Search

Clerodendrum viscosum is a traditionally used medicinal plant. The present study aimed to analyze a detailed cytotoxic effect of the nonpolar petroleum ether fraction (AQPEF) of leaf aqueous extract of C. viscosum Vent. (LAECV) in Allium cepa root tip cells. The LAECV was fractionated with petroleum ether and tested for A. cepa toxicity at early hours (2 and 4 h treatment) at concentrations 0, 50, 100, 150 and 200 {micro}g mL-1. The highest aberrant cell percentage (10.45{+/-}0.46%) was scored from 150 {micro}g mL-1 followed by100 {micro}g mL-1 (8.75{+/-}0.26%) concentration at 4 h treated samples. The AQPEF treatment induced a significant (p

Saccharin has been a controversial dietary component because of its potential to aggravate a number of human health disorders. The genotoxic properties of saccharin affect the normal karyokinesis process and results in chromosomal aberrations. In this backdrop, the current study has been formulated to evaluate the genotoxic potential of aqueous saccharin solution using Allium cepa L. assay. Three different concentrations of saccharin solution (0.25%, 0.5% and 1%) and a negative control were used for the root growth inhibition assay. The root length of Allium cepa significantly reduced under saccharin treatments and the effective concentration (EC50) value of the aqueous saccharin solution was determined as 0.587%. The genotoxic effects were determined for the root tip meristematic cells through mitotic index (MI) and mitotic depression (MD) at 3, 6 and 12 h of study. The MI registered highest value without saccharin at low exposure period (17.0 ± 1.5%) while a significant reduction with saccharin application culminated in the lowest MI for 1% saccharin solution at 12 h (3.4 ± 0.4%). MD was found to have a concomitant increase regarding the exposure of the chemical. Higher dose of saccharin for longer exposure time had a gradual decrease in the prophase and simultaneous increase in metaphase and anaphase. Further microscopic observations revealed eight different types of chromosomal aberrations in the A. cepa root tip cells with Anaphase Bridge assuming the highest score. Thus the current study clearly establishes the genotoxic consequences of aqueous solution of saccharin warranting its moderate and regulated dietary intake.

The extensive production and utilisation of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) in consumable items may enhance significant increase in fauna and flora exposure. Studies showing the interactive effect of NPs in biological systems are limited. Herein, we showed the cytogenotoxic effects of TiO2 and ZnO NPs, and their mixture (1:1) using the Allium cepa assay. Mitotic index (MI) and chromosomal aberrations (CAs) were assessed in A. cepa L. bulbs exposed to each NP and their mixture at concentrations of 5, 10, 20, 40 and 80 mg L−1, respectively. The recovery effect of the root tip cells from the cytogenotoxic effects of the nanoparticles was also investigated. TiO2, ZnO NPs and their mixture significantly (p

Already a short-term Cd treatment induces changes in gene expression in barley root tips via IAA and ROS signaling during mild and severe Cd stress, respectively. Even a short, 30 min, Cd treatment of roots induced a considerable alteration in gene expression in the barley root tips within an hour after the treatments. The very early activation of MYB1 transcription factor expression is partially regulated by auxin signaling in mildly stressed seedlings. An increase in allene oxide cyclase and NADPH oxidase expression was a distinguishing feature of root tips response to mild Cd stress and their expression is activated via IAA signaling. Meanwhile, early changes in the level of dehydrin transcripts were detected in moderately and severely stressed root tips, and their induction is related to altered ROS homeostasis in cells. The early activation of glutathione peroxidase expression by mild Cd stress indicates the involvement of IAA in the signaling process. In contrast, early ascorbate peroxidase expression was induced only with Cd treatment causing severe stress and ROS play central roles in its induction. The expression of cysteine protease was activated similarly in both mildly and severely Cd-stressed roots; consequently, both increased IAA and ROS levels take part in the regulation of cysteine protease expression. The Cd-evoked accumulation of BAX Inhibitor-1 mRNA was characteristic for moderately and severely stressed roots. Whereas decreased IAA level did not affect its expression, rotenone-mediated ROS depletion markedly reduced the Cd-induced expression of BAX Inhibitor-1. An early increase of alternative oxidase levels in the root tip cells indicated that the reduction of mitochondrial superoxide generation is an important component of barley root response to severe Cd stress.

Aluminium (Al) toxicity inhibits soybean root growth, leading to insufficient water and nutrient uptake. Two soybean lines (‘Magellan’ and PI 567731) were identified differing in Al tolerance, as determined by primary root length ratio, total root length ratio, and root tip number ratio under Al stress. Serious root necrosis was observed in PI 567731, but not in Magellan under Al stress. An F8 recombinant inbred line population derived from a cross between Magellan and PI 567731 was used to map the quantitative trait loci (QTL) for Al tolerance. Three QTL on chromosomes 3, 13, and 20, with tolerant alleles from Magellan, were identified. qAl_Gm13 and qAl_Gm20 explained large phenotypic variations (13–27%) and helped maintain root elongation and initiation under Al stress. In addition, qAl_Gm13 and qAl_Gm20 were confirmed in near-isogenic backgrounds and were identified to epistatically regulate Al tolerance via internal detoxification instead of Al3+ exclusion. Phylogenetic and pedigree analysis identified the tolerant alleles of both loci derived from the US ancestral line, A.K.[FC30761], originally from China. Our results provide novel genetic resources for breeding Al-tolerant soybean and suggest that internal detoxification contributes to soybean tolerance to excessive soil Al.

