Transcriptomic analysis between self- and cross-pollinated pistils of tea plants (<italic>Camellia sinensis</italic>).

Background: Self-incompatibility (SI) is a major barrier that obstructs the breeding process in most horticultural plants including tea plants (<italic>Camellia sinensis</italic>). The aim of this study was to elucidate the molecular mechanism of SI in tea plants through a high throughput transcriptome analysis. Results: In this study, the transcriptomes of self- and cross-pollinated pistils of two tea cultivars 'Fudingdabai' and 'Yulv' were compared to elucidate the SI mechanism of tea plants. In addition, the ion components and pollen tube growth in self- and cross-pollinated pistils were investigated. Our results revealed that both cultivars had similar pollen activities and cross-pollination could promote the pollen tube growth. In tea pistils, the highest ion content was potassium (K+), followed by calcium (Ca2+), magnesium (Mg2+) and phosphorus (P5+). Ca2+ content increased after self-pollination but decreased after cross-pollination, while K+ showed reverse trend with Ca2+. A total of 990 and 3 common differentially expressed genes (DEGs) were identified in un-pollinated vs. pollinated pistils and self- vs. cross-pollinated groups after 48 h, respectively. Function annotation indicated that three genes encoding UDP-glycosyltransferase 74B1 (UGT74B1), Mitochondrial calcium uniporter protein 2 (MCU2) and G-type lectin <italic>S</italic>-receptor-like serine/threonine-protein kinase (G-type RLK) might play important roles during SI process in tea plants. Conclusion: Ca2+ and K+ are important signal for SI in tea plants, and three genes including UGT74B1, MCU2 and G-type RLK play essential roles during SI signal transduction. [ABSTRACT FROM AUTHOR]