Showing papers on "Shoot published in 2005"
TL;DR: Information on the phylogenetic variation in shoot Si concentration may provide useful palaeoecological and archaeological information, and inform studies of the biogeochemical cycling of Si and those of the molecular genetics of Si uptake and transport in plants.
871 citations
TL;DR: In this article, the effect of grain soaking presowing in 1 mM salicylic acid (SA) and NaCl (0, 50, 100, 150 and 200 mM) on barley (Hordeum vulgare cv Gerbel) was studied.
Abstract: Effect of grain soaking presowing in 1 mM salicylic acid (SA) and NaCl (0, 50, 100, 150 and 200 mM) on barley (Hordeum vulgare cv Gerbel) was studied. Increasing of NaCl level reduced the germination percentage, the growth parameters (fresh and dry weight), potassium, calcium, phosphorus and insoluble sugars content in both shoots and roots of 15-day old seedlings. Leaf relative water content (RWC) and the photosynthetic pigments (Chl a, b and carotenoids) contents also decreased with increasing NaCl concentration. On the other hand, Na, soluble sugars, soluble proteins, free amino acids including proline content and lipid peroxidation level and peroxidase activity were increased in the two plant organs with increasing of NaCl level. Electrolyte leakage from plant leaves was found to increase with salinity level. SA-pretreatment increased the RWC, fresh and dry weights, water, photosynthetic pigments, insolube saccharides, phosphorus content and peroxidase activity in the stressed seedlings. On the contrary, Na+, soluble proteins content, lipid peroxidation level, electrolyte leakage were markedly reduced under salt stress with SA than without. Under stress conditions, SA-pretreated plants exhibited less Ca2+ and more accumulation of K+, and soluble sugars in roots at the expense of these contents in the plant shoots. Exogenous application (Grain soaking presowing) of SA appeared to induce preadaptive response to salt stress leading to promoting protective reactions to the photosynthetic pigments and maintain the membranes integrity in barley plants, which reflected in improving the plant growth.
651 citations
TL;DR: In this article, the authors showed that heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination.
Abstract: In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.
( Managing editor: Ping HE)
388 citations
TL;DR: Overexpression of OsPTF1 enhanced tolerance to Pi starvation in transgenic rice and showed significantly higher total root length and root surface area, which results in a higher instantaneous Pi uptake rate over their wild-type counterparts.
Abstract: We report here on a novel transcription factor with a basic helix-loop-helix domain for tolerance to inorganic phosphate (Pi) starvation in rice (Oryza sativa). The gene is designated OsPTF1. The expression of OsPTF1 is Pi starvation induced in roots while constitutively expressed in shoots, as shown by northern-blot analysis. Overexpression of OsPTF1 enhanced tolerance to Pi starvation in transgenic rice. Tillering ability, root and shoot biomass, and phosphorus content of transgenic rice plants were about 30% higher than those of the wild-type plants in Pi-deficient conditions in hydroponic experiments. In soil pot and field experiments, more than 20% increase in tiller number, panicle weight, and phosphorus content was observed in transgenic plants compared to wild-type plants at low-Pi levels. In Pi-deficient conditions, transgenic rice plants showed significantly higher total root length and root surface area, which results in a higher instantaneous Pi uptake rate over their wild-type counterparts. Microarray analysis for transgenic plants overexpressing OsPTF1 has been performed to investigate the downstream regulation of OsPTF1.
347 citations
TL;DR: Monitoring lipid peroxidation showed that both root and shoot malonyldialdehyde (MDA) contents of plants cultivated at the optimal salt concentration were lower than control ones, but MDA levels in both roots and shoots remained close to control ones.
334 citations
TL;DR: ZR was shown to be the main cytokinin present in bacterial cultural media as a complex with a high molecular weight component and was associated with an increase in plant shoot and root weight of approximately 30% over 8 days after inoculation.
Abstract: Hormone production by micro-organisms selected as antagonists of pathogenic fungi and the effect of their introduction into soil on hormone content and growth of lettuce plants were studied. Hormones in bacterial cultural media and in plant extracts were immunopurified and assayed using specific antibodies to indolyl-3-acetic acid (IAA), abscisic acid (ABA), and different cytokinins (zeatin riboside (ZR), dihydrozeatinriboside (DHZR) and isopentenyladenosine (iPA)). ZR was shown to be the main cytokinin present in bacterial cultural media as a complex with a high molecular weight component. Inoculation of lettuce plants with bacteria increased the cytokinin content of both shoots and roots. Accumulation of zeatin and its riboside was greatest in roots shortly 2 days after inoculation, when their content was 10 times higher than in control. Changes in the content of other hormones (ABA and IAA) were observed at the end of experiments only. Accumulation of cytokinins in inoculated lettuce plants was associated with an increase in plant shoot and root weight of approximately 30% over 8 days.