Lentil is now an integral part of prairie cropping systems. Climate forecasts point to variable and increased drought frequency, putting lentil production in jeopardy. Future lentil genotypes will require root systems that can extract more water under drought conditions. This study focuses on root diameter and root tip number, traits known to play an important role in water uptake during drought. We compared the total root length (TRL) in three soil horizons of both wild and cultivated lentil genotypes for three root diameter classes when plants were grown under moderate or severe drought, and when re-watered after exposure to moderate drought conditions. Our study demonstrates that roots of both wild and cultivated lentil genotypes can be categorized into very fine, fine and small diameter classes. Some wild lentil genotypes had significantly higher TRL in the B and C soil horizons when grown under severe or moderate drought and therefore, could act as resources for the transfer of root traits to cultivated lentil genotypes. Further evaluations focused on the root systems of interspecific recombinant inbred lines under drought conditions will be required to determine whether these traits are heritable.

The harmful potential of the Colorado potato beetle (Leptinotarsa decemlineata (Say)), and its resistance to many insecticides in current use have drawn the attention of specialists across the worl...

Due to continued industrial discharge, pollution of the aquatic system has emerged as a worldwide concern. This study was conducted to determine the possible genotoxic effect of industrial effluents (treated and untreated) by employing the Allium cepa chromosome aberrations test system. The result illustrated that the untreated effluent was more toxic compared to treated effluent, as it reduced the number of dividing cells in the root tip. All the samples of untreated effluent showed high genotoxic effect. On incrementing the dosage from 25% to 100% the gradual increasing effect was noted on A. cepa. The study states that effluent even after treatment remains genotoxic as it has the ability to initiate the chromosomal aberrations of various types.

The present investigation was undertaken to evaluate the genotoxic effect of zinc nanoparticles (ZnNPs) synthesized by leaf extract of Albizia saman on mitotic chromosomes of root tip meristematic ...

Hydroponic studies were conducted to investigate the role of iron plaque on transport and distribution of chromium (Cr) by rice seedlings. Microscopical observations indicate that iron plaque developed quickly at the root surface of rice seedlings, but the distribution of iron plaque was more intense near root base and less towards root tip. Results showed that rice seedlings exposed to Cr(III) depicted significantly higher capacity for Cr accumulation in plant tissues than Cr(VI) in the presence of iron plaque. However, transport of Cr within plant cells was more evident in Cr(VI) treatment with iron plaque than Cr(III) treatment. Results also showed that there are significant impact on transport of K, Mn and Zn in rice seedlings treated with Cr(VI) in the presence of iron plaque, while significant effect on transport of Mn and Zn were observed in Cr(III)-treated rice seedlings. Results from detached root test provide additional evidence to confirm the presence of iron plaque, that had different impact o...

Regulation of flowering is one of the key issues in crop yield. The Flowering Locus T ( FT ) gene is a well-known florigen, which integrates various signals from multiple flowering-regulation pathways to initiate flowering. We previously reported that there are at least six FT genes ( GmFTL1 – 6 ) in soybean displaying flowering activity. However, the individual functions of genes GmFTL1 – 6 remain to be identified. In this study, we cloned the GmFTL2 promoter ( GmFTL pro ) from soybean ( Glycine max ) cultivar Tianlong 1 and analyzed its motifs bioinformatically and its expression patterns using both a transgenic approach and quantitative RT-PCR (qRT-PCR). In GmFTL pro :: GUS transgenic lines, GUS signals were enriched in cotyledons, hypocotyledons, pollen, embryos, and root tips in a photoperiod-independent manner. qRT-PCR confirmed the GUS reporter results. Our results suggest that GmFTL2 expression is regulated by developmental and tissue-specific clues and plays roles in seedling establishment and the development of microgametophytes, embryos, and roots.

This unit presents a highly reliable protocol to produce and screen metaphase chromosome spreads from root tip cell suspensions of soybean (Glycine max), or other legumes. The procedures represent soybean-optimized versions of protocols developed for maize. The use of pressurized nitrous oxide to reliably generate metaphase-arrested chromosomes is crucial to overcoming one of the challenges of working with tiny and numerous soybean chromosomes. © 2017 by John Wiley & Sons, Inc.

Melia volkensii is a tree species growing in semi-arid regions of East Africa, and is recognized as one of the most valuable forestry species in such regions of Kenya. The use of root cutting is an easy method for its clonal propagation, but the most appropriate conditions have not been systematically examined. In this study, the relationship between diameter of root cut edge or fresh weight and formation frequency of adventitious bud were assessed. In addition, roots were divided into two fragments, and formation frequency of adventitious bud was compared between cross-sections roots without root tip and roots with root tip. Both the diameter of the cut edge and fresh weight of roots forming adventitious buds were significantly higher than in those not forming them (unpaired t-test, p15 mm and fresh weight >20 g, but it decreased (37.2%) in roots that did not meet this criteria. Based on anatomical analysis, an effect of the developmental stage of root fragments on adventitious bud formation was suggested, and root size is thought to reflect the stage of root development. The formation frequency of adventitious buds was 72% even in cross-sectioned roots, and the proportion was not significantly different from that of normal root tip (p>0.05). Therefore, it is concluded that root cutting using cross-sectioned roots are also available for clonal propagation.Keywords: Clonal forestry, anatomical analysis of root, availability of cross sectioned roots

