Skip to main content
SLU publication database (SLUpub)

Research article2002Peer reviewedOpen access

The role of auxin, pH, and stress in the activation of embryogenic cell division in leaf protoplast-derived cells of alfalfa

Pasternak, TP; Prinsen, E; Ayaydin, F; Miskolczi, P; Potters, G; Asard, H; Van Onckelen, HA; Dudits, D; Feher, A

Abstract

Culturing leaf protoplast-derived cells of the embryogenic alfalfa (Medicago sativa subsp. varia A2) genotype in the presence of low (1 muM) or high (10 mum) 2, 4-dichlorophenoxyacetic acid (2,4-D) concentrations results in different cell types. Cells exposed to high 2,4-D concentration remain small with dense cytoplasm and can develop into proembryogenic cell clusters, whereas protoplasts cultured at low auxin concentration elongate and subsequently die or form undifferentiated cell colonies. Fe stress applied at nonlethal concentrations (1 mM) in the presence of 1 muM 2,4-D also resulted in the development of the embryogenic cell type. Although cytoplasmic alkalinization was detected during cell activation of both types, embryogenic cells could be characterized by earlier cell division, a more alkalic vacuolar pH, and nonfunctional chloroplasts as compared with the elongated, nonembryogenic cells. Buffering of the 10 muM 2,4-D-containing culture medium by 10 mM 2-(N-morpholino)ethanesulfonic acid delayed cell division and resulted in nonembryogenic cell-type formation. The level of endogenous indoleacetic acid (IAA) increased transiently in all protoplast cultures during the first 4 to 5 d, but an earlier peak of IAA accumulation correlated with the earlier activation of the division cycle in embryogenic-type cells. However, this IAA peak could also be delayed by buffering of the medium pH by 2-(N-morpholino)ethanesulfonic acid. Based on the above data, we propose the involvement of stress responses, endogenous auxin synthesis, and the establishment of cellular pH gradients in the formation of the embryogenic cell type.

Published in

Plant Physiology
2002, Volume: 129, number: 4, pages: 1807-1819 Publisher: AMER SOC PLANT BIOLOGISTS

    UKÄ Subject classification

    Cell Biology
    Developmental Biology

    Publication identifier

    DOI: https://doi.org/10.1104/pp.000810

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/89989