ISSN:
1420-9071
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Leaves ofEuphorbia parasitised withUromyces are richer in hormones, and retain this high concentration longer, than the healthy leaves which gradually lose a part of their auxines. When treated with growth substances, the diseased pedicles become positively geotropic. This inversion may be explained by the presence of an excessive concentration of auxines due to the parasitic fungus. The same pedicles, after ultra-violet irradiation, show a negative phototropism, a phenomenon which might also be explained by the high level of hormones in the diseased plants. The question still remains: what is the exact source of these auxines? Since a biochemical study of the phenomenon, which might be undertaken by means of a pure culture of uromyces, has as yet not been atempted, it is at present only possible to suggest a hypothesis: (a) that the fungus makes the auxines from which the level of the auxines in the parasitised tissues is augmented, or (b) that the diseased plant reacts by making an excess of auxines, or (c) that the parasite, by the formation of special bodies, causes the activation of the precursors of the auxines.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02156024
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