Morphogenesis of blastospores of Nomuraea rileyi, an important entomogenous fungus.

Sabouraud-Maltose-Yeast extract liquid medium (SMY) was optimal for preparation of the blastospores of the entomopathogenic fungus Nomuraea rileyi, and the medium was used for morphogenesis study of the Nr09 strain of the fungus by incubation at 130r/min, 25℃, and illumination for 24h. The result showed that the conidia of N. rileyi produced germ tubes and developed into hyphae, with germination ratio at 42% in 24h after inoculation and 84% in 36h. Blastospores formed by the mode of constriction of hyphal terminals within 48h, and largely multiplied by successive budding of the spores, reaching the maximum in 78h.Budding patterns could be unipolar, bipolar, or multipolar. In summary, five developmental stages could be defined: (I) conidium swelling, (II) emergence of germ tubes, (III) elongation of germ tubes, (IV) initiation of blastospores, and (V) exponential growth of blastospores. Some crystals of calcium oxalate were produced by the fungus after incubation in 30h. By 84h, big vacuoles developed in the cells of 31% blastospores, suggesting the beginning of senescence. The blastospores of Nr09 prepared at exponential phase were used for transformation of an exogenous chitinase gene, Bbchit1, with a transformation frequency up to 79 transformants per μg DNA.