Root Excision Research Articles

Kinematic analysis and process optimization of root-cutting systems in field harvesting of garlic based on computer simulation technology.

Root cutting is an important process in garlic field harvesting but is the weakest link in the full mechanization of garlic production. To improve the current situation of technological backwardness and poor operational quality of mechanized garlic root-cutting in the main garlic-producing regions of China, this study combined the physical characteristics and agronomic requirements of garlic plants, and proposed an innovative floating root-cutting technology for garlic combine harvesters that enables the top alignment of bulb, adaptive profiling floating of cutter, and embedded cutting of roots. Through the kinematic analysis of the floating cutting process, the coordinate equations of the initial contact point of the bulb, the mathematical model of the floating displacement of the cutting component. Using computer simulation techniques, the dynamic simulation study of the floating cutting process was carried out in the rigid-flexible coupling numerical simulation model of root-cutting mechanism and garlic plant. The influence law of garlic conveying speed, extension spring preload force and stiffness on the floating displacement of the cutting component and the angular velocity of swing arm reset and its formation causes were analyzed by a single-factor simulation test. The key operating parameters of the root-cutting mechanism were optimized through the computerized virtual orthogonal test and fuzzy comprehensive evaluation. The significance of the factors affecting the floating cutting performance decreased in the following order: extension spring preload force, garlic conveying speed and extension spring stiffness. The optimal parameter combination of the root cutting mechanism obtained from the optimization were as follow: extension spring preload force was 16 N, garlic conveying speed was 0.8 m/s, and extension spring stiffness was 215 N/m. Tests conducted with the optimal parameter combination yielded a root excision rate of 92.72%, which meets the requirements of Chinese garlic field harvesting quality. This study provides computer simulation optimization methods for the optimal design of the root-cutting mechanism, and also provides technical and equipment support for the full mechanization of garlic production in China.

Mycorrhization and root excision effects on morphological and biomass production of carob (Ceratonia siliqua L.)

Ceratonia siliqua L. plant (carob tree) is a Mediterranean species. In Tunisia, natural distribution of this species is situated in humid zones in the north to the driest ones in the south of the country. Ceratonia siliqua regeneration depends on seeds quality and performances as well as on the practical vegetative propagation tools. Nowadays, carob tree cultivation is limited by the seedlings quality behind the juvenile stage caused by the deterioration of plant root system. This study investigates the effect of lone and mutual root excision technique and mycorrhization on carob seedlings growth performance. Two carob seeds origins were germinated then excised and/or mycorrhized using a sterile substate. For control seedlings, experiment was made without excision nor mycorrhization application. Seedlings were grown in green house. Mycorrhizae applied with excision ameliorated significantly plant length, leaf number, dry and fresh weight of external plant part and roots, collar root diameter and roots branching numbers. Survey of mycorrhizae effects proved also amelioration on carob growth and biomass production but indiscernibly than use of mycorrhization and excision techniques together. Excision alone does not take a part on seedling increasing performance. Mycorrhization of carob species applied with excision increased morphological plant status. Results highlighted the efficiency to use this process to promote plants behaviour by enhancing plant roots and growth in forest farming model in forest areas and agricultural lands.

Primary Root Excision Induces ERF071, Which Mediates the Development of Lateral Roots in Makapuno Coconut (Cocos nucifera).

Coconut (Cocos nucifera L.) is widely recognized as one of nature's most beneficial plants. Makapuno, a special type of coconut with a soft, jelly-like endosperm, is a high-value commercial coconut and an expensive delicacy with a high cost of planting material. The embryo rescue technique is a very useful tool to support mass propagation of makapuno coconut. Nevertheless, transplanting the seedlings is a challenge due to poor root development, which results in the inability of the plant to acclimatize. In this study, primary root excision was used in makapuno to observe the effects of primary root excision on lateral root development. The overall results showed that seedlings with roots excised had a significantly higher number of lateral roots, and shoot length also increased significantly. Using de novo transcriptome assembly and differential gene expression analysis, we identified 512 differentially expressed genes in the excised and intact root samples. ERF071, encoding an ethylene-responsive transcription factor, was identified as a highly expressed gene in excised roots compared to intact roots, and was considered a candidate gene associated with lateral root formation induced by root excision in makapuno coconut. This study provides insight into the mechanism and candidate genes involved in the development of lateral roots in coconut, which may be useful for the future breeding and mass propagation of makapuno coconut through tissue culture.

