CHLOROPLAST INHERITANCE IN COSMARIUM TURPINII BRÉB.

Chloroplast inheritance was studied in Cosmarium turpinii Bréb. with respect to both vegetative and zygotic transmission. Analyses were carried out on (1) reciprocal haploid x diploid crosses with respect to the number and size of the zygotic chloroplasts, (2) differential survival of chloroplasts in hypnospores of different mating type strains, and (3) the position of the chloroplasts in diploid zygotes. Morphological evidence indicates that the chloroplasts in the mature zygote are derived from the (+) mating type gamete with an infrequent contribution from the (–) mating type gamete. Additional evidence suggests that the chloroplast material of each of 2 Bones arising from the zygote is derived from the plastid material of a semicell of a gamete. Differential survival of the chloroplasts is interpreted as a result of physiological differences between cells of complementary mating types.