaOCl (3%) after each instrument size. Calcinase-Slide (lege artis, Dettenhausen, Germany) was used as a chelating agent with each instrument. The following parameters were evaluated: straightening of curved root canals, postoperative root canal cross-sections, safety issues and working time. Cleanliness of the root canal walls was investigated under the SEM using 5-score indices for debris and smear layer. Statistical analysis was performed using the following tests: Wilcoxon's test for straightening and working time was used (P < 0.05); Fisher's exact test for comparison of cross-sections and root canal cleanliness (P < 0.05). RESULTS: Both Ni-Ti systems maintained curvature well; the mean degree of straightening was less than 1 degrees for both systems. Following preparation with RaCe, 49% of the root canals had a round or oval diameter and 50% an irregular diameter, ProTaper preparations resulted in a round or oval diameter in 50% of the cases. For debris, RaCe and ProTaper achieved 47 and 49% scores of 1 and 2, respectively; there was no significant difference. For smear layer, RaCe and ProTaper achieved 51 and 33% scores 1 and 2, respectively; no statistically significant differences were apparent for the coronal and middle sections of the root canals, but RaCe performed significantly better in the apical region (Fisher's exact test, P = 0.0392). Two roots lost working length with RaCe instruments, whilst ProTaper preparation resulted in two roots loosing working length and one fractured instrument. Mean working time was shorter for ProTaper (90.9 s) than for RaCe (137.6 s); the difference was significant (Wilcoxon's test, P = 0.011). CONCLUSIONS: Both systems respected original root canal curvature well and were safe to use. Cleanliness was not satisfactory for both systems.

Dental Alloys↗
PubMed2006

Consequences of and strategies to deal with residual post-treatment root canal infection.

Bacterial sampling of prepared root canals is used to determine the presence and character of the remaining microbiota. However, it is likely that current sampling techniques only identify organisms in the main branches of the root canal system whereas it is unlikely that they can sample areas beyond the apical end-point of preparation and filling, or in lateral canals, canal extensions, apical ramifications, isthmuses and within dentinal tubules. Thus, it may be impossible by current techniques to identify residual post-treatment root canal infection. In histologic observations of root apices, bacteria have been found in inaccessible inter-canal isthmuses and accessory canals often in the form of biofilms. There is no in vivo evidence to support the assumption that these bacteria can be entombed effectively in the canal system by the root filling and thus be rendered harmless. As a consequence of this residual root infection, post-treatment apical periodontitis, which may be radiographically undetectable, may persist or develop as a defence mechanism to prevent the systemic spread of bacteria and/or their byproducts to other sites of the body. Histologic observation of root apices with surrounding bone removed from either patients or human cadavers has demonstrated that post-treatment apical periodontitis is associated with 50-90% of root filled human teeth. Thus, if the objective of root canal treatment is to eliminate apical periodontitis at a histological level, current treatment procedures are inadequate. It is essential that our knowledge of the local and systemic consequences of both residual post-treatment root infection and post-treatment apical periodontitis be improved. The continued development of treatments that can effectively eliminate root infection is therefore a priority in clinical endodontic research. Post-treatment disease following root canal treatment is most often associated with poor quality procedures that do not remove intra-canal infection; this scenario can be corrected via a nonsurgical approach. However, infection remaining in the inaccessible apical areas, extraradicular infection including apically extruded dentine debris with bacteria present in dentinal tubules, true radicular cysts, and foreign body reactions require a surgical intervention.

Bacterial Infections↗
PubMed2007

Regulation and manipulation of ABA biosynthesis in roots.

Overexpression of 9-cis-epoxycarotenoid dioxygenase (NCED) is known to cause abscisic acid (ABA) accumulation in leaves, seeds and whole plants. Here we investigated the manipulation of ABA biosynthesis in roots. Roots from whole tomato plants that constitutively overexpress LeNCED1 had a higher ABA content than wild-type (WT) roots. This could be explained by enhanced in situ ABA biosynthesis, rather than import of ABA from the shoot, because root cultures also had higher ABA content, and because tetracycline (Tc)-induced LeNCED1 expression caused ABA accumulation in isolated tobacco roots. However, the Tc-induced expression led to greater accumulation of ABA in leaves than in roots. This demonstrates for the first time that NCED is rate-limiting in root tissues, but suggests that other steps were also restrictive to pathway flux, more so in roots than in leaves. Dehydration and NCED overexpression acted synergistically in enhancing ABA accumulation in tomato root cultures. One explanation is that xanthophyll synthesis was increased during root dehydration, and, in support of this, dehydration treatments increased beta-carotene hydroxylase mRNA levels. Whole plants overexpressing LeNCED1 exhibited greatly reduced stomatal conductance and grafting experiments from this study demonstrated that this was predominantly due to increased ABA biosynthesis in leaves rather than in roots. Genetic manipulation of both xanthophyll supply and epoxycarotenoid cleavage may be needed to enhance root ABA biosynthesis sufficiently to signal stomatal closure in the shoot.

