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1.
Chemical characterization of root exudates from rice (Oryza sativa) and their effects on the chemotactic response of endophytic bacteria 总被引:3,自引:0,他引:3
Bacilio-Jiménez Macario Aguilar-Flores Sara Ventura-Zapata Elsa Pérez-Campos Eduardo Bouquelet Stephane Zenteno Edgar 《Plant and Soil》2003,249(2):271-277
Root exudates represent an important source of nutrients for microorganisms in the rhizosphere and seem to participate in early colonization inducing chemotactic responses of rhizospheric bacteria. We characterized the root exudates collected from rice plantlets cultured under hydroponic conditions and assessed their effects on the chemotaxis of two strains of endophytic bacteria, Corynebacterium flavescens and Bacillus pumilus, collected from the rice rhizosphere. We compared these chemotactic effects on endophytic bacteria with those on two strains of plant-growth-promoting bacteria, Azospirillum brasilense (isolated from the corn rhizosphere) and Bacillus sp. (from the rice rhizosphere). The root exudates were collected at different time intervals. The highest concentration and diversity of amino acids and carbohydrates were found during the first 2 weeks after seeding. Histidine, proline, valine, alanine, and glycine were the main amino acid residues identified during the 4 weeks of culture. The main carbohydrates identified were glucose, arabinose, mannose, galactose, and glucuronic acid. The chemotactic responses of the analyzed endophytic bacteria to root exudates were 3.9 to 5.1 times higher than those of A. brasilense and 2.2 to 2.8 times higher than Bacillus sp. Our results indicate that rice exudates may induce a higher chemotactic response for endophytic bacteria than for other bacterial strains present in the rice rhizosphere. 相似文献
2.
Summary Root exudates from healthy and diseased lentil plants (Lens culinaris) have been investigated in relation to the wilt disease caused byFusarium oxysporum f.lentis. In all ten amino acids and five sugars have been detected. The spore germination of the pathogen in root exudates indicated that 21-days root exudate was inhibitory. Glycine and phenylalanine were detected in 21-days exudate and were found to have an inhibitory effect upon the germination of the spores of the pathogen which may partly explain the lesser disease incidence when plants of more than 3 weeks are inoculated with the pathogen. 相似文献
3.
Summary Amino acids in exudates of uninoculated pea roots were compared quantitatively and qualitatively with exudates of roots inoculated with Gliocladium catenulatum. This fungus has the potential of causing severe root necrosis. Twenty-one amino acids were found in exudates of healthy roots and apparently some of these were utilized by the fungus. A relatively high concentration of ammonia was detected in exudates of inoculated pea roots, indicating an intense deamination by the fungus. No other imbalance in amino acids was found which could be related to known toxic effects of amino acids on plant tissues. 相似文献
4.
P. M. Bonish 《Plant and Soil》1973,39(2):319-328
Summary Pectolytic enzymes were studied in inoculated and uninoculated red clover (Trifolium pratense) seedlings grown aseptically in flasks containing distilled water or nitrogen-free salts media. Enzyme activity in root exudates and root extracts depended on the conditions of seedling growth. Tests with sodium polypectate and citrus pectin indicated the presence of two enzymes, specific for pectic acid and pectin respectively. Both enzymes were produced by uninoculated seedlings, and in seedlings inoculated with Rhizobium trifolii, R. leguminosarum or R. lupini, enzyme activity was not correlated with infectivity of the strains. re]19720814 相似文献
5.
To assess the influence of bacteria inoculation on carbon flow through maize plant and rhizosphere,14C allocation after14CO2 application to shoots over a 5-day period was determined. Plants were grown on C- and N-free quartz sand in two-compartment
pots, separating root and shoot space. While one treatment remained uninoculated, treatments two and three were inoculated
withPantoea agglomerans (D5/23) andPseudomonas fluorescens (Ps I A12), respectively, five days after planting. Bacterial inoculation had profound impacts on carbon distribution within
the system. Root/rhizosphere respiration was increased and more carbon was allocated to roots of plants being inoculated.
After five days of14CO2 application, more ethanol-soluble substances were found in roots of inoculated treatments and lower rhizodeposition indicated
intensive C turnover in the rhizosphere. In both inoculated treatments the intensity of photosynthesis measured as net-CO2-assimilation rates were increased when compared to the uninoculated plants. However, high C turnover in the rhizosphere reduced
shoot growth of D5/23 inoculated plants, with no effect on shoot growth of Ps I A12 inoculated plants. A separation of labeled
compounds in roots and rhizodeposition revealed that neutral substances (sugars) constituted the largest fraction. The relative
fractions of sugars, amino acids and organic acids in roots and rhizodeposition suggest that amino acid exudation was particularly
stimulated by bacterial inoculation and that turnover of this substance group is high in the rhizosphere. 相似文献
6.
