Arabidopsis ABCG28 is required for the apical accumulation of reactive oxygen species in growing pollen tubes

We found that AtABCG28 was expressed in the mature pollen grains and pollen tubes

Thanh Ha Thi Do; Hyunju Choi; Michael Palmgren; Enrico Martinoia; Jae-Ung Hwang; Youngsook Lee

2019

Scholarcy highlights

  • Tip-focused accumulation of reactive oxygen species is tightly associated with pollen tube growth and is critical for fertilization
  • In this study, we identified an ABC protein, AtABCG28, which is essential for pollen fertility
  • E–G, the Reactive oxygen species level was higher in pExp7A::enhanced yellow fluorescent protein:AtABCG28 root hairs than in wild-type root hairs. These results are consistent with our hypothesis that AtABCG28 expressed in root hair cells increases we visualized the localization of endogenous spermine and spermidine in the secretory vesicles and cell wall of the apex of growing pollen tube
  • We speculate that AtABCG28 either transports polyamine into secretory vesicles or is involved in trafficking of the secretory vesicles to the growing tip
  • Such functions of AtABCG28 could concentrate H2O2 to a high level at the pollen tube tip, where the vesicles accumulate. Such compartmentation of polyamines would protect the cytosol from polyamine toxicity and guide polyamines to the pollen tube tip
  • When vesicles fuse to the tip, polyamines are likely to be released into the apoplast, where they are deposited into the cell wall as stable components
  • The cysteine residues may undergo reversible thiol oxidation in response to changes in the oxidation status in the lumen of secretory vesicles or the apoplast, likely linking the activity of the AtABCG28 transporter to the control of cellular redox status required for pollen tube growth

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