Identification of Clones within Four Tree Fruit Species by Pollen Exine Patterns1

Abstract

Twenty sample clones of peach ( Prunus persica [L.] Batsch) and ten clones each of nectarine ( P. persica var. nectarina [Ait.] Maxim.), European plum ( P. domestica L.), sweet cherry ( P. avium [L.] L.) and apple ( Malus domestica Borkh.) were compared by scanning electron microscope (SEM) for characteristics of their pollen exine. The 4 taxa were separated into 3 groups by pollen grain size. Exine differences distinguished apple and sweet cherry pollens, which had similar size, and separated clones within each of the species. Peach and nectarine clones varied within the same ranges of pollen size and exine characteristics. Within P. persica , two patterns of ridging and the relative frequency, depth of impression, and size of pores categorized the clones individually. Plum exine patterns were distinct from those of other tree fruits, but ridging and pore characteristics of the exine separated plum clones into distinct categories. Apple cultivars, which had the narrowest ridges, were separated by the abundance and placement of pores in the exine. Sweet cherry clones also were distinguished by exine characteristics.