Proline-rich Extensin-like Receptor Kinases PERK5 and PERK12 are involved in Pollen Tube Growth

Abstract

Abstract

Background Cell wall integrity plays an essential role during polarized cell growth typical of pollen tubes and root hairs. Proline-rich Extensin-like Receptor Kinases (PERK) belong to the hydroxyproline-rich glycoprotein (HRGP) superfamily of cell surface glycoproteins.

Results Here, we identified two PERKs from Arabidopsis thaliana, PERK5 and PERK12 highly expressed in mature pollen. Pollen tube growth was impaired in the single and double perk5-1 perk12-1 loss of function mutants, with a moderate impact on seed production. When the segregation of self- and reciprocal-crosses of the perk5-1, perk5-2 and perk12-1 single mutants, and reciprocal-crosses of the perk5-1 perk12-1 double mutant were carried out, a male gametophytic defect was found, indicating that perk5-1 and perk12-1 mutants carry defective pollen tubes, resulting in deficient pollen transmission. Furthermore, double perk5-1 perk12-1 mutants show excessive accumulation of pectins and cellulose at the cell wall pollen of the tube tip. In addition, an upregulation of cytoplasmic ROS levels were detected by using 2,7-dichlorofluorescein diacetate probe (H₂DCF-DA), and in agreement, similar results were obtained with HyPer, a genetically encoded YFP-based radiometric sensor, which is used to follow the production of hydrogen peroxide (H₂O₂). Single and double perk5-1 perk12-1 mutants show higher levels of cytoplasmic H₂O₂ in their pollen tube tips.

Conclusions Taken together, our results suggest that PERK5 and PERK12 are necessary for proper pollen tube growth highlighting their role on cell wall assembly and ROS homeostasis.

Competing Interest Statement

The authors have declared no competing interest.