Evaluation of Pear Pollen Germination through Colorimetric and Cytometric Analyses

This study shows that the germination rate differs based on the method by which pollen is applied to the medium. After 3 h of incubation, the germination rate in the liquid medium (52.65%) was 2.46 times higher than that in the solidified medium (21.37%). This clearly demonstrates that there is a limitation to determining the germination rate in vitro using only the pollen identified from microscopic images, as opposed to all the pollen used in the assay. Colorimetric and cytometric analysis was performed to reduce drawbacks with respect to reliability, subjectivity of counts, and analysis time in the conventional method and improve the accuracy of measurement. The Congo Red (CR) absorbance of newly elongated pollen tubes was gradually increased at pollen concentrations of 1.25 to 5.0 mg·mL-1, and its trend line was expressed by the equation y = 0.127x + 0.0255 with R2 = 0.9938. Although no formula was established for calculating the actual germination rate, the slope of the equation obtained can be interpreted as reflecting the actual germination rate. Differences in pollen distribution between the positive control (PC) and negative control (NC) groups in the Q1-LR quadrant were observed, and the high-density region in the PC group on the dot plot formed a shifted transverse distribution to the right compared to that in the NC group. Although our observations need to be confirmed using larger numbers of pollen samples, we found that the percentage changes in events in the PC groups were expressed as a linear equation (y = 21.302x + 68.972) with a high R-squared value (0.9009). Taken together, these results demonstrate that monitoring the CR absorbance of newly elongated pollen tubes and the changes in pollen distribution along the FSC and SSC parameters will help verify pollen performance. KCI Citation Count: 0