Regulation of plant root angle is critical for obtaining nutrients and water and is an important trait for plant breeding. A plant’s final, long-term root angle is the net result of a complex series of decisions made by a root tip in response to changes in nutrient availability, impediments, the gravity vector and other stimuli. When a root tip is displaced from the gravity vector, the short-term process of gravitropism results in rapid reorientation of the root toward the vertical. Here, we explore both short- and long-term regulation of root growth angle, using natural variation in tomato to identify shared and separate genetic features of the two responses. Mapping of expression quantitative trait loci mapping and leveraging natural variation between and within species including Arabidopsis suggest a role for PURPLE ACID PHOSPHATASE 27 and CELL DIVISION CYCLE 73 in determining root angle.

The present study reports detailed and comparative karyomorphological and meiotic analyses in Swertia chirayita, S. nervosa and S. bimaculata of Eastern Himalaya. Chromosome analysis of these three Swertia species showed that the majority of cells were diploid with zygotic chromosome number 2n = 26 and gametic chromosome number n = 13. The mosaic chromosome number counts in root tip cells ranged from 9–24 chromosomes in S. bimaculata, to 11–24 chromosomes in both S. chirayita and S. nervosa. No variation was observed in pollen mother cells (PMCs) during meiosis. The modal karyotypes were determined as 2M + 12m + 10sm + 2m:sm for S. chirayita, 8M + 14m + 2sm + 2m:sm for S. nervosa and 6M + 16m + 2sm + 2M:st for S. bimaculata. Karyomorphological analysis of the three Swertia species have documented some distinct similarities between S. chirayita and S. nervosa in terms of their chromosomal category (small), mean chromosomal length (2.48μm, 2.62 μm), length of total chromatin (32.18μm, 34.14 μm) as well as p...

Texas bluegrass (Poa arachnifera Torr.) is a dioecious, perennial, cool-season grass native to southern Kansas, Oklahoma, western Arkansas and most of Texas. Its major use has been for forage on rangelands in Texas and Oklahoma. More recently, interspecific hybrids between Texas bluegrass and Kentucky bluegrass (P. pratensis L.) have been developed and commercially released as heat tolerant turfgrass. Currently, the 2C nuclear DNA content of Texas bluegrass is unknown. Therefore, flow cytometry was performed on an assortment of male and female Texas bluegrass genotypes (n = 24) collected from fourteen locations in Texas and Oklahoma to estimate DNA content in picograms (pg). The DNA content of Texas bluegrass fell into two groups based on collection location. Plants collected from northwest Oklahoma and five other locations west of 33.75, −98.39 (latitude, longitude) ranged from 9.64 ± 0.04 to 10.07 ± 0.09 pg. Plants collected from four sites in Texas, east of 33.20, −98.16 contained a DNA content that ranged from 14.02 ± 0.04 to 14.75 ± 0.13 pg. Based on a root tip chromosome count, a male Texas bluegrass plant estimated to be 9.96 pg, appeared to contain 56 chromosomes, indicating the smaller DNA content plants may be octaploids (2n = 8x = 56). Significant differences were not detected between male and female plants based on DNA content. Knowledge of the DNA content in Texas bluegrass should be useful in a breeding program for characterizing germplasm and identifying desired DNA content levels among parental genotypes.

Morphogenic responses, ROS generation and changes in enzymes activity induced by the short-term exposure of barley roots to Cd were very similar to those of triiodobenzoic acid (TIBA) treatment. Both Cd and TIBA markedly increased the amount of IAA in root apex. In addition, the treatment of roots with TIBA before Cd treatment had an additive effect on morphogenic responses, changes in enzymes activity and ROS generation. In turn, the application of auxin efflux/influx inhibitor 1-naphthoxyacetic acid (1-NOA) before Cd treatment significantly reduced the Cd-induced ROS generation, root growth inhibition and enzymes activity in spite of the elevated level of IAA in the root apex. The auxin signalling inhibitor p-chlorophenoxyisobutyric acid (PCIB) nearly fully eliminated some of these Cd-induced responses. These results indicated that the short-term Cd treatment-induced ROS generation, morphogenic responses and activity of some enzymes can be attributed to the disturbance of IAA homeostasis in root apex. While auxin efflux inhibitor TIBA evoked similar response to Cd, auxin efflux/influx inhibitor 1-NOA attenuated and auxin signalling inhibitor PCIB blocked these Cd-induced responses suggesting that apart from the elevated level of IAA in root apex its enter and accumulation inside of until closely undetermined cells or tissues is a prerequisite for the induction of characteristic root responses to short-term Cd exposure.

Despite the critical role of EMF in nutrient and carbon (C) dynamics, combined effects of global atmospheric pollutants on ectomycorrhizal fungi (EMF) are unclear. Here, we present research on EMF root-level community responses to elevated CO2 and O3. We discovered that belowground EMF community richness and similarity were both negatively affected by CO2 and O3, but the effects of CO2 and O3 on EMF communities were contingent on a site soil pH and cation availability gradient. These results contrast with our previous work showing a strong direct effect of CO2 and O3 on sporocarp community dynamics and production. We discuss the possible role of carbon demand and allocation by EMF taxa in the discrepancy of these results. EMF communities were structured by a legacy of spatially defined soil properties, changing atmospheric chemistry and temporal dynamics. It is therefore necessary to understand global change impacts across multiple environmental gradients and spatiotemporal scales.

