ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
In callus cultures of Nicotiana tabacum L. cv. Burley 21 we have examined the effect of two auxin concentrations (1 and 11.5 μMα-naphthaleneacetic acid) in the culture medium on K+, putrescine and nicotine levels and activities of putrescine-biosyn-thetic enzymes l-arginine decarboxylase (EC 4.1.1.19) and l-ornithine decarboxylase (EC 4.1.1.17). The calli grown on the low-auxin medium (with optimal auxin concentration for nicotine synthesis) had significantly lower concentrations of K+ and higher concentrations of nicotine than those grown on the high-auxin medium (with a supraoptimal auxin concentration). Furthermore, in the calli grown on both culture media, there was a positive correlation between the levels of HCIO4-soluble free putrescine and nicotine, as well as a negative correlation between those of HCIO4-soluble bound putrescine and the alkaloid. The results suggest that in tobacco callus K+ uptake, the accumulation of HCIO4-soluble free putrescine and nicotine synthesis are related processes that depend upon the concentration of auxin in the culture medium; a concentration of 1 μM NAA would increase HCIO4-soluble free putrescine level to a greater degree than that of 11,5 μM NAA, and consequently lead to a higher production of the alkaloid. Although both putrescine-biosynthetic enzymes are active in our callus cultures, ornithine decarboxylase activity was considerably greater. This interpretation is supported by the enhancement of the 35.5 kDa band and 38.9 kDa band (detected by SDS-PAGE) which showed ornithine and arginine decarboxylase activity, respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.1987.tb04279.x
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