329 citations
Journal Article•
TL;DR: It was concluded that inhibition in germination at equivalent water potentials of NaCl and PEG was mainly due to an osmotic effect rather than salt toxicity, and genotypic differences among pea cultivars in terms of salt and drought stress significantly differed.
Abstract: The effects of salt and drought stresses at the water potentials of -2, -4, -6 and -8 bars induced by NaCl and PEG 6000 (polyethylene glycol 6000) each, on germination and early seedling growth, were investigated for 3 pea cultivars (Bolero, Sprinter and Utrillo). Electrical conductivity (EC) values of the NaCl solutions were 4.5, 8.8, 12.7 and 16.3 dS m-1. Germination percentage, mean germination time, root and shoot length, and seedling fresh and dry weight were measured in the study. The objective was to determine genotypic differences among pea cultivars in terms of salt and drought stress and to determine factors (salt toxicity or osmotic stress due to PEG) inhibiting seed germination. The germination results revealed that the genotypes significantly differed for salt and drought stress. Bolero appeared to be more tolerant to salt stress, but Sprinter cv. gave higher values under drought stress. Both NaCl and PEG inhibited germination and seedling growth in all cultivars, but the effects of NaCl compared to PEG were less on germination and seedling growth. All cultivars were able to germinate at all NaCl levels without a significant decrease in germination, while a drastic decrease in germination was recorded at -6 bars of PEG. It was concluded that inhibition in germination at equivalent water potentials of NaCl and PEG was mainly due to an osmotic effect rather than salt toxicity.
320 citations
TL;DR: Evidence for benefits of NFB to Am fungus in the protection of host plants against the detrimental effects of salt is provided and bacterial-Am-legume tripartite symbioses could be a new approach to increase the salinity tolerance of legumes plants under salinity conditions.
Abstract: Through biological inoculation technology, the bacterial-mycorrhizal-legume tripartite symbiosis in saline conditions was documented and the effects of dual inoculation with Azospirillum brasilense (NFB) and Arbuscular mycorrhizal (Am) fungus Glomus clarum on the host plants ( Vicia faba ) in pot cultures were investigated at five NaCl levels (0.0 – 6.0 dSm -1 ) in irrigating water. Am faba plants showed decreases in salinity tolerance, % of mycorrhizal infection and higher accumulation of proline with increasing levels of salinity. Am infection significantly increased tolerance of salinity, mycorrhizal dependency, phosphorus level, phosphatases enzymes, nodule number, nitrogen level, protein content and nitrogenase enzymes of all salinized faba plants in comparison with control and non-Am plants either in the absence and presence of NFB. In shoot system of non-Am plants, Na + concentration was increased while the concentrations of K + , Mg + and Ca + were decreased with raising salinity stress. In Am plants, K + /Na + , Mg + /Na + and Ca + /Na + ratios were higher than that of non-Am plants at all salinity levels. The Na + level in shoots of Am plants showed slight increase with raising salinity meanwhile, K + and Ca + concentrations showed noticeable increases especially at higher salinity levels. The results clearly showed that the inoculation of NFB to Am plants had potentiality to increase the effects of Am fungi under salinity stress. This study provides evidence for benefits of NFB to Am fungus in the protection of host plants against the detrimental effects of salt. If so, bacterial-Am-legume tripartite symbioses could be a new approach to increase the salinity tolerance of legumes plants under salinity conditions. African Journal of Biotechnology Vol. 4 (3), pp. 210-222, 2005
282 citations
TL;DR: Grafting provides an alternative way to enhance salt tolerance, determined as fruit yield, in the tomato, and evidence is reported that the rootstock is able to reduce ionic stress.