SummaryOver-exploitation of endemic and threatened Tunceli garlic [Allium tuncelianum (Kollman) N. Ozhatay, B. Mathew & Siraneci] for household purposes has threatened the species and requires that a reliable, improved tissue culture protocol be developed for its conservation. Leaf tips, the middle portions of leaves, leaf bases, vertically-sectioned halved or quartered bulbs, horizontally-sectioned upper and lower bulb halves, and root tip explants were cultured on 1.0× Murashige and Skoog (MS) medium containing 1.0, 2.0, 3.0, 4.0, or 5.0 mg l–1 2,4-dichlorophenoxyacetic acid (2,4-D) or 1.0, 2.0, 3.0, 4.0, or 5.0 mg l–1 6-benzylaminopurine (BAP) plus 0.5 mg l–1 α-naphthaleneacetic acid (NAA). The results indicated that root tip explants were most suitable for bulblet regeneration on 1.0× MS medium containing 5.0 mg l–1 BAP plus 0.5 mg l–1 NAA. All other explants failed to regenerate on different concentrations of BAP plus NAA, or on 2,4-D. The regenerated bulblets were acclimatised at 24o ± 1oC and 80.0%...

Spondias mombin L., Nymphea lotus L. and Luffa cylindrica L. are commonly used in the traditional management of cancer in Nigeria. The genotoxic and anti-genotoxic effects of aqueous extracts of these plants was evaluated using the Allium cepa L. assay. Onion bulbs were exposed to 0.5–10 mg ml–1 concentrations (v/v) of each extract, prepared as practiced locally, for analyses of root growth inhibition and induction of cytogenetic damage, respectively. There was concentration-dependent, significant (p < 0.05) inhibition of root growth by the extracts when compared with the negative control. The EC50 for the decoctions of S. mombin, N. lotus and L. cylindrica were 1.3, 1.8 and 16.2 mg ml–1 respectively. All the extracts had mitodepressive effects on cell division, and induced chromosomal aberrations (p ˂ 0.05). They showed chemopreventive activity through reduction of cytological aberration induced by lead nitrate. These findings suggest inhibitory, anti-proliferative and anti-cytogenetic damage activities ...

Carrot psyllid Trioza apicalis was recently found to carry the plant pathogenic bacterium ‘Candidatus Liberibacter solanacearum’ (CLs). To confirm the transmission of bacteria by the psyllids and to dissect the symptoms caused in carrot plants by psyllid feeding and CLs infection, a greenhouse experiment with single psyllids feeding on separate plants was performed. A positive correlation was found between the amount of CLs bacteria in the psyllids and in the corresponding plants exposed to feeding, indicating CLs transmission. The female psyllid feeding caused more severe damage than male feeding, and resulted in a substantial decrease in the root weight. Female psyllid feeding also significantly reduced the carrot leaf weight and increased the number of curled leaves. The number of curled leaves was also increased by the nymphs when their number exceeded 10 per plant. A high titre of CLs bacteria significantly reduced root weight, while not affecting the weight or number of the leaves. However, the amount of CLs correlated with the number of leaves showing discolouration symptoms. Microscopy of infected carrot plants revealed that the phloem tubes throughout the whole plant, from leaf veins to the root tip, were colonized by bacteria. The bacterial cells appeared to be long and thin flexible rods with tapering ends and a transversally undulated surface. Microscopy also revealed collapsed phloem cells in the infected carrots. Damage in the phloem vessels is likely to reduce the sucrose transport from source leaves to the root, explaining the observed leaf discolouration and reduction in root weight.

Tomato is a model and economically important crop plant with little information available about gene expression in roots. Currently, there have only been a few studies that examine hormonal responses in tomato roots and none at a genome-wide level. This study examined the transcriptome atlas of tomato root regions (root tip, lateral roots, and whole roots) and the transcriptional regulation of each root region in response to the plant hormones cytokinin and auxin using Illumina RNA sequencing. More than 165 million 1×54 base pair reads were mapped onto the Solanum lycopersicum reference genome and differential expression patterns in each root region in response to each hormone were assessed. Many novel cytokinin- and auxin-induced and -repressed genes were identified as significantly differentially expressed and the expression levels of several were confirmed by qPCR. A number of these regulated genes represent tomato orthologues of cytokinin- or auxin-regulated genes identified in other species, including CKXs, type-A RRs, Aux/IAAs, and ARFs. Additionally, the data confirm some of the hormone regulation studies for recently examined genes in tomato such as SlIAAs and SlGH3s. Moreover, genes expressed abundantly in each root region were identified which provide a spatial distribution of many classes of genes, including plant defence, secondary metabolite production, and general metabolism across the root. Overall this study presents the first global expression patterns of hormone-regulated transcripts in tomato roots, which will be functionally relevant for future studies directed towards tomato root growth and development.

