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1.
J. Emanuelsson 《Plant and Soil》1984,78(3):325-334
Summary The purpose of the present work has been to investigate the influence of calcium supply on root growth in barley. The plants
were grown in pots, in which the upper part was a sand-perlite mixture and the lower part a test solution with varying calcium
concentration (10−6–10−2 M CaCl2). The two parts were separated by a peat layer impeding a calcium transport from the upper to the lower part.
The growth of the roots in the test media was examined daily by counting the total number of roots and the number of roots
with laterals. The development of the number of roots had an exponential course at all calcium concentrations and was enhanced
by increased calcium concentration. At harvest it was found that the size of the roots (length and dry weight) decreased with
decreasing calcium concentration to a certain extent. 相似文献
2.
3.
This greenhouse study aimed to determine the effect of colonization by the arbuscular mycorrhizal (AM) fungus (Glomus intraradices Schenck & Smith) on the “wild” tobacco (Nicotiana rustica L. var. Azteca), under soil–zinc (Zn) conditions. Plants of N. rustica were grown in AM or non-AM inoculated substrate and subjected to four soil–[Zn] concentrations (0, 50, 100, and 250 mg Zn kg−1 dry soil). The AM root colonization increased markedly from 14 to 81% with the increasing soil–[Zn] and the mycorrhizal structures were significantly more abundant at the highest soil–[Zn], suggesting that Zn may be involved directly or indirectly in AM root colonization. In addition, total Zn content or Zn concentrations in shoots and roots were shown to increase as soil–[Zn] increased in both AM and non-AM plants. As for the growth parameters studied, there were no significant differences between treatments despite the increase in Zn content or concentration. The AM roots subjected to the highest soil–[Zn] had a significant reduction by about 50% of total Zn content and Zn concentration compared to non-AM roots. Still, the relative extracted Zn percentage decreased dramatically as soil–[Zn] increased. Soil pH was significantly lower in non-AM than AM treatments at the highest soil–[Zn]. In summary, AM plants (particularly roots) showed lower Zn content and concentration than non-AM plants. In this regard, the AM fungi have a protective role for the host plant, thus playing an important role in soil-contaminant immobilization processes; and, therefore, are of value in phytoremediation, especially when heavy metals approach toxic levels in the soil. 相似文献
4.
Influence of external zinc and phosphorus supply on Cd uptake by rice (Oryza sativa L.) seedlings with root surface iron plaque 总被引:1,自引:0,他引:1
Rice seedlings were grown in hydroponic culture to determine the effects of external Zn and P supply on plant uptake of Cd
in the presence or absence of iron plaque on the root surfaces. Iron plaque was induced by supplying 50 mg l−1 Fe2+ in the nutrient solution for 2 day. Then 43-day-old seedlings were exposed to 10 μmol l−1 Cd together with 10 μmol l−1 Zn or without Zn (Zn–Cd experiment), or to 10 μmol l−1 Cd with 1.0 mmol l−1 P or without P (P–Cd experiment) for another 2 day. The seedlings were then harvested and the concentrations of Fe, Zn, P
and Cd in dithionite–citrate–bicarbonate (DCB) extracts and in roots and shoots were determined. The dry weights of roots
and shoots of seedlings treated with 50 mg l−1 Fe were significantly lower than when no Fe was supplied. Adsorption of Cd, Zn and P on the iron plaque increased when Fe
was supplied but Cd concentrations in DCB extracts were unaffected by external Zn or P supply levels. Cd concentrations in
shoots and roots were lower when Fe was supplied. Zn additions decreased Cd concentrations in roots but increased Cd concentrations
in shoots, whereas P additions significantly increased shoot and root Cd concentrations and this effect diminished when Fe
was supplied. The percentage of Cd in DCB extracts was significantly lower than in roots or shoots, accounting for up to 1.8–3.8%
of the plant total Cd, while root and shoot Cd were within the ranges 57–76% and 21–40% respectively in the two experiments.
