Brassinolide is a selective ribosomal cistron regulator in onion leaf base tissue.
Outer epidermal cells from the basal, equatorial, near-apical, and apical regions of the third turgid onion (Allium cepa L. var. yellow, sweet Spanish) leaf base were treated (3 and 6 h in the dark = T3 and T6, respectively) with brassinolide (Br, a brassinosteroid plant growth regulator; effects on excised pieces compared with those in water controls: there were no statistical differences between the T3 and T6 results). Br induced increases in the volume and changes in morphologies of the major nucleoli to a greater extent than observed for major nucleoli in basal through near-apical controls. No major nucleoli were activated in control or Br-treated apical tissue. Minor nucleolar organizer regions in control and Br-treated tissue remained inactive in all locations. We propose that Br is a major ribosomal cistron regulator.
Karagiannis
C S
CS
Department of Plant Biology, Southern Illinois University at Carbondale 62901, USA.
Pappelis
A J
AJ
Yopp
J H
JH
D000490:Allium / Q000187:drug effects* / Q000235:genetics; D060406:Brassinosteroids; D002777:Cholestanols / Q000494:pharmacology*; D004275:DNA, Ribosomal / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D017343:Genes, Plant; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects; D013260:Steroids, Heterocyclic / Q000494:pharmacology*
D060406:Brassinosteroids; D002777:Cholestanols; D004275:DNA, Ribosomal; D010937:Plant Growth Regulators; D013260:Steroids, Heterocyclic; C023623:brassinolide