PI4Kα1 loss-of-function leads to pollen lethality. A, Scanning electron microscope micrograph of pollen grains from Col-0, self-fertilized pi4kα1-1 heterozygous plants, self-fertilized pi4kα1-2 heterozygous plants, and self-fertilized pi4kα1-1 homozygous plants expressing PI4Kα1pro:PI4Kα1-3′-UTR (insertion no. 18). Shriveled pollen grains are pseudocolored in yellow and normal pollen grains are pseudocolored in blue. Close-up is shown for pi4kα1-1 pollen on the right. Scale bar: 50 µm. B, Quantification of the percentage of normal (blue) versus deformed/shriveled (yellow) pollen grains from Col-0, self-fertilized pi4kα1-1 heterozygous plants, self-fertilized pi4kα1-2 heterozygous plants, and self-fertilized pi4kα1-1 homozygous plants expressing PI4Kα1pro:PI4Kα1-3′UTR (insertion no. 18). n indicates the number of pollens counted for each genotype. Statistics used chi-square test. n.s, non-significant; ***P < 0.001. C, Observation of Col-0 and pi4kα1-1 shriveled pollen grains by transmission electron microscopy. Right parts show close-up of the region indicated on the left part. c, cytosol; PM, plasma membrane; i, intine; e, exine; PC, pollen coat.