Pollen viability

One approach is to evaluate viability prior to germination. The most common test is the fluorochromatic reaction (FCR test) based in fluorescein diacetate (FDA) (Heslop-Harrison and Heslop-Harrison, 1970; Pinillos and Cuevas, 2008). This test evaluates the integrity of the plasmalemma of the pollen vegetative cell and activity of nonspecific esterases of the cytoplasm, and only viable pollen grains will fluoresce under the microscope (Fig. 6). Another commonly used viability test is Alexander staining (Alexander, 1969); viable pollen stains crimson red while aborted pollen stains green. Additional tests such as the use of tetrazolium dyes, X-Gal, isatin or Baker’s reagent can also be used (see Dafni and Firmage, 2000 for a review). However, in most viability tests not all the viable pollen grains are able to germinate, and consequently the percentage of pollen germination is usually lower than the percentage of viable pollen.

Fig. 6. Pistachio pollen stained with FDA: viable pollen grains show bright fluorescence compared to non-viable pollen grains.

1297PN revised Fig 6