Assessment of the viability of mature pollen grains by lifetime acidity, detected using the indicator dye neutral red

Lifetime acidity, detected by the concentration of hydrogen ions (pH), is the most important physiological indicator of cells. One approach to assess the cell lifetime acidity is to use the synthetic dye neutral red. Using the example of mature pollen grains of Oxytropis baschkirensis Knjasev, it was found that this indicator dye at a concentration of 0.01% reflects the value of their lifetime acidity, staining native cells in red color (acidic pH 6.8–6.9), non–native cells – in yellow color (alkaline pH 7.2–7.5). These data are confirmed by the identification of the viability of red-colored pollen grains by their successful germination into pollen tubes (1) under in vitro conditions on the nutrient medium optimized for sucrose concentration (5%); (2) under in planta conditions on the stigma of the pistil. The results obtained make it possible to recommend neutral red for fairly simple, fast and reliable lifetime assessment of the quality of mature pollen grains of plants growing in various environmental conditions, including extreme ones, as well as for rapid assessment of pollen quality during hybridization in genetic and breeding studies of economically valuable crops.