The role of Ca and Ca channels in the gametophytic self-incompatibility of Pyrus pyrifolia.

In S-RNase-based self-incompatibility, S-RNase was previously thought to function as a selective RNase that inhibits pollen whose S-haplotype matches that in the pistil. In this study, we showed that S-RNase has a distinct effect on the regulation of Ca-permeable channel activity in the apical pollen tube in Pyrus pyrifolia. While non-self S-RNase has no effect, self S-RNase decreases the activity of Ca channels and disrupts the Ca gradient at the tip of the growing pollen tube during the gametophytic self-incompatibility (GSI) response.

Reciprocal regulation of Ca²+-activated outward K+ channels of Pyrus pyrifolia pollen by heme and carbon monoxide.

• The regulation of plant potassium (K+) channels has been extensively studied in various systems. However, the mechanism of their regulation in the pollen tube is unclear. • In this study, the effects of heme and carbon monoxide (CO) on the outward K+ (K+(out)) channel in pear (Pyrus pyrifolia) pollen tube protoplasts were characterized using a patch-clamp technique.

Identification of hyperpolarization-activated calcium channels in apical pollen tubes of Pyrus pyrifolia.

The pollen tube has been widely used to study the mechanisms underlying polarized tip growth in plants. A steep tip-to-base gradient of free cytosolic calcium ([Ca(2+)](cyt)) is essential for pollen-tube growth. Local Ca(2+) influx mediated by Ca(2+)-permeable channels plays a key role in maintaining this [Ca(2+)](cyt) gradient.