Thus, the main barrier to Cd uptake seemed to be the root tissue and the contribution of iron plaque on root surfaces to plant
Cd uptake was minor. The changes in plant Cd uptake were not due to Zn or P additions altering Cd adsorption on iron plaque,
but more likely because Zn or P interfered with Cd uptake by the roots and translocation to the shoots. 相似文献
5.
In this study, 900-bp (signed as p including nucleotides –1 to –886) and partly deleted (signed as dp including nucleotides
–1 to –414) COMT (caffeate/5-hydroxyferulate O-methyltransferase) promoters from Populus tremuloides Michx. were fused to the GUS reporter gene, and the tissue-specific expression patterns of the promoters were determined in Betula pendula Roth along the growing season, and as a response to mechanical bending and wounding. The main activity of the PtCOMTp- and
PtCOMTdp-promoters, determined by the histochemical GUS assay, was found in the developing xylem of stems during the 8th–13th
week and in the developing xylem of roots in the 13th week of the growing season. The GUS expression patterns did not differ
among the xylem cell types. The PtCOMT promoter-induced GUS expression observed in phloem fibres suggests a need for PtCOMT
expression and thus syringyl (S) lignin synthesis in fibre lignification. However, the PtCOMTdp-promoter induced GUS expression
in stem trichomes, which may contribute to the biosynthesis of phenylpropanoid pathway-derived compounds other than lignin.
Finally, a strong GUS expression was induced by the PtCOMT promoters in response to mechanical stem bending but not to wounding.
The lack of major differences between the PtCOMTp- and PtCOMTdp-promoters suggests that the deleted promoter sequence (including
nucleotides −415 to −886) did not contain a significant regulatory element contributing to the GUS expression in young B. pendula trees. 相似文献
6.
Summary Barley seeds have been germinated in gas mixtures containing ethylene (up to 20 vpm) and various amounts of oxygen (0.5–21.0
per cent). When oxygen was adequate, ethylene had no effect on germination but decreased root growth and increased top growth.
Ethylene-treated roots were short, broad and curled. When inadequate oxygen slowed seedling growth, ethylene had no effect
on roots but increased top growth. Effects of carbon dioxide concentration and of the residual effects of ethylene on seedling
growth are also discussed. 相似文献
7.
Woltering EJ Balk PA Nijenhuis-Devries MA Faivre M Ruys G Somhorst D Philosoph-Hadas S Friedman H 《Planta》2005,220(3):403-413
The regulation of gravistimulation-induced ethylene production and its role in gravitropic bending was studied in Antirrhinum majus L. cut flower stems. Gravistimulation increased ethylene production in both lower and upper halves of the stems with much higher levels observed in the lower half. Expression patterns of three different 1-aminocyclopropane-1-carboxylate (ACC) synthase (ACS) genes, an ACC oxidase (ACO) and an ethylene receptor (ETR/ERS homolog) gene were studied in the bending zone of gravistimulated stems and in excised stem sections following treatment with different chemicals. One of the ACS genes (Am-ACS3) was abundantly expressed in the bending zone cortex at the lower side of the stems within 2 h of gravistimulation. Am-ACS3 was not expressed in vertical stems or in other parts of (gravistimulated) stems, leaves or flowers. Am-ACS3 was strongly induced by indole-3-acetic acid (IAA) but not responsive to ethylene. The Am-ACS3 expression pattern strongly suggests that Am-ACS3 is responsible for the observed differential ethylene production in gravistimulated stems; its responsiveness to IAA suggests that Am-ACS3 expression reflects changes in auxin signalling. Am-ACS1 also showed increased expression in gravistimulated and IAA-treated stems although to a much lesser extent than Am-ACS3. In contrast to Am-ACS3, Am-ACS1 was also expressed in non-bending regions of vertical and gravistimulated stems and in leaves, and Am-ACS1 expression was not confined to the lower side cortex but evenly distributed over the diameter of the stem. Am-ACO and Am-ETR/ERS expression was increased in both the lower and upper halves of gravistimulated stems. Expression of both Am-ACO and Am-ETR/ERS was responsive to ethylene, suggesting regulation by IAA-dependent differential ethylene production. Am-ACO expression and in vivo ACO activity, in addition, were induced by IAA, independent of the IAA-induced ethylene. IAA-induced growth of vertical stem sections and bending of gravistimulated flowering stems were little affected by ethylene or 1-methylcyclopropene treatments, indicating that the differential ethylene production plays no pivotal role in the kinetics of gravitropic bending. 相似文献
8.
