Developmental studies on Euphorbia esula. Evidence of competition for water as a factor in the mechanism of root bud inhibition

Seedlings of leafy spurge (Euphorbia esula L.) were grown in sand culture under controlled conditions and experiments were designed to test the hypothesis that competition for water between the root buds and the parent shoot is a significant factor in the mechanism of root bud inhibition. It was shown that the water content of the root buds increased by approximately 25% within 24 h of the removal of the parent shoot. Root bud length increased significantly between 24 and 48 h from shoot removal but while some of the buds continued to grow others were apparently reinhibited. Shoots with all immature tissue removed continued to exert a high degree of root bud inhibition but this inhibition was markedly reduced by keeping the plants in a high humidity. Increasing the humidity from approximately 50 to 95% also caused a significant increase in the rate of emergence and elongation of shoots produced from root buds following the removal of the parent shoot. This effect on emergence was suppressed by conditions presumed to reduce the degree of root bud aeration. Taken as a whole, the results lend considerable support to the concept of internal competition for water as a factor in the mechanism of root bud inhibition.

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Factors Affecting Translocation of 2,4-D in Leafy Spurge

Weed Science ◽

10.1017/s0043174500036791 ◽

1974 ◽

Vol 22 (2) ◽

pp. 167-171 ◽

Cited By ~ 3

Author(s):

James H. Hunter ◽

G. I. McIntyre

Keyword(s):

Acetic Acid ◽

Leafy Spurge ◽

Nitrogen Supply ◽

Euphorbia Esula ◽

Factors Affecting ◽

Bud Growth ◽

Dichlorophenoxy Acetic Acid ◽

Root Buds

The translocation of foliar-applied14C-labelled 2,4-D [(2,4-dichlorophenoxy)acetic acid] in seedlings of leafy spurge (Euphorbia esulaL.) was investigated. Approximately 90% of the tracer was extracted from the tissues with 80% ethanol. Seven days after treatment 48% of the14C in the shoot extract and 75% of that extracted from the root were identified chromatographically as 2,4-D. Translocation out of the treated leaves and into the shoot, root, and root buds was significantly increased both by decapitation of the shoot and by increasing the nitrogen supply. This effect is attributed to the marked promotion of bud growth produced by both of these treatments.

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

Canadian Journal of Botany ◽

10.1139/b98-138 ◽

1998 ◽

Vol 76 (7) ◽

pp. 1227-1231 ◽

Cited By ~ 5

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.

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Developmental studies on leafy spurge (Euphorbia esula). Histology of the adventitious shoot apex

Canadian Journal of Botany ◽

10.1139/b72-078 ◽

1972 ◽

Vol 50 (3) ◽

pp. 635-641

Author(s):

Teresa W. M. Ho ◽

M. V. S. Raju

Keyword(s):

Shoot Apex ◽

Adventitious Shoot ◽

Leafy Spurge ◽

Leaf Primordium ◽

Nuclear Volume ◽

Euphorbia Esula ◽

Developmental Studies ◽

Adventitious Buds ◽

Stages Of Development ◽

Nucleolar Volume

Histological analyses of adventitious shoot apices of leafy spurge (Euphorbia esula L.) showed variation in the number of mantle layers at various stages of development. The older shoots (stages III and IV) tended to have a larger number of mantle layers than the younger ones (stages I and II) some of which contained two or three layers. The procambial differentiation was acropetal extending from the axis into the leaf primordium and the same pattern was noticed in all stages of development of adventitious buds and shoots. The shoot apex contained larger nuclei and nucleoli in the midsector than in the peripheral sectors and the nuclei in the former had fewer nucleoli. The total volume of nucleoli per nucleus was more in the midsector than in the peripheral sector. However, the ratio of total nucleolar volume to nuclear volume was very similar in all the sectors, suggesting uniform metabolic activity in the adventitious shoot apex.

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AC 263,222 absorption and fate in leafy spurge (Euphorbia esula)

Weed Science ◽

10.1017/s0043174500091001 ◽

1998 ◽

Vol 46 (5) ◽

pp. 510-513 ◽

Cited By ~ 5

Author(s):

W. Mack Thompson ◽

Scott J. Nissen ◽

Robert A. Masters

Keyword(s):

Hplc Analysis ◽

Leafy Spurge ◽

Euphorbia Esula ◽

Total Recovery ◽

Plant Parts ◽

Crown Root ◽

Leaf Surfaces ◽

Below Ground ◽

Ac 263,222 ◽

Root Buds

Absorption, translocation, and metabolism of AC 263,222 by leafy spurge were studied over 8 d. Based on the amount of herbicide applied and recovered from the leaf surfaces, 40% of applied AC 263,222 was absorbed by leafy spurge 2 d after treatment (DAT), with no further absorption observed by 8 DAT. Eight DAT, 19% of applied [14C]-AC 263,222 had translocated to below-ground plant parts while 4% was exuded from the roots into the sand media. AC 263,222 was not metabolized 2 DAT in the crown, root, and root buds, but 42% was metabolized in the treated leaves. Only 17% of recovered [14C] was AC 263,222 in treated leaves 8 DAT (83% metabolized), while AC 263,222 accounted for 70% of recovered [14C] in the root and root buds. HPLC analysis indicated that the balance of [14C] was associated with a single, polar metabolite. Total recovery of [14C] was 88% at 8 DAT.

