Pollen Surface Sculpture of Wheat, Rice, Maize and Five Sorghum Species.

Abstract

Pollen surface sculpture provides very useful information about taxonomy and evolution of plants. Pollen exine sculpture of five Sorghum species and those of wheat (Triticum aestivum L.), rice (Oryza sativa L.), and maize (Zea mays L.) were compared using a scanning electron microscope (SEM). Differences in pollen surface structure occurred at the genus level and at the species level among Sorghum species at various ploidy levels. S. bicolor (2n=20), S. halepense (2n=40), and S. purpureo-sericeum (2n=10) had similar pollen exine sculptures, whereas S. versicolor (2n=10) and S. nitidum (2n=10) had distinctly different pollen surface sculptures from that of S. bicolor. Sizes of seeds and pollen grains were correlated to some extent. Maize had the largest seed and pollen, and S. nitidum had the smallest seed and pollen. For those species in which sizes did not differ greatly, variations of pollen sizes also were negligible. Ploidy level in Sorghum genus did not seem to have a great impact on pollen sizes.