Date of this Version
Visual classification of sorghum [Sorghum bicolor (L.) Moench] grain for the waxy phenotype is subjective and can be confounded by genetic background, maturity, environment, and experience of the classifier. Rapid iodine staining methods for identifying the waxy phenotype in sorghum grain and waxy genotypes in sorghum pollen were developed. Mature single sorghum seeds were placed in 48-well micro-plates and crushed. Water was added and the mixture heated to 95°C for 1 h to gelatinize the starch. After cooling, iodine solution was added and color scored after 10 to 60 s allowing for very high sample throughput. Sorghum pollen was analyzed for waxy genotype by mixing isolated pollen with iodine solution and viewing under a microscope at 40x. Waxy pollen was visually distinguishable from wild-type pollen using freshly collected as well as aged pollen. These methods will allow large-scale screening of both mature sorghum grains as well as sorghum pollen for waxy characteristics.