Guided Endodontic Micro-Surgery (GEMS): A Novel Approach for a Targeted Apicoectomy—A Report of 3 Cases

AbstractGuided endodontic microsurgery, also known as guided endodontic microsurgery, is a surgical procedure used to treat failed endodontically treated teeth with periapical infections. Guided endodontic microsurgery can be problematic in some situations, such as when there are tough anatomical features or limited surgical access. Some of these complex cases can be managed using cone beam computed tomography imaging, CAD software design, and 3D printing technologies. A surgical stent was manufactured using a 3D printer in each of the three cases. Prior to surgery, the infection location, depth, and angulation of preparation were determined to protect sensitive anatomical components. The target location is chosen to ensure precise root excision and avoid infection during surgery. Infected root tip resection and biopsy were accomplished in one step by rotating a trephine bur in the surgical stent hole. Once the root preparation and the retrograde filling were completed, bone graft material can be added to the surgical site and then the tissues were sutured to achieve primary closure. Surgical stents produce effective targeted apicoectomy with a certain angle and depth of preparation. In addition, the soft tissue is reflected or protected with the unique features of the stent.

Differing responses of root morphology and physiology to nitrogen application rates and their relationships with grain yield in rice

Root morphology and physiology influence aboveground growth and yield formation in rice. However, root morphological and physiological differences among rice varieties with differing nitrogen (N) sensitivities and their relationship with grain yield are still unclear. In this study, rice varieties differing in N sensitivity over many years of experiments were used. A field experiment with multiple N rates (0, 90, 180, 270, and 360 kg ha−1) was conducted to elucidate the effects of N application on root morphology, root physiology, and grain yield. A pot experiment with root excision and exogenous application of 6-benzyladenine (6-BA) at heading stage was used to further verify the above effects. The findings revealed that (1) under the same N application rate, N-insensitive varieties (NIV) had relatively large root biomass (root dry weight, length, and number). Grain yield was associated with root biomass in NIV. The oxidation activity and zeatin (Z) + zeatin riboside (ZR) contents in roots obviously and positively correlated with grain yield in N-sensitive varieties (NSV), and accounted for its higher grain yield than that of NIV at lower N application rates (90 and 180 kg ha−1). (2) The root dry weight required for equal grain yield of NIV was greater than that of NSV. Excision of 1/10 and 1/8 of roots at heading stage had no discernible effect on the yield of Liangyoupeijiu (NIV), and it significantly reduced yield by 11.5% and 21.3% in Tianyouhuazhan (NSV), respectively, compared to the treatment without root excision. The decrease of filled kernels and grain weight after root excision was the primary cause for the yield reduction. Root excision and exogenous 6-BA application after root excision had little influence on the root activity of NIV. The oxidation activity and Z + ZR contents in roots of NSV decreased under root excision, and the increase in the proportion of excised roots aggravated these effects. The application of exogenous 6-BA increased the root activity of NSV and increased filled kernels and grain weight, thereby reducing yield loss after root excision. Thus, the root biomass of NIV was large, and there may be a phenomenon of “root growth redundancy.” Vigorous root activity was an essential feature of NSV. Selecting rice varieties with high root activity or increasing root activity by cultivation measures could lead to higher grain yield under lower N application rates.

The size and the age of the metabolically active carbon in tree roots.

