ANATOMY OF SPOROSORI OF POLYMYXA-GRAMINIS, THE VECTOR OF INDIAN PEANUT CLUMP VIRUS, IN ROOTS OF SORGHUM-BICOLOR

Anatomical studies of Polymyxa graminis, the vector of West African an d Indian peanut clump virus (IPCV), have been limited. Light, laser co nfocal, and in situ scanning electron microscopy were used to study ma ture or nearly mature sporosori of the vector in roots of Sorghum bico lor. Large numbers of sporosori occurred in host tissue, including the epidermis, cortical parenchyma, and endodermis, sometimes almost fill ing host cells. In cross-sections of sporosori, 10-40 individual, clos ely aggregated resting spores were typically observed. In three-dimens ions, sporosori frequently appeared to contain up to several hundred r esting spores. Resting spores appeared to form by cleavage of sporogen ic plasmodia; mature resting spores were approximately 4-7 mu m in dia meter. Resting spores became more spherical as they matured, and angul ar spaces developed in the interstices between many of the resting spo res within sporosori. The amount of apparent space between resting spo res within sporosori appeared different when examined by laser confoca l compared to in situ scanning electron microscopy.