title: The Arabidopsis KINβγ Subunit of the SnRK1 Complex Regulates Pollen Hydration on the Stigma by Mediating the Level of Reactive Oxygen Species in Pollen.
abstract: Pollen-stigma interactions are essential for pollen germination. The highly regulated process of pollen germination includes pollen adhesion, hydration, and germination on the stigma. However, the internal signaling of pollen that regulates pollen-stigma interactions is poorly understood. KINβγ is a plant-specific subunit of the SNF1-related protein kinase 1 complex which plays important roles in the regulation of plant development. Here, we showed that KINβγ was a cytoplasm- and nucleus-localized protein in the vegetative cells of pollen grains in Arabidopsis. The pollen of the Arabidopsis kinβγ mutant could not germinate on stigma, although it germinated normally in vitro. Further analysis revealed the hydration of kinβγ mutant pollen on the stigma was compromised. However, adding water to the stigma promoted the germination of the mutant pollen in vivo, suggesting that the compromised hydration of the mutant pollen led to its defective germination. In kinβγ mutant pollen, the structure of the mitochondria and peroxisomes was destroyed, and their numbers were significantly reduced compared with those in the wild type. Furthermore, we found that the kinβγ mutant exhibited reduced levels of reactive oxygen species (ROS) in pollen. The addition of H2O2 in vitro partially compensated for the reduced water absorption of the mutant pollen, and reducing ROS levels in pollen by overexpressing Arabidopsis CATALASE 3 resulted in compromised hydration of pollen on the stigma. These results indicate that Arabidopsis KINβγ is critical for the regulation of ROS levels by mediating the biogenesis of mitochondria and peroxisomes in pollen, which is required for pollen-stigma interactions during pollination.
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Xin-Qi
authors.initials: XQ
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Chang Zhen
authors.initials: CZ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Dan Dan
authors.initials: DD
authors.lastname: Li
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Ting Ting
authors.initials: TT
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Xiao Na
authors.initials: XN
authors.lastname: Jia
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Xin-Ying
authors.initials: XY
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, China.
authors.forename: Xian Sheng
authors.initials: XS
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000235:genetics*; D002374:Catalase / Q000096:biosynthesis / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination / Q000235:genetics*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008928:Mitochondria / Q000235:genetics*; D050505:Mutant Proteins / Q000096:biosynthesis / Q000235:genetics; D020675:Peroxisomes / Q000235:genetics; D011058:Pollen / Q000235:genetics* / Q000254:growth & development; D054817:Pollination / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014867:Water / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002374:Catalase; D006861:Hydrogen Peroxide; D050505:Mutant Proteins; D017346:Protein Serine-Threonine Kinases; D017382:Reactive Oxygen Species; D014867:Water; C490323:CAT3 protein, Arabidopsis; C071570:SNF1-related protein kinases; C586644:KINbetagamma protein, Arabidopsis; C531469:At3g01090 protein, Arabidopsis