Little is known about the sources and age of C respired by tree roots. Previous research in stems identified two functional pools of non-structural carbohydrates (NSC): an "active" pool supplied directly from canopy photo-assimilates supporting metabolism and a "stored" pool used when fresh C supplies are limited. We compared the C isotope composition of water-soluble NSC and respired CO2 for aspen roots (Populus tremula hybrids) cut off from fresh C supply after stem-girdling or prolonged incubation of excised roots. We used bomb radiocarbon to estimate the time elapsed since C fixation for respired CO2 , water-soluble NSC and structural α-cellulose. While freshly excised roots (mostly <2.9 mm in diameter) respired CO2 fixed <1year previously, the age increased to 1.6-2.9year within a week after root excision. Freshly excised roots from trees girdled ~3months ago had respiration rates and NSC stocks similar to un-girdled trees but respired older C (~1.2year). We estimate that over 3months NSC in girdled roots must be replaced 5-7 times by reserves remobilized from root-external sources. Using a mixing model and observed correlations between Δ14 C of water-soluble C and α-cellulose, we estimate ~30% of C is "active" (~5mg C g-1 ).

An auxin-mediated regulatory framework for wound-induced adventitious root formation in tomato shoot explants.

Adventitious roots (ARs) are produced from non-root tissues in response to different environmental signals, such as abiotic stresses, or after wounding, in a complex developmental process that requires hormonal crosstalk. Here, we characterized AR formation in young seedlings of Solanum lycopersicum cv. 'Micro-Tom' after whole root excision by means of physiological, genetic and molecular approaches. We found that a regulated basipetal auxin transport from the shoot and local auxin biosynthesis triggered by wounding are both required for the re-establishment of internal auxin gradients within the vasculature. This promotes cell proliferation at the distal cambium near the wound in well-defined positions of the basal hypocotyl and during a narrow developmental window. In addition, a pre-established pattern of differential auxin responses along the apical-basal axis of the hypocotyl and an as of yet unknown cell-autonomous inhibitory pathway contribute to the temporal and spatial patterning of the newly formed ARs on isolated hypocotyl explants. Our work provides an experimental outline for the dissection of wound-induced AR formation in tomato, a species that is suitable for molecular identification of gene regulatory networks via forward and reverse genetics approaches.

Early Low-Fluence Red Light or Darkness Modulates the Shoot Regeneration Capacity of Excised Arabidopsis Roots.

In plants, light is an important environmental signal that induces meristem development and interacts with endogenous signals, including hormones. We found that treatment with 24 h of low-fluence red light (24 h R) or 24 h of darkness (24 h D) following root excision greatly increased the frequency of shoot generation, while continuous low-fluence red light in callus and shoot induction stages blocked the explants’ ability to generate shoots. Shoot generation ability was closely associated with WUS expression and distribution pattern. 1-N-naphthylphtalamic acid (NPA) disrupted the dynamic distribution of the WUS signal induced by early 24 h R treatment, and NPA plus 24 R treatment increased the average shoot number compared with early 24 h R alone. Transcriptome analysis revealed that differentially expressed genes involved in meristem development and hormone signal pathways were significantly enriched during 24 R or 24 D induced shoot regeneration, where early 24 h R or 24 h D treatment upregulated expression of WOX5, LBD16, LBD18 and PLT3 to promote callus initiation and formation of root primordia, and also activated WUS, STM, CUC1 and CUC2 expression, leading to initiation of the shoot apical meristem (SAM). This finding demonstrates that early exposure of explants to transient low-fluence red light or darkness modulates the expression of marker genes related with callus development and shoot regeneration, and dynamic distribution of WUS, leading to an increased ability to generate shoots.

Risk of bowel fistula following surgical management of deep endometriosis of the rectosigmoid: a series of 1102 cases.

