Role of mature leaves in inhibition of root bud growth inEuphorbia esulaL.

Weed Science ◽  
1999 ◽  
Vol 47 (5) ◽  
pp. 544-550 ◽  
Author(s):  
David P. Horvath
Keyword(s):  
Lateral Roots ◽  
Axillary Buds ◽  
Minor Effect ◽  
Correlative Inhibition ◽  
Auxin Transport Inhibitor ◽  
Naphthylphthalamic Acid ◽  
Bud Growth ◽  
A Minor ◽  
Root Buds

Earlier studies on the source of signals controlling correlative inhibition of root buds (underground adventitious buds located on the lateral roots) inEuphorbia esulaindicated that either growing meristems (apical or axillary buds) or fully expanded leaves could prevent root buds from breaking quiescence. An investigation of the production and transport requirements of the leaf-derived signal is described. As few as three leaves remaining on budless stems greatly reduced the growth of (but not the number of growing) root buds. Also, light and CO2fixation were necessary for the leaf effects on root bud growth, but not necessary for correlative inhibition imposed by growing axillary buds. Treatment of plants with Ametryn induced root bud growth on budless plants but not on plants with intact axillary buds. The polar auxin transport inhibitor N-1-naphthylphthalamic acid prevented transmission or the signal from growing axillary buds, but it had only a minor effect on the transmission of the leaf-derived signal. Treatment of plants with gibberellic acid (GA) induced growth of root buds under otherwise noninducing conditions to some extent in all plants. However, the greatest effects of GA were on plants with intact leaves (meristemless/budless and meristemless). GA had no significant effect on root bud quiescence under conditions that induced root bud growth.

scholarly journals The role of specific plant organs and polar auxin transport in correlative inhibition of leafy spurge (Euphorbia esula) root buds

1998 ◽  
Vol 76 (7) ◽  
pp. 1227-1231 ◽  
Author(s):  
David P Horvath
Keyword(s):  
Apical Dominance ◽  
Auxin Transport ◽  
Leafy Spurge ◽  
Polar Auxin Transport ◽  
Euphorbia Esula ◽  
Transport Inhibitor ◽  
Correlative Inhibition ◽  
Auxin Transport Inhibitor ◽  
Bud Growth ◽  
Root Buds

Localization of the source of the signal(s) controlling correlative inhibition of leafy spurge root buds (underground adventitious shoot buds located on the lateral roots) was studied by sequential removal of various plant organs. It was determined that full correlative inhibition of root buds was lost only after excision of all aerial tissue from the plant, or after excision of all aerial tissue except the stem. If mature leaves or growing axillary buds (or both) were left intact, no growth of root buds was observed. The synthetic auxin, alpha-NAA, prevented release of apical dominance and subsequent outgrowth of stem and crown buds when applied to the cut end of the stem or crown. Exogenous application of NAA to either the stem or the crown had little effect on root bud growth. Application of the auxin transport inhibitor NPA around the base of the crown had no effect on root bud quiescence. These data are not consistent with the previous studies (Weed Sci. 35: 155-159 (1987)) that indicate a role for auxin in maintenance of correlative inhibition of root bud growth in leafy spurge. The results of auxin transport inhibitor studies presented here suggest that correlative inhibition of root bud growth does not rely on the classic polar auxin transport system.Nomenclature: leafy spurge, Euphorbia esula L. #3 EPHES; NAA, naphthalene acetic acid; NPA, N-1-naphthylphthalamic acid; TIBA, 2,3,5-triiodobenzoic acid.Key words: root buds, apical dominance, auxin, NPA.

The Role of Aspterric Acid in Auxin-Regulated Reproductive Growth of Arabidopsis thaliana

2008 ◽  
Vol 63 (7-8) ◽  
pp. 554-556 ◽  
Author(s):  
Atsumi Shimad ◽  
Hisakazu Yamane ◽  
Yasuo Kimura
Keyword(s):  
Arabidopsis Thaliana ◽  
Seed Production ◽  
Untreated Control ◽  
Growth Inhibitor ◽  
Reproductive Growth ◽  
Normal Seed ◽  
Auxin Transport Inhibitor ◽  
Naphthylphthalamic Acid ◽  
Pollen Growth