The proximal end morphology of antemortem anagen head hair was compared with the characteristics documented to occur in postmortem hairs. Antemortem anagen and telogen head hairs (N = 967) were recovered following exposure to seven environments. Root morphology characteristics consistent with those reported in postmortem hairs were observed in 66 (14%) hairs exposed to a water, normal saline, outdoor soil, or indoor shower environment. Thirty-three anagen hairs (7%) exhibited a root band at the proximal end. The mean distance from the root tip to the onset of the root band ranged from 0.23 to 0.7 mm, depending on the environment. The mean distance from the root tip to the onset of the root band was 0.46 mm, with a mean band length of 0.44 mm. The results illustrate the need to better characterize postmortem banding through quantitative measurements, including the range for root tip to band distance and the overall band length.

Studying plant root kinematics is important for understanding certain aspects of root growth and movement, which are strictly correlated in plants. However, there is little available data on autonomous movements in plant roots, such as nutations, and the data that are available are poorly described. We investigated the autonomous movements during growth in primary maize roots by estimating the main kinematic parameters of nutations (i.e., the period of duration and amplitude) and the growth rate. The estimations of nutation parameters were performed by developing dedicated methods, which are based on the analysis of root tip displacement and tip velocity. The data relative to the tip displacements were obtained using tip tracing software developed by our team specifically for this purpose. The results confirmed that the nutational phenomenon covers the continuous range of periods and amplitudes, with certain dominant period-amplitude types, which we clustered into three groups: i) amplitudes less than 0.1 mm and 4–16 min periods, ii) amplitudes less than 0.1 mm and 20–120 min periods, and iii) amplitudes greater than 0.1 mm and 24–120 min periods.

A cytogenetic study was conducted on Rheum tanguticum populations from Huangnan Tibetan Au- tonomous Prefecture, China. The results revealed the chromosome numbers 2n=22 and the karyotype formulae are 2n=22=22m or 2n=22=2sm+20m, belonging to Stebbins 1A type. However, it was interesting to observe metaphases with variable B chromosomes (1, 2, 3, 4, 6, 7) in a few specimens. For the fi rst time, the occurrence of B chromosomes was reported in natural populations of R. tanguticum. The number of B chromosomes in R. tanguticum varied not only among individuals but also within the same root tip.

Cytotoxic evaluation of annatto (Bixa orellana L.) seed pulp extract on Allium cepa root tip cells was carried out. The annatto dye was extracted using different solvents viz. alkaline water, ethyl alcohol and chloroform : alcohol mixture (1 : 3). Crude extract evaporated and dry residual powder recovered. The powder was dissolved in water at different concentrations (0.1%, 0.5% and 1%) and was used to treat onion root tips for 12 h and the mitotic behaviour was recorded. The results were compared with a synthetic dye orange red at 2 concentrations (0.05 and 0.1%). Annatto extracts treated cells showed normal mitotic behaviour whereas orange red (0.1% w/v) showed complete arrest of cell division. The synthetic dye at low concentration (0.05% w/v) showed diverse forms of mitotic abnormalities like single or double nuclear lesions, single, double or multiple bridges, metaphase clumping, tropokinensis and chromosome fragments. Cyototoxicity test system based on A. cepa root tips has proved that annatto dye is significantly less toxic compared to its synthetic alternative, orange red.

Capparis spinosa L. flower buds (CS) aqueous extracts are used in Turkey traditional medicine for their diuretic, antihypertensive, poultice, tonic and other properties. The present study evaluates the genotoxic and antimutagenic effects of capers (C. spinosa L.) flower buds aqueous extract on the Allium cepa L root tip meristem cells. The experiment was carried out in three applications: (1) the onion bulbs were treated with 3.10–2 M Ethyl Methane sulfonate (EMS) for 2 h, after than the EMS treatment, the onion bulbs were treated with three different concentrations (10g/L, 20g/L and 30g/L) of aqueous extract from flowering buds for 24 h. (2) onion bulbs were treated with three different concentrations (10g/L, 20g/L and 30g/L) of aqueous extract for 24 h and then with 3.10–2 M EMS for 2 h (3) Onion bulbs were treated with three different concentrations (10g/L, 20g/L and 30g/L) of aqueous extract for 24 h without EMS treatment. 3.10–2 M EMS was used as positive control and tap water (pH 7.3) was u...

A new method for producing a NIAN type wheat maintenance line with the male sterile gene rfv 1 was described. That is the variety Xinong Fp1, a 1BL/1RS translocation line, as the acceptor and Triticum macha var. subletschchumicum, a non-1BL/1RS translocation line, as the donor, a directional substitution backcross was made and confirmed by chromosome of root tip preparations and SDS-PAGE analysis. The male sterile gene rfv 1 of Triticum macha var. subletschchumicum was transferred to the genome of Xinong Fp1. A new NIAN type wheat maintenance line with the male sterile gene rfv 1 was bred. The method described was successful in breeding a new male sterile type for hybrid wheat production.

Small bulbs of Allium cepa L. were cultivated for two days at various distances from a video display unit (computer or TV set). No effects could be observed on root growth or on the progress of normal mitosis in root tip cells. However, in a first experiment using colchicine-treated material, metaphase chromosomes with elongated centromeres were observed in a frequency which seemed to be inversely related to the distance of the onions from the screen. In a repeated, more comprehensive experiment, this relationship could not be confirmed. Instead, the occurrence of elongated centromeres was probably due to methodological variations. Thus, no biological damage could be demonstrated when root tips of ANium cepa were grown in front of video display units.