Abstract: With the aim of determining whether grafting could improve salinity tolerance of tomato (Lycopersicon esculentum Mill.), and what characteristics of the rootstock were required to increase the salt tolerance of the shoot, a commercial tomato hybrid (cv. Jaguar) was grafted onto the roots of several tomato genotypes with different potentials to exclude saline ions. The rootstock effect was assessed by growing plants at different NaCl concentrations (0, 25, 50, and 75 mM NaCl) under greenhouse conditions, and by determining the fruit yield and the leaf physiological changes induced by the rootstock after 60 d and 90 d of salt treatment. The grafting process itself did not affect the fruit yield, as non-grafted plants of cv. Jaguar and those grafted onto their own root showed the same yield over time under non-saline conditions. However, grafting raised fruit yield in Jaguar on most rootstocks, although the positive effect induced by the rootstock was lower at 25mMNaCl than at 50 and 75mM NaCl. At these higher levels, the plants grafted onto Radja, Pera and the hybrid Volgogradskij3Pera increased their yields by ~80%, with respect to the Jaguar plants. The tolerance induced by the rootstock in the shoot was related to ionic rather than osmotic stress caused by salinity, as the differential fruit yield responses among graft combinations were mainly related to the different abilities of rootstocks to regulate the transport of saline ions. This was corroborated by the high negative correlation found between fruit yield and the leaf Na1 or Cl2 concentrations in salt-treated plants after 90 d of salt treatment. In conclusion, grafting provides an alternative way to enhance salt tolerance, determined as fruit yield, in the tomato, and evidence is reported that the rootstock is able to reduce ionic stress.
278 citations
TL;DR: It is shown here that local induction of FT in a single Arabidopsis leaf is sufficient to trigger flowering, and this data suggest that the FT mRNA is an important component of the elusive “florigen” signal that moves from leaf to shoot apex.
Abstract: Day length controls flowering time in many plants. The day-length signal is perceived in the leaf, but how this signal is transduced to the shoot apex, where floral initiation occurs, is not known. In Arabidopsis, the day-length response depends on the induction of the FLOWERING LOCUS T (FT) gene. We show here that local induction of FT in a single Arabidopsis leaf is sufficient to trigger flowering. The FT messenger RNA is transported to the shoot apex, where downstream genes are activated. These data suggest that the FT mRNA is an important component of the elusive "florigen" signal that moves from leaf to shoot apex.
252 citations
TL;DR: It is suggested that neither ABA nor ethylene are directly involved in the effects of N form on leaf growth, and stimulation of leaf growth by NO(3)(-) was consistently associated with increased concentration of the physiologically active forms of cytokinins, zeatin andZeatin riboside, in the xylem exudate, indicating a major role for cytokinin as long-distance signals mediating the shoot response to NO( 3)(-) perception in roots.
Abstract: Leaf growth of many plant species shows rapid changes in response to alterations of the form and the level of N supply. In hydroponically-grown tomato (Lycopersicon esculentum L.), leaf growth was rapidly stimulated by NO(3)(-) application to NH(4)(+) precultured plants, while NH(4)(+) supply or complete N deprivation to NO(3)(-) precultured plants resulted in a rapid inhibition of leaf growth. Just 10 microM NO(3)(-) supply was sufficient to stimulate leaf growth to the same extent as 2 mM. Furthermore, continuous NO(3)(-) supply induced an oscillation of leaf growth rate with a 48 h interval. Since changes in NO(3)(-) levels in the xylem exudate and leaves did not correlate with NO(3)(-)-induced alterations of leaf growth rate, additional signals such as phytohormones may be involved. Levels of a known inhibitor of leaf growth, abscisic acid (ABA), did not consistently correspond to leaf growth rates in wild-type plants. Moreover, leaf growth of the ABA-deficient tomato mutant flacca was inhibited by NH(4)(+) without an increase in ABA concentration and was stimulated by NO(3)(-) despite its excessive ethylene production. These findings suggest that neither ABA nor ethylene are directly involved in the effects of N form on leaf growth. However, under all experimental conditions, stimulation of leaf growth by NO(3)(-) was consistently associated with increased concentration of the physiologically active forms of cytokinins, zeatin and zeatin riboside, in the xylem exudate. This indicates a major role for cytokinins as long-distance signals mediating the shoot response to NO(3)(-) perception in roots.
TL;DR: Effects of different concentrations of arsenite and arsenate on seed germination, relative root length and shoot height, arsenic accumulation in young seedlings, alpha-amylase, beta- amylase and total amylolytic activity in wheat were investigated to elucidate the toxicity of arsenic in the early developmental stage.
TL;DR: In this paper, the effects of the Se chemical forms, selenite and selenate, the rate of their application on shoot Se concentration and their influence on the antioxidative system of ryegrass (Lolium perenne cv. Aries), through the measurement of GSH-Px activity and lipid peroxidation, were evaluated in an Andisol of Southern Chile.