Seasonal dynamics of fine root biomass, root length density, specific root length, and soil resource availability in a Larix gmelinii plantation 总被引:1,自引:0,他引:1
Cheng Yunhuan Han Youzhi Wang Qingcheng Wang Zhengquan 《Frontiers of Biology in China》2006,1(3):310-317
Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive
to many global change factors. Despite the importance of fine root turnover in plant C allocation and nutrient cycling dynamics
and the tremendous research efforts in the past, our understanding of it remains limited. This is because the dynamics processes
associated with soil resources availability are still poorly understood. Soil moisture, temperature, and available nitrogen
are the most important soil characteristics that impact fine root growth and mortality at both the individual root branch
and at the ecosystem level. In temperate forest ecosystems, seasonal changes of soil resource availability will alter the
pattern of carbon allocation to belowground. Therefore, fine root biomass, root length density (RLD) and specific root length
(SRL) vary during the growing season. Studying seasonal changes of fine root biomass, RLD, and SRL associated with soil resource
availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover. The objective
of this study was to understand whether seasonal variations of fine root biomass, RLD and SRL were associated with soil resource
availability, such as moisture, temperature, and nitrogen, and to understand how these soil components impact fine root dynamics
in Larix gmelinii plantation. We used a soil coring method to obtain fine root samples (⩽2 mm in diameter) every month from May to October
in 2002 from a 17-year-old L. gmelinii plantation in Maoershan Experiment Station, Northeast Forestry University, China. Seventy-two soil cores (inside diameter
60 mm; depth intervals: 0–10 cm, 10–20 cm, 20–30 cm) were sampled randomly from three replicates 25 m × 30 m plots to estimate
fine root biomass (live and dead), and calculate RLD and SRL. Soil moisture, temperature, and nitrogen (ammonia and nitrates)
at three depth intervals were also analyzed in these plots. Results showed that the average standing fine root biomass (live
and dead) was 189.1 g·m−2·a−1, 50% (95.4 g·m−2·a−1) in the surface soil layer (0–10 cm), 33% (61.5 g·m−2·a−1), 17% (32.2 g·m−2·a−1) in the middle (10–20 cm) and deep layer (20–30cm), respectively. Live and dead fine root biomass was the highest from May
to July and in September, but lower in August and October. The live fine root biomass decreased and dead biomass increased
during the growing season. Mean RLD (7,411.56 m·m−3·a−1) and SRL (10.83 m·g−1·a−1) in the surface layer were higher than RLD (1 474.68 m·m−3·a−1) and SRL (8.56 m·g−1·a−1) in the deep soil layer. RLD and SRL in May were the highest (10 621.45 m·m−3 and 14.83m·g−1) compared with those in the other months, and RLD was the lowest in September (2 198.20 m·m−3) and SRL in October (3.77 m·g−1). Seasonal dynamics of fine root biomass, RLD, and SRL showed a close relationship with changes in soil moisture, temperature,
and nitrogen availability. To a lesser extent, the temperature could be determined by regression analysis. Fine roots in the
upper soil layer have a function of absorbing moisture and nutrients, while the main function of deeper soil may be moisture
uptake rather than nutrient acquisition. Therefore, carbon allocation to roots in the upper soil layer and deeper soil layer
was different. Multiple regression analysis showed that variation in soil resource availability could explain 71–73% of the
seasonal variation of RLD and SRL and 58% of the variation in fine root biomass. These results suggested a greater metabolic
activity of fine roots living in soil with higher resource availability, which resulted in an increased allocation of carbohydrate
to these roots, but a lower allocation of carbohydrate to those in soil with lower resource availability.
