Transcriptome Analysis of the Arabidopsis Papilla Cell by a Combination of Laser Microdissection and Next Generation Sequencer

In flowering plant, pollination is an important step for sexual reproduction. In Arabidopsis, pollination occurs on a surface of the stigmatic papilla cells. After pollen recognition, pollinated pollen rapidly starts hydration and germination. Pollen tube exactly penetrates into the stigmatic surface and finally fertilizes with a female gametophyte. To reveal a molecular mechanism of pollination system in the papilla cell, we conducted an accurately and comprehensive transcriptome analysis of Arabidopsis, using a laser microdissection (LM) technique and the next generation sequencer (NGS). The papilla cells of A. thaliana and A. halleri, a close relative of A. thaliana, were specifically isolated by LM, and total RNAs were extracted. After sample preparation, transcripts were sequenced using the SOLiD5500xl, and reads were mapped to the A. thaliana genome (TAIR10), as a reference genome sequence. Bioinformatics analysis was performed with various databases for their data mining. 65 million to 180 million reads were obtained from the papilla cells of both species, and 25 million to 45 million reads were mapped to the A. thaliana genome. Among them, 15 million to 19 million reads were mapped to coding region. Surprisingly, 17 thousand to 19 thousand genes were estimated to be expressed in the papilla cell of both species, which correspond to approximately a half of genes in the A. thaliana genome. In addition, 80% genes were common between both species. These results indicate that many genes were expressed in the papilla cell and the majority of them were conserved within both species.