Am. Droual et al., CHANGES IN THE ACCUMULATION OF CYTOSOLIC CYCLOPHILIN TRANSCRIPTS IN CULTURED PERIWINKLE CELLS FOLLOWING HORMONAL AND STRESS TREATMENTS, Journal of plant physiology, 151(2), 1997, pp. 142-150
Cyclophilins (CyPs) are a family of highly conserved proteins that cat
alyze cis-trans isomerization of peptidylprolyl bonds and also act as
chaperones. In spite of the biological importance of these enzymes, th
e regulation of the CyP genes remains poorly known. We found in periwi
nkle cell cultures that zeatin, abscisic acid, NaCl, LaCl3, high sucro
se concentration and cold stress caused an increase in the accumulatio
n of transcripts from a cytosolic CyP gene. By contrast, the expressio
n of the che CyP gene was neither heat shock-nor gibberellic acid-resp
onsive, whereas hypoxia or presence of phosphates in the medium led to
a rapid and severe decrease In the CyP messages. We also examined the
pattern of expression of the CyP gene in young periwinkle plants. CyP
transcripts accumulated in all organs studied, but in lower amounts i
n flower buds than in leaves and roots. From our data, we conclud that
: (i) CyP expression is often but not always associated with stress re
sponses; (ii) CyP transcript accumulation is independent of cell mitot
ic activity; and (iii) there is no correlation between the alkaloid bi
osynthesis and the content of CyP messages in the periwinkle cells.