ダイズとFusarium sp.との相互反応によるPhytoalexinの生成について

I. Phytoalexinの生成に及ぼす寄主植物の条件の影響およびPhytoalexinの性質についての2, 3の実験

抄録

Phytoalexin (PA for short) has been defined by Müller (1954) as antibiotics which are the result of an interaction between the host and the parasite, and which inhibit the growth of microorganism pathogenic to plants. In the present paper the results are dealt, of a study on the rate of production of PA, as affected by host plant conditions, and activities of PA, using soybean (Gylcine max Mer.) and Fusarium sp. which causes pod blight.
Drops of spore suspension of Fusarium were mounted on the inner surface of the seed rooms of the pods at different ages, and after centrifuging, the supernatant was tested for inhibitory action on the germination of fresh spores of Fusarium. It was found that the PA diffused distinctly into the drops placed on the young, unmatured pods, while hardly or not in the drops on the mature pods.
The PA productivity of the host tissue was determined by changing daily the drops placed on given points of young pods with new spore suspension, and by measuring the inhibitory action of the diffusates on each day. It was shown that the production of PA decreased remarkably on the second day, and sank nearly to zero on the fourth day.
PA in the diffusate from the pods lost most of its inhibitory activity, when heated at 100°C for 5 minutes or diluted to 1:8.