STUDY QUESTIONWhat are the risk factors and prevalence of bowel fistula following surgical management of deep endometriosis infiltrating the rectosigmoid and how can it be managed?SUMMARY ANSWERIn patients managed for deep endometriosis of the rectosigmoid, risk of fistula is increased by bowel opening during both segmental colorectal resection and disc excision and rectovaginal fistula repair is more challenging than for bowel leakage.WHAT IS KNOWN ALREADYBowel fistula is known to be a severe complication of colorectal endometriosis surgery; however, there is little available data on its prevalence in large series or on specific management.STUDY DESIGN, SIZE, DURATIONA retrospective study employing data prospectively recorded in the North-West Inter Regional Female Cohort for Patients with Endometriosis (CIRENDO) from June 2009 to May 2019, in three tertiary referral centres.PARTICIPANTS/MATERIALS, SETTING, METHODSOne thousand one hundred and two patients presenting with deep endometriosis infiltrating the rectosigmoid, who were managed by shaving, disc excision or colorectal resection. The prevalence of bowel fistula was assessed, and factors related to the complication and its surgical management.MAIN RESULTS AND THE ROLE OF CHANCEOf 1102 patients enrolled in the study, 52.5% had a past history of gynaecological surgery and 52.7% had unsuccessfully attempted to conceive for over 12 months. Digestive tract subocclusion/occlusion was recorded in 12.7%, hydronephrosis in 4.5% and baseline severe bladder dysfunction in 1.5%. An exclusive laparoscopic approach was carried out in 96.8% of patients. Rectal shaving was performed in 31.9%, disc excision in 23.1%, colorectal resection in 35.8% and combined disc excision and sigmoid colon resection in 2.9%. For various reasons, the nodule was not completely removed in 6.4%, while in 7.2% of cases complementary procedures on the ileum, caecum and right colon were required. Parametrium excision was performed in 7.8%, dissection and excision of sacral roots in 4%, and surgery for ureteral endometriosis in 11.9%. Diverting stoma was performed in 21.8%. Thirty-seven patients presented with bowel fistulae (3.4%) of whom 23 (62.2%) were found to have rectovaginal fistulae and 14 (37.8%) leakage. Logistic regression model showed rectal lumen opening to increase risk of fistula when compared with shaving, regardless of nodule size: adjusted odds ratio (95% CI) for disc excision, colorectal resection and association of disc excision + segmental resection was 6.8 (1.9–23.8), 4.8 (1.4–16.9) and 11 (2.1–58.6), respectively. Repair of 23 rectovaginal fistulae required 1, 2, 3 or 4 additional surgical procedures in 12 (52.2%), 8 (34.8%), 2 (8.7%) and 1 patient (4.3%), respectively. Repair of leakage in 14 patients required 1 procedure (stoma) in 12 cases (85.7%) and a second procedure (colorectal resection) in 2 cases (14.3%). All patients, excepted five women managed by delayed coloanal anastomosis, underwent a supplementary surgical procedure for stoma repair. The period of time required for diverting stoma following repair of rectovaginal fistulae was significantly longer than for repair of leakages (median values 10 and 5 months, respectively, P = 0.008)LIMITATIONS, REASONS FOR CAUTIONThe main limits relate to the heterogeneity of techniques used in removal of rectosigmoid nodules and repairing fistulae, the lack of accurate information about the level of nodules, the small number of centres and that a majority of patients were managed by one surgeon.WIDER IMPLICATIONS OF THE FINDINGSDeep endometriosis infiltrating the rectosigmoid can be managed laparoscopically with a relatively low risk of bowel fistula. When the type of bowel procedure can be chosen, performance of shaving instead of disc excision or colorectal resection is suggested considering the lower risk of bowel fistula. Rectovaginal fistula repair is more challenging than for bowel leakage and may require up to four additional surgical procedures.STUDY FUNDING/COMPETING INTEREST(S)CIRENDO is financed by the G4 Group (The University Hospitals of Rouen, Lille, Amiens and Caen) and the ROUENDOMETRIOSE Association. No financial support was received for this study. H.R. reports personal fees from ETHICON, Plasma Surgical, Olympus and Nordic Pharma outside the submitted work. The other authors declare no conflict of interests related to this topic.

