Plant growth regulators as putative physiological markers of developmental stage in Prunus persica

Prunus persica plants of different ages and states of maturation were analysed to compare their phytohormonal status. Endogenous levels of indole-3-acetic acid (IAA), abscisic acid (ABA), and several cytokinins (Cks): zeatin (Z), zeatin riboside ([9R]Z), dihydrozeatin ((diH)Z), dihydrozeatin riboside ((diH)Z[9R]), isopentenyl adenine (iP) and isopentenyl adenosine ([9R]iP), were measured in order to determine their possible use as physiological indices of phase change and maturation. A decrease in Ck levels (Z, [9R]Z, (diH)Z, (diH)[9R]Z, and iP, [9RiP) was found from the embryonic to juvenile stage as well as a decrease in the ratio of iP-type (iP and [9R]iP)/Z-type Cks paralleling the increase in tree age. ABA levels increased during maturation in Prunus persica and the ratio of Cks/IAA decreased with tree age. From our results, we propose that the balances of Cks/IAA and iP-type/Z-type Cks are good indices of different developmental states in Prunus persica.