scholarly journals Local auxin biosynthesis acts downstream of brassinosteroids to trigger root foraging for nitrogen

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhongtao Jia ◽  
Ricardo F. H. Giehl ◽  
Nicolaus von Wirén
Keyword(s):  
Lateral Roots ◽  
Root Surface ◽  
Nutrient Acquisition ◽  
Fine Tuning ◽  
Auxin Biosynthesis ◽  
N Availability ◽  
Hormonal Crosstalk ◽  
Soil Exploration ◽  
N Deficiency ◽  
Coding Variants

AbstractLateral roots (LRs) dominate the overall root surface of adult plants and are crucial for soil exploration and nutrient acquisition. When grown under mild nitrogen (N) deficiency, flowering plants develop longer LRs to enhance nutrient acquisition. This response is partly mediated by brassinosteroids (BR) and yet unknown mechanisms. Here, we show that local auxin biosynthesis modulates LR elongation while allelic coding variants of YUCCA8 determine the extent of elongation under N deficiency. By up-regulating the expression of YUCCA8/3/5/7 and of Tryptophan Aminotransferase of Arabidopsis 1 (TAA1) under mild N deficiency auxin accumulation increases in LR tips. We further demonstrate that N-dependent auxin biosynthesis in LRs acts epistatic to and downstream of a canonical BR signaling cascade. The uncovered BR-auxin hormonal module and its allelic variants emphasize the importance of fine-tuning hormonal crosstalk to boost adaptive root responses to N availability and offer a path to improve soil exploration by expanded root systems in plants.

scholarly journals Microstructural and physiological responses to cadmium stress under different nitrogen levels in Populus cathayana females and males

2020 ◽  
Vol 40 (1) ◽  
pp. 30-45 ◽  
Author(s):  
Miao Liu ◽  
Jingwen Bi ◽  
Xiucheng Liu ◽  
Jieyu Kang ◽  
Helena Korpelainen ◽  
...  
Keyword(s):  
Nitrogen Deficiency ◽  
Ion Homeostasis ◽  
N Availability ◽  
Cd Stress ◽  
Cd Accumulation ◽  
N Supply ◽  
Populus Cathayana ◽  
N Deficiency ◽  
Cellular Compartments ◽  
Cd Translocation

Abstract Although increasing attention has been paid to the relationships between heavy metal and nitrogen (N) availability, the mechanism underlying adaptation to cadmium (Cd) stress in dioecious plants has been largely overlooked. This study examined Cd accumulation, translocation and allocation among tissues and cellular compartments in Populus cathayana Rehder females and males. Both leaf Cd accumulation and root-to-shoot Cd translocation were significantly greater in females than in males under a normal N supply, but they were reduced in females and enhanced in males under N deficiency. The genes related to Cd uptake and translocation, HMA2, YSL2 and ZIP2, were strongly induced by Cd stress in female roots and in males under a normal N supply. Cadmium largely accumulated in the leaf blades of females and in the leaf veins of males under a normal N supply, while the contrary was true under N deficiency. Furthermore, Cd was mainly distributed in the leaf epidermis and spongy tissues of males, and in the leaf palisade tissues of females. Nitrogen deficiency increased Cd allocation to the spongy tissues of female leaves and to the palisade tissues of males. In roots, Cd was preferentially distributed to the epidermis and cortices in both sexes, and also to the vascular tissues of females under a normal N supply but not under N deficiency. These results suggested that males possess better Cd tolerance compared with females, even under N deficiency, which is associated with their reduced root-to-shoot Cd translocation, specific Cd distribution in organic and/or cellular compartments, and enhanced antioxidation and ion homeostasis. Our study also provides new insights into engineering woody plants for phytoremediation.

scholarly journals Do plants use root-derived proteases to promote the uptake of soil organic nitrogen?

2020 ◽  
Vol 456 (1-2) ◽  
pp. 355-367
Author(s):  
Lucy M. Greenfield ◽  
Paul W. Hill ◽  
Eric Paterson ◽  
Elizabeth M. Baggs ◽  
Davey L. Jones
Keyword(s):  
Protease Activity ◽  
Organic Nitrogen ◽  
N Uptake ◽  
Root Surface ◽  
Organic N ◽  
Soil Organic Nitrogen ◽  
Poor Access ◽  
N Deficiency ◽  
Almost All ◽  
Soil Protein