Application of 100 μm aspterric acid (AA), a pollen growth inhibitor, with different concentrations of indole-3-acetic acid (IAA) results in the recovery of normal pollen development of Arabidopsis thaliana. Treatment with 100 μm AA plus 5 mm IAA significantly induced the normal seed production. Treatment with 100 μm N-1-naphthylphthalamic acid (NPA), a polar auxin transport inhibitor, did not reduce the pollen growth but inhibited seed production. 100 μm NPA plus 5 mm IAA did not induce any seed production. The endogenous level of IAA in stems and leaves of A. thaliana treated with 100 μm AA was similar to that of the untreated control. In contrast to AA treatment, the IAA level by the treatment with 100 μm NPA was about twice as much as that of the untreated control. These results suggest that AA affects the Arabidopsis reproductive growth without inhibiting IAA biosynthesis and transport.

scholarly journals Heterogeneous phosphate supply influences maize lateral root proliferation by regulating auxin redistribution

2019 ◽  
Vol 125 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Xin Wang ◽  
Jingjing Feng ◽  
Philip J White ◽  
Jianbo Shen ◽  
Lingyun Cheng
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Root Tip ◽  
Root Proliferation ◽  
Rich Media ◽  
Maize Roots ◽  
Auxin Redistribution ◽  
Naphthylphthalamic Acid ◽  
Auxin Transporter

Abstract Background and Aims Roots take up phosphorus (P) as inorganic phosphate (Pi). Enhanced root proliferation in Pi-rich patches enables plants to capture the unevenly distributed Pi, but the underlying control of root proliferation remains largely unknown. Here, the role of auxin in this response was investigated in maize (Zea mays). Methods A split-root, hydroponics system was employed to investigate root responses to Pi supply, with one (heterogeneous) or both (homogeneous) sides receiving 0 or 500 μm Pi. Key results Maize roots proliferated in Pi-rich media, particularly with heterogeneous Pi supply. The second-order lateral root number was 3-fold greater in roots of plants receiving a heterogeneous Pi supply than in roots of plants with a homogeneous Pi supply. Root proliferation in a heterogeneous Pi supply was inhibited by the auxin transporter inhibitor 1-N-naphthylphthalamic acid (NPA). The proliferation of lateral roots was accompanied by an enhanced auxin response in the apical meristem and vascular tissues at the root tip, as demonstrated in a DR5::RFP marker line. Conclusions It is concluded that the response of maize root morphology to a heterogeneous Pi supply is modulated by local signals of Pi availability and systemic signals of plant P nutritional status, and is mediated by auxin redistribution.

scholarly journals The Economics of Credence Goods: An Experiment on the Role of Liability, Verifiability, Reputation, and Competition

2011 ◽  
Vol 101 (2) ◽  
pp. 526-555 ◽  
Author(s):  
Uwe Dulleck ◽  
Rudolf Kerschbamer ◽  
Matthias Sutter
Keyword(s):  
Asymmetric Information ◽  
Minor Effect ◽  
Credence Goods ◽  
Yield Efficiency ◽  
A Minor

Credence goods markets are characterized by asymmetric information between sellers and consumers that may give rise to inefficiencies, such as under- and overtreatment or market breakdown. We study in a large experiment with 936 participants the determinants for efficiency in credence goods markets. While theory predicts that liability or verifiability yield efficiency, we find that liability has a crucial, but verifiability at best a minor, effect. Allowing sellers to build up reputation has little influence, as predicted. Seller competition drives down prices and yields maximal trade, but does not lead to higher efficiency as long as liability is violated. (JEL D12, D82)

scholarly journals In anemia of multiple myeloma, hepcidin is induced by increased bone morphogenetic protein 2

Blood ◽  
2010 ◽  
Vol 116 (18) ◽  
pp. 3635-3644 ◽  
Author(s):  
Ken Maes ◽  
Elizabeta Nemeth ◽  
G. David Roodman ◽  
Alissa Huston ◽  
Flavia Esteve ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Morphogenetic Proteins ◽  
Bone Morphogenetic Protein 2 ◽  
Minor Effect ◽  
Morphogenetic Protein ◽  
Huh7 Cells ◽  
Serum Hepcidin ◽  
Stimulatory Capacity ◽  
A Minor

