The maize activator/dissociation system is functional in hexaploid wheat through successive generations

The aim of the present study was to provide useful background information and evidence of the functionality of the maize Activator/Dissociation (Ac/Ds) system in hexaploid wheat. Two transgenic parental wheat lines, one harbouring the immobilised Ac element (iAc) and the other the Ds element (pUbi[Ds-uidA]bar), were crossed. Transient GUS assays confirmed that the iAc transposase is active in hexaploid wheat. Selected F1 and F2 lines were analysed by PCR using primers specific to Ac, uidA and bar genes. The primer pair Ubi/bar-tag was used to detect excision of the Ds-uidA sequence, which occurred at a frequency of 39% in the F1 generation. Lines free of Ac and showing evidence of Ds excision were subject to Southern analysis, which indicated that at least one transposition event might have occurred in these lines. Although more evidence is required to unequivocally support the reintegration of the Ds element in the wheat genome, the evidence presented here nevertheless demonstrates the effectiveness and potential value of using this system to tag genes in wheat

Purification and characterization of an acyclic monoterpene primary alcohol:nadp+ oxidoreductase from catmint (Nepeta racemosa)

A soluble monoterpene primary alcohol:NADP+ oxidoreductase has been purified to apparent homogeneity from leaves of the catmint, Nepeta racemosa. The purified enzyme consisted of two polypeptides, with molecular masses of 42, 000 and 40, 000 Da, and contained zinc ions. A number of monoterpene alcohols (geraniol, nerol, citronellol, and their hydroxylated derivatives) were substrates, but the enzyme was inactive toward ethanol. The enzyme required NADP(H) as cofactor, with NAD(H) ineffective. Gas chromatographic and coupled mass spectrometric analysis of the reaction products showed that 10-hydroxygeraniol and 10-hydroxynerol were oxidized by the enzyme in the presence of NADP+, at both C-1 and C-10. These results are consistent with a role for this enzyme in the biosynthesis of iridoid monoterpenes

Interactions of Avocado (Persea americana) Cytochrome P-450 with Monoterpenoids

The microsomal fraction of avocado (Persea americana) mesocarp is a rich source of cytochrome P-450 active in the demethylation of xenobiotics. Cytochrome P-450 from this tissue has been purified and well characterized at the molecular level (DP O'Keefe, KJ Leto [1989] Plant Physiol 89: 1141-1149; KR Bozak, H Yu, R Sirevag, RE Christoffersen [1990] Proc Natl Acad Sci USA 87: 3904-3908). Despite this extensive characterization, the role of the enzyme in vivo was not established. Optical and electron paramagnetic resonance binding studies described here suggest that the monoterpenoids, nerol and geraniol, are substrates of avocado cytochrome P-450 (spectral dissociation constant of 7.2 and 35 micromolar, respectively). Avocado microsomes have been shown to catalyze the hydroxylation of these monoterpenoids, and both nerol and geraniol have been shown to inhibit the activity of avocado cytochrome P-450 toward the artificial substrate 7-ethoxycoumarin, with nerol a competitive inhibitor of this activity