__________
Translated from Acta Phytoecologica Sinica, 2005, 29(3): 403–410 [译自: 植物生态学报, 2005, 29(3): 403–410] 相似文献
9.
Aluminum (Al) affects numerous physiological processes in plants. However, Al tolerance mechanisms mediated by increased synthesis
of organic acids (OAs) have been outlined recently. In this study, we examined the role of OAs in the short (1–8 h) and long-term
(4 days) Al tolerance in maize seedlings. Exposure to Al stress for 4 days results in a rapid inhibition of root growth. Al
induced morphological changes in the maize roots, especially at a higher solution of Al concentration (1,000 μM Al). The increase
in Al accumulation in roots, including strongly elevated levels of Al accumulated in root cell walls suggests that Al tolerance
in maize is mediated in part by higher accumulation of Al in the roots. The enhanced citrate exudation, which was only observed
at 1,000 μM Al may lead to detoxification of Al by formation of OA–Al complexes in the root apoplast. This mechanism has been
suggested to play a significant role in Al resistance response in maize. The short-term responses underlying internal detoxification
via OA-chelators were also investigated. Succinate, malate, citrate and total root OA contents decreased markedly, 2 h after
the Al exposure. At 4 and 8 h time points, OA contents increased or remained unchanged, except for that of malate which decreased.
The level of OAs in shoots, on the other hand, showed alterations that were less pronounced in response to Al. Specifically,
the citrate and total OA concentrations significantly increased at 4 h, but showed a pronounced decrease at the 8 h time point.
Based on our findings, we propose that multiple responses, including Al exclusion by Al accumulation in root cells and citrate
efflux, may contribute towards higher Al resistance in maize. The rapid OA changes in responses to short-term Al treatment
may not be responsible for Al tolerance. However, increased OA synthesis observed in this study may be involved in diminishing
the stress triggered by Al. The molecular aspects underlying Al resistance mechanism via Al-induced expression of the enzymes
catalyzing OA synthesis and metabolism remain to be elucidated. 相似文献
10.
11.
12.
Root morphology is important in understanding root functions in forest ecosystems. However, the effects of ectomycorrhizal
colonization and soil nutrient availability on root morphology is not clear. In this study, root morphology in relation to
season, soil depth, soil nitrogen (N) availability, and mycorrhizal fungal colonization were investigated in a larch (Larix gmelinii) plantation in northeastern China. The first-order roots (or root tips) of larch were sampled four times in May, July, and
September of 2005, and May of 2006 from two depths of upper soil layer (0–10 and 10–20 cm) in the control and the N-fertilized
plots. The results showed that ectomycorrhizal (ECM) colonization rates for the first-order roots were reduced by 17% under
N fertilization. The peak of root colonization rates occurred in summer and was positively correlated with soil temperature.
ECM colonization significantly altered root morphology: root diameter was increased by 19 and 29%, root length shortened by
27 and 25%, and specific root length (SRL) reduced by 16 and 19% for the control and the N-fertilized plots, respectively.
N fertilization led to decreased root length, but did not affect root diameter and SRL. In addition, effects of ECM colonization
on root morphology varied with season and soil depth. The observed relationships among ECM fungal colonization, soil N availability,
and root-tip morphology should improve our understanding of how root tips respond to environmental changes in soil in temperate
forest ecosystems. 相似文献
13.
