Free Amino Acid Content of the Anthers of Male‐Sterile and Fertile Lines of Grain Sorghum, Sorghum bicolor (L.) Moench 1

Anthers of cytoplasmic‐genic, male‐sterile lines of Combine Kafir 60 and Martin grain sorghums ( Sorghum bicolor L. Moench) were analyzed for free amino acid content at two stages of microsporogenesis, and those of their counterpart fertile B‐lines and recovered restorer lines were examined at three stages. Total amino acid contents were similar for the sterile and the fertile lines at the tetrad stage, but at the free‐microspore stage, total amino acid contents were higher in the fertile lines. In three of the four comparisons among stages in the fertile lines the greatest accumulation of total amino acids occurred between the microspore and the pollen stages. Proline, tyrosine, and asparagine showed noteworthy differences in concentration between fertile (B‐ and Rlines) and male‐sterile (A) lines. As microsporogenesis proceeded, proline content rose sharply in the fertile lines but did not increase in the steriles. Tyrosine content increased in both the sterile and fertile lines, but the accumulation with advancing stages was more rapid in the fertile lines. In greenhouse plants asparagine content increased in the steriles, but decreased in the fertile lines, as microsporogenesis progressed. This trend was not manifested in field‐grown plants. Significant differences between stages and between fertile and sterile lines also were noted for other amino acids, particularly leucine, but the differences seemed either less pronounced or more inconsistent.