Abstract: Selenium (Se) is an essential micronutrient for animal and human nutrition, but whether it is essential to plants remains controversial. However, there are increasing experimental evidences that indicate a protective role of Se against the oxidative stress in higher plants through Se-dependent glutathione peroxidase (GSH-Px) activity. The effects of the Se chemical forms, selenite and selenate, the rate of their application on shoot Se concentration and their influence on the antioxidative system of ryegrass (Lolium perenne cv. Aries), through the measurement of GSH-Px activity and lipid peroxidation, were evaluated in an Andisol of Southern Chile. Moreover, a soil–plant relationship for Se was determined and a simple method to extract available Se from acid soils is proposed. In a 55-day experiment ryegrass seeds were sown in pots and soil was treated with sodium selenite or sodium selenate (0–10 mg Se kg−1). The results showed that the Se concentration in shoots increased with the application of both selenite and selenate. However, the highest shoot Se concentrations were obtained in selenate-treated plants. For both sources of Se, there was a significant positive correlation between the shoot Se concentration and the GSH-Px activity; and the Se-dependence of this enzymatic activity was related especially with the chemical form of applied Se rather than the Se concentration in plant tissues. Furthermore, the lipid peroxidation, as measured by Thiobarbituric Acid Reactive Substances (TBARS), decreased at low levels of shoot Se concentration, reaching the lowest level at approximately 20 mg Se kg−1 in plants and then increased steadily above this level. In addition, the acid extraction method used to evaluate available Se in soil showed a positive good correlation between soil Se and shoot Se concentrations irrespective of chemical form of Se applied.
TL;DR: AOX activity plays a role in shoot acclimation to low temperature in Arabidopsis, and AOX not only functions to prevent excess reactive oxygen species formation in whole tissues under stressful environmental conditions but also affects metabolism through more pervasive effects, including some that are extramitochondrial.
Abstract: The alternative oxidase (AOX) pathway of plant mitochondria uncouples respiration from mitochondrial ATP production and may ameliorate plant performance under stressful environmental conditions, such as cold temperatures, by preventing excess accumulation of reactive oxygen species. We tested this model in whole tissues by growing AtAOX1a-transformed Arabidopsis (Arabidopsis thaliana) plants at 12°C. For the first time, to our knowledge, in plants genetically engineered for AOX, we identified a vegetative shoot growth phenotype. Compared with wild type at day 21 after sowing, anti-sense and overexpressing lines showed, on average, 27% reduced leaf area and 25% smaller rosettes versus 30% increased leaf area and 33% larger rosette size, respectively. Lines overexpressing a mutated, constitutively active AOX1a showed smaller phenotypic effects. These phenotypic differences were not the result of a major alteration of the tissue redox state because the changes in levels of lipid peroxidation products, reflecting oxidative damage, and the expression of genes encoding antioxidant and electron transfer chain redox enzymes did not correspond with the shoot phenotypes. However, the observed phenotypes were correlated with the amount of total shoot anthocyanin at low temperature and with the transcription of the flavonoid pathway genes PAL1 and CHS. These results demonstrate that (1) AOX activity plays a role in shoot acclimation to low temperature in Arabidopsis, and that (2) AOX not only functions to prevent excess reactive oxygen species formation in whole tissues under stressful environmental conditions but also affects metabolism through more pervasive effects, including some that are extramitochondrial.
TL;DR: Results suggested that in leaves of garlic seedlings challenged by CdCl2 at higher concentrations, induction of these various enzymes is part of a general defense strategy to cope with overproduction of reactive oxygen.
TL;DR: The dynamics of redistribution of 65Zn, 54Mn, 63Ni, 57Co and 109Cd differed considerably, and the rapid redistribution of 63Ni from older to younger leaves throughout the experiment indicated a high mobility in the phloem, while 54Mm was mobile only in the xylem and 57Co was retained in the labelled root without being loaded into the xylesm.
TL;DR: Protocols for in vitro propagation of non-toxic variety of J. curcas through axillary bud proliferation and direct adventitious shoot bud regeneration from leaf segments have been established and crossing studies revealed that outcrosses with toxic J.Curcas do not affect the phorbol ester content of seeds borne on the non-Toxic variety.