《Journal of Plant Interactions》2013,8(3):263-270
Abstract Cd(II) adsorption of root exudates from sunflower (Helianthus annuus L.) seedling was investigated by Cd ion-selective electrode, Fourier Transform Infrared spectroscopy, and fluorescence spectroscopy. Root exudates from Helianthus annuus L. had strong adsorption ability toward Cd(II). The adsorption process was pH-dependent and the maximum adsorption capacity, 150.8 mg g?1, was observed at pH 7.0. Root exudates had pK a1 at 4.7 for carboxyl and pK a2 at 9.2 for phenolic, and amino groups. The aliphatic and aromatic (C?H) groups, amide III group, and the C (=O)?O and sulfonate groups were responsible for Cd(II) adsorption. The excitation emission matrix fluorescence spectroscopy showed protein-like substances participated in Cd adsorption and formed strong complexes, with conditional stability constants of 4.70 and 4.32, which is a little lower than that determined by potentiometric methods, 5.13. The strong Cd complexing ability of root exudates implies that root exudates may significantly affect mobility, toxicity, and phytoavailability of Cd. Cd binding of root exudates may be attributed to its interaction with the proteins, polysaccharides, and phenolic compounds in root exudates. 相似文献
7.
Sugar mill by-products compost may be a good soil amendment to promote tomato (Lycopersicon esculentum L.) growth. In addition, the compost may further promote plant growth by inoculation with N2-fixing bacteria. Compost from sugar-mill waste was prepared with and without the N2-fixing bacteria, Azotobacter vinelandii, Beijerinckia derxii and Azospirillum sp. and incubated for 50 days. Each compost type was added to 10 kg of soil in pots at rates of 0, 15, and 45 g with and
without fertilizer N at rates of 0, 0.75, and 1.54 g. A blanket application of P and K was applied to all pots. Shoot and
root dry weights and N content of the whole plant was measured at 55 days. Dry weight of tomato shoots was increased by 40%
by addition of fertilizer N and root weight was increased by 66%. Without fertilizer N the high rate of inoculated compost
increased shoot growth 180% and uninoculated compost increased shoot growth 112%. For most treatments with and without fertilizer
N, inoculated compost enhanced shoot growth and nitrogen content more than uninoculated compost. Root weights were nearly
doubled by addition of either compost in comparison to the 0 N treatment. At the low rate of compost addition without fertilizer
N, root weight was the same for uninoculated and inoculated compost but at the high rate of compost addition root weight was
32% higher for inoculated compost. The N2-fixing bacteria colonized roots when inoculated compost was used. Sugar mill by-products compost proved to be an effective
soil amendment for promoting the growth of tomato plants. 相似文献
8.
Maize (Zea mays L. cv. Alize) plants were grown in a calcareous soil in pots divided by 30-m nylon nets into three compartments, the central one for root growth and the outer ones for hyphal growth. Sterle soil was inoculated with either (1) rhizosphere microorganisms other than vesicular-arbuscular mycorrhizal (VAM) fungi, (2) rhizosphere microorganisms together with a VAM fungus [Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappel], or (3) with a gamma-irradiated inoculum as control. Plants were grown under controlled-climate conditions and harvested after 3 or 6 weeks. VAM plants had higher shootroot ratios than non-VAM plants. After 6 weeks, the concentrations of P, Zn and Cu in roots and shoots had significantly increased with VAM colonization, whereas Mn concentrations had significantly decreased. Root exudates were collected on agar sheets placed on the interface between root and hyphal compartments. Six-week-old VAM and non-VAM plants had similar root exudate compositions of 72–73% reducing sugars, 17–18% phenolics, 7% organic acids and 3% amino acids. In another experiment in which root exudates were collected on agar sheets with or without antibiotics, the amounts of amino acids and carbohydrates recovered were similar in VAM and non-VAM plants. However, threeto sixfold higher amounts of carbohydrates, amino acids and phenolics were recovered when antibiotics were added to the agar sheets. Thus, the high microbial activity in the rhizosphere and on the rhizoplane limits the exudates recovered from roots. 相似文献
9.
