The effect of temperature, polyamines and polyamine synthesis inhibitor on in vitro pollen germination and pollen tube growth of Prunus mume

Abstract

The effect of temperature (10, 25 or 35 °C), polyamines (Put, Spd, Spm) and polyamine (PA) synthesis inhibitor (MGBG) on in vitro pollen germination and pollen tube growth was investigated in Prunus mume cv. ‘Zaohua’. When pollen was incubated in a liquid medium for 24 h in darkness, distinct differences were observed in pollen germination and pollen tube growth among the temperatures. Similarly, differences were found among PAs, PA concentrations, and between the PAs and PA synthesis inhibitor MGBG. At 10 °C, Spd significantly stimulated pollen germination over the control except for Spd 0.5–2.5 mmol/l. At 25 °C, Put stimulated all pollen germination, but for the other two PAs, only Spd 0.01–0.05 mmol/l and Spm 0.025 mmol/l had stimulating effects on pollen germination. While at 35 °C, except for Put 0.25 mmol/l, Spd 0.025–0.25 mmol/l and Spm 0.025 mmol/l, the inhibitory of PAs on pollen germination was becoming stronger with the increasing concentrations. There were some differences between the percentage of pollen germination and pollen tube growth at different temperatures and different concentrations of PAs. When the concentration of Put and Spd was at 0.05 mmol/l, Spm at 0.005 and 0.025 mmol/l pollen tube was longer than that of the control at 10 °C, while when the concentrations became higher they would inhibit pollen tube growth. At 25 °C, except for Put 0.25 mmol/l, Spm 0.005 mmol/l slightly stimulated pollen tube growth, most of the treatments had inhibitory effect on pollen tube growth but for Spd from 0.01 to 0.25 mmol/l, pollen tube growth was stimulated and then dropped rapidly at 0.5 and 2.5 mmol/l. At higher temperature (35 °C) except for Put at 0.25 mmol/l all the PAs tested had inhibitory effect on pollen tube growth. Pollen germination and pollen tube growth were inhibited by MGBG at all temperatures and in all concentrations.