Abscisic Acid↗
PubMed2005

The influence of root assimilated inorganic carbon on nitrogen acquisition/assimilation and carbon partitioning.

Understanding of the influences of root-zone CO2 concentration on nitrogen (N) metabolism is limited. The influences of root-zone CO2 concentration on growth, N uptake, N metabolism and the partitioning of root assimilated 14C were determined in tomato (Lycopersicon esculentum). Root, but not leaf, nitrate reductase activity was increased in plants supplied with increased root-zone CO2. Root phosphoenolpyruvate carboxylase activity was lower with NO3(-)- than with NH4(+)-nutrition, and in the latter, was also suppressed by increased root-zone CO2. Increased growth rate in NO3(-)-fed plants with elevated root-zone CO2 concentrations was associated with transfer of root-derived organic acids to the shoot and conversion to carbohydrates. With NH4(+)-fed plants, growth and total N were not altered by elevated root-zone CO2 concentrations, although 14C partitioning to amino acid synthesis was increased. Effects of root-zone CO2 concentration on N uptake and metabolism over longer periods (> 1 d) were probably limited by feedback inhibition. Root-derived organic acids contributed to the carbon budget of the leaves through decarboxylation of the organic acids and photosynthetic refixation of released CO2.

Biological Transport↗
PubMed2005

Root architecture and wind-firmness of mature Pinus pinaster.

This study aims to link three-dimensional coarse root architecture to tree stability in mature timber trees with an average of 1-m rooting depth. Undamaged and uprooted trees were sampled in a stand damaged by a storm. Root architecture was measured by three-dimensional (3-D) digitizing. The distribution of root volume by root type and in wind-oriented sectors was analysed. Mature Pinus pinaster root systems were organized in a rigid 'cage' composed of a taproot, the zone of rapid taper of horizontal surface roots and numerous sinkers and deep roots, imprisoning a large mass of soil and guyed by long horizontal surface roots. Key compartments for stability exhibited strong selective leeward or windward reinforcement. Uprooted trees showed a lower cage volume, a larger proportion of oblique and intermediate depth horizontal roots and less wind-oriented root reinforcement. Pinus pinaster stability on moderately deep soils is optimized through a typical rooting pattern and a considerable structural adaptation to the prevailing wind and soil profile.

Biomechanical Phenomena↗
PubMed1985

The removal of root surface deposits.

The importance of adequate root surface instrumentation has received increasing emphasis. The purpose of this study was to determine the extent to which root planning could produce surfaces free of stainable deposits. Initial laboratory investigations on extracted, periodontally involved roots demonstrated that after meticulous root preparation, totally non-stainable surfaces could be obtained. These surfaces were shown to consist of either thin cementum or dentine. The efficacy of instrumenting periodontally involved buccal root surfaces on the anterior teeth of 33 patients, undergoing routine periodontal flap surgery was then evaluated. Root surfaces were instrumented either before or after the reflection of surgical flaps. Remaining bacterial deposits were disclosed with a gentian violet solution and the root surfaces then photographed. Further root planing, disclosure and photography were then carried out. These photographic slides were analysed for stainable deposits on the root surfaces using an image analysis system, based on densitometric principles, to measure the areas of stainable root surface deposits. The findings revealed that root planning under direct vision at the time of surgery was more effective than blind instrumentation. However, in no instance was any root surface found to be completely free of stainable deposits.

Adolescent↗
PubMed2000

Rhizosphere microbial community structure in relation to root location and plant iron nutritional status.

Root exudate composition and quantity vary in relation to plant nutritional status, but the impact of the differences on rhizosphere microbial communities is not known. To examine this question, we performed an experiment with barley (Hordeum vulgare) plants under iron-limiting and iron-sufficient growth conditions. Plants were grown in an iron-limiting soil in root box microcosms. One-half of the plants were treated with foliar iron every day to inhibit phytosiderophore production and to alter root exudate composition. After 30 days, the bacterial communities associated with different root zones, including the primary root tips, nonelongating secondary root tips, sites of lateral root emergence, and older roots distal from the tip, were characterized by using 16S ribosomal DNA (rDNA) fingerprints generated by PCR-denaturing gradient gel electrophoresis (DGGE). Our results showed that the microbial communities associated with the different root locations produced many common 16S rDNA bands but that the communities could be distinguished by using correspondence analysis. Approximately 40% of the variation between communities could be attributed to plant iron nutritional status. A sequence analysis of clones generated from a single 16S rDNA band obtained at all of the root locations revealed that there were taxonomically different species in the same band, suggesting that the resolving power of DGGE for characterization of community structure at the species level is limited. Our results suggest that the bacterial communities in the rhizosphere are substantially different in different root zones and that a rhizosphere community may be altered by changes in root exudate composition caused by changes in plant iron nutritional status.