Ethylene influences green plant regeneration from barley callus 总被引:3,自引:0,他引:3
The plant hormone ethylene is involved in numerous plant processes including in vitro growth and regeneration. Manipulating
ethylene in vitro may be useful for increasing plant regeneration from cultured cells. As part of ongoing efforts to improve
plant regeneration from barley (Hordeum vulgare L.), we investigated ethylene emanation using our improved system and investigated methods of manipulating ethylene to increase
regeneration. In vitro assays of regeneration from six cultivars, involving 10 weeks of callus initiation and proliferation
followed by 8 weeks of plant regeneration, showed a correlation between regeneration and ethylene production: ethylene production
was highest from ‘Golden Promise’, the best regenerator, and lowest from ‘Morex’ and ‘DH-20’, the poorest regenerators. Increasing
ethylene production by addition of 1-aminocyclopropane 1-carboxylic acid (ACC) during weeks 8–10 increased regeneration from
Morex. In contrast, adding ACC to Golden Promise cultures during any of the tissue culture steps reduced regeneration, suggesting
that Golden Promise may produce more ethylene than needed for maximum regeneration rates. Blocking ethylene action with silver
nitrate during weeks 5–10 almost doubled the regeneration from Morex and increased the Golden Promise regeneration 1.5-fold.
Silver nitrate treatment of Golden Promise cultures during weeks 8–14 more than doubled the green plant regeneration. These
results indicate that differential ethylene production is related to regeneration in the improved barley tissue culture system.
Specific manipulations of ethylene were identified that can be used to increase the green plant regeneration from barley cultivars.
The timing of ethylene action appears to be critical for maximum regeneration. 相似文献
14.
Effect of Waterlogged Soil Conditions on the Production of Ethylene and on Water Relationships in Tomato Plants 总被引:5,自引:0,他引:5
The roots of tomato plants (Lycopersicon esculentum Mill., cv.Moneymaker) were exposed to low concentrations of oxygen bywaterlogging the soil or by growing the plants in nutrient solutionflushed with nitrogen gas. After 24 h, the rate of ethyleneproduction by the petioles, main stem, and shoot apex was increasedby 46-fold and the petioles developed epinastic curvatures.Removing the roots did not reproduce these responses. The amountsof ethylene produced by shoot tissues in response to physicalwounding was greatly increased by waterlogging the soil. The production of ethylene by roots was suppressed by the absenceof oxygen. When the roots were transferred back to an aerobicenvironment ethylene production quickly exceeded that observedin roots maintained continuously in aerobic conditions. The enhanced rate of ethylene production in the shoots occurredin the absence of increased water stress as measured with aleaf pressure chamber; leaf water potentials were increasedrather than decreased by waterlogging for 30 h or more. Thiswas associated with stomatal closure and reduced transpiration.Resistance to water flow through the plant increased as transpirationdecreased in response to waterlogging. However, at similar ratesof transpiration, resistance was normally lower in waterloggedplants than in controls. 相似文献
15.
In order to investigate the effects of soil texture on possible non-hydraulic signals under field conditions, spring wheat
plants (Triticum aestivum L. cv. Cadensa) grown in sand and loam soils and with a well developed root system were exposed
to slow soil drying in the late vegetative stage of growth. Soil water potential and content were measured daily at different
depths and plant responses were measured in flag leaves. When the average soil water potential in the top soil layers (0–25
cm depth in sand and 0–45 cm depth in loam) dropped to –60 or –70 kPa and the lower soil layers were still at field capacity,
morning xylem [ABA] (0.03–0.04 vs. 0.06–0.08 mmol m-3) and midday leaf ABA concentration increased (250–300 vs. 400–450 ng/g
DW) and leaf conductance decreased relatively to well-watered (control) plants (0.75–0.88 vs. 0.64–0.70 mol m-2 s-1). These
responses took place before any decrease in leaf water potential occurred as compared with control plants, indicating that
they were triggered by root-borne signals due to reduced root water status in the top soil layers. At this stage the soil
water content was as low as 6% by volume, the fraction of roots in ‘wet’ soil was 0.12 and relative available soil water was
45% in sand and still high 20%, 0.48 and 70%, respectively, in loam of the whole soil profile indicating that roots were responding