Abstract Aims The capacity of plant roots to directly acquire organic nitrogen (N) in the form of oligopeptides and amino acids from soil is well established. However, plants have poor access to protein, the central reservoir of soil organic N. Our question is: do plants actively secrete proteases to enhance the breakdown of soil protein or are they functionally reliant on soil microorganisms to undertake this role? Methods Growing maize and wheat under sterile hydroponic conditions with and without inorganic N, we measured protease activity on the root surface (root-bound proteases) or exogenously in the solution (free proteases). We compared root protease activities to the rhizosphere microbial community to estimate the ecological significance of root-derived proteases. Results We found little evidence for the secretion of free proteases, with almost all protease activity associated with the root surface. Root protease activity was not stimulated under N deficiency. Our findings suggest that cereal roots contribute one-fifth of rhizosphere protease activity. Conclusions Our results indicate that plant N uptake is only functionally significant when soil protein is in direct contact with root surfaces. The lack of protease upregulation under N deficiency suggests that root protease activity is unrelated to enhanced soil N capture.

Colonization and invasion of peanut (Arachis hypogaea L.) roots by gusA-marked Bradyrhizobium sp.

2001 ◽  
Vol 79 (6) ◽  
pp. 733-738 ◽  
Author(s):  
Eiji Uheda ◽  
Hiroyuki Daimon ◽  
Fumiki Yoshizako
Keyword(s):  
Cell Wall ◽  
Arachis Hypogaea ◽  
Hair Cells ◽  
Root Hair ◽  
Root Nodules ◽  
Lateral Roots ◽  
Middle Lamella ◽  
Root Surface ◽  
Arachis Hypogaea L ◽  
Root Hair Cells

Tufted rosettes of long root hairs occur in axils of young lateral roots of peanut (Arachis hypogaea L.). Analyses of serial sections of the axils of emerging lateral roots revealed multiple layers of root hair cells. The cells of the outer layer partially overlie the adjacent cells of the inner layer. When Bradyrhizobium cells with an integrated gusA gene were inoculated onto peanut roots and the roots subsequently stained with X-gluc, blue spots indicating the presence of colonies of Bradyrhizobium were observed in the axils of lateral roots. Blue spots were also observed in other areas on the root surface. Transmission electron microscopy revealed that the primary wall of the base of root hair cells has a loose construction. Upon inoculation of Bradyrhizobium, bacteria entered only between root hair cells through the middle lamella. In other areas of the root surface other than axils of lateral roots, the cells had modified walls similar to those at the base of root hair cells. However, invasion by Bradyrhizobium of the cell wall was not observed.Key words: Arachis hypogaea, gusA-marked Bradyrhizobium, cell wall, invasion, root hair cell, root nodules.

Rhythmic patterns of nutrient acquisition by wheat roots

2002 ◽  
Vol 29 (5) ◽  
pp. 595 ◽  
Author(s):  
Sergey Shabala ◽  
Andrew Knowles
Keyword(s):  
Root Zone ◽  
Root Hairs ◽  
Rhythmic Activity ◽  
Root Apex ◽  
Root Surface ◽  
Ion Flux ◽  
Nutrient Acquisition ◽  
Wheat Roots ◽  
Non Invasive ◽  
Functional Zone

Oscillatory patterns in H+, K+, Ca2+ and Cl- uptake were observed at different regions of the root surface, including root hairs, using a non-invasive ion flux measuring technique (the MIFE™ technique). To our knowledge, this is the first report of ultradian oscillations in nutrient acquisition in the mature root zone. Oscillations of the largest magnitude were usually measured in the elongation region, 2–4 mm from the root apex. There were usually at least two oscillatory components present for each ion measured: fast, with periods of several minutes; and slow, with periods of 50–80 min. Even within the same functional zone, the periods of ion flux oscillations were significantly different, suggesting that they are driven by some internal mechanisms located in each cell rather than originating from one ‘central clock pacemaker’. There were also significant changes in the oscillatory characteristics (both periods and amplitudes) of fluxes from a single small cluster of cells over time. Analysis of phase shifts between oscillations in different ions suggested that rhythmic activity of a plasma membrane H+-pump may be central to observed rhythmic nutrient acquisition by plant roots. We discuss the possible adaptive significance of such an oscillatory strategy for root nutrient acquisition.

