An involvement of a new zinc finger protein PbrZFP719 into pear self-incompatibility reaction.

Abstract

Key message: This study indicated that the CCHC-type zinc finger protein PbrZFP719 involves into self-incompatibility by affecting the levels of reactive oxygen species and cellulose content at the tips of pollen tubes. S-RNase-based self-incompatibility (SI) facilitates cross-pollination and prevents self-pollination, which in turn increases the costs associated with artificial pollination in fruit crops. Self S-RNase exerts its inhibitory effects on pollen tube growth by altering cell structures and components, including reactive oxygen species (ROS) level and cellulose content. Presently, only a limited number of genes have been implicated in the gametophytic SI. In this study, the CCHC-type zinc finger proteins (ZFP), PbrZFP719, was found to be more highly expressed in pollen grains and pollen tubes than other ZFPs. Experimental over-expression of PbrZFP719 via pollen magnetofection and its knockdown using antisense oligonucleotides demonstrated that PbrZFP719 positively mediates pollen tube growth in pear. Further analyses revealed that variations in PbrZFP719 expression correlate with the changes in ROS levels and cellulose content at the tips of pollen tubes. Notably, PbrZFP719 expression was reduced in pollen tubes treated with self S-RNase. These results suggest that self S-RNase can inhibit pollen tube growth by decreasing ROS levels and cellulose content through the downregulation of PbrZFP719 expression. The information provide insights into a novel mechanism by which self S-RNase inhibits pollen tube growth during SI reaction and offers a refined approach for gene over-expression in pollen tube.