Root respiration and belowground carbon allocation respond to drought stress in a perennial grass (Bothriochloa ischaemum)

In order to accurately estimate the carbon (C) balance in arid and semi-arid grasslands, it is necessary to first understand how the demands of photosynthates and root carbon (C) are allocated in response to drought. To accomplish this goal, we used a 13C pulse labeling technique to assess correlations between root morphology and the amount of 13C in the root, which is a measure of respiration. We compared respiration changes via the excised root 13C of Bothriochloa ischaemum at various root excision times (i.e., 0, 6, 24, 48, 216, and 360 h after labeling). Our results showed that 13C and root respiration continued to increase until 216 h after labeling, and then they decreased after 360 h. Root respiration correlated significantly with the carbon labeled as being from the fine roots that were undergoing drought stress treatments. This indicates that later-photosynthates are the primary C source for root respiration. Fine root 13C positively correlated with fine root biomass and specific root length under serious drought conditions. This suggests that fine root growth is based primarily on recently derived photosynthates. Serious drought was shown to inflate the root/shoot ratio by increasing both the 13C and the biomass, which led to greater C allocation in the root system. Finally, the fine/coarse root ratios of 13C and biomass were greatest in the serious drought treatment. This suggests that fine roots have a higher C demand than coarse roots under drought stress. Fine root respiration was also found to stimulate new C demand in roots because the amount of 13C created during root respiration was positively correlated with tissue N concentration of fine roots.

A Network-Guided Genetic Approach to Identify Novel Regulators of Adventitious Root Formation in Arabidopsis thaliana.

Adventitious roots (ARs) are formed de novo during post-embryonic development from non-root tissues, in processes that are highly dependent on environmental inputs. Whole root excision from young seedlings has been previously used as a model to study adventitious root formation in Arabidopsis thaliana hypocotyls. To identify novel regulators of adventitious root formation, we analyzed adventitious rooting in the hypocotyl after whole root excision in 112 T-DNA homozygous leaf mutants, which were selected based on the dynamic expression profiles of their annotated genes during hormone-induced and wound-induced tissue regeneration. Forty-seven T-DNA homozygous lines that displayed low rooting capacity as regards their wild-type background were dubbed as the less adventitious roots (lars) mutants. We identified eight lines with higher rooting capacity than their wild-type background that we named as the more adventitious roots (mars) mutants. A relatively large number of mutants in ribosomal protein-encoding genes displayed a significant reduction in adventitious root number in the hypocotyl after whole root excision. In addition, gene products related to gibberellin (GA) biosynthesis and signaling, auxin homeostasis, and xylem differentiation were confirmed to participate in adventitious root formation. Nearly all the studied mutants tested displayed similar rooting responses from excised whole leaves, which suggest that their affected genes participate in shared regulatory pathways required for de novo organ formation in different organs.

Performance of Grafted Seedless Watermelon Plants with and without Root Excision under Inoculation with Fusarium oxysporum f. sp. niveum Race 2

Fusarium wilt of watermelon can be effectively managed by grafting with resistant rootstocks. Excision and regeneration of grafted seedling roots is a common practice among cucurbit-grafting nurseries that has not been thoroughly examined. The objectives of this study were to compare the performance of grafted and nongrafted watermelon plants under both greenhouse and field conditions when inoculated with Fusarium oxysporum f. sp. niveum (FON) race 2, and assess the effect of root excision on growth of grafted plants with Cucurbita moschata and Cucurbita maxima × C. moschata rootstocks. Two greenhouse experiments (Fall 2015 and Spring 2016) and one field trial (Spring 2016) of seedless watermelon ‘Melody’ were conducted in this study. In both greenhouse experiments, inoculated, nongrafted watermelon plants showed a significantly higher percentage of recovered Fusarium spp. colonies (70% to 75%) compared with grafted treatments (0% to 7.5%). Some plant growth measurements, including the longest vine length and aboveground fresh and dry weight, indicated less vigorous growth for nongrafted plants compared with the grafted treatments. Significantly higher percent recovery of Fusarium spp. below the graft union was observed in the grafted plants with root excision and regeneration treatment (3.7%) in contrast to the intact root treatment (0.5%), suggesting that the root excision method may possibly create entry points for FON infections. Overall, the root excision treatment showed little influence on aboveground growth and root characteristics of grafted plants. Yield of grafted watermelon with FON inoculation in the fumigated field trial was significantly higher than that of noninoculated, nongrafted ‘Melody’ (NGM) control as reflected by the increase of fruit number and size. Averaged over all the grafted treatments, the increase in marketable fruit number and weight reached 108.3% and 240.9%, respectively, and the total fruit number and weight increase was at 80.0% and 237.2%, respectively. However, grafted plants also exhibited greater levels of root-knot nematode infestation as indicated by the significantly higher root galling ratings. Results from this study demonstrated that grafting with squash rootstocks can effectively limit FON colonization in seedless watermelon plants, although more research in rootstock selection and testing is needed to optimize the use of grafted plants for improving plant growth and fruit yield.

