The control of root, vegetative shoot and flower morphogenesis in tobacco thin cell-layer expiants (TCLs)

Abstract

Thin cell-layer explants (TCLs) have been proposed as favorable tissues for the study of root, vegetative shoot and flower formation. We tested the effects of pH, light quality, light quantity, and IBA and kinetin concentrations on the morphogenesis of TCLs cultured individually on a liquid medium. Alterations of the amounts of exogenously supplied IBA and kinetin were sufficient to induce the formation of roots, vegetative shoots and flowers on TCLs cultured on otherwise identical media. The type and number of organs formed were sensitive to the intensity of light (55, 75, 100 and 120 muEinsteins m-2 sec-1) under which TCLs were grown. Evidence was obtained that the effects of light on TCL morphogenesis were associated with photochemical degradation of IBA in the medium. Evaluation of the organogenesis that occurred in TCLs cultured on a medium containing a range of IBA and kinetin concentrations showed that the number and type of organs formed, and overall growth, were dependent upon the initial concentrations of auxin and cytokinin. We have developed the TCL culture system into a sensitive and reproducible bioassay for the study of morphogenesis. The advantages of using the TCL morphogenesis bioassay for the identification and study of molecules (e.g. cell wall oligosaccharides) that may regulate morphogenesis are discussed.

Berberine Bridge enzyme-like oxidases orchestrate homeostatic control and signaling of oligogalacturonides in defense and wounding

“…The importance of OGs in plant signaling is emerging not only in plant-microbe interactions but also in events related to growth and development (11,14,(37)(38)(39)(40). Indeed, the ability of OGs to antagonize auxin points to these molecules as key factors at the crossroad between development and defense (11,41).…”

Oligosaccharins: oligosaccharide regulatory molecules

“…Oligogalacturonides, with dp 10-14, induce the formation of flowers and inhibit the formation of roots in tobacco explants when the explants are grown in media containing auxin and cytokinin at concentrations that, without the oligogalacturonides, either cause roots or no organs to form. 44,46,47 Oligogalacturonides with dp 12-14 are active at about 10™7 M.47 Oligogalacturonides of the same size and at the same concentration also inhibit the formation of roots in tobacco leaf disc explants (F. Cervone, University of Rome, personal communication).…”