Glutathione synthesis is essential for pollen germination in vitro

The depletion of glutathione by buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, reduced pollen germination rates to 2-5% compared to 71% germination in wildtype controls. The application of reduced glutathione (GSH), together with BSO, restored pollen germination and glutathione contents to control values, demonstrating that inhibition of glutathione synthesis is responsible for the decrease of pollen germination in vitro. The addition of indole-3-acetic acid (IAA) to media containing BSO restored pollen germination to control values, which demonstrated that glutathione depletion in pollen grains triggered disturbances in auxin metabolism which led to inhibition of pollen germination.This study demonstrates that glutathione synthesis is essential for pollen germination in vitro and that glutathione depletion and auxin metabolism are linked in pollen germination and early elongation of the pollen tube, as IAA addition rescues glutathione deficient pollen.Glutathione is an important antioxidant and redox buffer in eukaryotes and most prokaryotes that fulfills many roles in plant metabolism and plant defense during abiotic and biotic stress conditions in the sporophyte [1], but its role remains largely unknown for the gametophyte. In the sporophyte, glutathione is involved in the detoxification of reactive oxygen species (ROS), redox signaling, the modulation of gene expression and in the regulation of enzymatic activities [extensively reviewed by 1]. Glutathione is also involved in the detoxification of xenobiotics, herbicides [2,3] heavy metals such as cadmium [4-8], and protects proteins from oxidation by a process called glutathionylation [9-11]. The importance of glutathione for plant growth and development is highlighted by the observation that impaired glutathione synthesis correlates with growth defects [12,13], and that the complete absence of glutathione synthesis results in a lethal phenotype [14]. Additionally, the redox state of glutat