Bacteria↗
PubMed1978

Organization of peripheral nerves and spinal roots of the Atlantic stingray, Dasyatis sabina.

1. The sizes and numbers of axons in peripheral nerves and spinal roots were investigated in the stingray, Dasyatis sabina. 2. The axons of the dorsal and ventral roots do not mingle in peripheral nerves of this animal as they do in higher vertebrates. Thus, it was usually possible to split the peripheral nerve into two portions, one containing only dorsal root axons, the other containing only ventral root axons. This feature was useful for the analysis of certain aspects of spinal cord organization. 3. The fact that dorsal and ventral root axons were segregated in peripheral nerves enabled us to demonstrate, without experimental surgery, that the central processes of the dorsal root ganglion cells and the proximal ventral root axons were 10-20% narrower, on the average, than the distal processes of the same dorsal root ganglion cells or the distal parts of the same ventral root axons. 4. The stingray is remarkable in having very few unmyelinated axons in the dorsal roots, ventral roots, or peripheral nerves. This paucity of unmyelinated axons distinguishes the Atlantic stingrays from all other vertebrates whose roots and nerves have been examined for unmyelinated fibers. 5. Similar findings were obtained for one spotted eagle ray (Aetobatus narinari) and two cow-nose rays (Rhinoptera bonasus).

Animals↗
PubMedDate not supplied

Biometric study of the width, length and depth of the root trunk groove of human lower second molars.

One hundred human lower second molars, 51 from the left side and 49 from the right side, extracted due to their poor clinical and radiographic conditions were utilized in this study. Using a Contracer apparatus, the profiles of the buccal and lingual root surfaces of these teeth were traced on a millimeter-scaled paper. The profiles were registered from the cementoenamel junction (CEJ), millimeter by millimeter, up to the entrance of the furcation. The width, length and depth of the root trunk groove, as well as the length of the root trunk, were studied. After statistical analysis (p < 0.05) it was possible to conclude that: a) the mean width of the root trunk groove on the buccal surface was 3.6 mm and, on the lingual surface, 3.3 mm; b) the mean depth of the root trunk groove on the buccal surface was 0.88 mm and, on the lingual surface, 0.77 mm; c) the mean length of the root trunk groove on the buccal surface was 2.93 mm and, on the lingual surface, 3.61 mm. The mean length of the root trunk on the buccal surface was 3.09 mm and, on the lingual surface, 3.91 mm (p < 0.025). There was a coincidence between the length of the root trunk and that of its groove in 90.2% of the buccal surfaces of the samples from the left side, and in 77.5% of the samples from the right side; on the lingual surface, the coincidence occurred in 77.5% of the teeth from the left side, and on 88.3% of the teeth from the right side. This work revealed that there is a concavity on the root trunk region of the lower second molar, whose depth and width were greater on the buccal surface and whose length was greater on the lingual surface. The depth of the root trunk groove increased in the apical direction, with maximum depth in the last millimeter of the root trunk. The root trunk was longer on the lingual surface than it was on the buccal surface.

Anthropometry↗
PubMed1992

Tooth morphology following root resection procedures in maxillary first molars.

The Disto-Buccal root is the most commonly resected root in maxillary molars. This root resection procedure results in a unique environment dictated by the contours of the remaining roots and the residual furcation between them. Tooth morphology was evaluated in 50 extracted maxillary first molars after disto-buccal root resection. The following measurements were studied: 1) The maximum concavity (D) on the distal aspect of the resected molar; 2) the minimum mesio-distal dimension (d) of tooth structure between the two remaining roots; 3) the width (s) of the residual interradicular septum; and 4) the distance (p) from the pulp chamber floor to the root separation on the distal aspect of the resected molar. The mean measurements were (D) = 2.47 mm, (d) = 3.67 mm, (s) = 3.33 mm and (p) = 2.70 mm. The value of (p) was equal to or less than 3 mm in 86% of the teeth; this means that the distance from the finish line to the interradicular osseous peak is less than 2.04 mm (average biologic width), if the finish line is placed on solid tooth structure about 1 mm below the pulp floor. Six percent of the resected molars had an overall topography easily amenable to periodontal maintenance and restorative procedures with (D) less than 2 mm, (d) greater than 3 mm, (s) greater than 3 mm, and (p) greater than 3 mm. Poor root anatomy of the remaining roots after removal of the disto-buccal root in maxillary first molars may be considered as a contraindication for root resection procedures. Unfortunately, this poor topography can be ascertained only during the surgery and after removal of the disto-buccal root.