Abstract: Protocols for in vitro propagation of non-toxic variety of J. curcas through axillary bud proliferation and direct adventitious shoot bud regeneration from leaf segments have been established. Shoot bud proliferation from axillaries was assessed on an initial basal Murashige and Skoog (MS) salt medium supplemented with different concentrations of benzyladenine (BA), kinetin and thidiazuron (TDZ) followed by subculture to medium with 4.4-8.9 μM BA. Regardless of the concentration of BA in the subculture medium, shoot multiplication rate was optimum (10–12.3) with primary culture on medium supplemented with 2.3–4.5 μM TDZ. Efficient adventitious shoot regeneration from leaf tissues was achieved with culture on medium with 8.9–44.4 μM BA + 4.9 μM indole-3-butyric acid (IBA) followed by transfer to medium supplemented with 8.9 μM BA + 2.5 μM IBA. Similarity index between toxic Indian variety and the non-toxic variety based on 435 RAPD markers was 96.3%. Crossing studies followed by phorbol ester quantitation revealed that outcrosses with toxic J. curcas do not affect the phorbol ester content of seeds borne on the non-toxic variety.
TL;DR: S. nigrum can be classified as a Cd-hyperaccumulator, which provides a patentable new plant species for phytoremediation of CD-contaminated soils.
Abstract: A systematic investigation was conducted to screen for cadmium-hyperaccumulator from 54 species in 20 weed families using outdoor pot-culture experiment and small-scale field experiment. The results from the outdoor pot-culture experiment showed that Cd concentrations in the stems and leaves of Solatium nigrum L. growing in a soil spiked with 25 mg/kg Cd were up to 103.8 and 124.6 mg/kg (DW), respectively, which was greater than 100 mg/kg, minimum Cd concentration for a Cd-hyperaccumulator. The Cd enrichment factor (EF, concentration ratio in plant to soil) in shoots was as high as 2.68. Moreover, Cd accumulation in shoots was greater than that in roots (TF, concentration ratio in shoots to roots) and the plant biomass growth was not inhibited at the Cd concentrations tested compared with the control. The results of the small-scale field experiment also showed that the characteristics of Cd accumulation in S. nigrum were all consistent with the characteristics of Cd-hyperaccumulators. Thus S. nigrum can be classified as a Cd-hyperaccumulator. This work is important for further research in the areas of hyperaccumulators screening, and plant-tolerance physiology and evolution. It provides a patentable new plant species for phytoremediation of Cd-contaminated soils.
TL;DR: In this article, a hydroponic experiment was conducted in a phytotron at pH 5.5 to study the effects of nickel (Ni) on the growth and composition of metal micronutrients, such as copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), of barley (Hordeum vulgare L. Minorimugi).
Abstract: A hydroponic experiment was conducted in a phytotron at pH 5.5 to study the effects of nickel (Ni) on the growth and composition of metal micronutrients, such as copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), of barley (Hordeum vulgare L. cv. Minorimugi). Four Ni treatments were conducted (0, 1.0, 10, and 100 μM) for 14 d. Plants grown in 100 μM Ni showed typical visual symptoms of Ni toxicity such as chlorosis, necrosis of leaves, and browning of the root system, while other plants were free from any symptoms. Dry weights were the highest in plants grown in 1.0 μM Ni, with a corresponding increase in the chlorophyll index of the plants, suggesting that 1.0∼10 μM Ni needs to be added to the nutrient solution for optimum growth of barley plants. The increase of Ni in the nutrient solutions increased the concentrations of Cu and Fe in roots, while a decrease was observed in shoots. The concentrations of Mn and Zn in shoots and roots of plants decreased with increasing Ni supply in the nutri...
TL;DR: The results indicate that the total amount of P per shoot and shoot dry matter production at low P supply are most reliable parameters in ranking genotypes for P efficiency at early growth stage and that P acquisition ability should be most important mechanism for high P efficiency in such genotypes.