Salinity adversely affects plant growth and development. Halotolerant plant-growth-promoting rhizobacteria (PGPR) alleviate
salt stress and help plants to maintain better growth. In the present study, six PGPR strains were analyzed for their involvement
in salt-stress tolerance in Arachis hypogaea. Different growth parameters, electrolyte leakage, water content, biochemical properties, and ion content were analyzed in
the PGPR-inoculated plants under 100 mM NaCl. Three bacterial strains, namely, Brachybacterium
saurashtrense (JG-06), Brevibacterium
casei (JG-08), and Haererohalobacter (JG-11), showed the best growth of A. hypogaea seedlings under salt stress. Plant length, shoot length, root length, shoot dry weight, root dry weight, and total biomass
were significantly higher in inoculated plants compared to uninoculated plants. The PGPR-inoculated plants were quite healthy
and hydrated, whereas the uninoculated plant leaves were desiccated in the presence of 100 mM NaCl. The percentage water content
(PWC) in the shoots and roots was also significantly higher in inoculated plants compared to uninoculated plants. Proline
content and soluble sugars were significantly low, whereas amino acids were higher than in uninoculated plants. The MDA content
was higher in uninoculated plants than in inoculated plants at 100 mM NaCl. The inoculated plants also had a higher K+/Na+ ratio and higher Ca2+, phosphorus, and nitrogen content. The auxin concentration was higher in both shoot and root explants in the inoculated plants.
Therefore, it could be predicted that all these parameters cumulatively improve plant growth under saline conditions in the
presence of PGPR. This study shows that PGPR play an important role in inducing salinity tolerance in plants and can be used
to grow salt-sensitive crops in saline areas. 相似文献
10.
Bioassay based on thick and short root (Tsr) and hair deformation (Had) phenotypes were used to test the activity of Nod factors
produced byRhizobium sp. (Cicer) strains HS-1, Rcd-301, IC-59, IC-76 and Ca-181 on chickpea (Cicer arietinum) cv. ‘C-235’. Nod− mutants ofRhizobium sp. (Cicer) did not produce Tsr+ and Had+ phenotypes on chickpea, indicating the requirement of nodulation genes for their appearance. The strain HS-1 treated with
root exudates of pea (Pisum sativum), berseem (Trifolium alexandrinum) and lucerne (Medicago sativa) failed to produce the Tsr+ and Had+ phenotypes on chickpea. ConverselyR. leguminosarum bvs.viciae andtrifolii, R. meliloti, Rhizobium sp. (Sesbania), andRhizobium sp. (Cajanus) induced with chickpea root exudates did not show Tsr+ and Had+ phenotypes on chickpea. It appears that host specificity inRhizobium sp. (Cicer)-chickpea symbiosis is regulated by the production of host-specific factors which are not active on heterologous hosts. 相似文献
11.
Soluble root exudates were collected from three plants (Nicotiana tabacum L., Nicotiana rustica L. and Zea mays L.), grown under axenic and hydroponic conditions, in order to study their metal-solubilizing ability for Cd and other cations
(Cu, Fe, Mn, Ni, Zn). Nicotiana spp. and Zea mays L. root exudates differed markedly in C/N ratio, sugars vs. amino acids ratio and organic acids content. Metals from two soils were extracted with either root exudate solutions, containing
equal amounts of organic carbon, or distilled water as control. In the presence or absence of root exudates, the solubility
of Fe and Mn was much higher than of the four other metals tested. Root exudates increased the solubilities of Mn and Cu,
whereas those of Ni and Zn were not affected. Root exudates of Nicotiana spp. enhanced the solubility of Cd. The extent of Cd extraction by root exudates (N. tabacum L. N. rustica L. Zea mays L.) was similar to the order of Cd bioavailability to these three plants when grown on soil. An increase in Cd solubility
in the rhizosphere of apical root zones due to root exudates is likely to be an important cause of the relatively high Cd
accumulation in Nicotiana spp. 相似文献
12.
T. Yamamoto K. Yokotani-Tomita S. Kosemura S. Yamamura K. Yamada K. Hasegawa 《Journal of Plant Growth Regulation》1999,18(2):65-67
The allelopathy of a serious weed, barnyard grass (Echinochloa crus-galli L.), was investigated. Root exudates of young barnyard grass showed allelopathic effects and plant-selective activity and
inhibited root elongation of all plants tested. With respect to shoot growth, the exudates did not show inhibition of barnyard
grass only. The allelopathic substance was isolated and identified as p-hydroxymandelic acid by NMR. p-Hydroxymandelic acid strongly inhibited shoot growth and root elongation of all plants tested. The effects of three congeners
of p-hydroxymandelic acid were tested on rice shoot growth. In the biological activity exhibited in rice, shoot growth was related
to the hydroxyl groups.
