Transient and permanent changes of xylem sap exudation by root systems of Zea mays after application of hydrostatic and osmotic forces

2010 ◽  
Vol 37 (9) ◽  
pp. 813 ◽  
Author(s):  
Michael Fritz ◽  
Stephan Lorenzen ◽  
Maria Popova ◽  
Rudolf Ehwald
Keyword(s):  
Zea Mays ◽  
Reflection Coefficient ◽  
Surface Film ◽  
Root Exudation ◽  
Xylem Sap ◽  
Root Surface ◽  
Osmotic Gradient ◽  
Microflow Sensor ◽  
Exudation Rate ◽  
Peg 600

Effects of relatively small changes of hydrostatic and osmotic pressure on root exudation were studied with maize (Zea mays L.) plants grown in hydroculture to estimate the root reflection coefficient for the applied osmolyte (PEG 600). During the first seconds after a change in hydrostatic pressure, the exudation rate measured with a microflow sensor was instantaneously and strongly changed due to elastic deformation of the metaxylem vessels in the branched part of the main root axis. In osmotic experiments, a time of 10–20 s was required before the maximum change of the exudation rate was recorded. This retardation can be explained by diffusive saturation of the non-agitated root surface film and radial turgor propagation. A new standing osmotic gradient was reached within 4 min after a change of the water potential difference (osmotic, hydrostatic). The steady-state exudation rate J was altered by osmotic and hydrostatic forces with nearly equal efficiencies when branch roots were not injured. Hence, the reflection coefficient of the intact root for PEG 600 was close to unity. The results are in accord with nearly ideal reverse osmosis at high rates of water uptake by roots and confirm the absence of a significant hydraulic bypath circumventing the protoplasts.

scholarly journals Biological nitrification inhibition in maize—isolation and identification of hydrophobic inhibitors from root exudates

2021 ◽  
Author(s):  
Junnosuke Otaka ◽  
Guntur Venkata Subbarao ◽  
Hiroshi Ono ◽  
Tadashi Yoshihashi
Keyword(s):  
Root Exudation ◽  
Root Systems ◽  
Root Surface ◽  
Maize Root ◽  
Nitrification Inhibition ◽  
Isolation And Identification ◽  
N Losses ◽  
Chemical Structures ◽  
Maize Roots ◽  
Biological Nitrification

AbstractTo control agronomic N losses and reduce environmental pollution, biological nitrification inhibition (BNI) is a promising strategy. BNI is an ecological phenomenon by which certain plants release bioactive compounds that can suppress nitrifying soil microbes. Herein, we report on two hydrophobic BNI compounds released from maize root exudation (1 and 2), together with two BNI compounds inside maize roots (3 and 4). On the basis of a bioassay-guided fractionation method using a recombinant nitrifying bacterium Nitrosomonas europaea, 2,7-dimethoxy-1,4-naphthoquinone (1, ED50 = 2 μM) was identified for the first time from dichloromethane (DCM) wash concentrate of maize root surface and named “zeanone.” The benzoxazinoid 2-hydroxy-4,7-dimethoxy-2H-1,4-benzoxazin-3(4H)-one (HDMBOA, 2, ED50 = 13 μM) was isolated from DCM extract of maize roots, and two analogs of compound 2, 2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (HMBOA, 3, ED50 = 91 μM) and HDMBOA-β-glucoside (4, ED50 = 94 μM), were isolated from methanol extract of maize roots. Their chemical structures (1–4) were determined by extensive spectroscopic methods. The contributions of these four isolated BNI compounds (1–4) to the hydrophobic BNI activity in maize roots were 19%, 20%, 2%, and 4%, respectively. A possible biosynthetic pathway for zeanone (1) is proposed. These results provide insights into the strength of hydrophobic BNI activity released from maize root systems, the chemical identities of the isolated BNIs, and their relative contribution to the BNI activity from maize root systems.

Accumulation of Cd, Cu and Zn in shoots of maize (Zea mays L.) exposed to 0.8 or 20 nM Cd during vegetative growth and the relation with xylem sap composition

2015 ◽  
Vol 23 (4) ◽  
pp. 3152-3164 ◽  
Author(s):  
C. Nguyen ◽  
A. J. Soulier ◽  
P. Masson ◽  
S. Bussière ◽  
J. Y. Cornu
Keyword(s):  
Zea Mays ◽  
Vegetative Growth ◽  
Zea Mays L ◽  
Xylem Sap ◽  
20 Nm ◽  
Cu And Zn

Does root exudation of phenolics play a role in aluminium resistance in maize (Zea mays L.)?

