Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya street 35, Moscow-127276, Russia.
*Correspondence author: E-mail: kovaleva_l@mail.ru
We determined the contents of endogenous phytohormones and flavonols on in vitro germinating petunia (Petunia hybrida L.) male gametophyte and their effects on petunia pollen germination and pollen tube growth. The germination and growth of pollen tubes on the cultivation medium (containing 0.4 M sucrose and 1.6 mM H3BO3) increased the contents of IAA, ABA, gibberellins, cytokinins and flavonols (quercetin and kaempferol). The qualitative effects of exogenous compounds depended on their nature and concentration. All test compounds were most stimulatory at 10−12 M concentration. The applied exogenous ABA and gibberellin A3 stimulated the germination and growth of male gametophyte at all test concentrations (10−12–10−3 M). Gibberellin A3, proved most stimulatory to growth of pollen tubes. IAA stimulated the germination and growth of male gametophyte at 10−12 – 10−8 M concentrations, whereas, the inhibition was observed at 10−4 – 10−3 M concentrations. The test flavonols, stimulated both processes at 10−12–10−10 M concentrations and caused inhibition at 10−6–10−3 M concentrations. Synthetic cytokinin 6-BAP at 10−12–10−3 M concentrations inhibited both the germination and growth of pollen tubes. The 2,4-chlorphenoxy-2-methylpropionic acid (inhibitor of IAA transport) completely blocked both the processes, while the fluridone and paclobutrasol (known inhibitors of synthesis of ABA and gibberellins respectively), only inhibited the germination and growth of male gametophyte. In the presence of 2,4-chlorphenoxy-2-methylpropionic acid (inhibitor of IAA transport), exogenous ABA, gibberellin A3 and flavonols did not stimulate pollen germination.
Flavonols, germination, growth, male gametophyte, phytohormones, Petunia hybrida
