Identifying miRNAs and target genes associated with Allicin synthesis in Allium species

Plants in the Allium genus have a significant economic impact due to their production of important food and medicinal compounds. Despite their agricultural and pharmaceutical value, breeding programs for Allium species are lagging behind those of other major crop plants. MicroRNAs (miRNAs) are a group of small non-coding RNAs that regulate post-transcriptional gene expression. In order to identify distinct miRNAs and their target proteins involved in Allicin biosynthesis pathways under heat-stress conditions, available Allium species Expressed Sequence Tags (ESTs) and miRNA databases were extensively searched and bioinformatically analyzed. Three distinct miRNA candidates targeting seven genes in garlic were identified. The real-time RT-PCR analysis results revealed that miR5021 and miR565 regulate the Alliinase and Heat shock protein 70 (HSP70) genes under cold stress (4°C), while miR5184 regulates the same genes at elevated temperatures (37 and 45°C). Based on the High-Performance Liquid Chromatography (HPLC) results, the expression of the Alliinase gene was found to be higher in both stem and leaf tissues compared to the expression of miR5021 under cold stress conditions. This indicates the potential involvement of miR5021 in the biosynthetic pathway of Allicin production. Furthermore, the results of the elevated heat-stress treatment showed that the expression of the HSP70 gene under thermal stress conditions at 37°C in both stem and leaf tissue was significantly increased compared to the expression of miR5658 and miR5184 at 45°C. However the expression of the HSP70 gene in the stem tissue was significantly decreased compared to the expression of miR5658 and miR5184 genes. This experimental study aims to identify miRNAs associated with the allicin production pathway in two tissues of garlic: leaves and cloves. Among the main findings of this research, we can mention the identification of 3 miRNAs that are likely to play a role in the allicin synthesis pathway. The results of this study suggest that environmental factors may affect the biosynthesis of allicin in plants of the Allium family.