2001 ◽  
pp. 504-505
Author(s):  
P. S. Kidd ◽  
C. Poschenrieder ◽  
J. Barceló
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Root Exudation ◽  
Aluminium Resistance

Effects of biochar, compost and straw input on root exudation of maize (Zea mays L.): From function to morphology

2020 ◽  
Vol 297 ◽  
pp. 106952 ◽  
Author(s):  
Caixia Sun ◽  
Dan Wang ◽  
Xiangbo Shen ◽  
Chenchen Li ◽  
Jun Liu ◽  
...  
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Root Exudation

The chemical form of trivalent chromium in xylem sap of maize (Zea mays L.)

2006 ◽  
Vol 18 (4) ◽  
pp. 161-169 ◽  
Author(s):  
Shikha Juneja ◽  
Satya Prakash
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Xylem Sap ◽  
Trivalent Chromium ◽  
Chemical Form

scholarly journals Elevated CO2 and nitrate levels increase wheat root-associated bacterial abundance and impact rhizosphere microbial community composition and function

2020 ◽  
Author(s):  
Alla Usyskin-Tonne ◽  
Yitzhak Hadar ◽  
Uri Yermiyahu ◽  
Dror Minz
Keyword(s):  
Bacterial Abundance ◽  
Root Exudation ◽  
Microbial Community Composition ◽  
Wheat Root ◽  
Root Surface ◽  
Structure And Function ◽  
Secretion Systems ◽  
Functional Changes ◽  
And Function ◽  
Mannose Metabolism

AbstractElevated CO2 stimulates plant growth and affects quantity and composition of root exudates, followed by response of its microbiome. Three scenarios representing nitrate fertilization regimes: limited (30 ppm), moderate (70 ppm) and excess nitrate (100 ppm) were compared under ambient and elevated CO2 (eCO2, 850 ppm) to elucidate their combined effects on root-surface-associated bacterial community abundance, structure and function. Wheat root-surface-associated microbiome structure and function, as well as soil and plant properties, were highly influenced by interactions between CO2 and nitrate levels. Relative abundance of total bacteria per plant increased at eCO2 under excess nitrate. Elevated CO2 significantly influenced the abundance of genes encoding enzymes, transporters and secretion systems. Proteobacteria, the largest taxonomic group in wheat roots (~ 75%), is the most influenced group by eCO2 under all nitrate levels. Rhizobiales, Burkholderiales and Pseudomonadales are responsible for most of these functional changes. A correlation was observed among the five gene-groups whose abundance was significantly changed (secretion systems, particularly type VI secretion system, biofilm formation, pyruvate, fructose and mannose metabolism). These changes in bacterial abundance and gene functions may be the result of alteration in root exudation at eCO2, leading to changes in bacteria colonization patterns and influencing their fitness and proliferation.

Suberin deposition and band plasmolysis in the corn (Zea mays L.) root exodermis

1997 ◽  
Vol 75 (7) ◽  
pp. 1188-1199 ◽  
Author(s):  
Daryl E. Enstone ◽  
Carol A. Peterson
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Lateral Roots ◽  
Root Surface ◽  
Casparian Bands ◽  
Suberin Lamellae ◽  
Tight Connection ◽  
Casparian Band ◽  
Apoplastic Barrier ◽  
Suberin Lamella

The exodermal Casparian band in corn (Zea mays L.) was first seen 10 mm distal to the kernel 4 days after planting. From its inception, the band usually occupied most of the radial wall (as seen in a cross section of the root). Subsequent maturation of the band around the root was asynchronous into the region of emerging lateral roots. Thus, a continuous apoplastic barrier would have been absent over much of the young root surface. Suberin lamellae development was also asynchronous, as these structures formed in those cells which had Casparian bands. Frequently, a lamella was initially deposited in patches, progressing centripetally until a continuous lipid layer was formed around the cell protoplast. Many instances of band plasmolysis (typical of the endodermis) were observed in the developing uniform exodermis. It could occur in cells with no detectable Casparian bands, suggesting that the tight connection between the plasmalemma and the wall that causes this phenomenon is not due to hydrophobic attractions. The results are consistent with the idea that there are strong attractions between proteins of the membrane and wall in the region of the Casparian band. The tight connection between the plasmalemma and the wall was broken during the later stages of suberin lamella development. Key words: Zea mays L., Poaceae, band plasmolysis, exodermis, Casparian band, suberin lamella.

scholarly journals Metabolite Profile of Xylem Sap in Cotton Seedlings Is Changed by K Deficiency

