Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Production and secretion of α-galactosidase and endo-β-mannanase by carob (Ceratonia siliqua L.) endosperm protoplasts

Fanouris Kontos and Caroline G. Spyropoulos
Journal of Experimental Botany
Vol. 46, No. 286 (MAY 1995), pp. 577-583
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/23694876
Page Count: 7
  • Download ($42.00)
  • Cite this Item
Production and secretion of α-galactosidase and endo-β-mannanase by carob (Ceratonia siliqua L.) endosperm protoplasts
Preview not available

Abstract

Viable protoplasts were isolated for the first time from mature carob (Ceratonia siliqua L.) endosperm tissue. After 5 d of incubation 75% of the protoplasts were viable. During incubation they underwent vacuolation and produced the carob endosperm hydrolases, α-galactosidase and endo-β-mannanase, which were secreted in the incubation medium. The secretion of both enzymes were under Ca2+ control. Many characteristics of α-galactosidase and endo-β-mannanase production by protoplasts were the same as those of whole endosperms: their production did not require any hormonal signal and was inhibited in the presence of ABA or the leachate from the carob endosperm/seed coat. Moderate water stress (—2.0 MPa) neither affected the activity of these hydrolases nor their secretion by endosperm protoplast. However, when the osmoticum of protoplast incubation medium was higher, the production and secretion of both hydrolases were reduced. Comparison of the hydrolases activities in the incubation media of leached carob endosperms, which were incubated under normal and water stress (—1.5 MPa) conditions, with the activities of the protoplast-secreted hydrolases indicated that (i) carob endosperm cell wall acts as a barrier for the secreted enzymes and (ii) that water stress reduces the cell wall porosity of the carob endosperm cells, and thus the release of the secreted α-galactosidase and endo-β-mannanase is inhibited. The isolation of carob endosperm protoplasts offers a potent experimental system for the study of aspects of endosperm cell physiology, such as enzyme secretion.

Page Thumbnails

  • Thumbnail: Page 
[577]
    [577]
  • Thumbnail: Page 
578
    578
  • Thumbnail: Page 
579
    579
  • Thumbnail: Page 
580
    580
  • Thumbnail: Page 
581
    581
  • Thumbnail: Page 
582
    582
  • Thumbnail: Page 
583
    583