Received October 7, 1998; accepted March 29, 1999 相似文献
13.
Karin Hage‐Ahmed Anna Moyses Andreas Voglgruber Franz Hadacek Siegrid Steinkellner 《Journal of Phytopathology》2013,161(11-12):763-773
Arbuscular mycorrhizal fungi (AMF) can control soilborne diseases such as Fusarium oxysporum f.sp. lycopersici (Fol). Root exudates play an important role in plant–microbe interactions in the rhizosphere, especially, in the initial phase of these interactions. In this work, we focus on (i) elucidating dynamics in root exudation of Solanum lycopersicum L. in an intercropping system due to AMF and/or Fol; (ii) its effect on Fol development in vitro; and (iii) the testing of the root exudate compounds identified in the chromatographic analyses in terms of effects on fungal growth in in vitro assays. GC‐MS analyses revealed an AMF‐dependent increase in sugars and decrease in organic acids, mainly glucose and malate. In the HPLC analyses, an increase in chlorogenic acid was evident in the combined treatment of AMF and Fol, which is to our knowledge the first report about an increase in chlorogenic acid in root exudates of AM plants challenged with Fol compared with plants inoculated with AMF only, clearly indicating changes in root exudation due to AMF and Fol. Root exudates of AMF tomato plants stimulate the germination rate of Fol, whereas the co‐inoculation of AMF and Fol leads to a reduction in spore germination. In the in vitro assays, citrate and chlorogenic acid could be identified as possible candidates for the reduction in Fol germination rate in the root exudates of the AMF+Fol treatment because they proved inhibition at concentrations naturally occurring in the rhizosphere. 相似文献
14.
为研究混交过程中柏木根系分泌物对栾树细根生长的影响,以一年生栾树盆栽幼苗为研究对象,通过施加1株、2株、4株、8株4个浓度柏木根系分泌物(分别记为G1、G2、G4、G8)于栾树盆栽中,探讨柏木根系分泌物对栾树幼苗1~5级细根形态及N、P含量的影响。结果表明:(1)栾树细根直径随根序的增加而增大,施加根系分泌物显著减小了1~2级细根的直径(P0.05);细根比根长、比表面积均随根序的增加而减小,施加根系分泌物显著增大了1~2级细根的比根长及比表面积(P0.05);随根系分泌物施加浓度的提高,栾树比根长及比表面积先增大,而直径先减小,然后均趋于平缓波动的态势。(2)栾树细根N、P含量均随根序的增加而减小,而N/P在根序间的变化不显著;施加柏木根系分泌物显著增大了栾树1~2级细根的N、P含量(P0.05),但减小了1~5级细根的N/P;随根系分泌物施加浓度的提高,栾树细根P含量增大,N/P减小,而N含量先增加后呈现平缓变化的趋势。(3)栾树细根N、P含量均与其比根长、比表面积和直径等形态特征之间呈显著的相关关系(P0.05)。研究发现,柏木根系分泌物可改善土壤养分的有效性,从而缓解栾树植株的缺P症状,细根通过调整其形态以提高养分利用效率;柏木根系分泌物主要影响栾树1~2级细根的形态及N、P含量;4株柏木根系分泌物的剂量更有利于栾树根系的生长。 相似文献
15.
Séverin Nguemezi Tchameni Dieudonné Nwaga Louise Nana Wakam Eddy Leonard Mangaptche Ngonkeu Raymond Fokom Jean Kuaté Francois‐Xavier Etoa 《Journal of Phytopathology》2012,160(5):220-228
The effects of some selected arbuscular mycorrhizal (AM) fungi, Gigaspora margarita and Glomus mossae on the growth and the role of soluble amino acids of two contrasting cocoa cultivars (ICS84 tolerant and SNK10 sensitive) against black pod disease caused by Phytophthora megakarya were investigated. Root colonization by AM fungi is between 50 and 70% 18 weeks after planting. Tested AM fungi significantly increased all the plant growth parameters (height, number of leaves, shoot and root matter) and P uptake as compared to non‐inoculated plants in pot experiments. AM fungi inoculated cocoa reduced the disease severity. Compared to the control, the soluble amino acid levels increased with inoculation of the AM fungi strains in the necrotic stems of disease on inoculated cocoa plants. Significant relationships between amino acids and disease severity observed for two cocoa cultivars imply that the induction of specific amino acids synthesized by leaves, such as arginine, cysteine and glutamic acid, may represent potential candidate molecules for adaptation of such cultivars to P. megakarya disease. Inoculating seedlings with AMF in nurseries could enhance the development of cocoa plants protected against P. megakarya. 相似文献
16.
