This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by Balagué, C. Articles by Pech, J.-C. Search for Related Content PubMed PubMed Citation Articles by Balagué, C. Articles by Pech, J.-C. Agricola Articles by Balagué, C. Articles by Pech, J.-C.

Articles

Some Physiological Changes Occurring during the Senescence of Auxin-Deprived Pear Cells in Culture ¹

Ecole Nationale Superieure Agronomique de Toulouse, 145, Avenue de Muret 31076 Toulouse Cédex, France

Part of the changes in the hormonal balance involved in plant senescence is due to an auxin limitation. Some of its physiological consequences are studied using pear (Pyrus communis L.) cells cultured in a continuously renewed medium in which 2,4-dichlorophenoxyacetic acid (2,4-D) was absent. In these conditions, an assessment was made of the absence of nutrient deficiency.

In the period preceding cell death, the rate of respiration and ethylene production remain low, and no major changes were observed in the total protein and RNA content of the cells. Beginning around day 9, an important efflux of three amino acids (serine, threonine, and aspartic acid) occurs among which serine represents more than 52%. However, exogenous serine supplied to the medium fails to show any senescence promoting effect. At the same time, leucine uptake and incorporation sharply and simultaneously increased. The presence of 2,4-D inhibits both these phenomena and prevents cell death. It is proposed that auxin deprivation is responsible for unmasking a program of synthesis of new proteins involved in cell death.

¹ Supported by the Centre National de la Recherche Scientifique (Grant 031 874).