Abstract: A greenhouse experiment was carried out to study the severity of phosphorus (P) deficiency symptoms on leaves, shoot dry matter production, and shoot concentration and content (the total amount per shoot) of P in 39 bread wheat (Triticum aestivum L.) and 34 durum wheat (Triticum durum L.) genotypes grown in a severely P-deficient calcareous soil with low (20mgPkg−1 soil) and adequate (80mgPkg−1 soil) P supply for 39 days. As the seed P concentration or content can affect plant performance under P-deficient conditions, the seeds of the genotypes used in the present study were also analyzed for P concentration. Phosphorus efficiency (relative shoot growth) of genotypes, calculated by the ratio of shoot dry matter production under low P to that under adequate P supply, significantly differed among the genotypes, and varied between 46.7% and 78.6%. Phosphorus efficiency ranged from 51% to 71% with an average of 61% for bread and from 47% to 79% with an average of 66% for durum wheat genotypes. There was no correlation between P efficiency ratio and P concentration of plants (R2=0.0001), but P efficiency of all bread and durum wheat genotypes showed a very significant correlation with the P content (the total amount of P per shoot) (R2=0.333***). The relationship between the P efficiency and total amount of P per shoot was much more significant in bread (R2=0.341***) than in durum wheat (R2=0.135*). Like shoot P concentrations, also severity of visible leaf symptoms of P deficiency on older leaves, including leaf chlorosis and necrosis, did not correlate with P efficiency. In most cases, genotypes showing higher P efficiency had higher absolute shoot dry weight under P deficient conditions. Under P deficient conditions, the absolute shoot dry weight very significantly correlated with shoot P content (R2=0.665***), but the correlation between the absolute shoot dry weight and shoot P concentration tended to be negative. There was also variation in native seed P reserve of the genotypes, but this variation had no influence on the P efficiency. The results indicate that the total amount of P per shoot and shoot dry matter production at low P supply are most reliable parameters in ranking genotypes for P efficiency at early growth stage. In wheat germplasm tested in the present study, several wheat genotypes are available showing both very high P efficiency and very high shoot content and concentration of P suggesting that P acquisition ability should be most important mechanism for high P efficiency in such genotypes. On the other hand, there are also genotypes in the germplasm having more or less same P concentration or P content in shoot but differing substantially in P efficiency, indicating importance of P utilization at cellular level in P efficiency. All these results suggest that P efficiency mechanisms can be different from one genotype to other within a given plant species.
TL;DR: The fact of the apparent absence of free CK in the buds of wind-protected plants and the typical upward decreasing gradients of free and conjugated CKs suggest that the bulk of the CK is synthesized in the root cap, exported through the xylem and accumulates at sites of highest transpiration where cuticles do not yet exist or do not protect against water loss.
Abstract: To clarify how root-synthesized cytokinins (CKs) are transported to young shoot organs, CK distribution patterns were analysed in free-CK-responsive ARR5::GUS transformants of Arabidopsis thaliana (L.) Heynh. together with free plus bound CKs using specific CK monoclonal antibodies. Plants were subjected to two different growth conditions, completely protected from any air movement, or exposed to gentle wind 3 h before harvesting. In wind-protected plants the strongest ARR5::GUS expression was found in the root cap statocytes, spreading upwards in the vascular cylinder. This pattern in roots was congruent with that found by CK immunolocalization. Shoots of wind-protected plants displayed either no or only low ARR5::GUS expression in the stem vascular bundles, nodal ramifications, and the bases of flower buds; shoot vascular bundles showed patterns of acropetally decreasing staining and the apical parts of buds and leaves were free from ARR5::GUS expression. In wind-exposed plants ARR5::GUS expression was considerably increased in shoots, also in basal-to-apical decreasing gradients. Immunolabelled shoots showed differential staining, with the strongest label in the vascular bundles of stems, leaves, and buds. The fact of the apparent absence of free CK in the buds of wind-protected plants and the typical upward decreasing gradients of free and conjugated CKs suggest that the bulk of the CK is synthesized in the root cap, exported through the xylem and accumulates at sites of highest transpiration where cuticles do not yet exist or do not protect against water loss.
TL;DR: 16S ribosomal DNA (rDNA) sequencing identified KNP9 as a strain of Pseudomonas putida, which is growth promoting and has been isolated from Panki Power Plant, Kanpur, India.
Abstract: Heavy metals, being phytotoxic, cause growth inhibition and even plant death. Siderophore-producing bacterial strain KNP9 is growth promoting and has been isolated from Panki Power Plant, Kanpur, India. It simulated significant (p > 5%) root and shoot growth of mung bean to the extent of 16.48% and 28.80%, respectively in the presence of CdCl2 (110 μM). However, the increase in root and shoot growth was 20% and 19.5%, respectively, in the presence of (CH3COO)2Pb (660 μM). Moreover, concentration of accumulated lead and cadmium in root and shoot was also reduced in the presence of this isolate ranging from 37.5 to 93.19%. A moderate reduction in chlorophyll content (39.14%) in the presence of 110 μM CdCl2 was rescued by bioinoculant KNP9. However, the 19.58% decrease in chlorophyll content in the case of lead acetate remained unchanged even in the presence of KNP9. Nevertheless, 16S ribosomal DNA (rDNA) sequencing identified KNP9 as a strain of Pseudomonas putida.
