The nuclear phenomenon of Phytophthora capsici Leonian in connection with the two types of sporangial germination

Abstract

Nuclear phenomenon of the fungus, Phytophthora capsici Leonian, has been examined at the sporangial stage in two types of germination. Nuclei in sporangia, in germ-tubes, and in zoospores stained well with a modified HCl-Giemsa technique. Distinct differences with regard to the appearance of nuclei (DNA) in the germinating stage were observed. There are two groups of sporangia which differ in form and number of the nuclei. In one group, the nuclei are globate and large, varying between 3 and 28 in number. In the other group, the nuclei are more elongate and small, varying from 23 to 49 or more in number. In the former group, there is a high correlation between the number of globated and large-sized nuclei and the length of sporangia, but it is not so in the latter group.
Number of zoospores in the former group sporangium ranges from 8 to 28. When zoospores are released from sporangium, they are still uninucleate. These may result in indirect germination. In the other group of sporangia, however, zoospores retain polynuclear condition for a long time, and this seems to cause direct germination. The occurrence of these large and small nuclear types is in a proportion of 83.9:16.2.
These facts are in accord with the data given by numerous studies relating an appearance of the two types of sporangial germination. The two types of sporangial germination proved the inherent nature of their occurrence having for their rates 83.9 and 16.1 for indirect and direct germination of sporangium, respectively.