Growth factors and nitrogen sources of Piricularia oryzae Cavara.
1953 Volume 17 Issue 1 Pages 9-15
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1953 Volume 17 Issue 1 Pages 9-15
Recently it has been shown that some plant pathogenic fungi require growth factors for their normal development. The present paper describes experimental studies about the growth factors and nitrogen sources of Piricularia oryzae Cav. (rice blast disease fungus).
From the cultural experiment on synthesized media, it is shown that biotin is the essential and indispensable growth factor.
While vitamin B1 is a complemental factor for this fungus growth.
Optimum concentration of biotin for this fungus lies in the range of 2.3mγ/ml-3.0mγ/ml.
While, as above mentioned, biotin and vitamin B1 are essential growth factors of the present fungus, the biotin is almost always detectable in slight amounts in the organic compounds, which are usually given as nutrition materials in the culture media of fungi, for example, sucrose. Therefore, the cultural studies of this fungus which were made without paying attention to the biotin should be investigated again. According to the present experiments, nitrate is good nitrogen source for Piricalaria oryzae Cav. and ammonium salts is not good, probably because the dropping of pH value which may be caused by the unequivalent absorption of ammonium ion brings about a bad condition for this fungus growth. Nitrite cannot be assimilated by this fungus. The various amino-acids and amides differ in value from each other as nitrogen source for this fungus. Glycocoll l-alanine, aspartic-acid, d-glutamic-acid and asparagine are used to better advantage than nitrate. The worth of urea, dl-valine, l-leucin, l-cystin dl-norleucine, dl-methionine, tyrosine, arginine hydrochloride, dl-ornithine hydrochloride as nitrogen source is inferior to that of nitrate and creatine, taurine and dl-α aminobutyric acid are sure to be inadequate nitrogen sources for the present fungus.
In conclusion it is sure that for this fungus some aminoacids and amides are better nitrogen source, though some inorganic nitrogenous compounds such as nitrate are also assimilated well.