Fruit quality of seedless watermelon grafted onto squash rootstocks under different production systems.

The market demand for seedless watermelon has been continuously increasing because of consumer preference. Grafting is a useful tool to manage soilborne diseases in watermelon production, but the use of squash rootstocks may negatively affect watermelon fruit quality. Currently, most research has focused on seeded cultivars, while grafting effects on seedless watermelons remain largely unknown. This multi-season study was conducted to assess the effects of squash rootstocks, including both Cucurbita maxima × C. moschata and C. moschata cultivars, with intact or excised and regenerated roots, on fruit quality of seedless watermelon 'Melody' using both instrumental and sensory measurements under different production scenarios. The grafted watermelon plants were also challenged by field inoculation with Fusarium oxysporum f.sp. niveum. A combination of instrumental measurements and consumer sensory analyses suggested that fruit quality of the seedless watermelon 'Melody' was not impacted by the use of the squash rootstocks used in this study, which included soluble solids content, titratable acidity, pH and most fruit sensory properties. Watermelon flesh firmness was increased by grafting but the grafting effect on lycopene content was inconclusive. Root excision and regeneration did not influence the grafting effect, whereas the grafting effect on flesh firmness varied among the rootstocks under Fusarium inoculation. Overall, grafting with squash rootstocks did not reduce fruit quality attributes of 'Melody' but improved texture. Our results support incorporating grafting into integrated management programs for seedless watermelon production. © 2017 Society of Chemical Industry.

Effects of root excision mulched with film on photosynthesis characteristics of poplar shelterbelts in black soil region

Root excision mulched with film is an effective method which can minimize decrease in crop production in negative-effect area. However, the measure may have adverse effects on the cropland shelterbelt. Taking no treatment as CK, the effects of root excisions mulched with film at distance 0.5, 1, 2 and 3 m from the trunk on photosynthesis characteristics of poplar shelterbelts in black soil region were discussed. The results indicated that root excision mulched with film had no significant effect on poplar leaf water content. Early in July, the time of peak and trough in the treatments were earlier than CK. Different treatments of root excision mulched with film made daily average value of net photosynthetic rate of poplar leaves significantly lower than CK, and there were significant difference among different treatments. During August to September, root excision mulched with film induced daily average value of net photosynthetic rate of poplar leaves still lower than CK, but the lowered range was somewhat reduced, root excision mulched with film at the distance 3 m from the trunk had no significant difference from CK. After root excision mulched with film, transpiration curve appeared in many forms. At the distances 2 and 3 m from the trunk, daily average value of transpiration rate of poplar leaves had no significant difference from CK. At the distances 0.5 and 1 m from the trunk, the decrease in transpiration rate in July was greater than that of photosynthetic rate, resulting in the significantly high water use efficiency than CK. Compared with CK, daily dynamics of water use efficiency in the other treatments had no change, however, daily average value of water use efficiency in the other treatments had significant change, and some of the changes were adverse. Comprehensive comparison indicated that root excision mulched with film at the distance 3 m from the trunk had no significant effect on the photosynthetic characteristics of poplar leaves, and this treatment was significantly superior to others.