Abstract Hepcidin is the principal iron-regulatory hormone and a pathogenic factor in anemia of inflammation. Patients with multiple myeloma (MM) frequently present with anemia. We showed that MM patients had increased serum hepcidin, which inversely correlated with hemoglobin, suggesting that hepcidin contributes to MM-related anemia. Searching for hepcidin-inducing cytokines in MM, we quantified the stimulation of hepcidin promoter-luciferase activity in HuH7 cells by MM sera. MM sera activated the hepcidin promoter significantly more than did normal sera. We then examined the role of bone morphogenetic proteins (BMPs) and interleukin-6 (IL-6), the major transcriptional regulators of hepcidin. Mutations in both BMP-responsive elements abrogated the activation dramatically, while mutations in the IL-6–responsive signal transducer and activator of transcription 3-binding site (STAT3-BS) had only a minor effect. Cotreatment with anti–BMP-2/4 or noggin-Fc blocked the promoter induction with all MM sera, anti–IL-6 blocked it with a minority of sera, whereas anti–BMP-4, -6, or -9 antibodies had no effect. BMP-2–immunodepleted MM sera had decreased promoter stimulatory capacity, and BMP-2 concentrations in MM sera were significantly higher than in normal sera. Our results demonstrate that BMP-2 is a major mediator of the hepcidin stimulatory activity of MM sera.

Activité mitotique et croissance des bourgeons axillaires provoquées par la décapitation de jeunes plants de fève (Vicia faba)

1979 ◽  
Vol 57 (22) ◽  
pp. 2478-2488 ◽  
Author(s):  
Jeanne Couot-Gastelier
Keyword(s):  
Vicia Faba ◽  
Axillary Buds ◽  
Intact Plants ◽  
Terminal Bud ◽  
Vicia Faba L ◽  
Cell Layers ◽  
Cambial Zone ◽  
Bud Growth ◽  
Axillary Bud Growth

Buds of intact plants of Vicia faba L. are partially inhibited. Decapitation of the terminal bud of plants with four leaves leads to the reactivation of all the axillary buds, but to the growth of only the basal ones. The first events induced by the terminal bud excision do not occur at the level of the axillary buds, but affect rather the main axis.The kinetic study of the mitotic reactivation shows that the activation begins in cell layers of the cambial zone in the subapical internodes of the stem 1 h after decapitation and after 4 h in the more basal ones.The subapical axillary buds are first reactivated, but only temporarily, 8 h after the principal bud excision. The lower axillary buds are reactivated later, after 12 h, and their growth then becomes autonomous.These results are discussed with regard to the regulatory role of the main axis on axillary bud growth.

scholarly journals Removal of the phage-shock protein PspB causes reduction of virulence in Salmonella enterica serovar Typhimurium independently of NRAMP1

2014 ◽  
Vol 63 (6) ◽  
pp. 788-795 ◽  
Author(s):  
Inke Wallrodt ◽  
Lotte Jelsbak ◽  
Line E. Thomsen ◽  
Lena Brix ◽  
Sébastien Lemire ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Single Gene ◽  
Systemic Infection ◽  
Minor Effect ◽  
Membrane Stress ◽  
Knock Out ◽  
Serovar Typhimurium ◽  
A Minor

The phage-shock protein (Psp) system is believed to manage membrane stress in all Enterobacteriaceae and has recently emerged as being important for virulence in several pathogenic species of this phylum. The core of the Psp system consists of the pspA–D operon and the distantly located pspG gene. In Salmonella enterica serovar Typhimurium (S. Typhimurium), it has recently been reported that PspA is essential for systemic infection of mice, but only in NRAMP1+ mice, signifying that attenuation is related to coping with divalent cation starvation in the intracellular environment. In the present study, we investigated the contribution of individual psp genes to virulence of S. Typhimurium. Interestingly, deletion of the whole pspA–D set of genes caused attenuation in both NRAMP1+ and NRAMP1− mice, indicating that one or more of the psp genes contribute to virulence independently of NRAMP1 expression in the host. Investigations of single gene mutants showed that knock out of pspB reduced virulence in both types of mice, while deletion of pspA only caused attenuation in NRAMP1+ mice, and deletion of pspD had a minor effect in NRAMP1− mice, while deletions of either pspC or pspG did not affect virulence. Experiments addressed at elucidating the role of PspB in virulence revealed that PspB is dispensable for uptake to and intracellular replication in cultured macrophages and resistance to complement-induced killing. Furthermore, the Psp system of S. Typhimurium was dispensable during pIV-induced secretin stress. In conclusion, our results demonstrate that removal of PspB reduces virulence in S. Typhimurium independently of host NRAMP1 expression, demonstrating that PspB has roles in intra-host survival distinct from the reported contributions of PspA.