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Transcriptome analysis of leafy spurge (Euphorbia esula) crown buds during shifts in well-defined phases of dormancy

Weed Science ◽

10.1614/ws-06-06r1.1 ◽

2006 ◽

Vol 54 (5) ◽

pp. 821-827 ◽

Cited By ~ 20

Author(s):

David P. Horvath ◽

James V. Anderson ◽

Mauricio Soto-Suárez ◽

Wun S. Chao

Keyword(s):

Gene Expression ◽

Gibberellic Acid ◽

Microarray Analysis ◽

Transcriptome Analysis ◽

Seasonal Changes ◽

Leafy Spurge ◽

Euphorbia Esula ◽

Ethylene Signaling ◽

Root Buds

Microarray analysis was used to follow changes in gene expression coinciding with seasonal changes in the dormancy status of crown buds of field-grown leafy spurge. Known cold-regulated genes were induced, and numerous gibberellic acid–responsive genes were down-regulated during the transition from paradormancy to endodormancy. Genes involved in photomorphogenesis were induced during endodormancy. Also, ethylene signaling responses were observed during ecodormancy rather than endodormancy. These results provide additional insights into the signals regulating expression of several genes previously associated with transition from paradormancy to growth in root buds.

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

Weed Science ◽

10.1017/s0043174500078966 ◽

1987 ◽

Vol 35 (2) ◽

pp. 155-159 ◽

Cited By ~ 13

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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Evidence of competition for water as a factor in the mechanism of root-bud inhibition in milkweed (Asclepias syriaca)

Canadian Journal of Botany ◽

10.1139/b84-057 ◽

1984 ◽

Vol 62 (2) ◽

pp. 379-384 ◽

Cited By ~ 5

Author(s):

Andrew I. Hsiao ◽

Gordon I. McIntyre

Keyword(s):

Complete Removal ◽

Significant Degree ◽

Sand Culture ◽

Single Pair ◽

Asclepias Syriaca ◽

Shoot Tissue ◽

Shoot Production ◽

Low Humidity ◽

Rate Of Emergence ◽

Root Buds

In experiments with seedlings of milkweed, Asclepias syriaca L., grown in sand culture under controlled conditions, growth of the root buds was significantly increased within 24 h of the excision of the parent shoot. However, only a few of the measured buds continued to grow, the growth of most of the remianing buds being arrested within 48 h of their release from inhibition. At low humidity (approx. 30–50% relative humidity (RH)), the decapitated disbudded stem, bearing only a single pair of leaves, promoted the early growth of the root buds but strongly inhibited their subsequent elongation and emergence as shoots. The mature stem itself, when completely defoliated, also exerted a significant degree of inhibition of root-shoot production. At high humidity (93–100% RH), which reduced transpiration by approximately 50%, this inhibiting effect of mature shoot tissue was either eliminated or greatly reduced, while the rate of emergence and subsequent growth of shoots produced from the root buds following the complete removal of the parent shoot were also significantly increased. The results suggest, as a working hypothesis, that transpiration-induced reduction in water potential (ψ) plays a major role in the mechanism of root-bud inhibition.

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Genetic variation in North American leafy spurge (Euphorbia esula) determined by DNA markers

Weed Science ◽

10.1017/s0043174500093140 ◽

1997 ◽

Vol 45 (3) ◽

pp. 446-454 ◽

Cited By ~ 20

Author(s):

Martha L. Rowe ◽

Donald J. Lee ◽

Scott J. Nissen ◽

Brunella M. Bowditch ◽

Robert A. Masters

Keyword(s):

Genetic Variation ◽

North American ◽

Rapd Markers ◽

Leafy Spurge ◽

Euphorbia Esula ◽

Range Of Movement ◽

Multiple Introductions ◽

Cpdna Markers ◽

Intrapopulation Genetic Variation ◽

High Degree

Levels of inter- and intrapopulation genetic variation were determined in five North American populations of leafy spurge using chloroplast DNA (cpDNA) RFLPs and RAPD markers. Thirteen plastome types were identified among 123 individuals collected from five geographically separated populations. Number of plastomes within a population ranged from one to seven, with four of the populations having a predominate type plus one or more rarer types. Some plastome types were shared by populations, but plastome distribution among populations was nonrandom. RAPD markers indicated greatest relatedness among individuals within a population. Relatedness among populations as established through RAPDs was greater for geographically closer populations; this relationship was not observed for cpDNA markers. Differences in the range of movement for pollen and seed may account for differences between results of the cpDNA and RAPD analyses. The high degree of genetic variability among North American leafy spurge suggests possible multiple introductions or a high degree of variability within leafy spurge populations in its native range.

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