Production of phytotoxic substances by Alternaria triticina

1979 ◽  
Vol 57 (11) ◽  
pp. 1255-1258 ◽  
Author(s):  
C. S. K. Vijaya Kumar ◽  
A. S. Rao

The culture filtrate of Alternaria triticina Prasada & Prabhu inhibited germination and root elongation of seeds of a resistant variety (HD 1982) and a susceptible variety (Kalyan Sona) of wheat. The filtrate-induced symptoms on the leaves of wheat plants were similar to those induced by the fungus. Thin-layer chromatographic analysis of the crude toxin extracted in n-butanol, acetone, and petroleum ether revealed the presence of more than one phytotoxic compound in the culture filtrate of A. triticina. The toxic principles were thermostable and nonspecific and inhibited the growth of wheat. The possible role of toxic metabolites during pathogenesis is suggested.

1983 ◽  
Vol 61 (11) ◽  
pp. 2801-2806 ◽  
Author(s):  
A. Quispel ◽  
A. J. P. Burggraaf ◽  
H. Borsje ◽  
T. Tak

A comparison is made of the lipid requirements of some Frankia strains. Root-extract lipids from alder were essential for the isolation of Frankia strains from all nodules of Alnus glutinosa, Hippophaë rhamnoides, and in one case of Myrica gale and, at least in the case of A. glutinosa, they cannot be replaced by lecithin, Tween 80, or propionate. Many strains no longer need these lipids during subsequent cultivation. Strains from the spore-negative nodules of A. glutinosa need the lipids even after prolonged cultivation on most media, though they can adapt to media with propionate but without root-extract lipids after several transfers. These adapted strains must be distinguished from occasional revertants which, moreover, have a reduced infectivity. The results of silica-gel column and thin-layer chromatographic analysis combined with alkaline hydrolysis indicate that the active factors in the root-extract lipids are special fatty acids either in free or in bound form.


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