Effects of Grafting Methods and Root Excision on Growth Characteristics of Grafted Muskmelon Plants

Grafting has been used for controlling certain soilborne diseases and improving abiotic stress tolerance in muskmelon (Cucumis melo) production. Grafting methods may vary considerably among geographic regions and nurseries, while excision of rootstock roots before graft healing may also be practiced, which allows root regeneration of the grafted plants. In this greenhouse study, four grafting methods including hole insertion, one-cotyledon, noncotyledon, and tongue approach methods were examined for their impacts on plant growth and root characteristics of ‘Athena’ muskmelon grafted onto ‘Strong Tosa’ interspecific hybrid squash rootstock (Cucurbita maxima × C. moschata). Nongrafted rootstock and scion plants were included as controls. Both the grafted and nongrafted plants were examined with or without root excision. The practice of root excision was unsuccessful with the tongue approach method, while it did not exhibit significant effects on graft quality and growth of plants grafted with the one-cotyledon and hole insertion methods. Grafted plants with root excision started to show active and rapid root regeneration at 8 days after grafting (DAG) and reached similar root length and surface area as the root-intact plants at 16 DAG. Plants grafted with the noncotyledon method showed a different root growth pattern with decreased root length and surface area at 16 DAG. As a result, this method reduced the quality of grafted plants. No significant differences in plant growth characteristics were observed among the hole insertion, one-cotyledon, and tongue approach grafted plants.

Membrane water permeability of maize root cells under two levels of oxidative stress.

Changes in the total water permeability of two cell membranes (plasmalemma and tonoplast), estimated by the effective diffusion coefficient of water (D ef), were controlled using the NMR method. The time dynamics of D ef in maize (Zea mays L.) root cells was studied in response to (i) root excision from seedling and the following 6-h incubation in the growth medium (wound stress) and (ii) the superposition of wound stress plus paraquat, which induces the excess of reactive oxygen species (ROS). The dynamics of lipid peroxidation, oxygen consumption, and heat production was studied to estimate general levels of oxidative stress in two variants of experiments. Under wound stress (the weak oxidative stress), the reversible by dithiothreitol increase in cell membrane water permeability was observed. The applicability of mercury test to aquaporin activity in our experiments was verified. The results of wound stress effect, obtained using this test, are discussed in terms of oxidative upregulation of aquaporin activity by ROS. The increase of oxidative stress in cells (wound-paraquat stress), contrary to wound stress, was accompanied by downregulation of membrane water permeability. In this case, ROS is supposed to affect the aquaporins not directly but via such processes as peroxidation of lipids, inactivation of some intracellular proteins, and relocalization of aquaporins in cells.

Effects of excising and washing treatments on the root respiration rates of Japanese cedar (Cryptomeria japonica) seedlings

Tree root respiration is an important component of the carbon balance in forest ecosystems; however, it is not clear whether root preparation treatments (such as excising and washing) affect root respiration measurements. Here, we aimed to compare the respiration rates of roots subjected to different treatments (i.e., washing with water vs. brushing without water, and excising vs. not excising) for 17-month-old seedlings of Cryptomeria japonica. Immediately after sampling an entire root system, the root respiration rate was measured on a mass basis using a closed static chamber system equipped with an infrared gas analyzer. We found that the respiration rates for roots that were excised 10–20 times were significantly higher than those for roots that were not excised. There was no significant difference in the root respiration rates between washing and brushing treatments. Our results indicate that large numbers of excisions (>10 times) could lead to bias in the measured changes in specific root respiration rates, and imply that differences between washing and brushing treatments do not affect the specific root respiration rate. We conclude that potential variation in recorded root respiration rates could be minimized by standardizing the root preparation technique, which should involve rapidly removing all loose soil and limiting the extent of root excision.