Contractile roots provide for a type of movement in plants that occurs in many plant species but has been given little attention. In the case of Easter lily (Lilium longiflorum Thunb. cv. Nelly White), root contraction serves to pull a bulb down into the soil where environmental conditions are more constant. The contraction is evidenced by a formation of epidermal wrinkles, starting at the base of the root and advancing toward the root tip. The movement function occurs in shallowly planted materials, is lessened at deeper locations, and ceases at a vermiculite depth of '15 cm. Examination of the cell shapes and volumes in the contracting sector indicates that movement of the bulb in the soil is achieved by a hydraulic shift in cortical cells. Root contraction is stimulated by light. Perception of the light stimulus does not occur in the root but occurs in the bulblet or possibly in the subtending leaf. Responsiveness to light fades with aging of the root, and experiments with light of different wavelengths indicate that the contraction response is preferentially triggered by blue light. The autonomous movement of plant stems or bulbs down into the soil occurs through the contraction of roots. This type of movement was first noted by Theophrastus (� 300 BCE) and was described more recently by Tittmann (1819) in roots of Daucus carota L. Contractile roots (CR) were first seriously studied by De Vries (1880) and Rimbach (1898, 1926) and reviewed by Galil (1980). They have been reported to occur in >400 species of both monocotyledonous and dicotyledonous supertending organs, such as bulbs, corms, hypocotyls, (e.g., De Vries, 1880; Galil, 1980; Rimbach, 1902, 1926). Contractile roots pull these organs down through the substratum until they reach a location that is presumed to be advantageous in terms of insulation from hostile surface environments. Contractile roots also may pull bulblets away from the bulb scale, providing the benefit of dispersal.

Karyotype analysis (through Image Analyzing System) of Withania somnifera revealed 7 (2n=48: 4Asmsc+4Bm+14Cm+4Dsm+2Est+18Fm+2Gsm) morphologically distinct chromosome types. The karyotypes showed prevalence of chromosomes with median primary constrictions. Satellites were associated with short arm of 4A-type chromosomes. Chromosome length in the complement varies from 1.43 to 2.64 μm. The karyotype was symmetric in nature (TF%: 42.26). Root tip squash preparations revealed polysomatomy (2n=12: 5.8%, 2n=18: 4.8%, 2n=24: 2.9%, 2n=36: 25.0%, 2n=48: 57.7% and 2n=72: 3.8%) with predominance of 2n=48 chromosomes. The meiocytes had 2n=48 chromosomes always with an average of 23.52 II+0.95 I per cell. The bivalents formed rods (rods: 20.64±0.15, rings: 2.90±0.17) mostly at diplotene with mean chiasma of 26.45±0.25 per cell. A persistent feature in 76.2% metaphase I cells was the presence of secondary association of chromosomes and the chromosomes tended to form groups of 3 (8.0%), 6 (32.0%), 9 (16.0%) and 12 (44.0%). Secondary polyploidy has been attributed as the possible cause of secondary association of chromosomes and the basic chromosome number of the species has been suggested to be x=12.

Using the nullisomic back-cross procedure, four wheat-rye chromosome substitution 2R (2D) lines with different agronomic performance, designated WR02-145-1, WR01-145-2, WR02-145-3, and WR02-145-4, were produced from a cross between 2D nullisomic wheat (Triticum aestivum L. cv. “Xiaoyan 6”) and rye (Secale cereale L. cv. “German White”). The chromosomal constitution of 2n=42=21 in WR02-145 lines was confirmed by cytological and molecular cytogenetic methods. Using genomic in situ hybridization on root tip chromosome preparations, a pair of intact rye chromosomes was detected in the WR02-145 lines. PCR using chromosome-specific primers confirmed the presence of 2R chromosomes of rye in these wheat-rye lines, indicating that WR02-145 lines are disomic chromosome substitution lines 2R(2D). The WR02-145 lines are resistant to the powdery mildew (Erysiphe graminis DC. f. sp. tritici E. Marchal) isolates prevalent in northern China and may possess gene(s) for resistance to powdery mildew, which differ from the previously identified Pm7 gene located on chromosome 2RL. The newly developed “Xiaoyan 6”- “German White” 2R (2D) chromosome substitution lines are genetically stable, show desirable agronomic traits, and are expected to be useful in wheat improvement. (Managing editor: Li-Hui Zhao)

A hundred and ninety-three hairy root lines were produced from Korea ginseng ( P. ginseng ). These hairy root lines were classified into five different types, depending on their phenotypes. Metabolic profiling by 1 H NMR analysis indicated that the glutamine concentration was about five-fold higher in hairy root types with sluggish growth rates and low branching phenotypes than other hairy root types. Glutamine was detected at much higher levels in root tip zones when compared to those of root elongation zones. When the segments of the high branching hairy root were cultured in a medium containing more than 30 mM glutamine, root growth and lateral root formation were significantly reduced. It is known that nitrate is a major nitrogen source and can act as regulatory signal on the root development. In this study, we identify and suggest that glutamine plays an important role in root growth and phenotypes in ginseng hairy roots.

