ABSTRACT
In both Oenothera villaricae Dietrich and O. picensis ssp. picensis, chromosomes are transmitted as two Renner complexes. Reciprocal combinations of the Renner complexes produce eight different F1 hybrids, but only seven are viable. Each species, and each F1 hybrid, produces three sizes of pollen, approximately 50% small sterile grains, 15% medium-sized viable grains and 35% large viable grains. Medium- and large-sized grains were separated manually and subjected to random amplified polymorphic DNAs (RAPDs) analysis. A pattern of RAPD amplifications was obtained which indicates that, for each species and F1 hybrid, one specific Renner complex characterizes the medium- and another the large-sized viable pollen. The results indicate that pollen size is determined in part by the pollen genotype and in part by the genotype of the other pollen grains developing within the same anther.
ABSTRACT
The present study demonstrates that rhodamine 123 penetrates the callose walls surrounding plant microspores before they are released from tetrads. The stain accumulates in active mitochondria due to the electrical potential across the mitochondrial membrane. Accumulation of dye does not occur in mitochondria of fixed cells and fades quickly when mitochondrial activity is inhibited by exposure to carbonyl cyanide m-chlorophenyl hydrazone. Rhodamine can be used as a viability test for microspores still within tetrads, thus making it possible to determine when during development genes leading to pollen sterility are expressed. Rhodamine 123 is excited by blue (550 nm) light and can thus be used with confocal laser scanning microscopy. Anthers of Nicotiana tabacum, Oenothera villaricae, Silene dioica and Lycopersicum esculentum were studied here.
