Linked Life Data

12102512

Source:http://linkedlifedata.com/resource/pubmed/id/12102512

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
2002-7-9
pubmed:abstractText
Land plants encountering low water potentials (low psiw) close their stomata, restricting CO2 entry and potentially photosynthesis. To determine the impact of stomatal closure, photosynthetic O2 evolution was investigated in leaf discs from sunflower (Helianthus annuus L.) plants after removing the lower epidermis at low psiw. Wounding was minimal as evidenced by O2 evolution nearly as rapid as that in intact discs. O2 evolution was maximal in 1% CO2 in the peeled discs and was markedly inhibited when psiw was below -1.1 MPa. CO2 entered readily at all psiw, as demonstrated by varying the CO2 concentration. Results were the same whether the epidermis was removed before or after low psiw was imposed. Due to the lack of an epidermis and ready movement or CO2 through the mesophyll, the loss in O2 evolving activity was attributed entirely to photosynthetic metabolism. Intact leaf discs showed a similar loss in activity when measured at a CO2 concentration of 5%, which supported maximum O2 evolution at low psiw. In 1% CO2, however, O2 evolution at low psiw was below the maximum, presumably because stomatal closure restricted CO2 uptake. The inhibition was larger than in peeled discs at psiw between -1 and -1.5 MPa but became the same as in peeled discs at lower psiw. Therefore. as photosynthesis began to be inhibited by metabolism at low psiw, stomatal closure added to the inhibition. As psiw became more negative, the inhibition became entirely metabolic.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0305-7364
pubmed:author
pubmed:issnType
Print
pubmed:volume
89 Spec No
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
861-70
pubmed:dateRevised
2009-10-19
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Photosynthetic oxygen evolution at low water potential in leaf discs lacking an epidermis.
pubmed:affiliation
College of Marine Studies and College of Agriculture and Natural Resources, University of Delaware, Lewes 19958, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't