to soil water availability and not soil water content at a certain evaporative demand. In addition, similar responses occurred
at high and low evaporative demands (3.4–5.2 vs. 0.6–4.0 mm/day of potential evapotranspiration).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Some characteristics of the rice (Oryza sativa L.) root were found in the experiment of unilaterally irradiating the roots which were planted in water: (i) All the seminal roots, adventitious roots and their branched roots bent away from light, and their curvatures ranged from 25° to 60°. The curvature of adventitious root of the higher node was often larger than that of the lower node, and even larger than that of the seminal root, (ii) The negative phototropic bending of the rice root was mainly due to the larger growth increment of root-tip cells of the irradiated side compared with that of the shaded side, (iii) Root cap was the site of light perception. If root cap was shaded while the root was irradiated the root showed no negative phototropism, and the root lost the characteristic of negative phototropism when root cap was divested. Rice root could resume the characteristic of negative phototropism when the new root cap grew up, if the original cells of root cap were well protected while root cap was divested, (iv) The growth increment and curvature of rice root were both influenced by light intensity. Within the range of 0–100 μmol · m2 -s−1, the increasing of light intensity resulted in the decreasing of the growth increment and the increasing of the curvature of rice root, (v) The growth increment and the curvature reached the maximum at 30°C with the temperature treatment of 10–40°C. (vi) Blue-violet light could prominently induce the negative phototropism of rice root, while red light had no such effect. (vii) The auxin (IAA) in the solution, as a very prominent influencing factor, inhibited the growth, the negative phototropism and the gravitropism of rice root when the concentration of IAA increased. The response of negative phototropism of rice root disappeared when the concentration of IAA was above 10 mg · L−1 相似文献
17.
J. F. Gonçalves L. A. Tabaldi D. Cargnelutti L. B. Pereira J. Maldaner A. G. Becker L. V. Rossato R. Rauber M. D. Bagatini D. A. Bisognin M. R. C. Schetinger F. T. Nicoloso 《Biometals》2009,22(5):779-792
A hydroponic experiment was carried out to characterize the oxidative stress responses of two potato cultivars (Solanum tuberosum L. cvs. Asterix and Macaca) to cadmium (Cd). Plantlets were exposed to four Cd levels (0, 50, 100, 150 and 200 μM) for 7 days.
Cd concentration was increased in both roots and shoot. Number of sprouts and roots was not decreased, whereas Cd treatment
affected the number of nodal segments. Chlorophyll content and ALA-D activity were decreased in both cultivars, whereas carotenoids
content was decreased only in Macaca. Cd caused lipid peroxidation in roots and shoot of both cultivars. Protein oxidation
was only verified at the highest Cd level. H2O2 content was increased in roots and shoot of Asterix, and apparently, a compensatory response between roots and shoot of Macaca
was observed. SOD activity was inhibited in roots of Asterix at all Cd treatments, whereas in Macaca it was only increased
at two highest Cd levels. Shoot SOD activity increased in Asterix and decreased in Macaca. Root CAT activity in Asterix decreased
at 100 and 150 μM, whereas in Macaca it decreased only at 50 μM. Shoot CAT activity was decreased in Macaca. Root AsA content
in Macaca was not affected, whereas in shoot it was reduced at 100 μM and increased at 200 μM. Cd caused increase in NPSH
content in roots and shoot. Our results suggest that Cd induces oxidative stress in both potato cultivars and that of the
two cultivars, Asterix showed greater sensitivity to Cd levels. 相似文献
18.
Renata Matraszek 《Acta Physiologiae Plantarum》2008,30(3):361-370
The author studied the effect of different nickel concentrations (0, 0.4, 40 and 80 μM Ni) on the nitrate reductase (NR) activity
of New Zealand spinach (Tetragonia expansa Murr.) and lettuce (Lactuca sativa L. cv. Justyna) plants supplied with different nitrogen forms (NO3
−–N, NH4
+–N, NH4NO3). A low concentration of Ni (0.4 μM) did not cause statistically significant changes of the nitrate reductase activity in
lettuce plants supplied with nitrate nitrogen (NO3
−–N) or mixed (NH4NO3) nitrogen form, but in New Zealand spinach leaves the enzyme activity decreased and increased, respectively. The introduction
of 0.4 μM Ni in the medium containing ammonium ions as a sole source of nitrogen resulted in significantly increased NR activity
in lettuce roots, and did not cause statistically significant changes of the enzyme activity in New Zealand spinach plants.