In Brazil leaf infusions of the plant Pterocaulon polystachyum DC (Asteraceae) are used to treat digestive problems. We used plants from six P. polystachyum populations to prepare fresh aqueous leaf infusions at the concentration normally used in Brazil (2.5 g L-1) and at twice (5 g L-1) and four times (10 g L-1) this concentration. We rooted onion bulbs in a water control or one of the infusions for 24 h and used the in vivo onion (Allium cepa) root-tip cell test to investigate the potential mutagenicity of the infusions by calculating the mitotic index for the control and the experimental treatments and comparing them using the Chi-squared test (chi2, p = 0.05). There was a highly significant decrease in the mitotic index of root-tip cells treated with infusion as compared to those exposed to water only. These results indicate that P. polystachyum infusions present cytotoxic and anti-proliferative activity and therefore have therapeutic potential.

To identify the region in which a root perceives a decrease in the ambient water potential and changes its elongation rate, we applied two agar blocks (1 × 1 × 1 mm3) with low water potential bilaterally to primary roots of maize (Zea mays) at various positions along the root. When agar blocks with a water potential of −1.60 MPa (−1.60-MPa blocks) or lower were attached to a root tip, the rate of elongation decreased. This decrease did not result from any changes in the water status of elongating cells and was not reversed when the −1.60-MPa blocks were replaced by −0.03-MPa blocks. The rate decreased slightly and was unaffected, respectively, when −1.60-MPa blocks were applied to the so-called decelerating region of the elongating zone and the mature region. However, the rate decreased markedly and did not recover for several hours at least when such blocks were attached to the accelerating region. In this case, the turgor pressure of the elongating cells decreased immediately after the application of the blocks and recovered thereafter. The decrease in elongation rate caused by −1.60-MPa blocks applied to the root tip was unaffected by additional −0.03-MPa blocks applied to the accelerating region and vice versa. We concluded that a significant reduction in root growth could be induced by water stress at the root tip, as well as in the accelerating region of the elongating zone, and that transmission of some signal from these regions to the decelerating region might contribute to the suppression of cell elongation in the elongation region.

Due to their central role in sugar metabolism and signalling plant hexokinases have been studied in great detail, however, little is known about the spatial and temporal expression and the sub-cellular distribution of individual hexokinase isoforms. Based on in planta and in vitro studies the recently isolated tobacco hexokinase 2 (Hxk2) could be located in the chloroplast stroma and biochemically characterized. Hxk2 represents the first innerplastidic hexokinase described from higher plants. Promoter studies indicate that Hxk2 is mainly expressed in cells of the vascular starch sheath and xylem parenchyma, in guard cells and root tips. We propose a role for Hxk2 in starch and secondary metabolism in the mentioned tissues.

Wastewater was collected from two municipal wastewater treatment plants and twelve different industries representing five lines of business (chemical, metallic, petrochemical, pulp- and paper, and textile dye industries). Effect on the growth of Allium roots was measured after five days of exposure. Growth inhibition values, EC50 and EC30, showed no toxic effect for eight of the fourteen plants. The most toxic effect was found in wastewater from one of the pulp- and paper plants. Allium root tip cells were analyzed for chromosome aberrations after 24 h of exposure. Wastewater from nine of the fourteen plants was able to induce chromosome aberrations at a statistically significant level. The textile dye industry was the only line of business which did not show any genotoxic effect. Three of the plants (municipal wastewater, metallic, and pulp- and paper) showed genotoxicity in spite of being nontoxic in the growth inhibition experiment.

were cultivated in various concentrations of the wastewater, and after 48 h one root tip from each bulb was harvested and processed for cytological studies by the aceto-orcein squash technique. After 96 h, mean lengths of root bundles were obtained and the Effect Concentration (EC) values calculated. Treatment with wastewater resulted in significant dose- dependent root growth inhibition.

In the present study, 30 seeds of Vicia faba (2n=12) treated with 0.005% colchicine for 8 h produced 15 polyploids. The success of induction of polyploidy by this method was 50%, which is very high as compared to any other methods used so far in this species. Presoaking the seeds in distilled water for ∼20 h proved more effective in inducing the polyploidy. Typical polyploid characters like gigantism, bigger leaves, flowers and pods etc. were exhibited by the induced colchitetraploids, however, they had reduced pollen fertility and number of seeds/pod and plant as compared to diploids. Polyploidy was confirmed by chromosome counts (2n=4x=24) at meiosis as well as at root tip mitosis. The method is easy and reliable for successful induction of polyploidy with colchicine in this species. We also recommend this method for induction of polyploids in other leguminous crops.

There is little cytological information for Pistacia species in the literature and they are old or require confirmation. This study aims to adapt a chromosome count procedure for Pistacia species and to determine chromosome numbers of four Pistacia species in root tip cells. Chromosome counts were performed for P. vera L., P. terebinthus L., P. atlantica Desf. and in a new species P. eurycarpa Yalt., which have been characterized at the molecular level. Dehulled Pistacia nuts were stratified and treated with 500 ppm GA3 and then germinated on plates. Growing root tips were used for counting at c-metaphase of mitosis cells. A good chromosome counting procedure was established for Pistacia species that provided well-spread and well-stained chromosome at metaphase of mitosis. Chromosome numbers of all four Pistacia species were found to be 2n = 30. Chromosome numbers of P. atlantica and P. eurycarpa (syn. P. atlantica subsp. kurdica) species are reported here for the first time as 2n = 30. This study provides important information on pistachio cultivars/rootstocks for breeders and cytogeneticists.

