A Gradient of Endogenous Calcium Forms in Mucilage of Graviresponding Roots of Zea mays

Moore, Randy; Fondren, W. M.

doi:10.1093/oxfordjournals.aob.a087523

Cited by 17 publications

(13 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The role of calcium in the transductiola of the gravity stimulus is not yet known, but in one model it is proposed that calcium is redistributed in the mucilage of the root cap upon gravistimulation (Moore and Fondren 1988). It has also been proposed that this redistribution of calcium affects Golgi activity and this change in the level of secretion may be involved in the gravitropic response (Bennet et al 1990).…”

Section: Discussionmentioning

confidence: 99%

Purification and immunolocalization of an annexin-like protein in pea seedlings

Clark

Dauwalder

Roux

1992

Planta

View full text Add to dashboard Cite

As part of a study to identify potential targets of calcium action in plant cells, a 35-kDa, annexin-like protein was purified from pea (Pisum sativum L.) plumules by a method used to purify animal annexins. This protein, called p35, binds to a phosphatidylserine affinity column in a calcium-dependent manner and binds 45Ca2+ in a dot-blot assay. Preliminary sequence data confirm a relationship for p35 with the annexin family of proteins. Polyclonal antibodies have been raised which recognize p35 in Western and dot blots. Immunofluorescence and immunogold techniques were used to study the distribution and subcellular localization of p35 in pea plumules and roots. The highest levels of immunostain were found in young developing vascular cells producing wall thickenings and in peripheral root-cap cells releasing slime. This localization in cells which are actively involved in secretion is of interest because one function suggested for the animal annexins is involvement in the mediation of exocytosis.

show abstract

Section: Discussionmentioning

confidence: 99%

Purification and immunolocalization of an annexin-like protein in pea seedlings

Clark

Dauwalder

Roux

1992

Planta

View full text Add to dashboard Cite

show abstract

“…The onset of gravicurvature by these decapped roots correlates positively with the accumulation of mucilage at their tips (1). (c) Mucilage contains gravitropic effectors (12,14,16). (d) An accumulation of calcium in mucilage along one side of the root cap induces curvature toward the calcium, irrespective of the orientation of the roots with respect to gravity (9).…”

Section: Structure Of the Cap/root Interfacementioning

confidence: 99%

Inducing Gravitropic Curvature of Primary Roots of Zea mays cv Ageotropic

1990

Self Cite

View full text Add to dashboard Cite

Primary roots of the mutant 'Ageotropic' cultivar of Zea mays are nonresponsive to gravity. Their root caps secrete little or no mucilage and touch the root only at the extreme apex. A gap separates the cap and root at the periphery of the cap. Applying mucilage from normal roots or substances with a consistency similar to that of mucilage to tips of mutant roots causes these roots to become strongly graviresponsive. Gravicurvature stops when these substances are removed. Caps of some mutants secrete small amounts of mucilage and are graviresponsive. These results indicate that (a) the lack of graviresponsiveness in the mutant results from disrupting the transport pathway between the cap and root, (b) movement of the growth-modifying signal from the cap to the root occurs via an apoplastic pathway, and (c) gravity (18). This indicates that the lesion for gravitropism is downstream from gravity-detection, perhaps in transmitting the signal from the cap to the root. We studied this by examining the nature of the cap/root interface of mutant roots. MATERIALS AND METHODSAlmost all models for root gravitropism involve a similar sequence of events. Detection of gravity occurs in the root cap and probably involves sedimentation of amyloplasts in columella cells (2,5,15). This change in cellular structure somehow generates a chemical and/or electrical signal in the cap (2,4,5). This signal moves from the root cap to the elongating zone of the root, which is 2 to 6 mm behind the cap. There, the signal preferentially inhibits cellular elongation along the lower side of the root, thus causing the root to curve down (4,5,15).Although we cannot identify the gravitropic signal, much evidence indicates that it moves from the cap to the root before gravicurvature. For example, decapped roots are nonresponsive to gravity (7,23,24), and removing half of the cap of vertically oriented roots induces curvature toward the remaining half-cap (6). Inserting barriers into one side of a root between the root cap and elongating zone causes curvature away from the barrier (26). Taken together, these results suggest that root gravitropism involves movement of a growth-modifying signal from the root cap to the root.The objective of this research was to use mutants to characterize the pathway by which the gravitropic signal moves from the root cap to the root in primary roots of Zea mays.'

show abstract

“…However, inhibiting its activity in plants has not previously been reported to be deleterious to growth and development. The root cap mucilage layer has been theorized to serve as a conduit for root signalling and growth (Baluska et al 1996;Moore and Fondren 1988). The discovery of a complex of enzymes secreted from the root cap may in part explain how such signalling can operate outside the cellular environment (Wen et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of a rhizosphere β-galactosidase from Pisum sativum L.

et al. 2008

View full text Add to dashboard Cite

Plant enzyme activities in the rhizosphere potentially are a resource for improved plant nutrition, soil fertility, bioremediation, and disease resistance.Here we report that a border cell specific β-galactosidase is secreted into the acidic extracellular environment surrounding root tips of pea, as well as bean, alfalfa, barrel medic, sorghum, and maize. No enzyme activity was detected in radish and Arabidopsis, species that do not produce viable border cells. The secreted enzyme activity was inhibited by galactose and 2-phenylethyl 1-thio-β-D-galactopyranoside (PETG) at concentrations that altered root growth without causing cell death. A tomato galactanase encoding gene was used as a probe to isolate a full length pea cDNA clone (BRDgal1) from a root cap-border cell cDNA library. Southern blot analysis using full length BRDgal1 as a probe revealed 1-2 related sequences within the pea genome. BRDgal1 mRNA expression was analysed by whole mount in situ hybridization (WISH) and found to occur in the outermost peripheral layer of the cap and in suspensions of detached border cells. No expression was detected within the body of the root cap. Repeated efforts to develop viable hairy root clones expressing BRDgal1 antisense mRNA under the control of the CaMV35S promoter, whose expression in the root cap is limited to cells at the root cap periphery only during root emergence, were unsuccessful. These data suggest that altered expression of this enzyme is deleterious to early root development.

show abstract

A Gradient of Endogenous Calcium Forms in Mucilage of Graviresponding Roots of Zea mays

Cited by 17 publications

References 11 publications

Purification and immunolocalization of an annexin-like protein in pea seedlings

Purification and immunolocalization of an annexin-like protein in pea seedlings

Inducing Gravitropic Curvature of Primary Roots of Zea mays cv Ageotropic

Identification and characterization of a rhizosphere β-galactosidase from Pisum sativum L.

Contact Info

Product

Resources

About