TL;DR: GB absorbed by seeds, after translocation to the seedlings, enhanced their capacity to maintain greater water content, and higher seedling vigor by virtue of increased PN, reduced RMP and leakage of important ions under heat stress.
Abstract: Heat stress adversely affects plant growth and development, while glycinebetaine (GB) plays a protective role under stressful conditions. The objective of this study was to assess the optimum level of GB for use as a presowing seed treatment and the subsequent effect on the heat tolerance of barley (Hordeum vulgare L. cv. Haider-93) seedlings. Among a range of GB levels, the 20 mM concentration emerged as the most effective in enhancing seed germination, shoot fresh and dry weight and shoot water content under heat stress, and this level was selected for further studies. Time course changes revealed that the seedlings developing from 20 mM GB treated seeds had greater shoot dry weight, net photosynthetic rate (PN), leaf water potential (ψw) and reduced relative membrane permeability (RMP), compared to no-GB treated plants under heat stress. Correlations between dry weight and high PN (r = 0.881), low ψw (r = −0.938) and RMP (r = −0.860) of shoots suggested the involvement of GB in heat stress tolerance. Leakage of Ca2+ and NO3− was the greatest followed by K+ and PO43− under no-GB seed treatment, and GB application under heat stress appreciably reduced the leakage of all these ions, particularly Ca2+, K+ and NO3−. In conclusion GB absorbed by seeds, after translocation to the seedlings, enhanced their capacity to maintain greater water content, and higher seedling vigor by virtue of increased PN, reduced RMP and leakage of important ions under heat stress. These results have implications for final field stand under the conditions where the ambient temperature is supra-optimal for barley growth.
TL;DR: The observed increase in BvSUT1 gene expression supports the idea that sucrose loading into the phloem is defective, resulting in its accumulation in the leaf, and helps identify how Mg deficiency alters carbon partitioning in sugar beet (Beta vulgaris L.) plants.
Abstract: Magnesium deficiency has been reported to affect plant growth and biomass partitioning between root and shoot. The present work aims to identify how Mg deficiency alters carbon partitioning in sugar beet (Beta vulgaris L.) plants. Fresh biomass, Mg and sugar contents were followed in diverse organs over 20 days under Mg-sufficient and Mg-deficient conditions. At the end of the treatment, the aerial biomass, but not the root biomass, of Mg-deficient plants was lower compared to control plants. A clear inverse relationship between Mg and sugar contents in leaves was found. Mg deficiency promoted a marked increase in sucrose and starch accumulation in the uppermost expanded leaves, which also had the lowest content of Mg among all the leaves of the rosette. The oldest leaves maintained a higher Mg content. [14C]Sucrose labelling showed that sucrose export from the uppermost expanded leaves was inhibited. In contrast, sucrose export from the oldest leaves, which are close to, and export mainly to, the roots, was not restricted. In response to Mg deficiency, the BvSUT1 gene encoding a companion cell sucrose/H+ symporter was induced in the uppermost expanded leaves, but without further enhancement of sucrose loading into the phloem. The observed increase in BvSUT1 gene expression supports the idea that sucrose loading into the phloem is defective, resulting in its accumulation in the leaf.
TL;DR: In this article, growth, cadmium accumulation and potassium and calcium status were studied in two halophytes from Aizoaceae family: Sesuvium portulacastrum and Mesembryanthemum crystallinum.
TL;DR: It has been shown that plant growth was positively correlated to the metabolization of ketoglutaric acid, and negatively linked to the metabolites of phenylalanine and other substrates, which shows that microbial activity is also affected.