Localized Induction of the ATP-Binding Cassette B19 Auxin Transporter Enhances Adventitious Root Formation in Arabidopsis

Adventitious roots emerge from aerial plant tissues, and the induction of these roots is essential for clonal propagation of agriculturally important plant species. This process has received extensive study in horticultural species but much less focus in genetically tractable model species. We have explored the role of auxin transport in this process in Arabidopsis (Arabidopsis thaliana) seedlings in which adventitious root initiation was induced by excising roots from low-light-grown hypocotyls. Inhibition of auxin transport from the shoot apex abolishes adventitious root formation under these conditions. Root excision was accompanied by a rapid increase in radioactive indole-3-acetic acid (IAA) transport and its accumulation in the hypocotyl above the point of excision where adventitious roots emerge. Local increases in auxin-responsive gene expression were also observed above the site of excision using three auxin-responsive reporters. These changes in auxin accumulation preceded cell division events, monitored by a cyclin B1 reporter (pCYCB1;1:GUS), and adventitious root initiation. We examined excision-induced adventitious root formation in auxin influx and efflux mutants, including auxin insensitive1, pin-formed1 (pin1), pin2, pin3, and pin7, with the most profound reductions observed in ATP-binding cassette B19 (ABCB19). An ABCB19 overexpression line forms more adventitious roots than the wild type in intact seedlings. Examination of transcriptional and translational fusions between ABCB19 and green fluorescent protein indicates that excision locally induced the accumulation of ABCB19 transcript and protein that is temporally and spatially linked to local IAA accumulation leading to adventitious root formation. These experiments are consistent with localized synthesis of ABCB19 protein after hypocotyl excision leads to enhanced IAA transport and local IAA accumulation driving adventitious root formation.

Effects of Root Excision and Water Stress on Root Hydraulics and TaPIPs Expression in Wheat Seedlings

Root excision can break water balance between water uptake by roots and transpriation in shoots and induce hydraulic responses of roots,which is helpful to explain how hydrostatic gradient regulates root hydraulic traits.To explore the regulation mechanisms of root hydraulics to the broken whole plant water balance by root excision and water stress,we investigated the changes of individual root(Lproot) and cortex cell(Lpcell) hydraulic conductivities of wheat(Triticum aestivum,cv.Changwu 134) after root excision and water stress with root and cell pressure probes.The transcription levels of TaPIP1;2 and TaPIP2;5 were also measured with quantitative real-time PCR.Root excision or water stress treatment significantly reduced the leaf transpiration rate and stomatal conductance of wheat seedlings,but the Lproot or Lpcell of the remained roots had no significant changes.The transpiration rate,stomatal conductance,leaf water potential,Lproot,and Lpcell of root-excised plants were significantly higher than those of plants under water stress.However,these parameters of plants with both root excision and water stress were significantly lower than those with a single treatment or the control.Irrespectively of root excision or water stress,Lpcell had a significantly positive correlation with Lproot(R2= 0.97,P 0.05),which suggested the accordance in root water uptake ability at cell level and individual root level.Root excision significantly up-regulated the relative mRNA contents of TaPIP1;2 and TaPIP2;5 in wheat roots,but water stress had an effect of down-regulation.The relative mRNA contents of TaPIP1;2 and TaPIP2;5 of root excised and water stressed seedlings were the lowest in the four treatments.These results may suggest that root excision could reduce the tolerance of wheat seedling to the following water stress;cortex cell hydraulic conductivity could be accordant with individual root hydraulic conductivity during wheat root hydraulics regulation;and TaPIP1;2 and TaPIP2;5 may be involved in regulating root hydraulics of wheat.

Large aortic root pseudoaneurysm occurring late after aortic root repair and valve replacement for endocarditis

A 68-year-old male presented with Group B Streptococcus aortic valve (AV) endocarditis with aortic root abscess and refractory sepsis. An emergency cardiac surgery was performed with root abscess drainage, excision and debridement of necrotic tissue, reconstruction of annulus, and AV replacement. Fifteen months later he presented with a huge aortic root pseudoaneurysm (PA). This case illustrates late occurrence of aortic root PA following AV surgery for endocarditis.