Comparison of carbon storage under aerobic and anoxic conditions

1998 ◽  
Vol 38 (8-9) ◽  
pp. 77-84 ◽  
Author(s):  
M. Majone ◽  
P. Massanisso ◽  
R. Ramadori
Keyword(s):  
Mixed Culture ◽  
External Source ◽  
Hydrolysis Rate ◽  
Minor Effect ◽  
Aerobic Conditions ◽  
Anoxic Conditions ◽  
Rate Limiting Step ◽  
A Minor ◽  
Rate Limiting

In various activated sludge systems, the biomass grows under transient (unbalanced) conditions and the storage response (formation of internal polymers as the fastest adaptation to the changing environment) becomes important. Till now the role of storage on population dynamics has been deeply investigated under anaerobic (EBPR processes) or aerobic (bulking control) conditions. Little attention has been given to processes including anoxic conditions even though in many of them storage phenomena are likely to occur (anoxic selectors, nitrogen removal processes with addition of an external source of readily biodegradable COD or with aerobic contact/anoxic stabilization). For these reasons, the aim of the present work was to investigate storage and succeeding use of stored products under anoxic and mixed (anoxic/aerobic) conditions. Batch experiments have shown that a mixed culture selected under aerobic conditions and intermittent feed (acetate-limited medium), was also able to take up acetate (90–100 mgCOD/gCOD h) and store it as PHB (35–40 mgCOD/gCOD h) under anoxic conditions. After acetate depletion, the stored PHB was used for growth and maintenance. The NUR on acetate in the presence of storage was 20 mgN/gVSS h (which corresponded to a COD removal of 6.9 mgCOD/mgN) while it dropped to 10–3 mgN/gVSS h in the “endogenous phase” when denitrification was on the stored PHB. The presence of aerobic conditions instead of anoxic ones had a major positive effect on the rate and yield of PHB storage while it had only a minor effect on the rate of PHB consumption. The latter observation can be explained by assuming that the hydrolysis of the stored product is the rate limiting step of the “endogenous” metabolism and that the hydrolysis rate is not highly dependent on aerobic-anoxic conditions. Cross-comparison of PHB storage and consumption under aerobic/anoxic conditions made it possible to determine that, in the particular mixed culture under investigation, all aerobic heterotrophs able to store were also able to denitrify.

scholarly journals Correlative Inhibition and Dormancy in Root Buds of Leafy Spurge (Euphorbia esula)

Weed Science ◽  
1987 ◽  
Vol 35 (2) ◽  
pp. 155-159 ◽  
Author(s):  
Scott J. Nissen ◽  
Michael E. Foley
Keyword(s):  
Acetic Acid ◽  
Late Summer ◽  
Growing Season ◽  
Leafy Spurge ◽  
Euphorbia Esula ◽  
Correlative Inhibition ◽  
Napthaleneacetic Acid ◽  
Bud Growth ◽  
Indole 3 Acetic Acid ◽  
Root Buds

Root buds of leafy spurge (Euphorbia esulaL. # EPHES) were found to be quiescent during most of the growing season due to correlative inhibition rather than innate dormancy. Excised root buds taken from plants that were fully flowering showed reduced elongation, indicating a period of innate dormancy. This innate dormancy could be eliminated by chilling plants for 8 days at 4 C. Root buds from plants showing late summer regrowth were no longer innately dormant. IAA (indole-3-acetic acid) and NAA (1-napthaleneacetic acid) completely inhibited the growth of excised leafy spurge root buds at concentrations of 10−3and 10−5M, respectively. A significant increase in root bud elongation was produced by 1 mM TIBA (2,3,5-triiodobenzoic acid) applied to stem and root tissue. These data provide further evidence for the involvement of IAA in correlative control of root bud growth in leafy spurge.

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