Standardization of cytological behavior of pollens in sorghum by Image analysis

The development of iso-nuclear male sterile (A) and maintainer (B) line along with male fertile (R) lines, referred to as fertility restorers, helped in cost-effective seed production and deployment of hybrids. The pollen viability/fertility for maintenance (B-line) and restoration (R-line) remains a significant phenotyping hurdle in developing new lines. We carried out the present investigation to evaluate the pollen fertility status of Cytoplasmic Genetic Male Sterility (CGMS) based hybrids in sorghum. The experimental material consisted of 238 CGMS based hybrids developed from the crossing of individuals of (296B xIS 188551) - based Recombinant Inbred Line (RIL) population (F7:F8) with male-sterile line (296A). The experiment was conducted in the rainy and post-rainy seasons during 2016 to evaluate pollen fertility. The authors illustrated the pollen fertility status by counting pollen counts using two methods: viz., visual counting by the naked eye, and image analysis using ImageJ (NIH, USA) software. We compared results between counts recorded visually and ImageJ reads for randomly selected 50 individuals each during the rainy and post-rainy seasons. The pollen counts from ImageJ were 95% efficient in detecting sterile vs. fertile counts. These results provide a better, efficient, and quick tool for characterizing the pollen behavior and also add value to the genetics studies by accounting for the quantitative variation encoded by multiple loci.