Dental Pulp Cavity↗
PubMed1989

[Connective tissue attachment to root surfaces in periodontal disease. Initial attachment of human gingival fibroblasts].

We studied the effect of periodontal treatment (scaling, SC; root planning, RP; scaling followed by citric acid, SC + CA; and root planing followed by citric acid, RP + CA) of periodontally diseased root surfaces on the initial attachment of human gingival fibroblasts in vitro. Root slices were prepared from surgically extracted human normal and periodontally involved teeth. Each treated root slice was placed in a well of a 24-well plate containing a PBS-antibiotic solution (penicillin, 200 units/ml; streptomycin, 200 micrograms/ml) for 1 hr. at 4 degrees C. Then, to each well was added 1 x 10(4) cells in 1 ml of alpha-MEM, and the plates were incubated for 24 hr. After the root slices were fixed and stained, the morphological changes and the numbers of attached cells were determined under a dissecting microscope. The fibroblasts on the controls (untreated normal roots) and the RP-roots appeared spindle-shaped with a few cell processes. The cells on the SC-roots were rounded or slightly elongated. The cells on the roots treated with citric acid (SC + CA and RP + CA) had were flat and seemed well attached to the surface. The number of cells attached on RP- and RP + CA-roots was increased to the control level, but those on SC- and SC + CA-roots were showed about 60% of the control. No significant differences in the numbers of cells were found between RP and RP + CA treatment or between SC and SC + CA treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Adhesion↗
PubMed2002

Results of root canal treatment in dogs: 127 cases (1995-2000).

OBJECTIVE: To evaluate results of root canal treatment in dogs. DESIGN: Retrospective study. SAMPLE POPULATION: 127 tooth roots in 64 dogs. PROCEDURE: Radiographs obtained before surgery, immediately after surgery, and during follow-up examinations after surgery were evaluated by 2 individuals. Treatment was considered successful if the periodontal ligament space was normal and possible preoperative root resorption, if present, had ceased. Treatment was considered to show no evidence of failure if possible preoperative root resorption had ceased but a preexisting periapical lesion had remained the same or only decreased in size and not complete resolved. Treatment was considered to have failed if a periapical lesion or root resorption developed subsequent to endodontic treatment, if a preexisting periapical lesion had increased in size, or if possible preoperative root resorption appeared to continue after endodontic treatment. RESULTS: Follow-up time ranged from 1 to 60 months (mean, 13 months). Treatment was classified as successful for 87 (69%) roots, as showing no evidence of failure for 33 (26%) roots, and as having failed for 7 (6%) roots. The success rate was lower for canine teeth than for maxillary fourth premolar teeth. Roots with a preexisting periapical lucency or preexisting root resorption had lower success rates. The use of intracanal medication and the method and quality of obturation were not associated with outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that root canal treatment offers a viable option for salvage of periodontally sound but endodontically diseased teeth in dogs.

Animals↗
PubMed2026

Glucose-TOR Signaling Regulates Root Hair Elongation in Arabidopsis via the RHD6-RSL4 Transcriptional Cascade.

Root hairs are tubular protrusions of root epidermal cells that expand the root surface area to facilitate water and nutrient uptake. The target of rapamycin (TOR) kinase has been identified as a positive regulator of root hair elongation, and the RHD6-RSL4 bHLH transcriptional cascade is well established as a core module that governs root hair morphogenesis. However, whether TOR signaling acts upstream of the RHD6-RSL4 pathway and how glucose signals are integrated into this transcriptional regulatory network during root hair development remain incompletely understood. In this study, transcriptome profiling combined with pharmacological and genetic functional assays was performed to elucidate the TOR-mediated transcriptional regulatory pathway of root hair elongation in Arabidopsis. Chemical inhibition of TOR triggered genome-wide transcriptional reprogramming in seedling roots, including disruption of auxin and ethylene signal transduction and pronounced downregulation of hundreds of genes related to root hair development. Glucose-activated TOR signaling modulates the expression of root hair-specific (RHS) genes mainly through the core RHD6-RSL4 transcriptional cascade. The transcription of RSL1-RSL5 was strongly dependent on functional TOR activity, whereas RHD6 transcript abundance was specifically induced by glucose-TOR signaling under carbon-starvation recovery conditions. Genetic overexpression of either RHD6 or RSL4 partially rescued root hair elongation defects caused by TOR suppression, confirming that the RHD6-RSL4 cascade functions as a critical downstream transcriptional module of glucose-TOR signaling. Collectively, this work establishes a transcriptional framework in which glucose-TOR signals modulate root hair elongation via transcriptional activation of the master bHLH regulators RHD6 and RSL4.