Abstract: Plants inoculated with arbuscular mycorrhizal (AM) fungi utilize more soluble phosphorus from soil mineral phosphate than non-inoculated plants. However, there is no information on the response of soil microflora to mineral phosphate weathering by AM fungi and, in particular, on the catabolic diversity of soil microbial communities. The AM fungus, Glomus intraradices was examined for (i) its effect on the growth of Acacia holosericea, (ii) plant-available phosphate and (iii) soil microbial activity with and without added rock phosphate. After 4-months culture, AM fungal inoculation significantly increased the plant biomasses (by 1.78× and 2.23× for shoot and root biomasses, respectively), while mineral phosphate amendment had no effect in a sterilized soil. After 12-months culture, the biomasses of A. holosericea plants growing in a non-sterilized soil amended with mineral phosphate were significantly higher than those recorded in the control treatment (by 2.5× and 5× for shoot and root biomasses, respectively). The fungal inoculation also significantly stimulated plant growth, which was significantly higher than that measured in the mineral phosphate treatment. When G. intraradices and mineral phosphate were added together to the soil, shoot growth were significantly stimulated over the single treatments (inoculation or amendment) (1.45×). The P leaf mineral content was also higher in the G. intraradices+mineral phosphate treatment than in G. intraradices or rock phosphate amendment. Moreover, the number of fluorescent pseudomonads has been significantly increased when G. intraradices and/or mineral phosphate were added to the soil. By using a specific type of multivariate analysis (co-inertia analysis), it has been shown that plant growth was positively correlated to the metabolization of ketoglutaric acid, and negatively linked to the metabolisation of phenylalanine and other substrates, which shows that microbial activity is also affected. G. intraradices inoculation is highly beneficial to the growth of A. holosericea plants in controlled conditions. This AM symbiosis optimises the P solubilization from the mineral phosphate and affects microbial activity in the hyphosphere of A. holosericea plants.
TL;DR: The results indicate that root feeding can significantly alter the nutritional quality of shoots by changes in secondary metabolite levels and hence the performance of a specialist shoot feeder.
Abstract: Plants may respond to herbivore attacks by changing their chemical profile. Such induced responses occur both locally and systemically throughout the plant. In this paper we studied how Brassica nigra (L.) Koch (Brassicaceae) plants respond to two different root feeders, the endoparasitic nematode Pratylenchus penetrans Cobb (Tylenchida: Pratylenchidae) and the larvae of the cabbage root fly Delia radicum L. (Diptera: Anthomyiidae). We tested whether the activities of the root feeders affected the survival and development of the shoot feeding crucifer specialist Pieris rapae (L.) (Lepidoptera: Pieridae) via systemically induced changes in the shoots. Overall, P. rapae larvae grew slower and produced fewer pupae on plants that were infested with root feeders, especially on plants infested with P. penetrans. This effect could not be attributed to lower water or protein levels in these plants, as the percentage of water in the controls and root infested shoots was similar, and protein content was even higher in root infested plants. Both glucosinolate as well as phenolic levels were affected by root feeding. Initially, glucosinolate levels were the lowest in root infested plants, but on P. penetrans infested plants they increased more rapidly after P. rapae started feeding than in controls or D. radicum infested plants. Plants with D. radicum feeding on their roots had the highest phenolic levels at all harvest dates. Our results indicate that root feeding can significantly alter the nutritional quality of shoots by changes in secondary metabolite levels and hence the performance of a specialist shoot feeder. [KEYWORDS: above-ground ; below-ground interactions ; black mustard ; Brassicaceae ; cabbage ; cabbage root fly ; Delia radicum ; endoparasitic nematodes ; induced plant responses ; glucosinolates ; phenolics ; Pratylenchus penetrans ; proteins]
TL;DR: Both young and mature submerged leaves of Elodea canadensis treated for 1 month with 100 μM Cd added to the growth water medium showed a decreased photosynthetic activity, not only ascribable to lowered chlorophyll contents.
TL;DR: The high capacity of sorghum seedlings to recover after salt stress relief appears to be related to an adequate partition of carbon between shoots and roots and to changes in absorption, transport and re-translocation of salts.
TL;DR: The effect of thidiazuron (TDZ) was investigated on in vitro shoot proliferation from nodal explants of Rauvolfia tetraphylla and regenerated shoots rooted best on MS medium containing 0.5μM indole-3-butyric acid (IBA).
Abstract: The effect of thidiazuron (TDZ) was investigated on in vitro shoot proliferation from nodal explants of Rauvolfia tetraphylla. Murashige and Skoog (MS) medium containing TDZ (0.5–10μM) was effective in inducing shoot buds and maintaining high rates of shoot multiplication on hormone free medium. The highest shoot regeneration frequency (90%) and mean number (18.50 ± 1.25) of shoots per explant were achieved from nodal segments cultured on MS medium supplemented with 5μM TDZ for 4 weeks prior to transfer to MS medium without TDZ for 8 weeks. The regenerated shoots rooted best on MS medium containing 0.5μM indole-3-butyric acid (IBA). Micropropagated plantlets were hardened to survive ex vitro conditions and were then established into soil.