Density-dependent pollen germination and tube growth in vitro is a well-documented phenomenon, termed the pollen population effect, but far less is known about its molecular basis. We present evidence to support phytosulfokine-α [Y(SO3H)IY(SO3H)TQ; PSK-α] as a native bioactive factor contributing to this effect. Mature pollen grains of Nicotiana tabacum L. var.macrophylla were incubated in liquid medium for 2 h. Pollen germination frequency increased in a density-dependent manner from 625 to 46,000 grains/ml. Conditioned medium, obtained from the medium of pollen cultured at a density of 10,000 pollen grains/ml for 12 h, promoted the germination of pollen cultured at a low density (625 grains/ml). A rabbit antiserum against PSK-α specifically inhibited the promotive effect of conditioned medium. Quantification by enzyme-linked immunosorbent assay showed that the conditioned medium contained 0.4 nM of PSK-α. Exogenous PSK-α also stimulated pollen germination in the low-density culture. These results indicate that PSK-α is an important regulator involved in the pollen population effect.
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Received: 15 March 2000 / Accepted: 24 May 2000
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Chen, Y., Matsubayashi, Y. & Sakagami, Y. Peptide growth factor phytosulfokine-α contributes to the pollen population effect. Planta 211, 752–755 (2000). https://doi.org/10.1007/s004250000370
- Key words:Nicotiana (pollen germination) – Phytosulfokine-α– Sulfated peptide – Peptide growth factor – Pollen germination – Pollen population effect