Cytogenetics of Lantana Camara Cultivars Differing in Fertility

Lantana L., a member of the Verbenaceae, is a genus consisting of approximately 150 species. One of the species, L. camara, widely used in the landscape for its abundant flowering throughout summer and its drought tolerance, can invade natural areas and agricultural land through seed dispersal and outcross with the native Florida species, Lantana depressa. Development of cultivars that are either sterile or have reduced sterility would decrease invasive potential, and may also increase flowering and bloom period. Some cultivars of L. camara, such as 'Miss Huff', have been marketed as being sterile. The purpose of this study was to verify the mechanisms for male sterility of the triploid highly sterile cultivar ‘Miss Huff’ when compared to the tetraploid, fertile cultivar, ‘Red Bandana’. Meiosis and pollen formation were evaluated. Inflorescences from each cultivar were collected in sizes ranging from 1 mm to 2 cm. These were fixed in a fresh, cold methanol: acetic acid solution (3:1, v/v) and stored for at least 24 hours. Approximately 12-15 anthers were placed on each slide, stained with modified carbol fuchsin, and thoroughly macerated prior to evaluation under a microscope. Pollen in ‘Miss Huff’ was present as polyads and was variable in size, likely due to aberrant chromosome segregation at meiosis I. This finding indicates that the sterility of 'Miss Huff' is due to abnormal meiosis I as a result of either triploidy or aneuploidy.