Rapid Iodine Staining Techniques for Identifying the Waxy Phenotype in Sorghum Grain and Waxy Genotype in Sorghum Pollen

• Published in: Crop science 2004-05, Vol.44 (3), p.764-767
• Main Authors: Pedersen, J. F., Bean, S. R., Funnell, D. L., Graybosch, R. A.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; Genotype; Genotype & phenotype; Genotypes; Grain; Identification and classification; Iodine; Phenotype; Pollen; Sorghum; Stains & staining; Varietal selection. Specialized plant breeding, plant breeding aims; Yield, quality, earliness, varia
• ISSN: 0011-183X; 1435-0653
• DOI: 10.2135/cropsci2004.7640

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 40×. 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.