Profiling of Lactuca sativa L. Small RNAs

microRNAs (miRNAs) are small non-coding RNAs and play significant regulatory roles in all stages of organism development. Most recently, several studies made the discovery that some plant-derived miRNAs can accumulate in the serum of humans or plant-feeding animals to regulate mammalian or influenza viruses gene expression. These findings raise the speculation that microRNAs provide cross-kingdom regulation. To better understand the potential impact that plants may have on animal physiology at the molecular level, the miRNA profiling of lettuce (Lactuca sativa L), a widely cultivated and favorite vegetable throughout the world, was examined using solexa deep sequencing method. A total of 8 705 454 reads representing 3 479 305 unique sequences from lettuce small RNA pool was obtained. Based on the sequence similarity and the presence of stem-loop secondary structure, 678 765 reads of sequences match to the 22 known miRNA families annotated in miRBase. Besides, 388 lettuce novel miRNAs candidates were first identified. The potential mammalian target genes of the most abundant or novel miRNAs of lettuce were predicted, especially to humans. The further experiments will conduct to assess our prediction. Our works not only contribute the ever-increasing miRNAs database but also supply us a better understand of plant miRNAs to human health.