2020 ◽  
Vol 11 ◽  
Author(s):  
Xin Zhang ◽  
Guo Wang ◽  
Huiyun Xue ◽  
Jinbao Zhang ◽  
Qinglian Wang ◽  
...  
Keyword(s):  
High Performance ◽  
Xylem Sap ◽  
Dry Weight ◽  
Metabolite Profile ◽  
Root Surface ◽  
Mineral Nutrient ◽  
Root Surface Area ◽  
Nutrient Contents ◽  
Kegg Pathways ◽  
K Deficiency

Xylem sap, belonging to the plant apoplast, not only provides plant tissues with inorganic and organic substances but also facilitates communication between the roots and the leaves and coordinates their development. This study investigated the effects of potassium (K) deficiency on the morphology and the physiology of cotton seedlings as well as pH, mineral nutrient contents, and metabolites of xylem sap. In particular, we compared changes in root–shoot communication under low K (LK) and normal K (NK, control) levels. Compared to control, LK stress significantly decreased seedling biomass (leaf, stem, and root dry weight; stem and root length; root surface area and root volume) and the levels of K, Na (sodium), Mg (magnesium), Fe (iron), and Zn (zinc) in xylem sap. A total of 82 metabolites in sap analyzed by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) showed significant differences between the two conditions; among these, 38 were up-regulated more than 2-fold, while the others were down-regulated less than 0.5-fold. In particular, several metabolites found in the cell membrane including three cholines (glycerophosphatecholine, 2-hexenylcholine, and caproylcholine) and desglucocoroloside and others such as malondialdehyde, α-amino acids and derivatives, sucrose, and sugar alcohol significantly increased under LK stress, indicating that cell membranes were damaged and protein metabolism was abnormal. It is worth noting that glycerophosphocholine was up-regulated 29-fold under LK stress, indicating that it can be used as an important signal of root–shoot communication. Furthermore, in pathway analyses, 26 metabolites were matched to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways; L-aspartic acid, which was associated with 10 KEGG pathways, was the most involved metabolite. Overall, K deficiency reduced the antioxidant capacity of cotton seedlings and led to a metabolic disorder including elevated levels of primary metabolites and inhibited production of secondary metabolites. This eventually resulted in decreased biomass of cotton seedlings under LK stress. This study lays a solid foundation for further research on targeted metabolites and signal substances in the xylem sap of cotton plants exposed to K deficiency.

scholarly journals A dynamic rhizosphere interplay between tree roots and soil bacteria under drought stress

2021 ◽  
Author(s):  
Yaarao Oppenheimer-Shaanan ◽  
Gilad Jakoby ◽  
Maya Laurenci Starr ◽  
Romiel Karliner ◽  
Gal Eilon ◽  
...  
Keyword(s):  
Forest Soil ◽  
Soil Bacteria ◽  
Bacterial Species ◽  
Root Exudation ◽  
Nitrogen Sources ◽  
Microbial Interactions ◽  
Tree Roots ◽  
Carbon And Nitrogen ◽  
Custom Made ◽  
Exudation Rate

<p>Root exudates are thought to play an important role in plant-microbial interactions. In return, soil bacteria can increase the bioavailability of soil minerals, which is typically decreasing in situations such as drought. Here we describe an exudate-driven microbial priming on <em>Cupressus</em> saplings grown outside in forest soil in custom-made rhizotron boxes. A 1-month imposed drought and inoculations with <em>Bacillus subtilis </em>and <em>Pseudomonas</em> <em>stutzeri</em>, bacteria species forest soil isolation, were applied in a factorial design. We revealed that both bacteria associated with <em>Cupressus</em> roots and were more abundant in rhizosphere than in bulk soil. Moreover, root exudation rate increased in inoculated trees under drought with >100 first identified metabolites from <em>Cupressus</em> roots. Among these metabolites, phenolic acid compounds, quinate, and others, were used as carbon and nitrogen sources by both bacterial species. Furthermore, soil phosphorous bioavailability was maintained only in inoculated trees, where a drought-induced decrease in leaf phosphorus and iron was prevented. We provide evidence that changes in exudation rate and composition under drought and bacteria inoculation, support the idea of root recruitment of beneficial bacteria. In turn, trees secreted further carbon source to the rhizosphere and hosted more bacteria, benefited from improved nutrition.</p>

scholarly journals Diurnal Changes of the Exudation Rate and the Mineral Concentration in Xylem Sap after Decapitation of Grafted and Non-grafted Cucumbers

1982 ◽  
Vol 51 (3) ◽  
pp. 293-298 ◽  
Author(s):  
Masaharu MASUDA ◽  
Kiyoshi GOMI
Keyword(s):  
Xylem Sap ◽  
Diurnal Changes ◽  
Mineral Concentration ◽  
Exudation Rate
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