In this study, the cytogenetic effects of boric acid (BA) were investigated in root tip cells of Allium cepa L. The roots of A. cepa were treated with the concentration of 1 g/l, 2 g/l and 4 g/l of BA for 10 and 20 h treatment pariods. BA significantly decreased the mitotic index (MI) compared to the control at all concentrations and treatment periods. However, the decreasing of the MI was not dose-dependent. BA slightly increased the percentage of abnormal cells.

Eumusa series of banana contains the majority of commercially important cultivars, which are interspecific hybrids of two wild species of bananas, Musa acuminata Colla (AA Group) and Musa balbisiana Colla (BB Group). Most of the banana cultivars are diploids or triploids. Occurrences of ‘laggard’ and ‘bridge’ during anaphase were considered as aberrant. Aberrant anaphase cells were observed in the root tip cells of wild Musa acuminata Colla (AA Group) (natural and tissue cultured materials), M. balbisiana Colla (BB Group) and thecommon local banana cultivars: Pisang Mas (AA Group), Pisang Berangan (AAA Group), Pisang Rastali (AAB Group), Pisang Raja (AAB Group), Pisang Awak (ABB Group) and Pisang Abu Nipah (BBB Group). Frequencies of aberrant anaphase cells were scored and statistically analyzed. Results indicated that somatically, 1) cultivated bananas were more stable than wild bananas, 2) triploids were more stable than diploids and 3) M. balbisiana or . genome was more stable than M. acuminat...

The shape of mitotic prophase chromosomes has been studied in root tip nuclei by confocal microscopy and 3D-image analysis. Crepis capillaris chromosome no. 1 was used as a test object. Chromosome conformation was studied in early, mid- and in late prophase. In mid- and late prophase, individual chromosomes could be distinguished on the basis of their length. Early prophase chromosomes could not be distinguished as individuals. The central axes of prophase chromosomes were traced with an automated computer procedure and then represented as a string of 3D coordinates. This representation facilitated measurement along the chromosome axis of shape parameters such as curvature (amount of bending), torsion (helical winding) and torsion sign (helical handedness). Stretches of early prophase chromosomes showed full helical turns, which could be left- or right-handed. In the later prophase stages curvature and torsion were statistically analysed. Our data on 40 mid-prophase chromosomes no. 1 show that they are still highly curved, but full helical turns were no longer found. Instead, an overall meandering pattern was observed. In late prophase, one central loop persisted, flanked by two preferential regions of high curvature.

We are reporting the successful isolation of wheat chromosome arm 1DS by flow cytometry. A chromosome suspension was prepared for the 1DS ditelosomic line and the normal ‘Chinese Spring’ (CS) by chopping 2-day-old root tip meristems, synchronized by hydroxyurea, in HEPES-magnesium sulfate buffer containing propidium iodide. Chromosomes were analyzed and sorted with a FACS Vantage flow cytometer and cell sorter. An extra peak was observed in the flow karyotype of the ditelosomic line that was absent in ‘CS’. The estimated size of chromosomes from the extra peak matched with the expected size of chromosome 1DS. Chromosomes from the putative 1DS peak were analyzed by both fluorescent microscopy and N-banding analysis. A total of 571 chromosomes from two separate experiments were analyzed, and all were observed to be telosomics except for 2 which were broken. About 82% of these telosomics showed the diagnostic N-band of 1DS, the remaining were unbanded and are probably also 1DS. This strategy can also be used to sort other wheat arms.

Chromosomal study was carried in the dividing root-tip cells of Cannabis sativa (Family : Cannabinaceae). The diploid chromosome number of this species is 2n=20. Karyotype analysis reveals that all the 9 chromosomes in female somatic cells are metacentric and 1 chromosome is submetacentric whereas the X and Y chromosome in male cells is sub-metacentric. The Y chromosome is longer than X chromosome. The third pair bears the satellite.

Varietal differences in root system morphology in tea-rooted cuttings were examined by using a cylindrical net (radius of 3 cm) in a nursery bed. To determine the spatial distribution of the root, 11 tea cultivars were grown for about 9 months. The depth of the root penetration site on the net from the horizonal, the primary root length out of the net, and the root's total fresh weight were measured. The horizontal distance of the root tip from the stem, the vertical root depth, the actual root length, and the spreading angle of the root system were calculated. A principal component analysis was used to identify the important characteristics of the tea root system morphology. The root system morphology was primarily determined by the spatial distribution of the root and the root amount as an index of the root number and weight, in which the cultivar varied significantly. Yamanoibuki, Okuhikari, Sayamakaori, and Meiryoku formed in a relatively large root system, but Kanayamidori, Ooiwase, and Saemidori formed in a small root system. Fushun showed the large root amount and the small spreading angle of the root system ; Okumidori showed a large spreading angle of the system.

Onion (Allium cepa L.) adventitious roots were treated with lead, which was found to accumulate in increasing amounts in the apoplasts of root tips if the metal continued to be present in the roots' external environment. Ultrastructural observations made it possible to formulate the hypothesis that there are two protective mechanisms against lead in onion root tip cells: (i) the amount of polysaccharides in the cell wall and the thickness of the wall increases, this allows more lead to be accumulated in a manner that is not harmful to the cell; and (ii) lead is expelled from inside the cell through plasmatubules to the root tip apoplast, this makes it possible to inactivate the lead that has a toxic effect on the root symplast.