Low Concentration of Aluminum-Stimulated Pollen Tube Growth of Apples (Malus domestica)

Aluminum (Al) is an important element in soil constitution. Previous studies have shown that high concentration of Al affects the normal growth of crops, resulting in crop yield reduction and inferior quality. Nevertheless, Al has also been referred to as a beneficial element, especially when used at low concentrations, but the cytological mechanism is not clear. Influences of low concentration AlCl(3) on the pollen tube growth of apple (Malus domestica) and its possible cytological mechanism were investigated in this study. The results showed that 20 μM AlCl(3) promoted pollen germination and tube elongation; 20 μM AlCl(3) enhanced Ca(2+) influx but did not affect [Ca(2+)]c of the pollen tube tip; and 20 μM AlCl(3) decreased acid pectins in pollen tubes but increased esterified pectins and arabinan pectins in pollen tubes. According to the information provided in this research, 20 μM AlCl(3) stimulated growth of pollen tubes by enhancing Ca(2+) influx and changing cell wall components.