Fig. 1. Expression of CAF1 components in pollen. (A) RT-PCR was performed from RNAs extracted from mature Arabidopsis thaliana pollen grains and shows expression of MSI1, FAS1 and FAS2. (B-D) Wild-type pollen development. Nuclei are stained with DAPI. The uni-nucleate microspore (B) undergoes an asymmetrical mitosis, leading to the bicellular stage (C). At that stage the pollen grain contains a large vegetative cell and a small generative cell with a nucleus showing relatively higher chromatin compaction. (D) The generative cell divides, giving rise to two sperm cells with highly condensed chromatin. (E-G) Expression pattern of promMSI1-MSI1-mRFP1 in pollen in microspore (E), and developing pollen at bicellular stage (F) and tricellular stage (G). Confocal sections. Scale bars: 10 µm. G, generative cell; S, sperm cell; V, vegetative cell.