Linked Life Data

16658661

Source:http://linkedlifedata.com/resource/pubmed/id/16658661

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2010-6-29
pubmed:abstractText
The photosynthetic assimilates in leaves of Perilla crispa attached to the plant were labeled by treating the leaves with (14)CO(2). When subsequently detached, these leaves exuded a negligible amount of radioactivity from the cut petiole into water. Ethylenediaminetetraacetate (EDTA), citric acid, and ethyleneglycol-bis (beta-aminoethyl ether) N,N'-tetraacetate greatly increased exudation of labeled assimilates into a solution bathing the petioles. The optimal concentration of EDTA was 20 mm, and maximal exudation took place between 2 and 4 hours after excision. Up to 22% of the radioactivity fixed in the leaf was exuded into an EDTA solution as compared to an export of 38% from attached leaves. The amount of radioactivity in the exudate was much reduced at low temperature. Presence of EDTA was required in the collecting solution for only 1 to 2 hours; upon transfer to water, exudation continued as in continuous presence of EDTA. Ca(2+) completely inhibited the effect of EDTA.Anatomical studies indicated that callose formation on the sieve plates near the cut surface of the petioles was less in leaves on EDTA than on water.More than 95% of the radioactivity exuded by detached leaves was present in the sugars verbascose, stachyose, raffinose, and sucrose, which are translocated in the phloem of Perilla. Labeled glucose, fructose, and galactinol were detected in the leaf blade and petiole, but not in exudates.The addition of EDTA to a solution bathing the petiole of detached leaves of Chenopodium rubrum and Pharbitis nil also increased the exudation of labeled assimilates. In these two species, label appeared only in a compound that cochromatographed with sucrose.It is concluded that the radioactive products in the solution are actually exuded by the phloem. Possibly EDTA chelates Ca(2+) that otherwise participates in the reactions that seal cut phloem.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Jan
pubmed:issn
0032-0889
pubmed:author
pubmed:issnType
Print
pubmed:volume
53
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
96-103
pubmed:dateRevised
2010-9-14
pubmed:year
1974
pubmed:articleTitle
Enhancement of Phloem exudation from cut petioles by chelating agents.
pubmed:affiliation
Michigan State University-Atomic Energy Commission Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
pubmed:publicationType
Journal Article