INTRODUCTION MicroRNAs (miRNAs) are a group of small, noncoding endogenous RNA (21-25 nucleotides long) with an important role in gene expression regulation by targeting specific mRNAs in plants, animals and humans. To date, no miRNAs from marigold (Calendula officinalis), one of the best known medicinal plants, have been identified. OBJECTIVES AND BACKGROUND Identification of plant microRNAs that survive the passage through the gastrointestinal tract following digestion in mice MATERIALS AND METHODS - Small plant RNA isolation and extraction -Sequencing data analysis and plant miRNA identification -Animal experiment RESULTS The cDNA libraries of two tissues from Calendula (petals and inflorescence) were prepared and small RNAseq were conducted according to Illumina's protocols. A total number of 4 miRNAs, with 0 mismatches, (mir166a, lus-mir166e, ppt-mir894 and ath-mir8175), were identified based on their sequence complementarities. CONCLUSIONS The potentially conserved miRNAs from Calendula were identifiend only in inflorescence, the part that is being used for medicinal purposes. These aspects could lead to a better comprehension of the relationship between exogenous plant genetic material and the changes that occur in mammals following oral ingestion. REFERENCES 1.Wen J-Z, Liao J-Y, Zheng L-L, Xu H, Yang J-H et al. A Contig- Based Strategy for the Genome-Wide Discovery of MicroRNAs without Complete Genome Resources. PLoS ONE. 2014;9: e88179. 2.Liang GF, Zhu YL, Sun B, Shao Y, Jing A, Wang J et al. Assessing the survival of exogenous plant microRNA in mice. Food Sci Nutr. 2014. 3.Zhang L, Hou D, Chen x, et al. Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of cross-kingdom regulation by microRNA. Cell Research. 2012; 22:107-126.