At a high nickel level (Ni 40 or 80 μM), a significant decrease in the NR activity was observed in New Zealand spinach plants
treated with nitrate or mixed nitrogen form, but it was much more marked in leaves than in roots. An exception was lack of
significant changes of the enzyme activity in spinach leaves when plants were treated with 40 μM Ni and supplied with mixed
nitrogen form, which resulted in the stronger reduction of the enzyme activity in roots than in leaves. The statistically
significant drop in the NR activity was recorded in the aboveground parts of nickel-stressed lettuce plants supplied with
NO3
−–N or NH4NO3. At the same time, there were no statistically significant changes recorded in lettuce roots, except for the drop of the
enzyme activity in the roots of NO3
−-fed plants grown in the nutrient solution containing 80 μM Ni. An addition of high nickel doses to the nutrient solution
contained ammonium nitrogen (NH4
+–N) did not affect the NR activity in New Zealand spinach plants and caused a high increase of this enzyme in lettuce organs,
especially in roots. It should be stressed that, independently of nickel dose in New Zealand spinach plants supplied with
ammonium form, NR activity in roots was dramatically higher than that in leaves. Moreover, in New Zealand spinach plants treated
with NH4
+–N the enzyme activity in roots was even higher than in those supplied with NO3
−–N. 相似文献
19.
Shoot and root mass of tobacco plants treated with only 0.05 μM boron was decreased by 25 and 50 %, respectively, when compared
to plants sufficiently supplied with B (2 and 5 μM). Leaf B content of 0.05 μM B-treated plants decreased (about 80–90 %)
when compared to 2 μM B treated plants; this drop of B content were not as marked (about 25–45 %) in roots. Leaf and root
nitrate contents in B-deficient plants were 45–60 % and 35–45 % lower, respectively, than those from 2 and 5 μM B treated
plants. It is suggested that B deficiency might decrease nitrate uptake rather than nitrate reductase activity in tobacco
plants. 相似文献
20.
To investigate the biocontrol effectiveness of the antibiotic producing bacterium, Pseudomonas aureofaciens 63–28 against the phytopathogen Rhizoctonia solani AG-4 on Petri plates and in soybean roots, growth response and induction of PR-proteins were estimated after inoculation
with P. aureofaciens 63–28 (P), with R. solani AG-4 (R), or with P. aureofaciens 63–28 + R. solani AG-4 (P + R). P. aureofaciens 63–28 showed strong antifungal activity against R. solani AG-4 pathogens in Petri plates. Treatment with P. aureofaciens 63–28 alone increased the emergence rate, shoot fresh weight, shoot dry weight and root fresh weight at 7 days after inoculation,
when compared to R. solani AG-4; P + R treatment showed similar effects. Peroxidase (POD) and β-1,3-glucanase activity of P. aureofaciens 63–28 treated roots increased by 41.1 and 49.9%, respectively, compared to control roots. POD was 26% greater in P + R treated
roots than R. solani treated roots. Two POD isozymes (59 and 27 kDa) were strongly induced in P + R treated roots. The apparent molecular weight
of chitinase from treated roots, as determined through SDS-PAGE separation and comparison with standards, was about 29 kDa.
Five β-1,3-glucanase isozymes (80, 70, 50, 46 and 19 kDa) were observed in all treatments. These results suggest that inoculation
of soybean plants with P. aureofaciens 63–28 elevates plant growth inhibition by R. solani AG-4 and activates PR-proteins, potentially through induction of systemic resistance mechanisms. 相似文献