RHD6-RSL4 cascade↗
PubMed2000

A Ca(2+)-dependent cysteine protease is associated with anoxia-induced root tip death in maize.

Imposition of anoxia on maize (Zea mays cv. B73) seedlings for 48 h or longer led to the death of the root tip. The necrosis extended into the root axis during postanoxic treatment, leading to the mortality of 30-50% of the seedlings. Using zymography, protease profiles in the root tissues of anoxic seedlings were studied. O2 deprivation for 24 h or longer repressed pre-existing protease activities and induced a novel soluble enzyme in the roots. The anoxia-induced protease (AIP) activity was predominant in the root apex at 24 h of anoxia and, subsequently, became the most abundant soluble activity in the root axis as well. The induction of AIP and its in vitro renaturation were Ca(2+)-dependent. Inhibitor sensitivity studies indicated that AIP is a cysteine protease. In SDS-acrylamide gels, the enzyme activity migrated as a 23.5 kDa polypeptide. The anoxic induction of the activity was repressed by cycloheximide treatment, suggesting that new protein synthesis was required for the AIP appearance. Excision of the root tip (de-tipping) before anoxia led to a superior recovery of seedlings from stress injury. De-tipped seedlings showed lesser root damage and an increased production of lateral roots compared to intact seedlings. Furthermore, the superior anoxia tolerance of de-tipped seedlings was associated with a decreased AIP activity. Thus, the appearance of AIP activity in the root tip at 24 h of anoxia was spatially and temporally associated with the root tissue death. These studies further indicate that the root tip elimination early during anoxia may provide an adaptive advantage.

Anaerobiosis↗
PubMed1997

Computer based imaging and analysis of root gravitropism.

Two key issues in studies of the nature of the gravitropic response in roots have been the determination of the precise pattern of differential elongation responsible for downward bending and the identification of the cells that show the initial motor response. The main approach for examining patterns of differential growth during root gravitropic curvature has been to apply markers to the root surface and photograph the root at regular intervals during gravitropic curvature. Although these studies have provided valuable information on the characteristics of the gravitropic motor response in roots, their labor intensive nature limits sample size and discourages both high frequency of sampling and depth of analysis of surface expansion data. In this brief review we describe the development of computer-based video analysis systems for automated measurement of root growth and shape change and discuss some key features of the root gravitropic response that have been revealed using this methodology. We summarize the capabilities of several new pieces of software designed to measure growth and shape changes in graviresponding roots and describe recent progress in developing analysis systems for studying the small, but experimentally popular, primary roots of Arabidopsis. A key finding revealed by such studies is that the initial gravitropic response of roots of maize and Arabidopsis occurs in the distal elongation zone (DEZ) near the root apical meristem, not in the main elongation zone. Another finding is that the initiation of rapid elongation in the DEZ following gravistimulation appears to be related to rapid membrane potential changes in this region of the root. These observations have provided the incentive for ongoing studies examining possible links between potential growth modifying factors (auxin, calcium, protons) and gravistimulated changes in membrane potential and growth patterns in the DEZ.

Arabidopsis↗
PubMedDate not supplied

[Different methods of forming root systems in plants using maize and flax seedlings as examples].

Comparison of the appearance and development of lateral roots in the flax and maize seedlings has shown the way of root branching in the flax, as distinct from that in most plants. Some primordia in the flax main root did not develop immediately into lateral roots, but remained quiescent, which determines different reactions of the maize and flax root systems to experimental influences. Decapitation of the main root in the maize did not leads to a significant increase in the number of lateral roots, while in the flax, their number noticeably increased due to the development of previously quiescent primordia into lateral roots. The treatment with synthetic auxin did not induce the formation of additional primordia and lateral roots in the maize roots. In the flax, the number of primordia increased significantly and that of lateral roots increased to a somewhat lesser extent. Apparently, the development of a primordium into a lateral root proceeds in two stages and they have different regulation.

Flax↗