Stand morphology of Townsville lucerne (Stylosanthes humilis) : Seasonal growth and root development

1968 ◽  
Vol 8 (34) ◽  
pp. 533 ◽  
Author(s):  
BWR Torssell ◽  
JE Begg ◽  
CW Rose ◽  
GF Byrne
Keyword(s):  
Root Length ◽  
Lateral Roots ◽  
Heavy Rain ◽  
Root Surface ◽  
Root Surface Area ◽  
General Description ◽  
Seasonal Growth ◽  
Wet Season ◽  
Average Growth ◽  
Stylosanthes Humilis

This paper describes the seasonal growth and morphology of a four-year-old pasture of Townsville lucerne (Stylosanthes humilis) used in a detailed microenvironmental study conducted at Katherine, N.T., during the 1966-67 wet season. Rapid germination and penetration of the tap root followed an early storm rain of 38 mm at the end of September, and most of the seedlings survived the next seven weeks without rain. A second germination followed heavy rain at the end of November, and by the end of December the main development of lateral roots commenced and the rate of shoot development increased. The highest average growth rate, 31 g/m2/day for the period March 31-April 14, was after the last rain of the season and preceded by ten weeks of above average rainfall. Growth continued for a further two weeks while the roots continued to deplete available soil water. During the main period of growth, approximately 80 per cent of root length and 70 per cent of root surface area was in the top 30 cm of soil. The density of root length varied very little below 30 cm. Growth and development are discussed in relation to grass competition and drought adaptation, and fitted to a general description of the life cycle of Townsville lucerne under northern Australian conditions.

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.

OPR3 is expressed in phloem cells and is vital for lateral root development in Arabidopsis

2013 ◽  
Vol 93 (2) ◽  
pp. 165-170 ◽  
Author(s):  
Shuaizhang Li ◽  
Jiajia Ma ◽  
Pei Liu
Keyword(s):  
Root Development ◽  
Lateral Root ◽  
Lateral Roots ◽  
Gus Activity ◽  
Auxin Biosynthesis ◽  
Lateral Root Development ◽  
Helix Loop Helix ◽  
Meja Treatment ◽  
Potential Binding ◽  
Temporal And Spatial

Li, S., Ma, J. and Liu, P. 2013. OPR3 is expressed in phloem cells and is vital for lateral root development in Arabidopsis. Can. J. Plant Sci. 93: 165–170. Jasmonates, a group of oxylipin phytohormones in angiosperms, play important roles in regulating plant growth and development and in responding to environmental stimuli. AtOPR3, a 12-oxo-phytodienoic acid (OPDA) reductase in Arabidopsis thaliana, has been proven to be vital in catalyzing jasmonate biosynthesis. Here, the temporal and spatial expression of AtOPR3 was investigated by promoter-GUS fusion in A. thaliana. In pOPR3::GUS transgenic plants, the GUS activity was detected in roots, leaves and all floral organs, and was highly induced by MeJA treatment. In addition, the GUS activity was principally detected in the phloem cells of the leaf veins. The sequence of the OPR3 promoter region was predicted to have 49 potential binding sites for transcription factors including the well-known Myc-like basic helix-loop-helix, GATA, MADS, MYB-like and Homeobox proteins. In consistent with an expression of OPR3 in lateral roots, there are more lateral roots in the opr3 mutant plants, in which OPR3 expression is knocking-out. In addition, the involvement of auxin biosynthesis in JA-regulated lateral root development is implied by our observation that the transcripts of ASA1, a gene involved in auxin biosynthesis, are decreased in opr3 plants.

scholarly journals Biogeochemical Effects of a Forest Understory Plant Invasion Depend More On Dissimilar Nutrient Economies Than Invader Biomass

2021 ◽  
Author(s):  
Laura Y Podzikowski ◽  
Marissa Lee ◽  
Catherine Fahey ◽  
Justin Wright ◽  
S. Luke Flory ◽  
...  
Keyword(s):  
Native Species ◽  
Soil Nutrient ◽  
Arbuscular Mycorrhizal ◽  
Nutrient Acquisition ◽  
Forest Understory ◽  
Soil Conditions ◽  
N Availability ◽  
Invasive Grass ◽  
Acquisition Strategies ◽  
Nutrient Economy