The influence of rhizosphere microorganisms and vesicular-arbuscular (VA) mycorrhiza on manganese (Mn) uptake in maize (Zea mays L. cv. Tau) plants was studied in pot experiments under controlled environmental conditions. The plants were grown for 7 weeks in sterilized calcareous soil in pots having separate compartments for growth of roots and of VA mycorrhizal fungal hyphae. The soil was left either uninoculated (control) or prior to planting was inoculated with rhizosphere microorganisms only (MO-VA) or with rhizosphere microorganisms together with a VA mycorrhizal fungus [Glomus mosseae (Nicol and Gerd.) Gerdemann and Trappe] (MO+VA). Mycorrhiza treatment did not affect shoot dry weight, but root dry weight was slightly inhibited in the MO+VA and MO-VA treatments compared with the uninoculated control. Concentrations of Mn in shoots decreased in the order MO-VA > MO+VA > control. In the rhizosphere soil, the total microbial population was higher in mycorrhizal (MO+VA) than nonmycorrhizal (MO-VA) treatments, but the proportion of Mn-reducing microbial populations was fivefold higher in the nonmycorrhizal treatment, suggesting substantial qualitative changes in rhizosphere microbial populations upon root infection with the mycorrhizal fungi. The most important microbial group taking part in the reduction of Mn was fluorescent Pseudomonas. Mycorrhizal treatment decreased not only the number of Mn reducers but also the release of Mn-solubilizing root exudates, which were collected by percolation from maize plants cultivated in plastic tubes filled with gravel quartz sand. Compared with mycorrhizal plants, the root exudates of nonmycorrhizal plants had two fold higher capacity for reduction of Mn. Therefore, changes in both rhizosphere microbial population and root exudation are probably responsible for the lower acquisition of Mn in mycorrhizal plants. 相似文献
17.
Shanker Bhat Sullia 《Plant and Soil》1973,39(1):197-200
Summary The effects of root exudates and extracts of Cassia tora L. and Crotalaria medicaginea Lamk., on some dominant rhizosphere fungi isolated from the plants were studied. Root extracts induced a high degree of stimulation in rate of growth of a majority of the fungi tested. Root exudates caused only a marginal effect which was positive on all the fungi except Trichoderma lignorum which was inhibited by the root exudate of C. medicaginea. 相似文献
18.
19.
The effect of root exudates from P-deficient onion on root colonisation by an arbuscular mycorrhizal fungus was examined.
Onions (Allium cepa L.) were grown in solution culture at phosphorus concentrations of 0 (P0) and 2 (P2) mg P l–1. Root exudates were collected and fractionated with Amberlite XAD-4 resin to give EtOH and water soluble fractions. Onions
inoculated with the arbuscular mycorrhizal fungus Gigaspora margarita Becker & Hall were grown with or without (control) root exudates and exudate fractions in a growth chamber. After 24 days,
arbuscular mycorrhiza levels and appressoria formation had increased in plants treated with P0-root exudate or the P0-EtOH
fraction when compared to corresponding P2 treatments or control plants. P0 and P2 water-soluble fractions did not significantly
affect either aspect of fungal development. These results suggest that hydrophobic compounds found in root exudates from P-deficient
onion increase appressorium formation and, therefore, enhance mycorrhiza development.
Accepted: 2 June 1998 相似文献
20.
The influence of boron starvation on the root exudates content in soybean seedlings (Glycine max. L. Merr.) and the effect of exudates pretreatment on the pre-infection processes in symbiotic system Br. japonicum strain 636 and soybean were investigated. Root cell membrane stability of boron starved soybean plants (-B) decreased compared
to the control. The concentrations of all analyzed metabolites (reducing sugars, free amino acids, organic acids, soluble
phenols and total flavonoids) from root exudates of -B plants were lower than the control concentrations. Analysis of polyphenols
after HPLC chromatography of root exudates showed significant difference of peak numbers between chromatograms of exudates
obtained from boron starved and from control plants.
Bacterial culture treatment with root exudates from -B plants showed decreased growth, chemotaxis and attachment ability toward
the host root compared to the control exudate treatments. These changes were accompanied by decreased nodulation and acetylene
reduction activity of boron starved soybean plants. 相似文献