Multiple regulatory mechanisms influence the activity of the transposon, Tam3, of Antirrhinum.
In Antirrhinum, several unique regulations of the transposon, Tam3, have been described. Tam3 activity in Antirrhinum is strictly controlled by the growing temperature of plants (low-temperature-dependent transposition: LTDT), by chromosomal position of Tam3 copy and by two specific repressor genes Stabiliser (St) and New Stabiliser (NSt). Here, the effects of the St and NSt loci on Tam3 transposition are compared. In cotyledons and hypocotyls, Tam3 is active even at high growing temperatures, indicating that LTDT does not operate when these organs are developing. This developmental regulation of Tam3 activity is differentially influenced by the St and NSt loci: St permits Tam3 transposition in cotyledons and hypocotyls, whereas NSt suppresses it in these organs. The effects of these host genes on Tam3 activity at the molecular level were examined. It was found that neither of these genes inhibits the transcription of the Tam3 transposase gene nor its translation, and that the Tam3 transposase has the potential to catalyze transposition in the St and NSt lines. The differences between the effects of St and NSt imply that they regulate Tam3 activity independently. Our molecular data indicate that their influence on Tam3 transposition seems to be nonepigenetic; possible mechanisms for their activity are discussed.
Uchiyama
Takako
T
Laboratories of Plant Breeding and.
Saito
Yumiko
Y
Laboratories of Plant Breeding and.
Kuwabara
Hiroyuki
H
Laboratories of Plant Breeding and.
Fujino
Kaien
K
Laboratories of Crop Physiology, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
Kishima
Yuji
Y
Laboratories of Plant Breeding and.
Martin
Cathie
C
Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich, Norfolk NR4 7UH, UK.
Sano
Yoshio
Y
Laboratories of Plant Breeding and.
D032161:Antirrhinum / Q000235:genetics* / Q000502:physiology*; D018548:Cotyledon / Q000502:physiology; D004251:DNA Transposable Elements / Q000502:physiology*; D044127:Epigenesis, Genetic; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D017343:Genes, Plant / Q000502:physiology; D018546:Hypocotyl / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis
D004251:DNA Transposable Elements; D010940:Plant Proteins