Abstract There is an increasing need to better understand how and why invasion impacts differ across heterogeneous landscapes. One hypothesis predicts invader impacts are greatest where the invader is most abundant (the mass ratio hypothesis; MRH). Alternatively, invader impacts may be greatest in communities where the nutrient acquisition strategies of the invader are most dissimilar from those of native species (the nutrient economy dissimilarity hypothesis; NEDH). We tested whether the effects of an invasive grass, Microstegium vimineum, on soil biogeochemistry were best explained by MRH, NEDH, or both. At three locations (Indiana, North Carolina, and Georgia), invaded and reference plots were established across a nutrient economy gradient. Plots varied in the relative abundance of arbuscular mycorrhizal (AM) vs. ectomycorrhizal (ECM) associated overstory trees, reflecting gradients in biotic nutrient acquisition strategies and edaphic factors. At two locations, we found NEDH predicted invader effects on soil conditions. The net effect of M. vimineum homogenized soil properties across the nutrient economy gradient towards conditions consistent with AM-dominated stands; as such, the nutrient economy gradients observed in uninvaded plots were mostly absent in invaded plots. At one location with high N availability and intermediate acidity, both ECM-dominance (NEDH) and invader abundance (MRH) predicted differences in soil moisture, pH, and nitrification rates. Collectively, these results suggest the biogeochemical consequences of M. vimineum depend, in part, on pre-invasion soil nutrient economies. Where pre-invasion conditions are known, we provide a scalable and predictive approach to determine where impacts on biogeochemical cycling of C and N may be greatest.

Structure of ectomycorrhizae formed by Wilcoxina mikolae var. mikolae with Picea mariana and Betula alleghaniensis

1991 ◽  
Vol 69 (10) ◽  
pp. 2149-2157 ◽  
Author(s):  
Pamela F. Scales ◽  
R. L. Peterson
Keyword(s):  
Electron Microscopy ◽  
Picea Mariana ◽  
Lateral Roots ◽  
Root Apex ◽  
Root Surface ◽  
Betula Alleghaniensis ◽  
Oblique Angle ◽  
Hartig Net ◽  
Wilcoxina Mikolae ◽  
Scanning Electron

The structure of ectomycorrhizae synthesized between the E-strain fungus, Wilcoxina mikolae var. mikolae and two tree species, Picea mariana and Betula alleghaniensis, was characterized by light microscopy and scanning electron microscopy. For both mycorrhizal types, mantle formation was visible on lateral roots within 10 days of inoculation. Picea mariana ectomycorrhizae had a very thin mantle whereas B. alleghaniensis ectomycorrhizae had a mantle consisting of several layers. For both mycorrhizal types, the innermost mantle hyphae were embedded in a considerable amount of mucigel on the root surface. A well-developed Hartig net with labyrinthic growth occurred in both types of mycorrhizae. Betula alleghaniensis ectomycorrhizae had a paraepidermal Hartig net, and the root epidermal cells were radially elongate at an oblique angle. The Hartig net of P. mariana ectomycorrhizae penetrated the epidermis and all layers of the cortex. The cytoplasmic density of the intercellular hyphae was greatest towards the root apex. Ectomycorrhizal associations formed by E-strain fungi were similar to ectomycorrhizae formed by other fungi. Key words: E-strain, ectomycorrhizae, Wilcoxina, Picea, Betula, Hartig net.

scholarly journals Activation of MAPK signaling pathway during nitrogen-deficiency responses in Ulva Prolifera

2020 ◽  
Author(s):  
Juanjuan Yang ◽  
Yi Yin ◽  
Dachun Yu ◽  
Lihong He ◽  
Shan Lu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Nitrogen Deficiency ◽  
Mapk Signaling ◽  
Ulva Prolifera ◽  
N Availability ◽  
Nitrogen Deprivation ◽  
Cell Wall Regeneration ◽  
Green Tides ◽  
Wall Regeneration ◽  
N Deficiency

Abstract Background: Ulva prolifera is one of the main seaweeds (or macroalgae) species that causes “green tides”. This alga inhabits the estuarine areas that exhibit changes in nutrient contents, which include changes in nitrogen (N) levels, while the mechanisms through which these microalgae resist N deficiency remains unclear. Results: We amplified the full-length sequences and quantified expression of genes involved in the nitrogen metabolism process, the data indicated that nitrate reductase, nitrite reductase, and glutamine synthase increased after nitrogen deprivation in Ulva prolifera. Hence, although the ratio of cell-wall regeneration did not change, the apoptosis rates of protoplasts of Ulva prolifera increased after this deficiency. Furthermore, a decreased in N supplies triggered the activation of MAPK signaling, and SB239063, a p38 MAPKα/β inhibitor, enhanced the effects of N deficiency on the mortality of protoplasts and decreased the capacity for cell-wall regeneration. Conclusions: All the data provided evidence that MAPK signaling had functional roles in helping U. prolifera adapt to fluctuations in N availability within a short time. Hence, the application of biochemical reagents on cell-wall regeneration on the surface of protoplasts provided a new perspective in the genetic breeding of Ulva prolifera.

Sign in / Sign up

Export Citation Format

Share Document